Final

Question 1

Who discovered x-rays and when?

Answer 1

Wilhelm Conrad Roentgen on November 8, 1895

Question 2

X-rays are a form of what kind of radiation?

Answer 2

Electromagnetic/ionizing

Question 3

Radiation that produces positively and negatively charged particles (ions) when passing through matter; the production of these ions is the event that may cause injury to normal biologic tissue
If electromagnetic radiation is of high enough frequency, it can transfer sufficient energy to some orbital electrons to remove them from the atoms to which they were attached; foundation of the interactions of x-rays with human tissue
Conversion of atoms to ions; makes tissues valuable for creating images but has the undesirable result of potentially producing some damage in the biologic material
Adding or losing an electron X-rays knock electrons out of orbit and change things on a cellular level that can hurt us or offspring

Answer 3

Ionization

Question 4

6 consequences of ionization in human cells

Answer 4

Creation of unstable atoms
Production of free electrons (Compton scatter produces recoil electrons)
Production of low energy x-ray photons
Creation of reactive free radicals capable of producing substances poisonous to the living cell
Creation of new biologic molecules detrimental to the living cell
Injury to the cell that may manifest itself as abnormal function or loss of function

Question 5

The degree to which the diagnostic study accurately reveals the presence or absence of disease in the patient
Maximized when essential images are produced under recommended radiation protection guidelines
Provides the basis for determining whether an imaging procedure or practice is justified

Answer 5

Diagnostic efficacy

Question 6

<p><p><p><p>Who carries the responsibility for determining the medical necessity of a procedure for the patient?</p></p></p></p>

Answer 6

<p><p><p><p>The referring physician accepts basic responsibility for protecting the patient from radiation exposure that is not useful and relies on qualified imaging personnel who accept a portion of the responsibility for the patient's welfare by providing the high-quality imaging services</p></p></p></p>

Question 7

<p><p><p><p>The intention behind these concepts of radiologic practice is to keep radiation exposure and consequent dose to the lowest possible level</p>

<p>Because no dose limits have been established for the amount of radiation that patients may receive for individual imaging procedures, this philosophy should be established and maintained and must show that we have considered reasonable actions that will reduce doses to patients and personnel below required limits</p>

<p>Radiation-induced cancer does not have a fixed threshold (a dose level below which individuals would have no chance of developing this disease); therefore, because it appears that no safe dose levels exist for radiation-induced malignant disease, radiation exposure should be kept low for all medical imaging procedures and this should serve as a guide to radiographers and radiologists for the selection of technical exposure factors</p>
</p></p></p>

Answer 7

<p><p><p><p>As low as reasonably achievable (ALARA)</p>

<p>Optimization for radiation protection (ORP)</p>
</p></p></p>

Question 8

<p><p><p><p>3 basic principles/cardinal rules of radiation protection</p>
</p></p></p>

Answer 8

<p><p><p><ol>
	<li>Time</li>
	<li>Distance</li>
	<li>Shielding</li>
</ol>
</p></p></p>

Question 9

<p><p><p><p>3 things the Radiation Safety Officer (RSO) is expressly charged by the hospital administration to be directly responsible for in the ALARA program</p>
</p></p></p>

Answer 9

<p><p><p><ol>
	<li>Execution</li>
	<li>Enforcement</li>
	<li>Maintenance</li>
</ol>
</p></p></p>

Question 10

<p><p><p><p>The probability of injury, ailment, or death resulting from an activity</p></p></p></p>

Answer 10

<p><p><p><p>Risk (general)</p></p></p></p>

Question 11

<p><p><p><p>The possibility of inducing a radiogenic cancer or genetic defect after irradiation</p></p></p></p>

Answer 11

<p><p><p><p>Risk (medical with reference to the radiation sciences)</p></p></p></p>

Question 12

<p><p><p><p>A method that can be used to improve understanding and reduce fear and anxiety for the patient that compares the amount of radiation received over a given period of time based on an annual US population exposure of approximately 3 millisieverts per year</p></p></p></p>

Answer 12

<p><p><p><p>Background equivalent radiation time (BERT)</p></p></p></p>

Question 13

<p><p><p><p>A subunit of the sievert (Sv) equal to 1/1000 of a sievert</p></p></p></p>

Answer 13

<p><p><p><p>Millisievert (mSv)</p></p></p></p>

Question 14

<p><p><p><p>International System of Units (SI) unit of measure for the radiation quantity "equivalent dose"</p></p></p></p>

Answer 14

<p><p><p><p>Sievert (Sv)</p></p></p></p>

Question 15

<p><p><p><p>A two phase radiation dose awareness and dose reduction program for patients through the process of education for these individuals, for the community, for health care workers employed in the medical imaging profession, and for physicians</p></p></p></p>

Answer 15

<p><p><p><p>Tools for Radiation Awareness and Community Education (TRACE) Program</p></p></p></p>

Question 16

<p><p><p><p>2 phases of the TRACE program</p>

| </p></p></p>

Answer 16

<p><p><p><ol>
	<li>Formulating new policies and procedures to promote radiation safety and the implementation of patient and community education</li>
	<li>Technological enhancements</li>
</ol>
</p></p></p>

Question 17

<p><p><p><p>4 main components (technologic enhancements) of the TRACE program</p>
</p></p></p>

Answer 17

<p><p><p><ol>
<li>Embedded software capable of recording and reporting dose</li>
<li>Timely notification of the patient and the referring physician when the radiation dose is greater than 3 Gy</li>
<li>The substantial lowering of computed tomography (CT) doses</li>
<li>Alterations to existing protocols</li>
</ol>
</p></p></p>

Question 18

<p><p><p><p>2 sources of radiation (both contribute a percentage of the total amount of radiation that humans receive during their lifetime)</p>
</p></p></p>

Answer 18

<p><p><p><ol>
	<li>Natural</li>
	<li>Manmade</li>
</ol>
</p></p></p>

Question 19

<p><p><p><p>Radiation that is always present in the environment</p></p></p></p>

Answer 19

<p><p><p><p>Natural</p></p></p></p>

Question 20

<p><p><p><p>Radiation created by humans for specific purposes</p></p></p></p>

Answer 20

<p><p><p><p>Manmade</p></p></p></p>

Question 21

<p><p><p><p>The ability to do work- that is, to move an object against resistance</p></p></p></p>

Answer 21

<p><p><p><p>Energy</p></p></p></p>

Question 22

<p><p><p><p>Kinetic energy that passes from one location to another and can have many manifestations (many types of this exist)</p></p></p></p>

Answer 22

<p><p><p><p>Radiation</p></p></p></p>

Question 23

<p><p><p><p>The full range of frequencies and wavelengths of electromagnetic waves</p>

<p>Each frequency within this has a characteristic wavelength and energy Higher frequencies are associated with shorter wavelengths and higher energies; therefore, as the wavelength ranges from largest to smallest, frequencies and energy cover the corresponding smallest to largest ranges</p>
</p></p></p>

Answer 23

<p><p><p><p>Electromagnetic spectrum</p>

| </p></p></p>

Question 24

<p><p><p><p>The number of crests of a wave that move past a given point in a given unit of time; hertz (Hz), cycles per second</p></p></p></p>

Answer 24

<p><p><p><p>Frequency</p></p></p></p>

Question 25

The distance between successive crests of a wave (meters)

Answer 25

Wavelength

Question 26

A unit of energy equal to the quantity of kinetic energy an electron acquires as it moves through a potential difference of 1 volt

Answer 26

Electron volts (eV)

Question 27

This form of radiation can travel through space in the form of a wave but can interact with matter as a particle of energy

Dual nature

Photons moving in waves and interactive with matter

Answer 27

Wave-particle duality

|

Question 28

Bundles of energy

Answer 28

Photons

Question 29

7 types of electromagnetic waves (longer wavelength, lower frequency, lower energy to shorter wavelength, higher frequency, higher energy)

Answer 29

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1. Radio waves
2. Microwaves
3. Infrared
4. Visible light
5. Ultraviolet (low and high energy)
6. X-rays
7. Gamma rays

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Question 30

2 parts the electromagnetic spectrum can be divided into

Answer 30

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1. Ionizing
2. Nonionizing

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Question 31

3 forms of ionizing radiation

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Answer 31

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1. X-rays
2. Gamma rays
3. High-energy ultraviolet radiation (energy higher than10 eV)

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Question 32

5 forms of non-ionizing radiation

|

Answer 32

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1. Low-energy ultraviolet
2. Visible light
3. Infrared rays
4. Microwaves
5. Radio waves

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Question 33

The amount of energy transferred to electrons by ionizing radiation

Answer 33

Radiation dose

|

Question 34

Does not have the sufficient kinetic energy to eject electrons from the atom

Answer 34

Non-ionizing radiation

Question 35

A radiation quantity used for radiation protection purposes when a person receives exposure from various types of ionizing radiation

Attempts to specify numerically the differences in transferred energy and therefore biologic harm produced by different types of radiation

Enables the calculation of effective dose (EfD)

SI unit: Sievert

Correlates the absorbed dose in biologic tissue with the type of energy of the radiation to which the human has been subjected (x-rays, gamma rays, etc.), applies only to ionizing types of radiation

Answer 35

Equivalent dose (EqD)

|

Question 36

4 forms of particulate radiation

|

Answer 36

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1. Alpha particles
2. Beta particles
3. Neutrons
4. Protons

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Question 37

Subatomic particles that are ejected from atoms at very high speeds

They possess sufficient kinetic energy to be capable of causing ionization by direct atomic collision

No ionization occurs when the subatomic particles are at rest

Answer 37

Particulate radiation

|

Question 38

Emitted from nuclei of very heavy elements such as uranium and plutonium during the process of radioactive decay

Each contain two protons and two neutrons

Are simply helium nuclei (e.i., helium atoms minus their electrons)

Have a large mass (approximately 4 times the mass of a hydrogen atom) and a positive charge twice that of an electron

Weighting factor is 20 times higher than x-rays

Less penetrating than beta particles (fast electrons)

They lose energy quickly as they travel a short distance in biologic matter (i.e., into the superficial layers of the skin), so they are considered virtually harmless as an external source of radiation (a piece of ordinary paper can absorb them or function as a shield)

Can be very damaging as an internal source of radiation if emitted from a radioisotope deposited in the body (ex: in the lungs, they can be absorbed in the relatively radiosensitive epithelial tissue and are very damaging to that tissue)

Answer 38

Alpha particles/rays

|

Question 39

Identical to high speed electrons except for their origin (emitted from within the nucleus of radioactive atoms that relieve their instability through the process of beta decay)

8,000 times lighter than alpha particles and have only one unit of electrical charge (-1) as compared with the alpha's two units of electrical charge (+2); will not interact as strongly with their surroundings as alpha particles and are therefore capable of penetrating biologic matter to a greater depth than alpha particles with far less ionization along their paths

With a lesser probability of interaction: can penetrate matter more deeply and therefore cannot be stopped by an ordinary piece of paper like an external alpha particle

For energies less than 2 millielectron volts, either a 1-cm thick block of wood or a 1-mm thick lead shield would be sufficient for absorption

Answer 39

Beta particles

|

Question 40

Positively charged components of an atom

Have a relatively small mass that, however, exceeds the mass of an electron by a factor of 2800

Decide the type of element

Answer 40

Protons

|

Question 41

Number of the protons in the nucleus of an atom constitutes this number

Answer 41

Atomic/Z number

Question 42

The electrically neutral components of an atom and have approximately the same mass as a proton

Answer 42

Neutrons

Question 43

Two atoms that have the same number of protons but a different number of neutrons in their nuclei (same element)

Answer 43

Isotopes

Question 44

Takes into account the dose for all types of ionizing radiation (ex: alpha, beta, gamma, x-ray) to various irradiated organs or tissues in the human body (ex: skin, gonadal tissue, thyroid)

By including specific weighting factors for each of those body parts mentioned, this takes into account the chance or risk that each of those body parts will develop a radiation-induced cancer (somatic); in the case of the reproductive organs, the risk of genetic damage is considered

Because this includes all of the organ weighting factors, it represents the uniform whole-body dose that would give an equivalent biologic response or chance of cancer

Answer 44

Effective dose (EfD)

|

Question 45

Produced when ionizing radiation penetrates body tissue and ejects electrons from the atoms composing the tissues

Answer 45

Biologic damage

Question 46

Result of destructive radiation at the atomic level

Answer 46

Molecular change

Question 47

Caused by molecular changes which leads to abnormal cell function or even entire loss of cell function

If excessive cellular damage occurs, the living organism will have a significant possibility of exhibiting genetic or somatic changes such as mutations, cataracts, leukemia, etc.

Answer 47

Cellular damage

|

Question 48

Changes in the blood count that results from non-negligible exposure to ionizing radiation

Answer 48

Organic damage

Question 49

2 sources of ionizing radiation that humans are exposed to

Answer 49

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1. Natural
2. Manmade

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Question 50

Environmental sources of ionizing radiation

Answer 50

Natural (background) radiation

Question 51

3 components of natural radiation

|

Answer 51

• Terrestrial radiation (e.g., radon, thoron)
• Cosmic radiation (solar and galactic, intensity increases with altitude)
• Internal radiation from radioactive atoms (radionuclides)

Question 52

Earth gives off this terrestrial radiation; 37% of natural background radiation exposure comes from this

Largest contributor to background radiation

In homes: crawl spaces, floor drains, sump pumps, and porous cement block foundations

The Environmental Protection Agency (EPA) considers this to be the second leading cause of lung cancer in the US

Answer 52

Radon

|

Question 53

4 ways to indicate the amount of radiation received by a patient from diagnostic x-ray procedures

Answer 53

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1. Entrance skin exposures (including skin and glandular dose; greatest amount of radiation and why you don't want SOD to be small)
2. Bone marrow dose
3. Gonadal dose
4. Fetal dose in pregnant women

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Question 54

4 ways to decrease patient dose

|

Answer 54

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1. Increase distance
2. Shield
3. Beam restriction
4. High kVp, low mAs

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Question 55

2 technical factors

|

Answer 55

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1. Peak kilovoltage (kVp)
2. Milliampere-seconds (mAs)

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Question 56

Controls the quality/penetrating power of the photons in the x-ray beam, and to some degree also affects the quantity or number of photons in the x-ray beam

Highest energy level of photons in the x-ray beam, determines what kind of interaction will occur (high or low energy)

Although all photons in a diagnostic x-ray beam don't have the same energy, the most energetic photons in the beam can have no more energy than the electrons that bombard the target

Answer 56

Peak kilovoltage (kVp)

|

Question 57

Controls the quantity of radiation that is directed toward a patient during a selected x-ray exposure

Answer 57

Milliampere-seconds (mAs)

mA x s = mAs

Question 58

If an interaction occurs, electromagnetic energy is transferred from the x-rays to the atoms of the patient's biologic material

A total loss of radiation energy

Answer 58

Absorption

|

Question 59

The amount of energy absorbed per unit mass

Answer 59

Absorbed dose (D)

Question 60

3 factors affecting absorption

|

Answer 60

1. Atomic number
2. How tightly bound the atom's electrons are
3. Thickness of part (ex: femur vs finger)

Question 61

What reaction is the biggest concern for a technologist (occupational)?

Answer 61

Compton reactions produce scatter

Question 62

What is the anode (target) made of?

Answer 62

Tungsten/tungsten rhenium alloy

Question 63

2 reasons tungsten and tungsten rhenium alloy are used as target materials

Answer 63

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1. High melting points
2. High atomic numbers (tungsten [74] and rhenium [75])

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Question 64

Why does the anode (target) need to have a high melting point?

