Chapter 4: Radiation Biology

Question 1

ionization

Answer 1

is produced through the photoelectric effect of Compton scatter and results in the formation of a positive atom and a dislodged negative ion

Question 2

roentgen

Answer 2

• measure of radiation based on the amount of ionization occurring in air
• 1 R= ≈2 billion (2.08 x 10^9) ion pairs in 1 cubic sm (cm^3) of air
• does not describe the amount of radiation absorbed by matter.

Question 3

exposure rate

Answer 3

dose of exposure/unit of time

Question 4

Radiation Absorbtion Dose (RAD)

Answer 4

• traditional unit of measuring the amount of radiation energy absorbed by matter
• 1 rad = 100 ergs of energy per gram of tissue (100erg/g)

Question 5

Roentgen Equivalent Man (REM)

Answer 5

• Traditional unit of measurement used to compare BIOLOGICAL effects of different kinds of radiation in the human body
• multiply rad by a weighted constant specific to the type of radiation

Question 6

Curie (Ci)

Answer 6

traditional unit of radioactivity 1 Ci = 3.7 x 10^10 decays per second

Question 7

Gray (Gy)

Answer 7

• SI equivalent to rad (amount of energy absorbed by the tissue)
• 1 Gy = 100 rads

Question 8

Sievert (Sv)

Answer 8

• SI equivalent to rem (biological effects of radiation)

- 1 Sv = 100 rems

Question 9

Becquerel (Bq)

Answer 9

• SI equivalent to curie (measure of radioactivity)
• = 1 nucleus decay per second
• 1 Ci = 3.7 x 10^10 Bq

Question 10

true or false; any dose of radiation, no matter how small, may have a biological effect

Answer 10

true

Question 11

true or false; biological effects are caused by all types of ionizing radiation

Answer 11

true

Question 12

direct theory

Answer 12

suggest that cell damage results when ionizing radiation directly hits critical areas, or targets, within the cell

Question 13

indirect theory

Answer 13

suggests that x-ray photons are absorbed within the cell and cause the formation of toxins, which in turn damage the cell

Question 14

critical organ

Answer 14

an organ that, if damaged, diminishes the quality of a person’s life. Critical organs exposed during dental imaging procedures in the head and neck region include the following:

• thyroid gland
• bone marrow
• skin
• lens of the eye

Question 15

Linear Energy Transfer (LET)

Answer 15

Amount of energy that an ionizing particle transfers to a material as it travels over a distance

Question 16

Does higher LET or lower LET confer more biological effects?

Answer 16

higher LET

Question 17

higher LET radiations

Answer 17

• alpha particles
• protons
• neutrons

Question 18

lower LET radiations

Answer 18

• electrons
• positrons
• gamma rays
• x-rays

Question 19

radiation weighting factor (Wr)

Answer 19

• Formerly Quality Factor
• value specific to each radiation type
• used to determine the equivalent dose for uniform whole-body exposure

Question 20

tissue weighting factor (Wt)

Answer 20

• value specific to the sensitivity of each tissue type

- used to determine effective dose based on individual organs/tissue exposed

Question 21

somatic effects

Answer 21

• are seen in a person who has been irradiated
• non-reproductive cells
• the exposed organism becomes ill but no genetic transmission

Question 22

genetic effects

Answer 22

• are not seen in the irradiated person but are passed on to future generations
• no illness in organism
• damage in the next generation

Question 23

name a factor in environmental exposure/contamination

Answer 23

low-level radiation exposure

Question 24

MPD

Answer 24

“maximum permissible dose”, maximum dose equivalent that a body is permitted in a specific period.

Question 25

The MPD for an occupationally exposed adult individual is

Answer 25

50 mSv/year (0.05 Sv/year, 5.0 rem/year)

Question 26

the MPD for a nonoccupationally exposed adult individual is

Answer 26

1 mSv/year (0.1 rem/year)