Radiation Physics and Radiobiology Flashcards by Rachel Brenner

What are the 4 requirements to produce x-rays?

Source of free electrons
Accelerating of electrons
Focusing of electrons
Deceleration of electons

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What is the source of free electrons in x-ray production?

Thermionic emission - mA settings determine the amount of current that will be sent to the filament

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What accelerates the electrons in x-ray production?

Voltage applied to the cathode

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What is the target area of the anode made of?

Tungsten with rhenium

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What are the filament wires made of?

Thoriated tungsten

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What is the focusing cup made of?

Molybdenum or nickel

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What % of electrons hitting the anode are converted into x-rays?

1% x-rays
99% is heat

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What is the smallest subdivision of an element that maintains all the physical and chemical properties of the element?

Atom

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What makes up the nucleus of an atom?

Protons and nuetrons

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What makes up the atomic number (Z)?

Number of protons in the nucleus

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What makes up the atomic mass (A)?

Sum of the protons and neutrons in the nucleus

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What are electrons?

Negatively charged particles located outside the nucleus and have no mass

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Tungsten atomic #

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What is the maximum number of electrons in the valence shell?

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Tungsten EBE in K,L,M,N shell

K=69.5
L=12
M=3
N=1

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What is the formula to find out the number of electrons in a shell?

2n^2

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What is ionization?

Electron is removed from an orbital shell

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What charge will an atom of if an electron is removed?

Positive

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This type of radiation occurs when a high speed electron interacts with the charge of the nucleus

Brems

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What is the energy of Brems photon?

Equal to the amount of energy lost by the projectile electron

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The type of radiation occurs when a high speed electron interacts with a tungsten atom and ejects an inner shell electron

Characteristic

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What is the energy of the characterisitic photon?

Equal to the difference between the electron binding energies of the orbital shell that contained the vacancy and the orbital shell that filled the vacancy

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Smallest bit of electromagnetic energy is:

Quantum or photon

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What is frequency measured in?

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What is the relationship between frequency and wavelength?

Inverse

What is the relationship between energy and and frequency?

Direct

What is secondary radiation?

Radiation that is emitted from atoms of matter (characteristic radiation)

What is remnant radiation?

Radiation exiting the patient

What are the fundaments of x-rays?

Travel in wave form Form of Electromagnetic energy Heterogeneous and polyenergetic (wide variety of wavelengths and energies) Travel in straight lines Can ionize matter Travel at the speed of light Contain no mass or electrical charge

What type of scatter is caused by partial absorption of the x-ray photon?

Compton

During compton scatter, the x-ray photon interacts with _______ shell electron

Outer

Compton interaction can result in foward scatter which results in:

Degradation of image contrast

Compton interaction can result in side scatter which results in:

Occupational exposure

Compton interaction can result in backward scatter which results in:

Patient exposure

What type of scatter occurs when the x-ray photon is absorbed?

Photoelectric

During photoelectric scatter, the x-ray photon interacts with _______ shell electron

Inner

What is the primary source of patient radiation exposure?

Photoelectric interaction

This type of scatter occurs when the x-ray photon interacts with the atom and excites the atom

Coherent (classical)

Unit of absorbed dose

Gray

1 Gray = ___ rads

100

Unit of dose equivalent

Sievert

1 Sv = ____ rems

100

Exposure is the unit of radiation exposure that will yield _______ coulombs/kg of air

2.58x10^-4

Unit of measurement of radioactivity

Becquerel

What is the type of dose-response curve that shows no amount of radiation is safe

Non-threshold

What is the type of dose-response curve that shows some amount of radiation is required before a measureable effect can take place

Threshold

What is the type of dose-response curve that shows that an observed response is directly proportional to the dose

Linear

What is the type of dose-response curve that shows that an observed response is no directly proportional to the dose

Non-linear (curvilinear)

What is the type of dose-response curve that shows a constantly varying slope

Sigmoidal

What is the type of dose-response curve are x-rays?

Non-thrsehold linear

What is the most radiosensitive cell in the body?