Answer 64

99% of x-ray production is heat

Question 65

Particles associate with electromagnetic radiation that have neither mass nor electric charge and travel at the speed of light

Answer 65

X-ray photons

Question 66

Built-in filtration that results from the composition of the tube and housing

Answer 66

Inherent filtration

Question 67

3 examples of inherent filtration

|

Answer 67

• The thickness of the glass envelope of the tube
• The dielectric oil that surrounds the tube
• The glass window of the housing

Question 68

Any filtration that occurs outside the tube and housing and before the image receptor

Answer 68

Added filtration

|

Question 69

3 examples of added filtration

|

Answer 69

1. A certain thickness of added aluminum in the collimator
2. The collimator device
3. The mirror is designed to reflect the collimator light to simulate the primary beam field size for positioning purpose

Question 70

Removes low-energy x-ray photons, thereby decreasing patient dose; equal to the sum of inherent and added filtration that does not include any compound or compensating filters that may be added later

The percentage of photons attenuated decreases as photon energy increases, even when filtration is increased

Answer 70

Total filtration (permanent)

|

Question 71

What is the amount of total filtration at 70 kVp?`

Answer 71

2.5 mm aluminum (Al) equivalence

Question 72

The x-ray photon beam that emerges from the x-ray tube (source) and is directed toward the image receptor before they run into anything

Answer 72

Primary radiation/photons

Question 73

For a typical diagnostic x-ray unit, the energy of the average photon in the x-ray beam is about what the energy of the most energetic photon?

Answer 73

One third, 33%

Question 74

The reduction in the number of primary photons in the x-ray beam through absorption and scatter as a beam passes through the patient in its path (matter)

Any process decreasing the intensity of the primary photon beam that was directed toward a destination

Answer 74

Attenuation

|

Question 75

A change of direction that may also involve a partial loss of radiation energy

Answer 75

Scatter

Question 76

Some primary photons will traverse the patient without interacting and reach the radiographic image receptor (IR)

Answer 76

Direct transmission

Question 77

Other primary photons can undergo Compton and/or coherent interactions and as a result may be scattered or deflected with a potential loss of energy; such photons may still traverse the patient and strike the IR

Answer 77

Indirect transmission

Question 78

2 most common methods used to limit the effects of indirectly transmitted x-ray photons

Answer 78

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1. Air gaps
2. Radiographic grids

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Question 79

Photons that pass through the patient being radiographed and reach the IR

Answer 79

Exit/image-formation photons

Question 80

5 types of interactions between x-radiation and matter

Answer 80

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1. Coherent
2. Photoelectric absorption
3. Compton scattering
4. Pair production
5. Photodisintegration

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Question 81

2 interactions important in diagnostic radiology

Answer 81

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1. Compton scattering
2. Photoelectric absorption

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Question 82

3 other names for coherent scattering

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Answer 82

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1. Classical scattering
2. Elastic scattering
3. Unmodified scattering

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Question 83

No ionization

A relatively simple process that results in no loss of energy as x-rays scatters

Occurs with low-energy photons

Because the wavelengths of both incident and scattered waves are the same, no net energy has been absorbed by the atom

Incoming and scattered photons have same energy; vibrates the atom and causes the photon to change direction with no loss of energy

The incoming low-energy x-ray photon interacts with an atom and transfers its energy by causing some or all of the electrons of the atom to vibrate momentarily

The electrons then radiate energy in the form of electromagnetic waves

These wave nondestructively combine with one another to form a scattered wave, which represents the scattered photon

Its wavelength and energy/penetrating power are the same as those as the incident photon

Generally, the emitted photon may change in direction less than 20 degrees with respect to the direction of the original photon

Answer 83

Coherent scattering (classical, elastic, or unmodified)

Question 84

2 processes of coherent scattering (classical, elastic, or unmodified)

Answer 84

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1. Thompson
2. Rayleigh

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Question 85

With what energy photons does coherent scattering (classical, elastic, or unmodified) occur?

Answer 85

Typically less than 10 keV

Question 86

The most important mode of interaction between x-ray photons and the atoms of the patient's body for producing useful images; have to have this to have a picture

Makes image more black and white and responsible for patient dose

On encountering an inner-shell electron in the K or L shells, the incoming x-ray photon surrenders all its energy to the electron and the photon ceases to exist

The atom responds by ejecting the electron from its inner shell, thus creating a vacancy in that shell

To fill the opening, an electron from an outer shell drops down to the vacated inner shell by releasing energy in the form of a characteristic photon

Then, to fill the new vacancy in the outer shell, another electron from the shell next farthest out drops down and another characteristic photon is emitted, and so on until the atom regains electrical equilibrium

Have to give off energy when moving into the inner shell in the form of x-rays; don't go very far and are absorbed

Initial electrons and low energy x-rays are absorbed

Answer 86

Photoelectric absorption

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Question 87

An electron ejected from its inner shell during photoelectric absorption

Possesses kinetic energy equal to the energy of the incident photon less the binding energy of the electron shell

May interact with other atoms thereby causing excitation or ionization, until all its kinetic energy has been spent

Usually absorbed within a few micrometers of the medium through which it travels; in the human body, this energy transfer results in increased patient dose and contributes to biologic damage of tissues

Answer 87

Photoelectron

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Question 88

An x-ray photon created by the electron transfer from one shell to another

As a result of the photoelectric interaction, a vacancy has been created in the inner shell of the target atom

For the ionized atom, this represents an unstable energy situation

The instability is alleviated by filling the vacancy in the inner shell with an electron from an outer shell, which spontaneously "falls down" into this opening

To do this, the descending electron must lose energy, that is, must pass from a less tightly bound atomic state (further from the nucleus) to a more tightly held state (closer to the nucleus)

The amount of energy loss involved is simply equal to the difference in the binding or "holding" energies associated with each electron shell

The "released" energy is carried off in the form of a photon

For a large atom such as those in lead, this energy can be in the kiloelectron volt range, whereas for the small or low atomic number atoms that are associated with the human body, the energy is on the order of 10 eV In general, ensuing vacancies in other electron shells are successively filled and associated characteristic photons are emitted until the atom achieves an electronic equilibrium

Low energy x-rays given off after a characteristic cascade

Answer 88

Characteristic photon/x-ray Fluorescent radiation

Question 89

2 by-products of photoelectric absorption

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Answer 89

1. Photoelectrons (those induced by interaction with external radiation)
2. Characteristic x-ray photons (fluorescent radiation)

Question 90

When the energy of photoelectrons and characteristic x-ray photons is locally absorbed in human tissue, both the dose to the patient and the potential for biologic damage increases, decreases or remains the same?

Answer 90

Increases

Question 91

2 things the probability of the occurrence of photoelectric absorption depends on

Answer 91

1. Energy (E) of the incident x-ray photons
2. Atomic (Z) number of the atoms comprising the irradiated object

Question 92

Used in the digital environment to replace density (film)

The quantity of ionizing radiation received by a radiologic device and used to produce a viewable image

Answer 92

Image receptor (IR) exposure

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Question 93

A monitor function that can change the lightness or darkness of the image on a display monitor; the intensity of the display monitor's light emission controlled by the radiographer

Has no affiliation with the controlling factors of density (mA and exposure time [mAs])

Not interchangeable with density

Answer 93

Brightness

|

Question 94

Sets the midpoint of the range of densities visible on the image, controls computer screen brightness

Answer 94

Window level

Question 95

Adjusting the window level, changing the brightness either to be increased or decreased throughout the entire range of densities

Answer 95

Windowing

Question 96

Increasing the window level on the displayed image (increased brightness) _______ the density on the hard copy image, whereas decreasing the window level on the monitor image (decreased brightness) _______ density on the hard copy

Answer 96

Decreases, increases

Question 97

The greater the difference in the amount of photoelectric absorption, the ________ the contrast in the radiographic image will be between adjacent structures of differing atomic numbers

Answer 97

Greater

Question 98

As absorption increases, the potential for biologic damage _______

Answer 98

Increases

Question 99

The difference between adjacent densities; one of the properties that comprise visibility of detail

Answer 99

Radiographic contrast

Question 100

The digital processing that produces changes in the range of density/brightness, which can be used to control contrast

Answer 100

Window width

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Question 101

Use of this may be needed to ensure visualization of tissues or structures that are similar in Z when mass density must be distinguished

Answer 101

Contrast media

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Question 102

Consists of solutions containing elements having a higher atomic number than surrounding soft tissue (e.g., barium or iodine based) that are either ingested or injected into the tissues or structures to be visualized

The high atomic number of the contrast media (barium = 56, iodine = 53) significantly enhances the occurrence of photoelectric interaction relative to similar adjacent structures that don't have contrast media

The inner-shell electrons of barium and iodine have a binding energy that is in the energy range of the x-ray photons that is most commonly used in general-purpose radiography (30 to 40 keV) meaning photoelectric absorption of the photons in the x-ray beam is greatly increased

Structures enhanced by this contrast appear lighter than adjacent structures that didn't receive the contrast (white)

Also leads to an increase in absorbed dose in the body structures that contain it

Answer 102

Positive contrast medium

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Question 103

Contrast mediums such as air or gas is also used for some radiologic examinations and result in areas of increased density on the completed image (black)

Answer 103

Negative contrast medium

Question 104

3 other names for Compton scattering

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Answer 104

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1. Incoherent scattering
2. Inelastic scattering
3. Modified scattering

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Question 105

What interaction is responsible for most of the scattered radiation produced during a radiographic procedure?

Answer 105

Compton (incoherent, inelastic, modified) scattering

Question 106

An incoming x-ray photon interacts with a loosely bound outer electron of an atom of the irradiated object

On encountering the electron, the incoming x-ray photon surrenders a portion of its kinetic energy to dislodge the electron from its outer-shell orbit, thereby ionizing the biologic atom

The freed electron possesses excess kinetic energy and is capable of ionizing other atoms

It loses its kinetic energy by a series of collisions with nearby atoms and finally recombines with an atom that needs another electron; this usually occurs within a few micrometers of the site of the original interaction

The incident x-ray photon that surrendered some of its kinetic energy to free the loosely bound outer-shell electron from its orbit continues on its way but in a new direction has the potential to interact with other atoms either by the process of photoelectric absorption or scattering; it may also emerge from the patient, in which case it may contribute to degradation of the radiographic image by creating an additional, unwanted exposure (radiographic fog), or in fluoroscopy, it may exposure personnel who are present in the room to scattered radiation

onizing, occurs in the body

X-ray photon has more energy going in than when it leaves the atom

Increases as kVp increases

Produces scatter, no diagnostic value

Answer 106

Compton (incoherent, inelastic, modified) scattering

Question 107

The dislodged electron resulting from Compton scattering

Answer 107

Compton scattered, secondary, or recoil electron

Question 108

The incident x-ray photon that surrendered some of its kinetic energy to free the loosely bound outer-shell electron from its orbit continues on its way but in a new direction

Answer 108

Compton scattered photon

Question 109

In diagnostic radiology, the probability of occurrence of Compton scattering relative to that of the photoelectric interaction __________ as the energy of the x-ray photon increases

Answer 109

Increases

Question 110

Who was the first person to die from x-rays?

Answer 110

Clarence Madsen Dally

Question 111

Radiation exposure received by radiation workers

Answer 111

Occupational radiation

Question 112

Biologic effects in humans caused by exposure to ionizing radiation, which appeared within minutes, hours, days, or weeks of the time of radiation exposure

Answer 112

Early deterministic somatic effects

Question 113

Biologic response whose severity varies with radiation dose; determined by the dose threshold

Answer 113

Deterministic

Question 114

2 effects of ionizing radiation that appear months or years after exposure

Answer 114

Late deterministic somatic effects | Late stochastic effects

Question 115

Nonthreshold, randomly occurring biologic effects of ionizing radiation Effects can result from relatively low radiation exposure, and can take a long time before they're demonstrated; the probability of occurrence depends on the radiation dose and type and energy of the radiation which means that some radiations are more biologically efficient for causing damage than others for a given dose Probability or frequency of the biologic response to radiation as a function of radiation dose Disease incidence increases proportionally with dose, and there is no dose threshold

Answer 115

Stochastic

Question 116

Effect of radiation that is seen in an individual and in subsequent unexposed generations

Answer 116

Genetic/heritable effects

Question 117

8 early deterministic somatic effects

Answer 117

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Nausea Fatigue Diffuse redness of the skin Loss of hair Intestinal disorders Fever Blood disorders Shedding of the outer layer of the skin

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Question 118

6 late deterministic somatic effects

Answer 118

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Cataract formation Fibrosis Organ atrophy Loss of parenchymal cells Reduced fertility Sterility

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Question 119

2 late stochastic effects

Answer 119

Cancer | Genetic (hereditary) effects

Question 120

What amount of radiation is considered completely safe?

Answer 120

No amount

Question 121

Sum of the weighted equivalent doses doses for all irradiated tissues or organs A measure of the overall risk arising from the irradiation of biologic tissue and organs that takes into consideration the exposure to the entire body based on the energy deposited in biologic tissue by ionizing radiation Incorporates both the effect of the type of radiation used and the variability in radiosensitivity of the specific organ or body part irradiated through the use of appropriate weighting factors; these factors determine the overall harm to those biologic components and the risk of developing a radiation induced cancer, or, for the reproductive organs, the risk of genetic damage Attempts to take into account the different levels of radiation effects on the parts of the body that are being irradiated to arrive at an index of overall harm to a human by beginning with EqD and then incorporating modifying or weighting factors which correspond to the relative degrees of radiosensitivity of various organs and tissues The quantity that summarizes the potential for biologic damage to a human from exposure to ionizing radiation Accounts for the risk to the entire organism brought on by irradiation of individual tissues and organs

Answer 121

Effective dose (EfD)

Question 122

2 things EfD takes into account

Answer 122

The type of radiation (e.g., x-radiation, gamma, neutron) The variable sensitivity of the tissues exposed to radiation

Question 123

Provides a common scale whereby varying degrees of biologic damage caused by equal absorbed doses of different types of ionizing radiation can be compared with the degree of biologic damage caused by the same amount of radiation

Answer 123

Sievert (Sv)

Question 124

Radiation quantity "that expresses the concentration of radiation delivered to a specific area, such as the surface of the human body" The amount of ionizing radiation that may strike an object such as the human body when in the vicinity of a radiation source Amount of radiation in air When a volume of air is irradiated with x-rays or gamma rays, the interaction that occurs between the radiation and neutral atoms in the air causes some electrons to be liberated from those air atoms as they are ionized. Consequently, the ionized air can function as a conductor and carry electricity because of the negatively charged free electrons and positively charged ions that have been created. As the intensity of x-ray exposure of the air volume increases, the number of electron-ion pairs produced also increases. Thus the amount of radiation responsible for the ionization of a well-defined volume of air may be determined by measuring the number of electron-ion pairs or charged particles in that volume of air; radiation ionization in the air A measure of ionization in air and not in other tissue

Answer 124

Exposure (X)

Question 125

The amount of energy per unit mass absorbed by an irradiated object This absorbed energy is responsible for any biologic damage resulting from exposure of the tissues to radiation; for this reason, this may be used to indicate the amount of ionizing radiation a patient receives during a diagnostic imaging procedure The deposition of energy per unit mass in the patient's body tissue from exposure to ionizing radiation As ionizing radiation passes through an object such as a human body, some of the energy of that radiation is transferred to that biologic material; it is actually absorbed by the body and stays within it Some structures in the body absorb more radiant energy than others

Answer 125

Absorbed dose (D)

Question 126

The product of the average absorbed dose in a tissue or organ in the human body and its associated radiation weighting factor (WR) chosen for the type and energy of the radiation in question A radiation quantity used for radiation purposes when a person receives exposure from various types of ionizing radiation; serves as a measure of absorbed energy resulting from ionization Attempts to take into account the potential variation in biologic harm that is produced by different kinds of radiation; both the type and energy of the radiation are considered Takes into account the weighting factor for the radiation you got (ex: x-ray = 1 versus alpha particle = 20)

Answer 126

Equivalent dose (EqD)

Question 127

Basic unit of electrical charge; represents the quantity of electrical charge flowing past a point in a circuit in 1 second when an electrical current of 1 ampere is used

Answer 127

Coulomb (C)

Question 128

SI unit of electrical current; number of flowing electrons A unit of electric current equal to a flow of one coulomb per second

Answer 128

Ampere (A)

Question 129

SI exposure unit equal to an electrical charge of 1 C produced in a kilogram of dry air by ionizing radiation Used for x-ray calibration because x-ray output intensity is measures directly with an ionization chamber; also used to calibrate radiation survey equipment

Answer 129

Coulombs per kilogram (C/kg)

Question 130

Kinetic energy released in a unit mass (kilogram) of air SI quantity that can be used to express radiation concentration transferred to a point, which may be at the surface of a patient's or radiographer's body X-ray tube output and inputs to image receptors are sometimes described in this Actually denotes a calculation of radiation intensity in air Replacing the traditional quantity, exposure Amount of radiation coming out of the tube

Answer 130

Air kerma "Kinetic energy released in material" "Kinetic energy released in matter" "Kinetic energy released per unit mass"

Question 131

What is the unit of kerma?

