RadProd

Question 1

The amount of energy absorbed per unit mass

Answer 1

Absorbed Dose

Question 2

When electromagnetic energy is transferred from the x-rays to the atoms of the patient’s biologic material

Answer 2

Absorption

Question 3

The reduction in the number of primary photons in the x-ray beam through absorption (a total loss of radiation energy) and scatter (a change in direction of travel that may also involve a partial loss of radiation energy) as the beam passes through the patient in its path.

Answer 3

Attenuation

Question 4

The “released” energy that is carried off in the form of a photon. It’s energy is directly related to the shell structure of the atom from which it was emitted.

Answer 4

Characteristic photon

Question 5

The “released” energy that is carried off in the form of a photon. It’s energy is directly related to the shell structure of the atom from which it was emitted. Also known as fluorescent radiation.

Answer 5

Characteristic x-ray

Question 6

A simple process that results in no loss of energy as x-rays scatter.
The incoming low-energy x-ray photon (<10 keV) 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 waves nondestructively combine with one another to form a scattered wave, which represents the scattered photon. Its wavelength and energy, or penetrating power, are the same as those of 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 6

Coherent scattering

Question 7

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

Answer 7

Compton scattered electron, or secondary, or recoil electron

Question 8

Compton scattering

In the Compton process, 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.

Answer 8

Compton scattering

Question 9

Compton scattering is also called…

Answer 9

• Incoherent scattering
• Inelastic scattering
• Modified scattering

Question 10

Photons (1 and 2) that emerge from the tissues and strike the radiographic IR below it.

Answer 10

Exit, or image-formation, photons

Question 11

Synonymous with characteristic x-rays.

Answer 11

Fluorescent radiation

Question 12

Term that replaces density in the digital environment. It is used because radiographic film is no longer used as the primary IR.

Answer 12

Image receptor (IR) exposure

Question 13

Measurement of different body structures denoted in grams per cubic centimeter.

Answer 13

Mass density

Question 14

The product of electron tube current and the amount of time in seconds that the x-ray tube is activated.

Answer 14

Milliampere-seconds (mAs)

Question 15

The incoming photon (equivalent in energy to at least 1.022 MeV) strongly interacts with the nucleus of the atom of the irradiated object and disappears. In the process, the energy of the photon is transformed into two new particles: a negatron (electron) and a positron. The negatron eventually recombines with any atom that needs another electron. The positron interacts destructively with a nearby electron. During the interaction, the positron and the electron annihilate each other, with their rest masses converted into energy, which appears in the form of two 0.511-MeV photons, each moving in the opposite direction.

Answer 15

Pair Production

Question 16

Example of unstavle nuclei ised in PET scanning

Answer 16

Fluorine-18 (F18), Carbon-11 (11C), Nitrogen-13 (N13)

Question 17

The highest energy level of photons in the x-ray beam.

Answer 17

Peak kilovoltage (kVp)

Question 18

An interaction that occurs at more than 10 MeV in high-energy radiation therapy treatment machines. High-energy photons collide with the nucleus of an atom, which directly absorbs the photon’s energy. This energy excess in the nucleus creates an instability that in most cases is alleviated by the emission of a neutron by the nucleus.

Answer 18

Photodisintegration

Question 19

A, 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. B, The atom responds by ejecting the electron, called a photoelectron, from its inner shell, thus creating a vacancy in that shell. C, 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. There is also some probability that instead of a characteristic photon, an Auger electron will be ejected.

Answer 19

Photoelectric absorption

Question 20

By products of photoelectric absorption

Answer 20

1. Photoelectrons (those induced by interaction with external radiation and the internally generated Auger electrons).
2. Characteristic x-ray photons (fluorescent radiation).

Question 21

The ejected orbital electron that possesses kinetic energy equal to the energy of the incident photon less the binding energy of the electron shell.

Answer 21

Photoelectron

Question 22

The emerging x-ray photon beam.

Answer 22

Primary radiation

Question 23

Differences in densities and the absorption properties among different body structures.

Answer 23

Radiographic contrast

Question 24

Degree of overall blackening on a radiographic film.

Answer 24

Radiographic density

Question 25

Undesirable, additional exposure that degrades the appearance of a completed radiographic image.

Answer 25

Radiographic fog

Question 26

Object that catches exit radiation. - Phosphor plate - Digital radiography receptor - Radiographic film

Answer 26

Radiographic image receptor (IR)

Question 27

Methods that have been devised to limit the effects of indirectly transmitted x-ray photons...