Lymphocyte

Law of Bergonie and Tribondeau states that radiosensitivity is increased or decreased with mitotic activity?

Increased

Law of Bergonie and Tribondeau states that radiosensitivity is increased or decreased with cell maturity?

Decreased

Law of Bergonie and Tribondeau states that radiosensitivity is increased or decreased with increased specialization?

Decreased

Rank the following in least radiosensitive to most radiosensitive Stem cell Muscle Lymphocyte Nerve

Nerve Muscle Stem cell Lymphocyte

Defines the rate of energy deposited per unit track length

Linear Energy Transfer (LET)

As LET increases, the quality factor for a given form of radiation will:

Increase

Defines the ability of aerobic conditions to enhance the effectiveness of radiation

Oxygen effect

Increasing the oxygenation of a cell, _________ the cell's sensitivity to radiation

Increases

What is the oxygen enhancement ratio for human tissue?

3.0

Defines the ability to produce biologic damage

Relative Biologic Effectiveness (RBE)

Increasing the LET of radiation will result in a/an _________ of RBE

Increase

Are diagnostic x-rays considered low or high LET?

Low

As LET increases, CSR will

decrease

Radiation interaction with water

Radiolysis

What is a free radical?

Highly reactive and unstable substance

Free radicals can combine to form toxic substances such as hydrogen peroxide. What is the chemical compound of hydrogen peroxide?

OH*+OH* H2O2

Radiation is __________ (indirectly/directly) the cause of biologial damage

Indirectly

Interphase death is also known as:

Apoptosis

What is interphase death?

Cell dies without attempting to divide

What is mitotic death?

Cell goes through one or two mitotic phases and then dies

What are the phases of mitosis?

Interphase Prophase Metaphase Anaphase Teleophase

What phase of mitosis is the cell most sensitive?

Metaphase

What happens in interphase?

DNA is copied

What happens in prophase?

Chromosomes pair up

What happens in metaphase?

Choromosomes line up at the equator

What happens in anaphase?

Sister chromatids pull apart

What happens in telophase?

Cell pinches in the middle and two identical daughter cells are formed

At what absorbed dose can a mitotic delay occur?

10 mGy

At what absorbed dose can reproductive failure occur?

1000-10000 mGy

Epilation, nausea, vomitting, erythema, fatigue, and epistaxis are examples of what type of effects?

Short term

Does acute or chronic exposure result in a greater life span shortening?

Acute (large dose over a short period of time)

How many grays = 10 days of life span shortening

10 mGy

What is the most radiosensitive part of the eye?

Lens of the eye

Cataracts follow what type of dose-response curve?

Nonlinear, threshold

Thyroid follows what type of dose-response curve?

Linear, nonthreshold

Breast follows what type of dose-response curve?

Linear, nonthreshold

Skin follows what type of dose-response curve?

Threshold

What dose can cause permanent sterility in males?

5-6 Gy

What dose can cause genetic mutations in males?

100 mGy

What is carcinogenesis?

Cancer formation after long exposure to radiation

What is the difference between local and general somatic effects?

Local is limited to the exposed individual and the specific area of exposure General is the radiation effects of the whole body

Are stochastic effects threshold or nonthreshold?

Nonthreshold

What are the 3 reasons children are especially sensitive to radiation?

Cells reproduce more frequently Longer life expectancy which gives long-term somatic effects time to develop Larger percentage of body is exposed to radiation

Hemopoietic syndrome (bone marrow syndrome) occurs with exposure doses ranging between:

1-10 Gy

When does death occur during hemopoietic syndrome?

3-6 weeks

Gastrointestinal syndrome occurs with exposure doses ranging between:

10-50 Gy

What are symptoms of GI syndrome?

Nausea, vomitting, fatigue

When does death occur with GI syndrome?

One week after exposure

Central nervous system syndrome (cardiovascular) occurs with exposure doses over:

50 Gy

When does death occur with CNS syndrome?

Within hours or day

Radiation Physics and Radiobiology Flashcards

(101 cards)