Answer 131

Gray (Gy)

Question 132

Kinetic energy released in a unit mass of tissue

Answer 132

Tissue kerma

Question 133

What is the unit of tissue kerma?

Answer 133

Gray (Gyt)

Question 134

The sum total of air kerma over the exposed area of the patient's surface; a measure of the amount of radiant energy that has been thrust into a portion of the patient's body surface Modern radiographic and fluoroscopic units have incorporated units have incorporated an ability to determine the entire amount of energy delivered to the patient by the x-ray beam Ability to determine the entire amount of energy delivered to the patient by the x-ray beam Ex: how much radiation goes to the 10 x 12 area you've collimated to

Answer 134

Dose area product (DAP)

Question 135

3 things the amount of energy absorbed by a structure depends on

Answer 135

Atomic number (Z) of the tissues comprising the structure The mass density of the tissue (kg/m^3) Energy of the incident photon (low-energy photons are more easily absorbed in a material such as biologic tissue than are high-energy photons)

Question 136

Absorption _______ as atomic number and mass density increase and also as photon energy decreases

Answer 136

Increases

Question 137

"Composite"/weighted average of the atomic numbers of the many chemical elements comprising the tissue

Answer 137

Effective atomic number (Zeff)

Question 138

What is the effective atomic number of bone and soft tissue?

Answer 138

Bone: 13.8 | Soft tissue: 7.4

Question 139

Bone absorbs ______ ionizing radiation than dose soft tissue in the diagnostic energy range of 23-150 kilovolts peak (kVp), because the photoelectric process for bone is the dominant mode of energy absorption within this range

Answer 139

More

Question 140

The probability of photoelectric interaction strongly depends on the atomic number of the irradiated material; the _______ the atomic number of material, the greater is the amount of energy absorbed by that material

Answer 140

Higher

Question 141

The amount of photoelectric absorption decreases and the amount of Compton scattering relative to the photoelectric interaction increases as the energy of the x-ray beam __________; the amount of Compton scattering in a material does not depend on the atomic number of the material

Answer 141

Increases

Question 142

As energy increases, the difference in the amount of absorption between any two tissues of different atomic number ____________

Answer 142

Decreases

Question 143

At all energies, mass density always has an effect on absorption; this effect is linear and ________ proportional

Answer 143

Directly

Question 144

SI unit of absorbed dose; an energy absorption of 1 Joule (J) per kilogram (kg) of matter in the irradiated object

Answer 144

Gray (Gy)

Question 145

The work done or energy expended when a force of 1 newton (N) acts on an object along a distance of 1 meter (m)

Answer 145

Joule (J)

Question 146

3 prefixes, subunits, symbols, fractions and factors

Answer 146

Centi-, c, 1/100, 10^-2 Milli-, m, 1/1000, 10^-3 Micro-, u, 1/1,000,000, 10^-6

Question 147

How do you convert grays to milligrays?

Answer 147

Number of grays (Gy) x 1000 = number of milligrays (mGy)

Question 148

The total amount of radiant energy transferred by ionizing radiation to the body during a radiation exposure Determined by the produce of the exposure value (R) and the size of the area (cm^2) that receives the total amount of radiation delivered

Answer 148

Surface integral dose (SID) | Historically known as exposure area product

Question 149

Equal absorbed doses of different types of radiation produce ________ amounts of biologic damage

Answer 149

Different

Question 150

An adjustment multiplier that has been used in the calculation of dose equivalence to specify the ability of a dose of any kind of ionizing radiation to cause biologic damage

Answer 150

Quality factor (Q)

Question 151

What is the weighting factor of x-radiation and alpha particles?

Answer 151

X-ray: 1 | Alpha: 20

Question 152

Radiation with a high LET transfers a _______ amount of energy into a small area and can therefore do more biologic damage than radiation with a low LET; as a result, a high-LET radiation has a quality factor that is ________ than the quality factor for a low-LET radiation

Answer 152

Large, greater

Question 153

Do you want a high or low LET?

Answer 153

Low

Question 154

Dimensionless factor (multiplier) used for radiation protection purposes to account for differences in biologic impact among various types of ionizing radiation Must be used to determine EqD Places risks associated with biologic effects on a common scale Type of radiation

Answer 154

Radiation weighting factor (WR)

Question 155

SI unit for EqD

Answer 155

Sievert (Sv)

Question 156

Equation for EqD

Answer 156

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EqD = absorbed dose (D) x radiation weighting factor (WR) sV = Gy x WR

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Question 157

How do you convert sieverts to millisieverts?

Answer 157

Number of millisieverts (mSv) = number of sieverts (Sv) x 1000

Question 158

2 examples of stochastic effects

Answer 158

Cancer | Genetic/hereditary abnormalities

Question 159

Equation of effective dose (EfD)

Answer 159

EfD = absorbed dose (D) x radiation weighting factor (WR) x tissue weighting factor (WT)

Question 160

Weighting factor that takes into account the relative detriment to each specific organ and tissue; a conceptual measure for the relative risk associated with irradiation of different body tissues to account for the carcinogenic sensitivity of each organ Value that denotes the percentage of the summer stochastic (cancer plus genetic) risk stemming from irradiation of tissue (T) to the all-inclusive risk, when the entire body is irradiated in a uniform fashion

Answer 160

Tissue weighting factor (WT)

Question 161

What tissue is most and least radiosensitive?

Answer 161

Most: gonads | Least: Bone surface

Question 162

Unit of EfD

Answer 162

Sieverts or millisieverts

Question 163

Surface of the patient that is toward the x-ray tube exposed to the unattenuated primary beam of x-rays Where dose to the patient is the highest

Answer 163

Entrance skin surface

Question 164

Used to describe radiation exposure of a population or group from low doses of different sources of ionizing radiation Determines as the product of the average EfD for an individual belonging to the exposed population or group and the number of persons exposed Used in radiation protection to describe internal and external dose measurements

Answer 164

Collective effective dose (ColEfD)

Question 165

The sum of effective dose equivalent from external radiation exposure and committed effective dose equivalent (CEDE) from internal radiation exposures Designed to take into account all possible sources of radiation exposure Radiation dosimetry quantity defined to monitor and control human exposure to ionizing radiation

Answer 165

Total effective equivalent dose (TEDE)

Question 166

When is exposure monitoring or personnel required?

Answer 166

Whenever radiation workers are likely to risk receiving 10% or more of the annual occupational EfD limit of 50 mSv (5 rem) in any single year as a consequence of their work related activities

Question 167

In keeping with ALARA, at what limit do most health care facilities issue dosimetry devices?

Answer 167

When personnel could receive approximately 1% of the annual occupational EfD limit in any month; approximately 0.04 mSv (4 mrem)

Question 168

5 personnel monitoring devices currently available

Answer 168

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Optically stimulated luminescence (OSL) dosimeter Extremity dosimeter (thermoluminescent dosimeter (TLD) ring) Film badge Thermoluminescent dosimeter (TLD) Pocket ionization chamber (pocket dosimeter)

```

Question 169

Where should the personnel dosimeter be placed during routine radiographic procedures when a protective apron is not being used?

Answer 169

Attached to the clothing on the front of the body at collar level

Question 170

Where should the personnel dosimeter be placed when a protective apron is worn (fluoroscopy, surgery, and special radiographic procedures)?

Answer 170

Outside the apron at collar level on the anterior surface of the body

Question 171

The unprotected head, neck, and lenses of the eye receive how many times more exposure than the protected body trunk?

Answer 171

10-20

Question 172

Where should the personnel dosimeter be placed as a second monitor when a protective apron is worn (during lengthy interventional fluoroscopy procedures [e.g., cardiac catheterization])?

Answer 172

The first/primary dosimeter is to be worn outside the protective apparel at collar level; the second should be worn beneath a wraparound-style lead apron at waist level to monitor the approximate equivalent dose to the lower body trunk

Question 173

Where should the personnel dosimeter be placed as a monitor for the embryo-fetus?

Answer 173

The primary dosimeter is to be worn at collar level; the second is worn at the abdomen

Question 174

Worn as a second monitor when performing radiographic procedures that require the hands to be near the primary x-ray beam; ring that can be used to monitor the equivalent dose to the hands Badge cover contains information such as the account number, participant's name and number, wear date, indication of hand (right or left), size, and reference number; even though these badges are worn under gloves to avoid contamination, such extremity monitors are laser-etched to ensure the retention of permanent identification The reusable element of the dosimeter is encapsulated with an engraved cover

Answer 174

Extremity dosimeter (thermoluminescent dosimeter [TLD] ring badge)

Question 175

4 types of personnel dosimeters used to measure individual exposure of the body to ionizing radiation

Answer 175

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Optically stimulated luminescence (OSL) dosimeter Film badge Thermoluminescent dosimeter (TLD) Pocket ionization chamber (pocket dosimeter)

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Question 176

What is the most common type of device used for monitoring of occupational exposure in diagnostic imaging?

Answer 176

Optically stimulated luminescence (OSL) dosimeter

Question 177

What does the OSL dosimeter contain?

Answer 177

A thin layer of aluminum oxide (Al2O3) detector

Question 178

How long can the OSL dosimeter be worn, and how long is it commonly worn?

Answer 178

It can be worn for up to 1 year; it is common practice to wear it for a period of 1-3 months

Question 179

3 materials the 3 different filters incorporated into the detector pack of the OSL dosimeter are made of respectively

Answer 179

Aluminum (Al) Tin Copper (Cu)

Question 180

3 different energy ranges of the OSL dosimeter that physically correlate with different penetration depths and therefore different effective radiation energies

Answer 180

"Deep" (most penetrating) "Eye" "Shallow" (skin)

Question 181

Which dosimeter can be worn the longest?

Answer 181

Optically stimulated luminescence (OSL) dosimeter

Question 182

Which dosimeter can read the lowest dose?

Answer 182

Optically stimulated luminescence (OSL) dosimeter

Question 183

At what degree can the OSL dosimeter provide an accurate reading?

Answer 183

1 mrem (10 uSv) for x-ray photons with energies ranging from 5 keV to greater than 40 MeV

Question 184

Serves as a basis for comparison with remaining dosimeters after they have been returned to the company for processing Supposed to be kept in a radiation-free area within an imaging facility so its optical density reading is zero

Answer 184

Control monitor

Question 185

7 advantages of the OSL dosimeter

|

Answer 185

Lightweight, durable, and easy to carry Contains an integrated, self-contained, preloaded packet Color-coded, contains graphic formats, and body location icons that provide easy identification Not affected by heat, moisture, and pressure Offers complete reanalysis Increased sensitivity, providing accurate readings as low as 10 uSv (1 mrem) for x-ray photons with energies from 5 keV-40 MeV Can be worn for longer periods of time (up to 1 year)

Question 186

3 disadvantages of the OSL dosimeter

Answer 186

Occupational radiation exposure is recorded only in the body area where the device is worn (not close to reproductive organs) Exposure cannot be determined on the day of occurrence Not an efficient monitoring device if it is not worn

Question 187

Dosimeter that records whole-body radiation exposure accumulated at a low rate over a long period of time

Answer 187

Film badges

Question 188

3 parts the film badge is composed of

Answer 188

Durable, lightweight plastic film holder Assortment of metal filters Film packet

Question 189

What are the metal filters inside the plastic holder of the film badge made of?

Answer 189

Aluminum or copper

Question 190

What dose ranges are film badges sensitive to?

Answer 190

As low as 0.1 mSv (10 mrem) to as high as 5000 mSv (500 rem); doses less than 0.1 mSv (10 mrem) are not usually detected and are reported as minimal (M) on a personnel monitoring report

Question 191

Degree of blackening

Answer 191

Density

Question 192

An instrument that measures occupational exposure by comparing optical densities of exposed film badge (dosimetry) films

Answer 192

Densitometer

Question 193

5 advantages of the film badge

Answer 193

Main: permanent legal record of personnel exposure Economical Used to record exposure to x-radiation, gamma radiation, and all but very low-energy beta radiation in a reliable manner Can discriminate among the types of radiation and the energies of these radiations Mechanical integrity

Question 194

3 disadvantages of film badges

Answer 194

Temperature and humidity extremes or wetting can cause fogging of the dosimetry film over long periods of time A radiation worker's exposure cannot be determined on the day of occurrence Can be worn for one month before being read

Question 195

How long can the film badge be worn for personnel monitoring before it is read?

Answer 195

1 month

Question 196

What is the film badge dosimeter sensitivity?

Answer 196

Most sensitive to photons having an energy level of 50 keV; for values above and below this energy range, dosimetry film sensitivity decreases

Question 197

What is the sensing material of the thermoluminescent dosimeter (TLD)?

Answer 197

Crystalline form (powder or, more frequently, small chips) of lithium fluoride (LiF)

Question 198

4 advantages of the TLD

Answer 198

The LiF crystals interact with ionizing radiation as human tissue does, hence this monitor determines dose more accurately Exposures as low as 5 mR (1.3 x 10^-6 C/kg) can be measured precisely Humidity, pressure, and normal temperature changes don't affect it After the TLD reading has been obtained, the crystals can be reused, making it somewhat cost effective

Question 199

What is the sensitivity of the TLD?

Answer 199

Exposures as low as 5 mR (1.3 x 10^-6 C/kg) can be measured precisely

Question 200

3 disadvantages of the TLD

Answer 200

High cost (twice the cost of a film badge service) Can be read only once/can't be reevaluated; the readout process destroys the stored information The calibrated dosimeters must be prepared and read with each group or batch

Question 201

What is the most sensitive type of personnel dosimeter

Answer 201

Pocket ionization chamber (pocket dosimeter)

Question 202

To what exposure range are pocket chambers used in medical imaging sensitive to?

Answer 202

0-5.2 x 10^-5 C/kg (0-200 mR)

Question 203

What is an advantage of the pocket ionization chamber?

Answer 203

Provide immediate exposure readouts

Question 204

3 disadvantages of the pocket ionization chamber

Answer 204

Fairly expensive Inaccurate readings No permanent legal record

Question 205

3 different gas-filled radiation detectors that serve as field instruments

Answer 205

Ionization chamber-type survey instrument ("cutie pie") Proportional counter Gieger-Muller (GM) detector

Question 206

Rate meter device (for exposure rate) used for area surveys and an accurate integrating or cumulative exposure instrument; it measures x-radiation and gamma radiation, and, if equipped with a suitable window, it can also record beta radiation

Answer 206

Ionization chamber survey meter (cutie pie)

Question 207

What ranges of radiation intensity can the ionization chamber survey meter (cutie pie) measure?

Answer 207

1 mR/hr-several thousand milliroentgens per hour (10-several thousand micrograys per hour)

Question 208

What is the greatest amount of radiation that can come out of the x-ray tube?

Answer 208

1 mR/hr (10 micrograys per hour)

Question 209

What is the radiation survey instrument of choice when determining exposure rates from patients?

Answer 209

Ionization chamber survey meter (cutie pie)

Question 210

3 disadvantages of the ionization chamber survey meter (cutie pie)

Answer 210

Delicate detector unit Without adequate warmup time, its meter drifts and produces an inaccurate reading Cannot be used to measure exposures produced by typical diagnostic procedures because the exposure times are too short to permit the meter to respond appropriately

Question 211

Survey instrument that serves no useful purpose in diagnostic imaging; generally used in a laboratory setting to detect alpha and beta radiation and small amounts of other types of low-level radioactive contamination Can discriminate between alpha and beta particles

Answer 211

Proportional counter

Question 212

Serves as the primary potable radiation survey instrument for area monitoring in nuclear medicine facilities Sensitive enough to detect particles or photons Audio

Answer 212

Geiger-Muller (GM) detector

Question 213

2 disadvantages of the GM detector

Answer 213

The meter reading is not independent of the energy of the incident photons meaning that photons of widely different energies cause the instrument to respond quite differently Likely to saturate or jam when placed in very high-intensity radiation area, giving a false reading

Question 214

A science that explores living things and life processes

Answer 214

Biology

Question 215

Basic units of all living matter and essential for life; fundamental component of structure, development, growth, and life processes in the human body Human body composed of trillions of these that exist in a multitude of different forms

Answer 215

Cells

Question 216

4 functions the cells perform for the body

Answer 216

Conduction of nerve impulses Contraction of muscles Support of various organs Transportation of body fluids such as blood

Question 217

Chemical building material for all living things; living contents of cell

Answer 217

Protoplasm

Question 218

3 cell chemical components

Answer 218

Protoplasm Organic compounds Inorganic compounds

Question 219

3 processes the protoplasm carries on

Answer 219

Complex process of metabolism Reception and processing of food and oxygen Elimination of waste products

Question 220

The breaking down of large molecules into smaller ones Enables the cell to perform the vital functions of synthesizing proteins and producing energy

Answer 220

Metabolism

Question 221

2 things protoplasm consists of that are either dissolved or suspended in water

Answer 221

Organic compounds | Inorganic compounds

Question 222

Those compounds that contain carbon, hydrogen, and oxygen

Answer 222

Organic compounds

Question 223

Compounds that do not contain carbon, occur in nature independent of living things

Answer 223

Inorganic compounds

Question 224

4 primary elements that comprise protoplasm

Answer 224

Carbon Hydrogen Oxygen Nitrogen

Question 225

2 elements carbon, hydrogen, oxygen and nitrogen combine with to form the essential major organic compounds

Answer 225

Phosphorus | Sulfur

Question 226

4 major classes of organic compounds that compose the cell

Answer 226

Proteins Carbohydrates Lipids Nucleic acids

Question 227

2 most important inorganic compounds

Answer 227

Water | Mineral salts/electrolytes

Question 228

8 essential functions of water

Answer 228

Acts as the medium in which acids, bases, and salts are dissolved Functions as a solvent by dissolving chemical substances in the cell Functions as a transport vehicle for material the cell uses or eliminates Maintains a constant body core temperature of 98.6 F (37 C) Provides a cushion for vital organs such as the brain and lungs Regulates concentration of dissolved substances Lubricates the digestive system Lubricates skeletal articulation (joints)

Question 229

What is the most abundant inorganic compound in the body?

Answer 229

Water

Question 230

3 ways in which mineral salts are of vital importance in sustaining cell life

Answer 230

Help produce energy Aid in the conduction of nerve impulses Responsible for the prevention of muscle cramping

Question 231

Basic constituent of all organic matter

Answer 231

Carbon

Question 232

3 elements carbon combines with to make life possible

Answer 232

Hydrogen Nitrogen Oxygen

Question 233

Most elementary building blocks of cells; formed when amino acids combine into long, chainlike molecular complexes

Answer 233

Proteins

Question 234

3 functions proteins are essential for

Answer 234

Growth Construction of new body tissue Repair of injured or debilitated tissue

Question 235

Provide the body with its shape and form and are a source of heat and energy Ex: those found in muscle

Answer 235

Structural proteins

Question 236

Function as organic catalysts Control the cell's various physiologic activities Cause an increase in cellular activity that in turn causes biochemical reactions to occur more rapidly to meet the needs of the cell; proper cell function depends on this Initiate vital chemical reactions within the cell at the appropriate time

Answer 236

Enzymatic proteins/"enzymes"

Question 237

Enzymes that can mend damages molecules and are therefore capable of helping the cell to recover from a small amount of radiation-induced damage; work effectively in both the diagnostic and therapeutic range If the radiation damage is excessive because of the delivered equivalent dose, the damage will be too severe for these enzymes to have a positive effect; ex: atomic bond

Answer 237

Repair enzymes

Question 238

Chemical secretions manufactured by various endocrine glands and carried by the bloodstream to influence the activities of other parts of the body; regulate body functions such as growth and development Ex: these produced by the thyroid gland located in the neck control metabolism throughout the body

Answer 238

Hormones

Question 239

Protein molecules produced by B lymphocytes (specialized cells in the bone marrow) Produced when other lymphocytes in the body (T lymphocytes) detect the presence of molecules that do not belong to the body Once the skin has been penetrated, this is the body's primary defense mechanism against infection and disease

Answer 239

Antibodies

Question 240

Foreign objects (ex: bacteria, flu, viruses), molecules that do not belong to the body

Answer 240

Antigens

Question 241

What is the primary energy source for the cell?

Answer 241

Glucose

Question 242

6 functions that lipids perform for the body

Answer 242

Acts as a reservoir for the long-term storage of energy Insulate and guard the body against the environment Support and protect organs such as the eyes and kidneys Provide essential substances necessary for growth and development Lubricate the joints Assist in the digestive process

Question 243

2 types of nucleic acids that are contained in cells and important to human metabolism

Answer 243