Answer 27

The most common methods include the following: •Air gap techniques •Radiographic grids

Question 28

Photons (2) that on their path before they hit the IR. They degrade the appearance of a completed radiographic image by blurring the sharp outlines of dense structures.

Answer 28

Small-angle scatter

Question 29

The midpoint of the range of densities visible on the image. Adjusting the window level, also known as windowing, refers to changing the brightness, either to be increased or decreased throughout the entire range of densities

Answer 29

Window level

Question 30

Differentiate between peak kilovoltage (kVp) and milliampere-seconds (mAs)

Answer 30

kVp is the highest energy level of photons in the x-ray beam. It controls the penetrating ability of the x-ray beam. mAs is the the product of electron tube current and the amount of time in seconds that the x-ray tube is activated.

Question 31

Describe the process of absorption, and explain the reason why absorbed dose in atoms of biologic matter should be kept as small as possible.

Answer 31

X-ray photons can interact with atoms of the patient's body and transfer energy to the tissue. The amount of energy absorbed per unit mass is referred to as the absorbed dose (D). This dose should be kept low to prevent the possibility of biologic damage in the patient.

Question 32

Differentiate among the following: primary radiation; exit, or image-formation, radiation; and scattered radiation.

Answer 32

Primary radiation: The emerging x-ray photon beam. Exit, or image-formation radiation: Noninteracting and small-angle scattered photons that pass through the patient and hit the IR. Scatter radiation: photons that change directions, involve a partial loss of energy, and do not hit the IR

Question 33

List two types of x-ray photon transmission, and explain the difference between them.

Answer 33

List two types of x-ray photon transmission, and explain the difference between them. Direct: When photons transverse the patient without interacting and still reach the image receptor. Indirect: When photons transverse the patient, undergo Compton and/or coherent interactions that may cause them to scatter or deflect with a potential loss of energy before striking the IR.

Question 34

The anode target is made of the metal tungsten or a metal alloy tungsten rhenium because...

Answer 34

1. High melting point 2. High atomic number (Tungsten: 74, Rhenium: 75)

Question 35

List the events that occur when x-radiation passes through matter.

Answer 35

When x-rays pass through matter, they are either attenuated (meaning they interact with the atoms of the patient's biologic tissue and are absorbed or scattered), or they pass through the patient as small-angle scatter photons or exit, image-forming radiation that hits the image receptor.

Question 36

The atomic numbers of compact bone, soft tissue, and air...

Answer 36

Compact bone: 13.8 Soft tissue: 7.4 Air: 7.6

Question 37

Describe the impact of positive contrast media on photoelectric absorption, and identify its effects regarding absorbed dose in the body structure that contains it.

Answer 37

Positive contrast media has a high atomic number that significantly enhances the occurrence of photoelectric interaction relative to similar adjacent structures that do not have contrast media. It also leads to an increase in absorbed dose in the body structures that contain it.

Question 38

Describe the effect of kVp on radiographic image quality and patient absorbed dose.

Answer 38

When kVp is increased, the patient receives a lower dose, but image quality may be compromised.

Question 39

Exit, or image-formation, radiation is composed of which of the following?

Answer 39

Non-interacting and small-angle scattered photons.

Question 40

Which of the following contributes significantly to the exposure of the radiographer?

Answer 40

Compton-scattered photons.

Question 41

Which of the following defines attenuation?

Answer 41

Absorption and scatter.

Question 42

In the radiographic kilovoltage range, which of the following structures undergoes the most photoelectric absorption?

Answer 42

Compact bone

Question 43

In which of the following x-ray interactions with matter is the energy of the incident photon partially absorbed?

Answer 43

Compton

Question 44

When a high atomic number solution is either ingested or injected into human tissue or a structure to visualize it during an imaging procedure, which of the following occurs?

Answer 44

B. Photoelectric interaction becomes significantly enhanced, leading to an increase in the absorbed dose in the body tissues or structures that contain the contrast medium.

Question 45

Which of the following influences attenuation? 1. Effective atomic number of the absorber. 2. Mass density. 3. Thickness of the absorber.

