9/30: Radiation Biology

Question 1

What are the radiation measurements?

Answer 1

Exposure dose
Absorbed dose
Equivalent dose
Effective dose

Question 2

This is a measure of the capacity of radiation to ionize air

Answer 2

Exposure

Question 3

What is the traditional and Metric unit for exposure?

Answer 3

Traditional: roentgen
Metric: air kerma

Question 4

This is the sum of the kinetic energy released in matter in exposure

Answer 4

Air kerma

Question 5

How is air kerma measured? What is the conversion?

Answer 5

coulomb/kg
1 R → 2.58 x 10^-4 coulomb/kg

Question 6

Roentgen produces how many ion pairs?

Answer 6

2.08 x 10^9

Question 7

What is RAD an acronym for?

Answer 7

Radiation absorbed dose

Question 8

What is the traditional and metric unit for absorption?

Answer 8

Traditional = RAD
Metric = Gy

Question 9

What is the conversion of RAD to Gy?

Answer 9

1 Gy→ 100 RAD

Question 10

This is to compare the biological effects of different types of radiation

Answer 10

Equivalent

Question 11

Radiation weighting factor depends on what?

Answer 11

Type and energy of the radiation involved

Question 12

What is the equation for equivalent dose?

Answer 12

Equivalent dose = absorbed dose + radiation weighting factor

Question 13

This is a measure of the biological effectiveness of a radiation to ionize matter

Answer 13

Quality factor

Question 14

What is the QF for x-radiation?

Answer 14

1

Question 15

REM is equivalent to what?

Answer 15

RAD x QF

Question 16

What are the traditional and metric units for Equivalent dose?

Answer 16

Traditional = REM
Metric = Sv

Question 17

What is the conversion for equivalent dose?

Answer 17

1 Sv = 100 rem

Question 18

This is used to calculate risk of radiation to human tissues on a common scale. The calculation is a product of the sum of dose equivalence to the specific tissue exposed and the biological tissue weighting factor

Answer 18

Effective dose

Question 19

What is the equation for effective dose?

Answer 19

Effective = W x H (tissue weight factor x equivalent dose)

Question 20

The use of the effective dose allows comparisons of what?

Answer 20

Different imaging techniques or be made on a common scale

Question 21

This is used to assess risk of non-uniform radiation to localized part of body and degree to which this would increase a person’s “whole body” risk of cancer induction and/or induction of genetic mutations

Answer 21

Effective dose

Question 22

Area exposed related to what?

Answer 22

Maximum size of the beam

Question 23

This is the interaction of X-radiation with matter

Answer 23

Ionization

Question 24

List all the types of ionization

Answer 24

No interaction: 9%
Coherent scattering: 7%
Photoelectric absorption: 27%
Compton scattering: 57%

Question 25

What ionization has the most effect?

Answer 25

Compton scattering

Question 26

This is when the x-ray photon enters object and exits with no change

Answer 26

No interaction

Question 27

This is when x-ray photon collides with an electrons and losses its energy, atoms state is altered

Answer 27

Photoelectric

Question 28

This is when an Xray photon collides with an outer orbital electron losing some energy, photon continues with less snergy, creating more scatter until all energy is lost

Answer 28

compton scattering

Question 29

This is when a photon interacts with an electron and changes directions, no change

Answer 29

Coherent scattering

Question 30

This ionization directly ionizes biological macromolecules

Answer 30

Direct effect

Question 31

This ionization has its photons absorbed by water → free radical → damage

Answer 31

Indirect effect

Question 32

How does direct and indirect contribute to biological effects?

Answer 32

Direct = ⅓ Indirect = ⅔

Question 33

What is the outcome of the direct effect of UV light on skin DNA?

Answer 33

Repair Inaccurate repair No repair

Question 34

What is the primary method of cell damage that results from radiolysis of water?

Answer 34

Indirect effect

Question 35

This is a free atom or molecule carrying an unpaired orbital electron in the outer shell

Answer 35

Free radical

Question 36

How do you get toxic substances from free radicals?

Answer 36

Want a stable structure so that causes toxic substances

Question 37

What are the types of dose-response curves?

Answer 37

Non-linear threshold Linear non-threshold Non-linear, non-threshold

Question 38

Describe non-linear threshold

Answer 38

Small doses have no effect until a threshold is met, then you get rapid response

Question 39

Describe linear, non-threshold curves

Answer 39

No threshold and dose is proportional to response

Question 40

Describe non-linear, non-threshold curves

Answer 40

Dose does not require threshold and it is not proportional to response

Question 41

Deterministic effects of radiation have a

Answer 41

Threshold and severity is proportional to dose

Question 42

This is a side-effect of head and neck cancer treatment

Answer 42

Radiation erythema

Question 43

Stochastic effects of radiation have

Answer 43

No dose threshold and probability of occurrence is proportional to dose but severity not on dose

Question 44

1 day of background radiation is how much exposure?

Answer 44

8.5 microSv

Question 45

Stochastic effects to somatic cells cause what?

Answer 45

malignancies

Question 46

Stochastic effects to germ cells cause what?

Answer 46

Genetic mutations that are inheritable

Question 47

This effect is only seen in the person affected, NOT future generations

Answer 47

Somatic mutations/effects

Question 48

This effect is not seen in the person affected, ONLY in future generations

Answer 48

Genetic effects/mutations

Question 49

What is the sequence of radiation injury?

Answer 49

Latent period Period of injury Period of recovery

Question 50

How can you have a shorter latent period?

Answer 50

Larger dose

Question 51

What factors modify effects on radiation?

Answer 51

Total dose Dose rate Oxygen Area exposed Cell type and function Age

Question 52

Who is at risk for radiation in terms of age?

Answer 52

Pediatric patients