```

Deoxyribonucleic acid (DNA) Ribonucleic acid (RNA)

```

Question 244

The master chemical in the nucleus Contains all the information the cell needs to function Carries the genetic information necessary for cell replication Controls cell division Determines a persons characteristics by regulating the sequence of amino acids in the person's constituent proteins during synthesis of these proteins

Answer 244

Deoxyribonucleic acid (DNA)

Question 245

Plays an essential part in the translation of genetic information from DNA into protein products by functioning as a messenger between DNA and the ribosomes, where synthesis occurs Carrier of information because DNA is stuck in the nucleus

Answer 245

Ribonucleic acid (RNA)

Question 246

3 types of ribonucleic acid (RNA)

Answer 246

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Messenger RNA (mRNA) Transfer RNA (tRNA) Ribosomal RNA (rRNA)

```

Question 247

How many chromosomes does a normal human being have in each somatic (nonproductive) cell?

Answer 247

46 different chromosomes (23 pairs)

Question 248

How many chromosomes do the reproductive/germ cells have?

Answer 248

Reproductive/germ cells exist singly, thus each has only 23 chromosomes, which pair up to form 46 chromosomes when a sperm fertilizes an egg

Question 249

Segments of DNA that serve as the basic units of heredity Control the formation of proteins in every cell through the intricate process of genetic coding

Answer 249

Genes

Question 250

The total amount of genetic material (DNA) contained within the chromosomes of a human being

Answer 250

Human genome

Question 251

The process of locating and identifying the genes in the genome

Answer 251

Mapping

Question 252

3 inorganic compounds

Answer 252

Acids Bases Salts/electrolytes

Question 253

Hydrogen-containing compounds that can attack and dissolve metal Ex: HNO3 (nitric acid)

Answer 253

Acids

Question 254

Alkali or alkaline earth compounds that can neutralize acids Ex: Mg(OH)2 (milk of magnesia)

Answer 254

Bases

Question 255

Chemical compounds resulting from the action of an acid and a base on each other Chemically they are substances that become ions in solution and acquire the capacity to conduct electricity Present in the human body, and the balance in our bodies is essential for normal function of our cells and organs Keep the correct proportion of water in the cell

Answer 255

Salts/electrolytes

Question 256

2 most important inorganic substances

Answer 256

Water | Mineral salts

Question 257

What is the primary inorganic substance contained in the human body?

Answer 257

Water, it is imperative for the correct amount of water in a cell to be maintained

Question 258

What percentage of the body weight does water comprise?

Answer 258

80-85%

Question 259

2 functions of water within the cell

Answer 259

The medium in which the chemical reactions that are the bases of metabolic activities occur Acts as a solvent, keeping compounds dissolved so that they can more easily interact and their concentration may be regulated

Question 260

4 functions of water outside the cell

Answer 260

Functions as a transport vehicle for material the cell uses or eliminates Responsible for maintaining a constant body core temperature of 98.6 F (37 C) Protects organs such as the brain and lungs Regulates concentration of dissolved substances Lubricates the digestive system and skeletal articulations

Question 261

What is the constant body core temperature?

Answer 261

98.6 F (37 C)

Question 262

3 things mineral salts are necessary for

Answer 262

Proper cell performance Creation of energy Conduction of impulses along nerves (wouldn't know if you're touching or moving anything without it)

Question 263

2 types of cell divisions that occur in the body

Answer 263

Mitosis | Meiosis

Question 264

A parent cell divides to form two daughter cells identical to the parent cell resulting in an approximately equal distribution of all cellular material between the two daughter cells The division and last phase of the cellular life cycle Somatic cells divide Process in which the nucleus first divides, followed by the division of the cytoplasm

Answer 264

Mitosis (M)

Question 265

Special type of cell division that reduces the number of chromosomes in each daughter cell to half the number of chromosomes in the parent cell Genetic/germ cells undergo a process of reduction division of half

Answer 265

Meiosis

Question 266

Female germ cell

Answer 266

Oogonium

Question 267

Male germ cell

Answer 267

Spermatogonium

Question 268

3 main parts the cell contains

Answer 268

Cell membrane Cytoplasm Nucleus

Question 269

4 components of the normal cell

Answer 269

Cell membrane Cytoplasm Cytoplasmic organelles Nucleus

Question 270

6 cytoplasmic organelles

Answer 270

```

Endoplasmic reticulum Golgi apparatus/complex Mitochondria Lysosomes Ribosomes Centrosomes

```

Question 271

Frail, semipermeable, flexible structure encasing and surrounding the human cell Allows penetration only by certain types of substances and regulates the speed at which these substances travel within the cell; plays a primary role in the cell's transport system

Answer 271

Cell membrane

Question 272

The protoplasm that exists outside the cell's nucleus Makes up the majority of the cell and contains large amounts of all the cell's molecular components (not DNA) All cellular metabolic functions occur in this

Answer 272

Cytoplasm

Question 273

6 things the cytoplasm is composed of

Answer 273

```

Water (primary) Proteins Carbohydrates Lipids Salts Minerals

```

Question 274

4 major tasks of the cytoplasm

Answer 274

Accepts and builds up unrefined materials and assembles from these materials new substances such as carbohydrates, lipids, and proteins Catabolism Packages substances for distribution to other areas of the cell or to various sites in the body through the circulation Eliminates waste products

Question 275

Contains all the miniature cellular components that enable the cell to function in a highly organized manner; little organs of cells Together these structures perform the major functions of the cell in a systemized way DNA determines each function mRNA carries the DNA code from the nucleus into the cytoplasm

Answer 275

Cytoplasmic organelles

Question 276

4 things the cytoplasmic organelles consist of

Answer 276

Tiny tubules Vesicles Granules Fibrils

Question 277

Vast, irregular network of tubules and vesicles spreading and interconnecting in all directions throughout the cytoplasm Enables the cell to communicate with the extracellular environment and transfer food and molecules from one part of the cell to another; functions as the highway system of the cell Ex: mRNA travels from the nucleus to different locations in the cytoplasm; lipids and proteins are routed into and out of the nucleus through the tubular network

Answer 277

Endoplasmic reticulum (ER)

Question 278

Minute vesicles that extend from the nucleus to the cell membrane Consist of tubes and a tiny sac located near the nucleus; unites large carbohydrate molecules and the combines them with proteins to form glycoproteins When the cell manufactures enzymes and hormones, this concentrates, packages, and transports them through the cell membrane so that they can exit the cell, enter the bloodstream, and be carried to the areas of the body where they are required

Answer 278

Golgi apparatus/bodies/complex

Question 279

Large, double-membranous, oval or bean-shaped structure that functions as the "powerhouse" of the cell because they supply the energy for cells Contain highly organized enzymes in their inner membranes that produce this energy for cellular activity by breaking down nutrients through the process of oxidative metabolism

Answer 279

Mitochondria

Question 280

Small, pealike sacs or single-membrane spherical bodies that are great importance for digestion within the cytoplasm Contain a group of different digestive enzymes that target proteins Primary function: the breaking down of unwanted large molecules that either penetrate into the cell through microscopic channels or are drawn in by the cell membrane itself

Answer 280

Lysosomes

Question 281

Very small spherical organelles that attach to the ER "Protein factories"; their job is to manufacture (synthesize) the various proteins that cells require by using the blueprints provided by the mRNA

Answer 281

Ribosomes

Question 282

Separated from the other parts of the cell by a double-walled membrane, this forms the heart of the living cell Spherical mass of protoplasm (nucleoplasm) that contains the genetic material, DNA, and protein Controls cell division and multiplication and the biochemical reactions that occur within the cell

Answer 282

Nucleus

Question 283

A protein machine that segregates chromosomes to two daughter cells during the cell division Delicate fibers that are attached to the centrioles and extend from one side of the cell to the other across the equator of the cell

Answer 283

Mitotic spindle

Question 284

4 distinct phases of the cellular life cycle that are identifiable

Answer 284

M (mitosis phase) G1 (pre-synthesis phase) S (synthesis phase) G2 (post-DNA synthesis phase)

Question 285

4 subphases mitosis (M) can be divided into

Answer 285

Prophase Metaphase Anaphase Telophase

Question 286

3 intervals of interphase

Answer 286

G1 S G2

Question 287

The period of cell growth that occurs before actual mitosis; cells are not yet undergoing division during this phase

Answer 287

Interphase (resting)

Question 288

The earliest phase among reproductive events; the gap in the growth of the cell that occurs between mitosis and DNA synthesis A form of RNA is synthesized in the cells that are to reproduce; this RNA is needed before actual DNA synthesis can efficiently begin

Answer 288

G1 (pre-synthesis phase)

Question 289

Each DNA molecule contained within the chromosome is first copied (replicated) and then is divided into two individual sister chromatids, each containing DNA molecules Each of these identical sister chromatids is now one half of the replicated chromosome The chromatids will join together to form another chromosome by the end of this phase A chromosome consists of two copies of the DNA that is contained in each chromatid Chromosome reproduces itself and splits longitudinally, thus forming two sister chromatids attached to each other at the centromere

Answer 289

S (synthesis phase)

Question 290

Highly coiled strand; one of the two duplicated portions of DNA in a replicated chromosome that appear during cell division

Answer 290

Chromatid

Question 291

Cells manufacture certain proteins and RNA molecules need to enter and complete the next mitosis When this phase is complete, cells enter the first phase of mitosis (prophase)

Answer 291

G2 (post-DNA synthesis phase)

Question 292

The first phase of cell division The nucleus enlarges, the DNA complex (the chromatid network of threads) coils up more tightly, and the chromatids become more visible Chromosomes enlarge, and the DNA begins to take structural form The nuclear membrane disappears, the centrioles migrate to opposite side of the cell and begin to regulate the formation of the mitotic spindle

Answer 292

Prophase

Question 293

Phase when cells are most radiosensitive At the beginning of this phase, the mitotic spindle forms between the centrioles Each chromosome, which now consists of two chromatids, lines up in the center/equator of the cell attached by its centromere to the mitotic spindle and forms the equatorial plate The centromeres duplicate, and each chromatid attaches itself individually to the spindle At the end, the chromatids are strung out along the mitotic spindle

Answer 293

Metaphase

Question 294

The duplicate centromeres migrate in opposite directions along the mitotic spindle and carry the chromatids to opposite sides of the cell; the cell is now ready to begin the last phase of division

Answer 294

Anaphase

Question 295

The chromatids undergo changes in appearance by uncoiling and becoming long, loosely spiraled threads Simultaneously, the nuclear membrane forms anew, and two nuclei (one for each new daughter cell) appear The cytoplasm also divides (cytokinesis) new the equator of the cell to surround the new nucleus After this cell division completes, each daughter cell has a complete cell membrane and contains exactly the same amount of genetic material (46 chromosome) as the parent cell

Answer 295

Telophase

Question 296

Fertilized ovum (zygote) splits after fertilization and two separate offspring develop

Answer 296

Monozygotic | Identical twins

Question 297

More than one ootid is available for fertilization, and the separate ootids are fertilized by separate spermatozoa

Answer 297

Dizygotic | Fraternal twins

Question 298

More than two dizygotic twins

Answer 298

Polyzygotic siblings

Question 299

3 important concepts that help us understand the way ionizing radiation causes injury and how the effects may vary in biologic tissue

Answer 299

Linear energy transfer Relative biologic effectiveness Oxygen enhancement ratio

Question 300

The average energy deposited per unit length of track by ionizing radiation as it passes through and interacts with a medium along its path A very important factor in assessing potential tissue and organ damage from exposure to ionizing radiation

Answer 300

Linear Energy Transfer (LET)

Question 301

What is the unit of LET?