Answer 45

All numbers affect attenuation

Question 46

A decrease in contrast of the image by adding an additional, unwanted exposure (radiographic fog) results from which of the following interactions between x-radiation and matter? 1. Compton scattering. 2. Pair production. 3. Photoelectric absorption

Answer 46

1 only

Question 47

Summary of All Interactions (Just to Practice)

Answer 47

Coherent: - Occurs at energies less than 10 keV (less than diagnostic range). - Doesn't usually occur in diagnostic x-ray, but if it does, the amount of noise it produces is extremely minimal. - The incoming low-energy electron interacts with the atom, causing it to become excited and vibrate one or all of the electrons. - This excitation causes a scattered photon of the same wavelength, energy, and frequency as the incident photon, just traveling in a different direction. Compton (incoherent, inelastic, modified) scatter: - Occurs at diagnostic range energies (approx. 35 keV). - The main source of image noise and occupational dose due to backscatter. - The incoming incident photon interacts with a loosely-bound outer electron. - The electron is ejected as a Compton Scattered electron (secondary or recoil electron). - A lower-energy scattered photon is also released. Photoelectric Absorption: - Occurs at diagnostic range energies. - The interaction that makes x-ray possible. - The incoming incident photon interacts with a tightly-bound inner shell electron, transferring all of its energy to the electron and disappearing. - The electron is ejected as the photoelectron. - The vacancy left by the photoelectron is then filled by an electron from the outer shells, which releases a characteristic photon (also called secondary radiation. it does not contribute to image noise and does not hit the IR). The energy of the characteristic photon is directly related to the shell structure. - If characteristic photon is not released, Auger effect may occur. - Electrons will keep dropping down until equilibrium is regained (characteristic cascade). - The greater the difference is in the amount of photoelectric absorption, the greater the contrast in the radiographic image will be between adjacent structures of differing atomic numbers. However, as absorption increases, so does the potential for biologic damage. Pair Production: - Occurs at energies of 1.02 MeV. - Useful in PET scanning. - High-energy incident photon interacts with the nucleus and releases a positron and negatron. - The negatron recombines with another atom that needs an electron. - The positron (a form of antimatter) reacts destructively with a nearby electron to cause an annihilation reaction that results in two photons (half of the original energy each, so about 0.511 MeV) traveling in different directions. Photodisintegration: - Occurs at energies above 10 MeV. - Useful in radiation therapy. - High-energy photon collides with the nucleus. - The energy is completely absorbed. - The excess energy instability is relieved by the ejection of a neutron from the nucleus

Question 48

This chapter explains the interactions of the projectile electrons that are accelerated from the cathode to the x-ray tube target. These interactions produce two types of x-rays; _____________ and _______________.

Answer 48

Characteristic ; Bremsstrahlung

Question 49

The energy of motion

Answer 49

Kinetic energy

Question 50

__________ objects have no kinetic energy.

Answer 50

Stationary

Question 51

Objects in motion have ___________ energy proportional to their ________ and to the _________ of their velocity

Answer 51

Kinetic ; Mass ; Square

Question 52

In determining the magnitude of the kinetic energy of a projectile, _________ is more important than ________.

Answer 52

Velocity ; Mass

Question 53

In an x-ray tube, the projectile is the

Answer 53

Electron

Question 54

All electrons have the same ________; Therefore electron kinetic energy is raised by raising the ______.

Answer 54

Mass ; kVp

Question 55

The distance between the filament and the x-ray tube target is only approximately __________.

Answer 55

1 cm

Question 56

Electrons traveling from from cathode to anode constitute the x-ray tube current and are sometimes called _______________ _____________.

Answer 56

Projectile Electrons

Question 57

The ___________ electron interacts with the _____________ electrons or the nuclear field of target atoms.

Answer 57

Projectile ; Orbital

Question 58

These interactions result in the conversion of __________ __________ __________ into __________ _________ (heat) and electromagnetic energy in the form of ____________ __________ (also heat) and x-rays.

Answer 58

Electron kinetic energy ; thermal energy ; infrared radiation

Question 59

Most of the kinetic energy of projectile electrons is converted into ___________.

Answer 59

Heat

Question 60

The projectile electrons interact with the _______ ________ _______ of the target atoms but do not transfer sufficient energy to these outer shell electrons to _______ them. Rather, the outer shell electrons are raised to an excited, or higher energy level.

Answer 60

Outer shell electrons ; ionize

Question 61

The outer shell electrons immediately drop back to their normal energy level with the emission of ________ ____________.

Answer 61

Infrared radiation

Question 62

Approximately _______ % of the kinetic energy of projectile electrons is converted to heat.