Answer 301

keV/μm

Question 302

2 radiation categories according to LET

Answer 302

Low-linear energy transfer radiation | High-linear energy transfer radiation (more damage)

Question 303

When low-LET radiation interacts with tissue it causes damage to a cell primarily through an _______ action that involves the production of molecules called __________ (bad for you)

Answer 303

Indirect, free radicals

Question 304

2 examples of low LET radiation

Answer 304

X-rays | Gamma rays

Question 305

6 examples of high LET radiation

Answer 305

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Alpha particles Beta particles Protons Ions of heavy nuclei Charged particles released from interactions between neutrons and atoms Low-energy neutrons

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Question 306

High LET = _______ RBE

Answer 306

High

Question 307

Because low-LET radiation generally causes sublethal damage to DNA, ______________ can usually reverse the damage

Answer 307

Repair enzymes

Question 308

Describes the relative capabilities of radiation with differing LETs to produce a particular biologic reaction

Answer 308

Relative biologic effectiveness (RBE)

Question 309

The ratio of the radiation dose required to cause a particular biologic response of cells or organisms in any oxygen-deprived environment to the radiation dose required to cause an identical response under normal oxygenated conditions

Answer 309

Oxygen enhancement ratio (OER)

Question 310

Oxygenated state

Answer 310

Aerobic

Question 311

Low oxygen

Answer 311

Anoxic

Question 312

When irradiated in an aerobic state, biologic tissue is more sensitive to radiation than when it's exposed to radiation under anoxic conditions

Answer 312

Oxygen effect

Question 313

In living systems, biologic damage resulting from exposure to ionizing radiation may be observed on 3 levels

Answer 313

Molecular Cellular Organic

Question 314

Any visible radiation-induced injuries of living systems at the cellular or organic level always begin with damage at this level Results in the formation of structurally changed molecules that may impair cellular functioning

Answer 314

Molecular level

Question 315

If radiation damages the germ cells, the damage may be passed on to future generations in this form

Answer 315

Genetic mutations

Question 316

2 classifications of ionizing radiation interaction on a cell

Answer 316

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Direct action (e.g., in DNA) Indirect action (e.g., in H2O)

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Question 317

Biologic damage occurs as a result of ionization of atoms on essential molecules that may potentially cause these molecules to become inactive or functionally altered

Answer 317

Direct action

Question 318

The effects produced by free radicals that are created by the interaction of radiation with water molecules Essentially all effects of irradiation in living cells result from this action

Answer 318

Indirect action

Question 319

Why do essentially all effects of irradiation in living cells result from indirect action?

Answer 319

Because the human body is composed of 80-85% water and less than 1% DNA

Question 320

Ionization of water molecules Production of free radicals, undesirable chemical reactions and biologic damage, and cell-damaging substances Organic free radical formation The final result of the interaction of radiation with water is the formation of an ion pair (H+ and OH–) and two free radicals (H* and OH*)

Answer 320

Radiolysis

Question 321

Molecule that maintains normal cell function that is believed to be present in every cell and is vital to the survival of the cell

Answer 321

Master/key molecule

Question 322

What is the master/key molecule presumed to be?

Answer 322

DNA

Question 323

4 examples of radiosensitive cells

Answer 323

Basal cells of the skin Blood cells such as lymphocytes (white blood cells) and erythrocytes (red blood cells) Intestinal crypt cells Reproductive germ cells

Question 324

3 examples of radioinsensitive cells

Answer 324

Brain cells Muscle cells Nerve cells

Question 325

As LET increases, the ability of the radiation to cause biologic effects also generally ________ until it reaches a maximal value

Answer 325

Increases

Question 326

The radiosensitivity of cells is directly proportional to their reproductive activity and inversely proportional to their degree of differentiation True for all types of cells in the human body The most pronounced radiation effects occur in cells having the least maturity and specialization or differentiation, the greatest reproductive activity, and the longest mitotic phases

Answer 326

Law of Bergoiné and Tribondeau

Question 327

Equal doses of ionizing radiation produce ________ degrees of damage in different kinds of human cells because of differences in cell radiosensitivity

Answer 327

Different

Question 328

The more mature and specialized in performing functions a cell is, the ________ sensitive it is to radiation

Answer 328

Less

Question 329

A whole-body dose of what delivered within a few days produces a measurable hematologic depression?

Answer 329

0.25 Gyt

Question 330

Precursors of red blood cells are among the most sensitive of human tissues; mature red blood cells are much less radiosensitive

Answer 330

Erythrocytes

Question 331

Signifies the whole body dose of radiation that can be lethal to 50% of the exposed population within 30 days Quantitative measurement that is fairly precise when applied to experimental animals LD 50 for humans may require more than 30 days for its full expression

Answer 331

LD 50/30

Question 332

What is the lethal dose of human beings usually given as and why?

Answer 332

LD 50/60 because a human's recovery is slower than that of laboratory animals, and death may still occur at a later time following a substantial whole-body exposure

Question 333

What is the estimated lethal whole-body dose for humans?

Answer 333

3.0-4.0 Gyt

Question 334

What is the most radiosensitive blood cells in the human body?

Answer 334

Lymphocytes

Question 335

At the dose level of what does complete blood cell recovery occur shortly after irradiation?

Answer 335

0.25 Gyt or less

Question 336

When a higher dose range of whole body radiation of what is received, the lymphocyte count decreases to zero within a few days (full recovery generally requires a period of several months after this level of exposure)?

Answer 336

0.5-1 Gyt

Question 337

Scavenger type of white blood cells that fight bacteria; if they're affected by radiation, they can't fight bacteria

Answer 337

Granulocytes

Question 338

Initiate blood clotting and prevent hemorrhage | If affected by radiation, your blood won't clot so you won't stop bleeding if you cut yourself

Answer 338

Thrombocytes/platelets

Question 339

Biologic effects of radiation that occur relatively soon after humans receive high doses of ionizing radiation Substantial evidence of the consequences of such effects comes from numerous laboratory animal studies and data from observation of some irradiated human populations Not common in diagnostic imaging Produced by a substantial dose of ionizing radiation

Answer 339

Early effects

Question 340

Ionizing radiation produces the greatest amount of biologic damage in the human body when a large dose of densely ionizing (_______-LET) radiation is delivered to a large or radiosensitive area of the body

Answer 340

High

Question 341

Biologic damage sustained by living organisms (such as humans) as a consequence of exposure to ionizing radiation

Answer 341

Somatic effects

Question 342

2 classifications of somatic effects depending upon the length of time from the moment of irradiation to the first appearance of symptoms of radiation damage

Answer 342

Early somatic effects | Late somatic effects

Question 343

Effects are directly related to the dose received; as the radiation dose increases, the severity of these effects also increases. These results have a threshold, a point at which they begin to appear and below which they are absent The amount of biologic damage depends on the actual absorbed dose of ionizing radiation Consequences include cell killing

Answer 343

Deterministic somatic effects (formerly called nonstochastic somatic effects)

Question 344

2 categories of late effects (both of these types of late radiation-induced changes are consequences of high-level radiation exposure or of low doses of radiation delivered over a long interval of time)

Answer 344

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Late deterministic somatic effects Late stochastic (probabilistic) effects

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Question 345

Depend on the time of exposure to ionizing radiation Requires a substantial dose of ionizing radiation to produce these biologic changes soon after irradiation With the exception of certain lengthy high-dose-rate procedures, diagnostic imaging examinations do not usually impose radiation doses sufficient to cause early deterministic effects High-dose effects include nausea, fatigue, erythema, epilation, blood disorders, intestinal disorders, fever, dry and moist desquamation, depressed sperm count in the male, temporary or permanent sterility in the male and female, and injury to the central nervous system (at extremely high radiation doses)

Answer 345

Early deterministic somatic effects

Question 346

A whole-body dose of what can result in many of the manifestations or organic damage occurring in succession (acute radiation syndrome- early deterministic somatic effects)?

Answer 346

6 Gyt

Question 347

Radiation sickness occurring in humans after whole-body reception of large doses of ionizing radiation delivered over a short period of time A collection of symptoms associated with high-level radiation exposure

Answer 347

Acute radiation syndrome (ARS)

Question 348

3 separate dose-related syndromes occur as part of the total-body syndrome (ARS)

Answer 348

Hematopoietic syndrome (bone marrow syndrome) Gastrointestinal syndrome Cerebrovascular syndrome

Question 349

Hematopoietic syndrome (bone marrow syndrome) occurs when people receive whole-body doses of ionizing radiation in what range that decreases the number of bone marrow stem cells?

Answer 349

1-10 Gyt

Question 350

Radiation exposure causes the number of red blood cells, white blood cells, and platelets in the circulating blood to decrease When the cells of the lymphatic system are damaged, the body loses some of its ability to combat infection Because additional bone marrow cells are destroyed, as the radiation dose escalates, the body becomes more susceptible to infections (mostly from its own intestinal bacteria) and more prone to hemorrhage; when death occurs, it’s a consequence of bone marrow destruction

Answer 350

Hematopoietic syndrome (bone marrow syndrome)

Question 351

Death may occur 6-8 weeks after irradiation in some sensitive human subjects who receive a whole-body dose exceeding what (hematopoietic syndrome [bone marrow syndrome])?

Answer 351

2 Gyt

Question 352

Gastrointestinal syndrome appears at a threshold dose of approximately what and peaks after a dose of what?

Answer 352

6 Gyt, 10 Gyt

Question 353

Without medical support to sustain life, exposed persons receiving doses of what may die 3-10 days after being exposed (gastrointestinal syndrome)?

Answer 353

6-10 Gyt

Question 354

Survival time doesn’t change with dose A few hours after the dose severe nausea, vomiting, and diarrhea persist for as long as 24 hours followed by a latent period as long as 5 days (during this time, the symptoms disappear); the manifest illness stage follows the period of false calm and the human subject experiences: severe nausea, vomiting, diarrhea and other signs and symptoms that may occur include: fever (as in hematopoietic syndrome), fatigue, loss of appetite, lethargy, anemia, leukopenia (decrease in the number of white blood cells), hemorrhage (GI tract bleeding occurs because the body loses its blood-clotting ability), infection, electrolyte imbalance, emaciation Examples of humans who died as a result: workers and firefighters at Chernobyl

Answer 354

Gastrointestinal syndrome

Question 355

What is the most radiosensitive part of the GI tract and why?

Answer 355

Small intestine because there’s a lot of absorption and cell regeneration

Question 356

Cerebrovascular syndrome results when the central nervous system cardiovascular system receive doses of what (a dose of this magnitude can cause death a few hours to 2-3 days after exposure after exposure)?

Answer 356

50 Gyt

Question 357

Eight signs and symptoms: excessive nervousness, confusion, severe nausea, vomiting, diarrhea, loss of vision, burning sensation of the skin, loss of consciousness A latent period lasting up to 12 hours follows and during this time, symptoms lessen or disappear After the latent period, the manifest illness stage occurs and during this period, the prodromal syndrome recurs with increased severity, and other symptoms appear, including: disorientation and shock, periods of agitation alternation with stupor, ataxia (confusion and lack of muscular coordination), edema in the cranial vault, loss of equilibrium, fatigue, lethargy, convulsive seizures, electrolytic imbalance, meningitis, prostration, respiratory distress, vasculitis, coma Damaged blood vessels and permeable capillaries permit fluid to leak into the brain and cause an increase in fluid content Final result of this damage is failure of the CNS and cardiovascular systems, which causes death withinn a matter of minutes Because the GI and hematopoietic systems are more radiosensitive than the CNS, they’re also severely damaged and fail to function after a dose of this magnitude (hematopoietic and GI syndrome also going on)

Answer 357

Cerebrovascular syndrome

Question 358

4 major response stages of ARS |

Answer 358

Prodromal, or initial, stage Latent period Manifest illness Recovery or death

Question 359

Stage of ARS that occurs within hours after a whole-body absorbed dose of 1 Gyt or more Characterized by nausea and vomiting Severity of these symptoms is dose related: the higher the dose, the more severe the symptoms

Answer 359

Prodromal, or initial, stage

Question 360

Stage of ARS about 1 week during which no visible symptoms occur

Answer 360

Latent period

Question 361

Stage toward the end of the 1st week of ARS | The period when signs and symptoms that affect the hematopoietic, GI, and cerebrovascular systems become visible

Answer 361

Manifest illness

Question 362

In severe high-dose cases, emaciated human beings eventually die If, after a whole-body sublethal dose such as 2-3 Gyt, exposed persons pass thru the first three stages of ARS but show less severe symptoms than those seen after superlethal doses of 6-10 Gyt, this may occur in about 3 months

Answer 362

Recovery or death

Question 363

Whole-body doses greater than what may cause the death of the entire pop in 30 days without medical support?

Answer 363

6 Gyt

Question 364

In the repair of sublethal damage, oxygenated cells, which receive more nutrients, have a _______ prospect for recovery than do hypoxic cells that consequently receive fewer nutrients

Answer 364

Better

Question 365

Shrinkage of organs and tissues

Answer 365

Atrophy

Question 366

Shedding of the outer layer of the skin (dry or moist/oozing) occurs at higher radiation doses (historical evidence)

Answer 366

Desquamation

Question 367

Moderate doses of radiation may result in temporary hair loss Large doses of radiation may result in permanent hair loss

Answer 367

Epilation or loss of hair (alopecia)

Question 368

3 effects of ionizing radiation on the skin

Answer 368

Radiodermatitis Desquamation Epilation or loss of hair (alopecia)

Question 369

Doses as low as what can depress the male sperm population and has the potential to cause genetic mutations in future gens; in girls and women, a gonadal dose of what may delay or suppress menstruation?

Answer 369

0.1 Gyt

Question 370

Temporary sterility may occur and last for as long as 12 months when the testes receive a radiation dose of what?

Answer 370

2 Gyt

Question 371

Permanent sterility of the testes is most likely to be induced by a radiation dose of what?

Answer 371

5 or 6 Gyt

Question 372

A single radiation exposure of what to the ovaries usually results in temporary sterility of the woman, whereas a dose of what results in permanent sterility?

Answer 372

2 Gyt | 5-6 Gyt

Question 373

Whole-body dose of ionizing radiation as low as what produce a measurable hematologic depression?

Answer 373

0.25 Gyt

Question 374

Study of cell genetics with emphasis on cell chromosomes

Answer 374

Cytogenetics

Question 375

A cytogenetic analysis of chromosomes may be accomplished through the use of a chromosome map consisting of a photomicrograph

Answer 375

Karyotype

Question 376

```

The phase of cell division in which chromosome damage caused by radiation exposure can be evaluated Chromosome aberrations (deviation from normal development or growth) and chromatid aberrations have been observed at this phase

```

Answer 376

Metaphase

Question 377

Radiation-induced damage at the cellular level may lead to measurable somatic and genetic damage in the living organism as a whole later in life; these outcomes are the long-term results of radiation exposure

Answer 377

Late effects

Question 378

3 examples of measurable late biologic damage

Answer 378

Cataracts Leukemia Genetic mutations

Question 379

Radiobiologists engaged in research have a common goal to establish relationships between radiation and dose-response Information obtained can be used to attempt to predict the risk of occurrence of malignancies in human populations that have been exposed to low levels of ionizing radiation Radiation dose-response relationship is demonstrated graphically through a curve that maps the observed effects of radiation exposure in relation to the dose of radiation received As radiation dose escalates, so do most effects How much radiation received to give you this response

Answer 379

Dose-response curves

Question 380

Straight line

Answer 380

Linear

Question 381

Curved to some degree

Answer 381

Nonlinear

Question 382

A point at which a response or reaction to an increasing stimulation first occurs With reference to ionizing radiation, below a certain radiation level or dose, no biologic effects are observed Biologic effects begin to occur only when this level or dose is reached

Answer 382

Threshold

Question 383

Any radiation dose has the capability of producing a biologic effect If ionizing radiation functions as the stimulus, and the biologic effect it produces is the response, and if a this relationship exists between radiation dose and a biologic response, some biologic effects will be caused in living organisms by even the smallest dose of ionizing radiation No radiation dose can be considered absolutely safe

Answer 383

Nonthreshold

Question 384

The equation that best fits the data has components that depend on dose to the first power (linear or straightline behavior) and also dose squared (quadratic/curved behavior)

Answer 384

Linear-quadratic

Question 385

The chance of a biologic response to ionizing radiation is directly proportional to the dose received Recommends curve of radiation dose-response for most types of cancer

Answer 385

Linear nonthreshold (LNT) curve

Question 386

Deterministic effects of significant radiation exposure such as skin erythema and hematologic depression may be demonstrated graphically Biologic response does not occur below a specific dose level Laboratory experiments on animals and data from human populations observed after acute high doses of radiation provided the foundation for this curve

Answer 386

Linear threshold dose-response curve

Question 387

When living organisms that have been exposed to radiation sustain biologic damage

Answer 387

Somatic (i.e., body) effects

Question 388

2 classifications of somatic effects

Answer 388

Stochastic effects | Deterministic effects

Question 389

The probability that the effect happens depends upon the received dose, but the severity of the effect does not Example: occurrence of cancer

Answer 389

Stochastic effects

Question 390

Both the probability and the severity of the effect depend upon the dose Example: a cataract

Answer 390

Deterministic effects

Question 391

8 teratogenic effects

Answer 391

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Embryonic, fetal, or neonatal death Congenital malformations Decreased birth weight Disturbances in growth and/or development Increased stillbirths Infant mortality Childhood malignancy Childhood mortality

```

Question 392

2 late stochastic effects

Answer 392

Cancer | Genetic (heritable) effects

Question 393

Consequences of radiation exposure that appear months or years after such exposure

Answer 393

Late somatic effects

Question 394

Late effects that can be directly related to the dose received; slow developing changes to the body from radiation exposure Not likely to occur from diagnostic imaging procedures

Answer 394

Late deterministic somatic effects

Question 395

Late responses in the body to radiation exposure that do not have a threshold occur in an arbitrary or probabilistic manner and have a severity that does not depend on dose Could be initiated by even the smallest amount of radiation exposure if many low probability occurrences were to be simultaneously realized.

Answer 395

Late stochastic effects

Question 396

No conclusive proof exists that low-level ionizing radiation exposure below what causes a significant increase in the risk of malignancy?

Answer 396

0.1 Sievert (Sv)

Question 397

3 major types of late effects

Answer 397

Carcinogenesis (stochastic event) Cataractogenesis (deterministic event) Embryologic effects (birth defects) (stochastic events)

Question 398

2 models used by researchers for extrapolation of risk from high-dose to low-dose data

Answer 398

Linear | Linear-quadratic (leukemia only)

Question 399

Most important late stochastic effect caused by exposure to ionizing radiation This effect is a random occurrence that does not seem to have a threshold and for which the severity of the disease is not dose-related

Answer 399

Cancer

Question 400

There is a high probability that a single dose of approximately what will induce the formation of cataracts?

Answer 400

2 Gy

Question 401

Radiation-induced cataracts in humans follow a what kind of relationship?

Answer 401

Threshold, nonlinear dose-response

Question 402

Most radiosensitive stage of gestation in humans

Answer 402

Organogenesis | First trimester

Question 403

Set of numeric dose limits that are based on calculations of the various risks of cancer and genetic (hereditary) effects to tissues or organs exposed to radiation

Answer 403

Effective dose (EfD) limiting system

Question 404

4 major organizations responsible for evaluating the relationship between radiation EqD and induced biologic effects and are also concerned with formulating risk estimates of somatic and genetic effects of irradiation

Answer 404

International Commission on Radiological Protection (ICRP) National Council on Radiation Protection and Measurements (NCRP) United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) National Academy of Sciences/National Research Council Committee on the Biological Effects of Ionizing Radiation (NAS/NRC-BEIR)

Question 405

Evaluates information on biologic effects of radiation and provides radiation protection guidance through general recommendations on occupational and public dose limits Considered the international authority on the safe use of sources of ionizing radiation Composed of a main commission with 12 active members, a chairman, and 4 standing committees, which include committees on radiation effects, radiation exposure, protection in medicine, and the application of its recommendations Since its inception in 1928, it has been the leading international organization responsible for providing clear and consistent radiation protection guidance through its recommendation for occupational dose limits and public dose limits Only makes recommendations, does not function as an enforcement agency; each nation must develop and enforce its own specific regulations

Answer 405

International Commission on Radiological Protection (ICRP)

Question 406

Reviews regulations formulated by the ICRP and decides ways to include those recommendations in US radiation protection criteria; nongovernmental, non-profit The council implements this task by formulating general recommendations and publishing their recommendations in the form of various reports Not an enforcement agency, enactment of its recommendations lies with federal and state agencies that have the power to enforce such standards after they have been established

Answer 406

National Council on Radiation Protection and Measurements (NCRP)

Question 407

Evaluates human and environmental ionizing radiation exposure and derives radiation risk assessments from epidemiologic data and research conclusions; provides information to organizations such as the ICRP for evaluation Another group that plays a prominent role in the formulation of radiation protection guidelines This group evaluates human and environmental ionizing radiation exposures from a variety of sources including radioactive materials, radiation-producing machines, and radiation accidents Uses epidemiologic data information acquired from the Radiation Effects Research Foundation and research conclusions to derive radiation risk assessments for radiation-induced cancer and for genetic (hereditary) effects

Answer 407

United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR)

Question 408

Reviews studies of biologic effects of ionizing radiation and risk assessment and provides the information to organizations such as the ICRP for evaluation Another advisory group that reviews studies of biologic effects of ionizing radiation and risk assessment

Answer 408

National Academy of Sciences/National Research Council Committee on the Biological Effects of Ionizing Radiation (NAS/NRC-BEIR)

Question 409

5 U.S. regulatory agencies

Answer 409

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Nuclear Regulatory Commission (NRC) Agreement states Environmental Protection Agency (EPA) U.S. Food and Drug Administration (FDA) Occupation Safety and Health Administration (OSHA)

```

Question 410

Oversees the nuclear energy industry and enforces radiation protection standards, publishes its rules and regulations in Title 10 of the U.S. Code of Federal Regulations, and enters into written agreements with state governments that permit the state to license and regulate the use of radioisotopes and certain other material within the state Federal agency that has the authority to control the possession, use, and production of atomic energy in the interest of national security; also has the power to enforce radiation protection standards Does not regulate or inspect x-ray imaging facilities; its main function is to oversee the nuclear energy industry Supervises the design and working mechanics of nuclear power stations, production of nuclear fuel, handling of expending fuel, and supervision of hazardous radioactive waste material Controls the manufacture and use of radioactive substances formed in nuclear reactors and used in research, nuclear medicine imaging procedures, therapeutic treatment, and industry Licenses users of radioactive materials and periodically makes unannounced inspections to determine whether these users are in compliance with the provisions of their licenses Writes standards that are presented as rules and regulations Has the authority to enter into written contracts with state governments; these agreements permit the contracting state to undertake the responsibility of licensing and regulating the use of radioisotopes and certain other radioactive materials within the state

Answer 410

Nuclear Regulatory Commission (NRC)

Question 411

Enforce radiation protection regulations through their respective health departments

Answer 411

Agreement states

Question 412

Facilitates the development and enforcement of regulations pertaining to the control of radiation in the environment

Answer 412

Environmental Protection Agency (EPA)

Question 413

Conducts an ongoing production radiation control program, regulating the design and manufacture of electronic products, including x-ray equipment To determine the level of compliance with standards in a given x-ray facility, it conducts on-site inspections of x-ray equipment Compliance with standards ensures the protection of occupationally and nonoccupationally exposed persons from faulty manufacturing

Answer 413

U.S. Food and Drug Administration (FDA)

Question 414

Functions as monitoring agency in places of employment, predominantly in industry Regulates occupation exposure to radiation

Answer 414

Occupation Safety and Health Administration (OSHA)

Question 415

2 functions of an RSO

Answer 415

Oversee the program’s daily operation | Provide for formal review of the program each year

Question 416

5 responsibilities of the RSO

Answer 416

Specifically responsible for developing an appropriate radiation safety program for the facility that follows internationally accepted guidelines for radiation protection Must ensure that the facility’s operational radiation practices are such that all people, especially those who are or could be pregnant, are adequately protected from unnecessary exposure To fulfill their responsibility, management of the facility must grant the RSO the authority necessary to implement and enforce the policies of the radiation safety program Review and maintain radiation-monitoring records for all personnel Be available to provide counseling for individuals

Question 417

Consistency in output in radiation intensity for identical generator settings from one individual exposure to the next The x-ray unit must be able to duplicate certain radiographic exposures for any given combo of kilovolts at peak (kVp), milliamperes (mA), and time May be verified by using the same technical exposure factors to make a series of repeated radiation exposures and then, observing with a calibrated ion chamber, how radiation intensity typically varies

Answer 417

Exposure reproducibility

Question 418

A variance of what is acceptable for exposure reproducibility?

Answer 418

5% or less

Question 419

Consistency in output radiation intensity at a selected kVp setting when changing from one mA and time combination to another (mAs); output of radiation that comes out The ratio of the difference in mR/mAs values between two successive generator stations to the sum of those mR/mAs values

Answer 419

Exposure linearity

Question 420

What must exposure linearity be?

Answer 420

Less than 0.1 (cannot exceed 10%)

Question 421

What is the model for the ALARA concept?

Answer 421

The relationship between ionizing radiation and potential risk is assumed to be completely linear and without any threshold In the interest of safety, risk of injury should be overestimated rather than underestimated

Question 422

Biologic effect and radiation dose are directly proportional

Answer 422

Linear

Question 423

2 all-inclusive categories encompass the radiation-induced responses of serious concern in radiation protection programs

Answer 423

Deterministic effects | Stochastic (probabilistic) effects

Question 424

Biologic somatic effects of ionizing radiation that can be directly related to the dose received that exhibit a threshold dose below which the response does not normally occur and above which the severity of the biologic damage increases as the dose increases When radiation-induced biologic damage escalates, it does so because greater numbers of cells interact with the increased number of x-ray photons that are present at higher radiation exposure Typically occur only after large doses of radiation but they could also result from long-term individual low doses of radiation sustained over several years; in either instance the cumulative amounts of such radiation doses are usually much greater than those typically encountered by a patient in diagnostic radiology

Answer 424

Deterministic effects

Question 425

3 early deterministic effects

Answer 425

Erythema Blood changes (decrease pf lymphocytes and platelets) Epilation Acute radiation syndrome

Question 426

3 syndromes of acute radiation syndrome (far more serious early deterministic consequences of radiation sickness)

Answer 426

Hematopoietic syndrome Gastrointestinal syndrome Cerebrovascular syndrome

Question 427

6 late deterministic somatic effects that may occur months or years after high-level radiation exposure

Answer 427

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Cataract formation Fibrosis Organ atrophy Loss of parenchymal cells Reduced fertility Sterility caused by a decrease in reproductive cells

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Question 428

The frequency of occurrence of high-dose deterministic effects follows what curve?

Answer 428

Nonlinear, threshold curve that is sigmoidal (S-shaped) with a threshold Not proportional to the dose

Question 429

Mutational, nonthreshold, randomly occurring biologic somatic changes; chances of occurrence increase with each radiation exposure

Answer 429

Stochastic (probabilistic) effects

Question 430

2 examples of stochastic (probabilistic) effects

Answer 430

Cancer | Genetic alterations

Question 431

What curves may be used to demonstrate stochastic (probabilistic) effects?

Answer 431

Linear and the linear-quadratic dose-response curves

Question 432

Current radiation protection philosophy is based on the assumption that what relationship exists between radiation dose and biologic response?

Answer 432

Linear nonthreshold relationship

Question 433

Current method for assessing radiation exposure and associated risk of biologic damage to radiation workers and the general public Concerns the upper boundary dose of ionizing radiation that results in a negligible risk of bodily injury or hereditary damage Upper boundary limits are designed to minimize the risk to humans in terms of deterministic and stochastic effects (upper limits do not include natural background and medical exposure) Upper boundary radiation exposure limits for occupationally exposed persons are associated with risks that are similar to those encountered by employees in other industries such as manufacturing, trade, or government, which are generally considered to be reasonably safe Radiation risks are derived from the complete injury caused by radiation exposure Includes, for the determination of EqD for tissues and organs, all radiation-vulnerable human organs that can contribute to potential risk, rather than only those human organs considered critical An attempt to equate the various risks of cancer and hereditary effects to the tissues or organs that were exposed to radiation

Answer 433

EfD limiting system

Question 434

3 ways EfD limits may be expressed

Answer 434

Whole-body exposure Partial-body exposure Exposure of individual organs

Question 435

The sum of what exposures is considered when EfD limits are established?

Answer 435

Both the external and internal whole-body exposures

Question 436

Embryo-fetus in utero is particularly sensitive to radiation exposure; epidemiologic studies of atomic bomb survivors exposed in utero provided conclusive evidence of a dose-dependent increase in the incidence of severe mental retardation for fetal doses greater than approximately what?

Answer 436

0.4 Sievert (Sv)

Question 437

What is the annual EfD limit for occupational exposure?

Answer 437

50 mSv

Question 438

What is the cumulative EfD (cumEfD) limit for occupational exposure?

Answer 438

10 mSv x age

Question 439

What is the annual EqD limit for occupational exposure to the lens of the eye?

Answer 439

150 mSv

Question 440

What is the annual EqD limit for occupational exposure to localized areas of the skin, hands, and feet?

Answer 440

500 mSv

Question 441

What is the annual EfD limit for continuous or frequent exposure to the public (ex: radiation therapy)?