Answer 62

99

Question 63

Only approximately ____% of projectile electron kinetic energy is used for the production of x-radiation.

Answer 63

1

Question 64

As sophisticated as it is, the x-ray imaging system is very ____________.

Answer 64

Inefficient

Question 65

The production of heat in the anode increases ________ with increasing x-ray tube current.

Answer 65

Directly

Question 66

Doubling the x-ray tube current ____________ the heat produced.

Answer 66

Doubles

Question 67

Heat production increases _________ with increasing kVp, at least in the diagnostic range.

Answer 67

Directly

Question 68

The efficiency of x-ray production is _____________ of tube current.

Answer 68

Independent

Question 69

Regardless of what mA is selected, the efficiency of x-ray production remains ____________.

Answer 69

Constant

Question 70

The efficiency of x-ray production increases with increasing ________.

Answer 70

kVp

Question 71

At 60 kVp, only ____% of the electron kinetic energy is converted to x-rays ; At 100 kVp,approx. ______% is converted to x-rays; and at 20 MV ______% is converted.

Answer 71

.5 ; 1 ; 70

Question 72

If the projectile electron interacts with an inner shell electron of the target atom rather than with an outer shell electron, __________ _________ can be produced.

Answer 72

Characteristic x-rays

Question 73

__________ __________ are emitted when an outer-shell electron fills an inner shell void.

Answer 73

Characteristic x-rays

Question 74

When the projectile electron ionizes a target atom by removing a K-shell electron, a ________ ________ ________ is produced in the K shell. This is a highly unnatural state for the target atom , and it is corrected when an outer shell electron falls into the void in the K shell.

Answer 74

Temporary electron void

Question 75

The transition of an orbital electron from an outer shell to an inner shell is accompanied by the emission of an ______.

Answer 75

X-ray

Question 76

The x-ray has energy equal to the ________ in the binding energies of the orbital electrons involved.

Answer 76

Difference

Question 77

X-rays are called ___ _________ because they result from the electron transitions into the K-shell.

Answer 77

K x-rays

Question 78

Similar characteristic x-rays are produced when the target atom is __________ by the removal of electrons of shells other than the K shell.

Answer 78

Ionized

Question 79

X-rays resulting from the electron transitions to the L shell are called ____ _________, and have much less energy than ____ _________ because the binding energy of an L-shell electron is much lower than that of a K-shell electron.

Answer 79

L X-rays ; K X-rays

Question 80

Only the K characteristic x-rays of __________ are useful for imaging.

Answer 80

Tungsten

Question 81

Although many characteristic x-rays can be produced, these can be produced only at ________ ________, equal to the differences in electron binding energies for the various electron transitions.

Answer 81

Specific energies

Question 82

The type of x-radiation is called ____________ because it is characteristic of the target element.

Answer 82

Characteristic

Question 83

The effective energy of characteristic x-rays ________ with increasing atomic number of the target element.

Answer 83

Increases

Question 84

Bremsstrahlung Radiation =

Answer 84

"Bending radiation"

Question 85

____________ x-rays are produced when a projectile electron is slowed by the nuclear field of a target atom nucleus

Answer 85

Brehmsstrahlung

Question 86

In the diagnostic range, most x-rays are ___________ x-rays

Answer 86

Bremsstrahlung

Question 87

A third type of interaction in which the projectile electron can lose its kinetic energy is an interaction with the ________ of the target atom. In this type of interaction, the kinetic energy of the projectile electron is also converted into _____________ energy.

Answer 87

Nuclear field ; Electromagnetic energy

Question 88

A projectile electron that completely avoids the orbital electrons as it passes through a target atom may come sufficiently close to the nucleus of the atom to come under under the influence of its ___________ ___________.

Answer 88

Electric field

Question 89

Because the electron is negatively charged, and the nucleus is positively charged, there is an ____________ _________ of attraction between them.

Answer 89

Electrostatic force

Question 90

____________ is a German word for "slowed down radiation"

Answer 90

Bremsstrahlung

Question 91

Bremsstrahlung x-rays can be produced at any projectile electron energy. K-characteristic x-rays require a an x-Ray the potential of at least _______ kVp.

Answer 91

69

Question 92

A _________ spectrum contains only specific values

Answer 92

Discrete

Question 93

A __________ spectrum contains all possible values

Answer 93

Continuous

Question 94

Characteristic X-ray Emission Spectrum for Tungsten contains ___ different x-Ray energies

Answer 94

15