Answer 441

1 mSv

Question 442

What is the annual EfD limit for infrequent exposure to the public?

Answer 442

5 mSv

Question 443

What is the annual EqD limits for the public to the lens of the eye?

Answer 443

15 mSv

Question 444

What is the annual EqD limits for the public to localized areas of the skin, hands, and feet?

Answer 444

50 mSv

Question 445

What is the annual EfD limit for education and training exposures (students) under the age of 18 years?

Answer 445

1 mSv

Question 446

What is the annual EqD limit for education and training exposures (students) to the lens of the eye?

Answer 446

15 mSv

Question 447

What is the annual EqD limit for education and training exposures (students) to localized areas of the skin, hands, and feet?

Answer 447

50 mSv

Question 448

What is the monthly EqD limit for embryo and fetus exposures?

Answer 448

0.5 mSv

Question 449

What is the EqD limit for embryo and fetus exposures during the entire gestation?

Answer 449

5.0 mSv

Question 450

What is the annual negligible individual dose?

Answer 450

0.01 mSv

Question 451

A radiation worker's lifetime EfD must be limited to his or her age in years times 10 mSv

Answer 451

Cumulative effective dose (CumEfD) limit

Question 452

2 exposures EfD limits include the possibility of

Answer 452

Internal exposure | External exposure

Question 453

The sum/total of both the internal and external equivalent doses

Answer 453

Effective dose (EfD)

Question 454

Provides a low-exposure cutoff level so that regulatory agencies may dismiss a level of individual risk as being of negligible risk

Answer 454

Negligible individual dose (NID)

Question 455

X-rays produced in the anode but not at the focal spot Photons that pass through the housing because the lead shielding around the tube for practical reasons cannot be made perfect Radiation generated in the x-ray tube that does not exit from the collimator opening but rather penetrates the protective tube housing and, to some degree, the sides of the collimator

Answer 455

Off-focus/leakage radiation

Question 456

X-rays emitted through the x-ray port tube window, or port

Answer 456

Useful, or primary, beam

Question 457

The housing enclosing the x-ray tube must be constructed so that the leakage radiation measured at a distance of 1 m from the x-ray source does not exceed what when the tube is operated at its highest voltage at the highest current that allows continuous operation?

Answer 457

1 mGya/hr (100 mR/hr)

Question 458

What is the radiographic examination table frequently made of?

Answer 458

Carbon fiber material

Question 459

Distance indicators must be accurate to within what percent of the SID?

Answer 459

2%

Question 460

Centering indicators must be accurate to within what percent of the SID?

Answer 460

1%

Question 461

Most versatile device for defining the size and shape of the radiographic beam; most often used with multipurpose x-ray units Box shaped and contains the radiographic beam defining system

Answer 461

Light-localizing variable-aperture rectangular collimator

Question 462

3 things that radiographic beam defining system consists of

Answer 462

Two sets of adjustable lead shutters mounted within the device at different levels A light source to illuminate the x-ray field and permit it to be centered over the area of clinical interest Mirror to deflect the light beam toward the patient to be radiographed

Question 463

Mounted as close as possible to the tube window to reduce the amount of off-focus, or stem, radiation coming from the primary beam exiting at various angles from the x-ray tube window; reduces patient dose resulting from off-focus radiation

Answer 463

Upper shutters (first set of shutters)

Question 464

4 x-ray beam limitation devices

Answer 464

Light-localizing variable-aperture rectangular collimator Aperture diaphragms Cones Cylinders

Question 465

2 things x-ray beam limitation devices do

Answer 465

Confine the useful, or primary, beam before it enters the area of clinical interest, thereby limiting the quantity of body tissue irradiated Reduces the amount of scattered radiation in the tissue and prevents unnecessary exposure to tissues not under examination

Question 466

All the radiation that arises from the interaction of an x-ray beam with the atoms of a patient or any other object in the path of the beam Compton interaction between the x-ray photons and electrons of the atoms within the attenuating object deflect x-ray photons from their initial trajectories; as a result, photons emerge from the object in all directions Greatly reduced in intensity relative to the incident beam; also quite weakened in energy and consequently in penetrability

Answer 466

Scatter radiation

Question 467

2 benefits of restricting x-ray field size to include only the anatomic structures of clinical interest

Answer 467

Significant reduction in patient dose because less scatter radiation is produced by a smaller field size Improves the overall quality of the radiographic image

Question 468

Mounted below the level of the light source and mirror and function to further confine the radiographic beam to the area of clinical interest Consists of two pairs of lead plates oriented at right angles to each other; each set may be adjusted independently so that an extensive variety of rectangular shapes can be selected

Answer 468

Lower shutters (second set of shutters)

Question 469

The brightness of a surface; quantifies the intensity of a light source (i.e., the amount of light per unit area coming from its surface) Determined for measuring the concentration of light over a particular field of view Light emission

Answer 469

Luminance

Question 470

The sum of the cross-table and along-the-table alignment differences between the x-ray and light beams must not exceed what of the SID?

Answer 470

2%

Question 471

Consists of electronic sensors in an IR holder that sends signals to the collimator housing; when activated, the collimators are automatically adjusted so that the radiation field matches the size of the IR May be activated with the turn of a key

Answer 471

Positive beam limitation (PBL)

Question 472

Regulatory standards require accuracy of what of the SID with PBL?

Answer 472

2-3%

Question 473

Simplest of all beam limitation devices Consists of a flat piece of lead with a hole of designated size and shape cut in its center; the dimensions of the hole determine the size and shape of the radiographic beam Different IR sizes and SIDs require aperture diaphragms of various sizes to accommodate them Placed directly below the window of the x-ray tube and confines the primary radiographic beam to dimensions suitable for covering a given size IR at a specified SID Limits field size, and thus the area of the body irradiated,

Answer 473

Aperture diaphragms

Question 474

3 shapes of aperture diaphragm openings

Answer 474

Rectangular Square Round

Question 475

Most common shape of aperture diaphragm

Answer 475

Rectangular |

Question 476

Circular metal tubes that attach to the x-ray tube housing or variable rectangular collimator to limit the x-ray beam to a predetermined size and shape

Answer 476

Cones

Question 477

Collimating device with the diameter of the upper end smaller than the diameter of the lower end

Answer 477

Flared metal tube

Question 478

Collimating device with the diameter the same at both the upper and lower ends

Answer 478

Straight cylinder

Question 479

Reduces exposure to the patient's skin and superficial tissue by absorbing most of the lower-energy photons (long-wavelength or soft x-rays) from the heterogenous beam Increases the mean energy, or "quality," of the x-ray beam aka "hardening" the beam; x-rays are more penetrating

Answer 479

Filtration

Question 480

What is the effect of filtration on the absorbed dose to the patient?

Answer 480

Because filtration absorbs some of the photons in a radiographic beam, it decreases the overall intensity (quantity, or amount) of incident radiation The remaining photons, as a whole, are more penetrating and therefore less likely to be absorbed in body tissue Hence, the absorbed dose to the patient decreases when the correct amount and type of filtration are placed in the radiographic beam

Question 481

2 types of filtration

Answer 481

Inherent | Added

Question 482

Filtration in the tube

Answer 482

Inherent filtration

Question 483

3 examples of inherent filtration

Answer 483

Glass envelope encasing the x-ray tube Insulating oil surrounding the tube Glass window in the tube housing

Question 484

The inherent filtration material amounts to approximately what aluminum equivalent?

Answer 484

0.5 mm aluminum equivalent

Question 485

The light-localizing variable-aperture rectangular collimator provides an additional what amount of aluminum equivalent to the inherent filtration (the reflective surface of the collimator mirror provides most of this aluminum equivalent)?

Answer 485

1 mm aluminum equivalent

Question 486

What is the requirement for total filtration?

Answer 486

2.5 mm aluminum equivalent at above 70 kVp

Question 487

Inherent filtration plus added filtration

Answer 487

Total filtration

Question 488

3 examples of added filtration

Answer 488

Sheets of aluminum (or the equivalent) of appropriate thickness Collimators Mirror

Question 489

Extra filtration located outside the glass envelope window of the tube housing above the collimator shutters Filtration below the tube

Answer 489

Added filtration

Question 490

Each x-ray tube and collimator system typically has a total inherent filtration of what aluminum equivalent?

Answer 490

1.5 mm equivalent

Question 491

Metal the is the most wide selected filter material in diagnostic radiology because it effectively removes low-energy (soft) x--rays from polyenergetic (heterogenous) x-ray beam without severely decreasing the x-ray beam intensity Lightweight, sturdy, relatively inexpensive, and readily available

Answer 491

Aluminum (Z=13)

Question 492

The thickness of a designated absorber (customarily a metal such as aluminum) required to decrease the intensity of the primary beam by 50% of its initial value Measure of beam quality/effective energy of the x-ray beam

Answer 492

Half-value layer (HVL)

Question 493

Dose reduction and uniform radiographic imaging of body parts that vary considerably in thickness or tissue composition may be accomplished by the use of these filters Partially attenuate x-rays that are directed toward the thinner, or less dense, area while permitting more x-radiation to strike the thicker, or denser area

Answer 493

Compensating filters

Question 494

3 materials compensating filters are constructed of

Answer 494

Aluminum Lead-acrylic Other suitable material

Question 495

3 types of compensating filters

Answer 495

Wedge filter Trough, or bilateral wedge filter Boomerang

Question 496

Used to provide uniform density when the foot is undergoing radiography Filter is attached to the lower rim of the collimator and positioned with its thickest part toward the toes and thinnest part toward the heel

Answer 496

Wedge filter

Question 497

3 examinations a trough, or bilateral wedge filter is used in

Answer 497

Lateral knee (patella) T-spine Dedicated chest radiographs

Question 498

3 materials that may make up the grid interspaces

Answer 498

Aluminum Plastic Wood

Question 499

Device made of parallel radiopaque strips alternately separated with low-attenuation strips; strips of lead with aluminum between them Placed between the patient and radiographic IR to remove scattered x-ray photons that emerge from the patient before they reach the film or other IR Increases patient dose, but improves quality of the recorded image Remove scattered x-ray photons

Answer 499

Radiographic grid

Question 500

When is a grid usually used?

Answer 500

When the thickness of the body part to be radiographed is greater than 10 cm

Question 501

The ratio of the height of the lead strips in the grid to the distance between them

Answer 501

Grid ratio

Question 502

2 types of grids

Answer 502

Focused grid | Parallel grid

Question 503

Grid whose lines follow divergence of beam, slanted in and meet at anode; used in diagnostic

Answer 503

Focused grid

Question 504

Has straight grid lines

Answer 504

Parallel grid

Question 505

2 things grids significantly improve

Answer 505

Radiographic contrast | Visibility of detail

Question 506

What is the minimum SSD for mobile radiographic units?

Answer 506

At least 30 cm (12 inches)

Question 507

What distance is generally used for mobile radiography?

Answer 507

100 cm (40 inches) or even 120 cm (48 inches)

Question 508

Temporary image produced conventionally by ionizing radiation after x-rays pass through an anatomic area of clinical interest

Answer 508

Invisible/latent image

Question 509

Invisible/latent image must be chemically processed to make the unseen image visible; the finished radiograph that results from this process

Answer 509

Analog image

Question 510

Anatomic information collected by a computer and shown on its display

Answer 510

Digital image

Question 511

Shades of gray that are displayed on the image

Answer 511

Contrast

Question 512

Number of different shades of gray that can be stored in memory and displayed on a computer monitor

Answer 512

Grayscale

Question 513

The numeric values of the digital image are aligned in a fixed number of arrays that form many individual miniature square boxes, each of which corresponds to a particular place in the image; these individual boxes collectively constitute this

Answer 513

Image matrix

Question 514

Each miniature square box in a matrix that collectively produce a 2D representation of the information contained in a volume of tissue

Answer 514

Picture element/pixel

Question 515

What do the size of the pixels determine?

Answer 515

The sharpness of the image

Question 516

Resolution is sharper when pixels are _______ and matrix is ________

Answer 516

Smaller, bigger

Question 517

What is an advantage and disadvantage of DR?

Answer 517

Advantage: contrast better because image can be manipulated Disadvantage: film offers better detail

Question 518

IRs used in DR convert the energy of x-rays into what?

Answer 518

Electrical signals

Question 519

What does indirect DR use?

Answer 519

A scintillator, such as amorphous silicon, to convert the x-ray energy into visible light The visible light is converted into electrical signals by an array of transistors (TFTs) or an array of charge-coupled devices (CCDs)

Question 520

What does direct DR use?

Answer 520

A photoconductor, such as amorphous selenium, to convert the x-ray energy directly into electrical signals

Question 521

The CR filmless cassette contains a photostimulable phosphor made of what?

Answer 521

Europium-activated barium fluorohalide

Question 522

Use of an image reading unit to scan the photostimulable phosphor image plate in CR uses what kind of beam?

Answer 522

Helium-neon laser beam

Question 523

Use of an image reading unit to scan the photostimulable phosphor image plate in CR, results in the emission of violet light that is changed into an electronic signal by what?

Answer 523

A photomultiplier tube

Question 524

Although the radiographer can manipulate the CR image of the patient's anatomy of interest to adjust image size, brightness, and contrast, this technologic flexibility does not excuse overexposing the patient Responsibility of the radiographer to minimize radiation exposure by using correct technical exposure factors the first time a patient is x-rayed If patients are overexposed by radiographers who claim the rationale that computerized images can be manipulated later on to produce a diagnostic-quality image, thereby avoiding the possibility of repeat exposures, patients are actually receiving higher radiation doses than are necessary to produce those initial images

Answer 524

Dose creep

Question 525

CR has ________ kilovoltage flexibility than does conventional screen-film radiography

Answer 525

Greater

Question 526

CR is _______ sensitive to scatter radiation, so a grid should probably be used more frequently except for the majority of pediatric patients

Answer 526

More (most)

Question 527

How long does the image stay on the CR imaging plate?

Answer 527

8 hours

Question 528

4 advantages DR systems offer advantages over both CR and conventional SFSs

Answer 528

Lower dose Ease of use Immediate imaging results Manipulation of the image

Question 529

Traditionally, fluoroscopic imaging systems have the x-ray tube positioned _____ the x-ray examination table and the image intensifier and spot film system mounted on a C-arm and centered over the x-ray examination table

Answer 529

Under

Question 530

Minification gain x flux gain

Answer 530

Brightness gain

Question 531

3 benefits of image intensification fluoroscopy

Answer 531

Increased image brightness Saving of time for for the radiologist Patient skin dose reduction (scatter goes back to floor)

Question 532

The x-ray image intensification system increases the overall brightness of fluoroscopic image how many times?

Answer 532

10,000 times

Question 533

Daytime vision

Answer 533

Photopic/cone vision

Question 534

Night vision

Answer 534

Scotopic/rod vision

Question 535

Because an image intensification system permits observing of the fluoroscopic image at ordinary brightness levels (regular white light) that radiologist makes use of what type of vision?

Answer 535

Daytime vision | Photopic/cone vision

Question 536

What is the input phosphor of a fluoroscopic image intensification system made of?

Answer 536

Cesium iodide

Question 537

What is the photocathode of a fluoroscopic image intensification system made of?

Answer 537

Photoemissive materials

Question 538

What is the output phosphor of a fluoroscopic image intensification system made of?

Answer 538

Zinc cadmium

Question 539

An electronic device that receives the image-forming x-ray beam and converts it into a visible-light image of high intensity

Answer 539

Image intensification tube

Question 540

When magnification in the fluoroscopic image is needed and the viewing mode is changed to the 17-cm mode (6.8 in) or even less (12 cm [4.8 cm]), the focal point of the electrons move to a _________ from the output phosphor

Answer 540

Greater distance away

Question 541

Fluoroscopy mA _________ automatically with magnification; the use of smaller-diameter modes results in increased pt dose Quality of the magnified image is somewhat _________ (new digital systems can magnify without increasing dose)

Answer 541

Increases, degraded

Question 542

Involves manual or automatic periodic activation of the fluoroscopic tube by the fluoroscopist, rather than lengthy continuous activation

Answer 542

Intermittent, or pulsed, fluoroscopy

Question 543

2 things intermittent/pulsed fluoroscopy does

Answer 543

Practice significantly decreases patient dose, especially in long procedures Helps extend the life of the tube

Question 544

Feature that allows the fluoroscopist to see the most recent image without exposing the patient to another pulse of radiation; reduces patient dose

Answer 544

Last-image-hold

Question 545

What is the kVp range for adults, depending on the body area being examined during fluoroscopy; mA range varies

Answer 545

75-110 kVp

Question 546

The SSD should not be less than what for stationary fluoroscopes?

Answer 546

38 cm (15 inches)

Question 547

Position of the input phosphor surface of the image intensifier in relation to the patient should be maintained as ________ as is practical to reduce the patient’s entrance exposure rate

Answer 547

Close

Question 548

What is the minimum SSD for mobile fluoroscopes?

Answer 548

No less than 30 cm (12 inches)

Question 549

Resettable device that times the x-ray beam-on time and sounds an audible alarm or temporarily interrupts the exposure after the fluoroscope has been activated for 5 minutes

Answer 549

Cumulative timer

Question 550

What is the current federal standard limit for entrance skin exposure rates of general-purpose intensified fluoroscopic units?

Answer 550

Maximum of 100 mGya per minute (10 R/min)

Question 551

A primary protective barrier of what lead equivalent is required for a fluoroscopic unit?

Answer 551

2-mm lead equivalent

Question 552

Patient-image intensifier distance should be as _______ as possible to reduce entrance dose (puts tube further)

Answer 552

Short

Question 553

With the C-arm x-ray tube positioned _______ the patient, scatter radiation is less intense

Answer 553

Under

Question 554

The lines composing the image are progressively scanned to provide the picture that appears on a monitor during a brief period of time The x-ray beam is turned off while the image is being scanned, thereby decreasing patient dose, and then pulsed back on for the next image

Answer 554

Pulsed progressive system

Question 555

Treating the patient as a whole person rather than just the area of concern

Answer 555

Holistic approach

Question 556

An interaction that produces a satisfying result through an exchange of information

Answer 556

Effective communication

Question 557

Unconscious actions or body language

Answer 557

Nonverbal communication

Question 558

2 types of patient motion

Answer 558

Voluntary motion | Involuntary motion

Question 559

Motion controlled by will

Answer 559

Voluntary motion

Question 560

Motion caused by muscle groups (digestive organs or heart)

Answer 560

Involuntary motion

Question 561

4 areas of the body that should be selectively shielded from the useful beam whenever possible

Answer 561

Lens of the eye Breasts Reproductive organs Thyroid

Question 562

Gonadal shielding should be used on patients during diagnostic x-ray procedures to protect the reproductive organs from exposure to the useful beam when these organs are in or within approximately what distance of a properly collimated beam?

Answer 562

5 cm

Question 563

Female reproductive organs receive about how many times more exposure during a given radiographic procedure involving the pelvic region than do the male reproductive organs, because the female reproductive organs are located within the pelvic region?

Answer 563

3 times

Question 564

A 1-mm lead flat contact shield for the female reduces exposure by about what percent?

Answer 564

50%

Question 565

A 1-mm lead contact shield for the male patient reduces exposure by about what percent?

Answer 565

90-95%

Question 566

When a female patient is in the supine position the shield should be placed approximately how far medial to each palpable anterior superior iliac spine (ASIS) to protect the ovaries?

Answer 566

2.5 cm (1 inch)

Question 567

4 basic types of gonadal shielding devices

Answer 567

Flat contact shields Shadow shields Shaped contact shields Clear lead shields

Question 568

Shield made of lead strips or lead-impregnated materials 1 mm thick Can be placed directly over the patient's reproductive organs Most effective when they're used as protective devices for patients having AP or PA while in a recumbent position; not suited for nonrecumbent positions or projections other than AP or PA

Answer 568

Flat contact shields

Question 569

If the flat contact shield is used during a typical fluoroscopic examination, it must be placed _____ the patient to be effective because the x-ray tube is located under the radiographic table

Answer 569

Under

Question 570

Shield made of radiopaque material and is suspended from above the radiographic beam-defining system, these shields hang over the area of clinical interest to cast a shadow; sterile field

Answer 570

Shadow shields

Question 571

Shields containing 1 mm of lead and are contoured to enclose the male reproductive organs Disposable or washable athletic supporters or jockey-style briefs function as carriers for these shields Not recommended for PA projections because it only covers the anterior and lateral surfaces

Answer 571

Shaped contact shields

Question 572

Shields made of transparent lead-acrylic material impregnated with approximately 30% lead by weight Ex: full spinal scoliosis examination

Answer 572

Clear lead shields

Question 573

Recorded detail in the radiographic image

Answer 573

Spatial resolution

Question 574

Blotchy radiographic image that results when an insufficient quantity of x-ray photons reaches the IR

Answer 574

Quantum noise/mottle

Question 575

What is the voltage ripple of a single phase generator?

Answer 575

100%

Question 576

What is the voltage ripple of a 3 phase 6 pulse generator?

Answer 576

13%

Question 577

What is the voltage ripple of a 3 phase 12 pulse generator?

Answer 577

4-6%

Question 578

What is the voltage ripple of a high frequency generator?

Answer 578

1-2%

Question 579

Product of x-ray electron tube current and the amount of time in seconds that the x-ray beam is on

Answer 579

Milliampere-seconds (mAs)

Question 580

As an alternative procedure instead of using a radiographic grid for reducing scattered radiation during certain examinations (e.g., cross-table lateral c-spine and areas of chest radiography) Technique that removes scatter radiation by using an increased OID which improves radiographic image contrast A complementary increase in SID may be made The scattered x-rays are disseminated in many directions at acute angles to the primary beam when the radiographic exposure is made Because of the increased distance between the anatomic structures being imaged and the IR, a higher percentage of the scattered x-rays produced is then less likely to strike the IR

Answer 580

Air-gap technique

Question 581

In general, the use of an air gap technique requires the selection of technical exposure factors are comparable to those used with what ratio grid?

Answer 581

8:1 ratio grid

Question 582

If the patient's gonads were included in the repeated imaged area, then the gonads would have received this

Answer 582

Double dose

Question 583

6 unnecessary radiologic procedures

Answer 583

Chest x-ray examination on scheduled admission to the hospital Chest x-ray as part of a preemployment physical Lumbar spine examination as part of a preemployment physical Chest x-ray or other unjustified examination as part of a routine health checkup Chest x-ray examination for mass screening for tuberculosis (TB) Whole-body multislice spiral computed tomography (CT) screening

Question 584

Most frequently reported patient radiation amount because it is the simplest to determine

Answer 584

Entrance skin exposure (ESE)

Question 585

Sensing devices most often used to measure skin dose directly

Answer 585

Thermoluminescent dosimeter (TLD)

Question 586

Absorbed dose to the most superficial layers of the skin

Answer 586

Skin dose

Question 587

The EqD to the reproductive organs that, if received by every human, would be expected to bring about an identical gross genetic injury to the total population, as does the sum of the actual doses received by exposed individual members of the population The consequences of substantial absorbed doses of gonadal radiation become significantly less when averaged over an entire population rather than applied to just a few of its members The average EqD to members of the population who are of childbearing age

Answer 587

Genetically significant dose

Question 588

What is the estimated GSD for U.S. population?

Answer 588

0.20 mSv (20 mrem)

Question 589

Most medical procedures result in fetal exposures of less than what?

Answer 589

Less than 0.01 Gy

Question 590

Product of the average absorbed dose (D) in a tissue or organ in the human body and its associated radiation weighting factor chosen for the type and energy of the radiation in question for radiation workers

Answer 590

Equivalent dose (EqD)

Question 591

4 imaging procedures that increase the radiographer's risk of exposure

Answer 591

General fluoroscopy (diagnostic) Mobile examinations C-arm fluoroscopy General radiographic procedures

Question 592

2 types of secondary radiation

Answer 592

Scatter radiation | Leakage radiation

Question 593

What is the minimum thickness protective aprons can be during fluoroscopy?

Answer 593

0.5 mm of lead equivalent

Question 594

Most effective means of protection from ionizing rdiation

Answer 594

Distance

Question 595

The intensity of radiation is inversely proportional to the square of the distance from the source Expresses the relationship between distance and intensity (quantity) of radiation and governs the dose received As the separation between the radiation source and measurement point increases, the quantity of radiation measured at the more distant position decreases by the square of the ratio of the original new distance from the source; this decrease in radiation intensity physically occurs because the area, which the same flux of x-rays at the original location now covers at the new location, has increased by the square of the relative distance change When the distance from a point source of radiation is doubled, the radiation at the new location spans an area four times larger than the original area; however, the intensity at the new distance is only one fourth the original intensity

Answer 595

Inverse square law (ISL)

Question 596

What is the formula for the inverse square law?

Answer 596

I1/I2=(d2)^2/(d1)^2

Question 597

2 most common materials used for structural protective barriers

Answer 597

Lead | Concrete

Question 598

4 accessory protective devices made of lead-impregnated vinyl (devices provide protection when not behind a stationary barrier)

Answer 598

Aprons Gloves Thyroid shields Protective eyeglasses

Question 599

3 factors the effectiveness of shielding material depends on

Answer 599

Atomic number Density Thickness

Question 600

Prevent direct, or unscattered, radiation from reaching personnel or members of the general public on the other side of the barrier Located perpendicular to the undeflected/primary line of travel of the x-ray beam Ex: wall behind wall bucky

Answer 600

Primary protective barrier

Question 601

2 specifications for a primary barrier at 130 kvp

Answer 601

Consists of 1.6 mm (1/16 inch) lead Extends 2.1 m (7 feet) upward from the floor of the x-ray room when the x-ray tube is 1.5 to 2.1 m (5 to 7 feet) from the wall in question

Question 602

Radiation that has been deflected from the primary beam | Made of leakage from the tube housing and scatter (primarily from the patient) radaition

Answer 602

Secondary radiation

Question 603

Protects against secondary radiation (leakage and scatter radiation) Any wall or barrier that is never struck by the primary x-ray beam (this does not mean that secondary radiation cannot hit primary barriers as well) Walls that are not in the direct line of travel of the primary beam

Answer 603

Secondary protective barriers

Question 604

2 specifications of secondary protective barriers

Answer 604

Should overlap the primary protective barrier by approximately 1.27 cm (1/2 inch) Consists of 0.8 mm (1/32-inch) of lead

Question 605

Protects the radiographer from secondary radiation (leakage and scatter) Located in x-ray rooms housing permanent or nonportable radiographic equipment To ensure maximal protection during radiographic exposures, personnel must remain completely behind the barrier Exposure cord must be short enough that the exposure switch can be operated only when the radiographer is completely behind the control-booth barrier

Answer 605

Control-booth barrier

Question 606

2 specifications of the control-booth barrier

Answer 606

Must extend 2.1 m (7 feet) upward from the floor | Must be permanently secured to the floor

Question 607

Diagnostic x-rays should scatter a minimum of how many times before reaching any area behind the control-booth barrier?

Answer 607

Two times

Question 608

The observation window in the control-booth barrier typically consists of what lead equivalent?

Answer 608

1.5-mm lead equivalent

Question 609

With appropriate lead equivalent in the control-booth barrier, exposure of the radiographer will not exceed a maximum allowance of how much radiation per week; in actual practice in a well-designed facility, exposure should not exceed how much radiation per week?

Answer 609

1 mSv (100 mrem) | 0.02 mSv (2 mrem)

Question 610

Contains clear lead-acrylic material impregnated with approximately 30% lead by weight Permits a panoramic view, allowing diagnostic imaging personnel to observe the patient more completely

Answer 610

Clear lead-acrylic secondary protective barrier

Question 611

3 specifications of modular x-ray barriers

Answer 611

Shatter resistant Can extend 2.1 m (7 feet) upward from the floor Available in lead equivalency from 0.3 to 2 mm

Question 612

Clear lead-acrylic overhead protective barriers can be used as overhead x-ray barrier to provide an open view during special procedures and cardiac catheterization; shielding typically offers what lead equivalency protection?

Answer 612

0.5-mm lead equivalency

Question 613

For 100 kVp, an apron must be equivalent to at least what thickness of lead?

Answer 613

0.25-mm

Question 614

Protective gloves must have what lead equivalent?

Answer 614

0.25-mm lead equivalent

Question 615

What is the minimum lead equivalent for thyroid neck shields?

Answer 615

0.5-mm lead equivalent

Question 616

What is the minimal lead equivalent protective level for protective eyeglasses

Answer 616

0.35 mm

Question 617

A spot film device protective curtain, or sliding panel, should have a minimum of what lead equivalent and should normally be positioned between the fluoroscopist and the patient to intercept scattered radiation above the tabletop?

Answer 617

0.25-mm lead equivalent

Question 618

A bucky slot shielding device should have at least what lead equivalent and must automatically cover the bucky slot opening in the side of the x-ray table during a standard fluoroscopic examination when the bucky tray is positioned at the foot end of the table which protects radiologist and radiographer at gonadal level ?

Answer 618

0.25-mm lead equivalent

Question 619

For mobile x-ray units that are non-remote-controlled, the cord leading to the exposure switch must be long enough to permit the radiographer to stand at least how far from the patient, the x-ray tube, and the useful beam (permits use of ISL)?

Answer 619

2 m (approximately 6 feet)

Question 620

Radiographer should attempt to stand how to the x-ray beam–scattering object (the patient) line (when protection factors of distance and shielding have been accounted for, this is the place at which the least amount of scattered radiation is received)?

Answer 620

At a right angle (90-degrees)

Question 621

During c-arm fluoroscopy, the exposure rate caused by scatter near the entrance surface of the patient (the x-ray tube side) ________ the exposure rate caused by scatter near the exit surface of the patient; the location of the _______ potential scatter dose is on the side of the patient away from the x-ray tube (i.e., the image intensifier side)

Answer 621

Exceeds; lower

Question 622

In most facilities room doors have attenuation for diagnostic energy x-rays equivalent to that provided by how much lead?

Answer 622

0.8 mm (1/32 inch) of lead

Question 623

3 categories of radiation sources generated in an x-ray room

Answer 623

Primary radiation Scatter radiation Leakage radiation

Question 624

Emerges directly from the x-ray tube collimator and moves without deflection toward a wall, dorr, viewing window, and so on Energy has not been degraded by scatter, and substantial portions of the initial beam may not have been attenuated

Answer 624

Primary radiation | Direct radiation

Question 625

Some isotopes have too many neutrons or protons; because of this, such isotopes spontaneously undergo changes or transformations to rectify the understandable arrangement

Answer 625

Radioisotopes

Question 626

Unstable and therefore radioactive isotope of the element iodine Prostate tracers are permanently implanted for prostate radiation therapy

Answer 626

Iodine-125 (125I)

Question 627

For a patient with thyroid cancer, it is desirable to strongly irradiate any residual thyroid tissue not removed by surgery using this isotope

Answer 627

Iodine-131 (131I)

Question 628

How thick are rolling lead shields?

Answer 628

1 inch

Question 629

What is the dose limit suggested by the EPA during an emergency situation for individuals engaged in nonlifesaving activities?

Answer 629

50 mSv per event

Question 630

What is the dose limit suggested by the EPA during an emergency situation for individuals engaged in lifesaving activities?

Answer 630

250 mSv per event