Rad 260: Safety

Question 1

Ionizing radiation

Answer 1

radiation that possesses the ability to remove electrons from atoms by a process called ionization

Question 2

Somatic effects

Answer 2

effects of radiation on the body being irradiated

Question 3

Genetic effects

Answer 3

effects of radiation on the genetic code of a cell; affects the next generation

Question 4

Natural background radiation

Answer 4

radiation contained in the unpolluted environment

Question 5

Artificially produced radiation

Answer 5

also called man-made radiation (e.g., medical x-rays)

Question 6

Primary radiation

Answer 6

radiation exiting the x-ray tube

Question 7

Exit radiation

Answer 7

(remnant radiation; image-producing radiation) x-rays that emerge from the patient and strike the image receptor

Question 8

Attenuation

Answer 8

absorption and scatter (loss of intensity) of the x-ray beam as it passes through the patient

Question 9

Heterogeneous beam

Answer 9

x-ray beam that contains photons of many different energies

Question 10

Photoelectric effect

Answer 10

absorption of x-ray photons in the atoms of the body

Question 11

Compton effect

Answer 11

scatter of x-ray photons from the atoms of the body

Question 12

Air kerma

Answer 12

unit of exposure

Question 13

Gray

Answer 13

unit of absorbed dose, measured in joules per kilogram (J/kg); 1 Gy = 1 J/kg

Question 14

Gray(a)

Answer 14

unit of radiation absorbed in air

Question 15

Gray(t)

Answer 15

unit of radiation absorbed in tissue

Question 16

Sievert

Answer 16

unit of effective/equivalent dose

Question 17

Becquerel

Answer 17

unit of activity

Question 18

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

Answer 18

organization that studies biological effects of ionizing radiation and publishes resulting data

Question 19

International Commission on Radiologic Protection (ICRP)

Answer 19

organization that publishes international radiation protection guidelines

Question 20

National Council on Radiation Protection and Measurements (NCRP)

Answer 20

organization that publishes radiation protection guidelines for the United States

Question 21

Nuclear Regulatory Commission (NRC)

Answer 21

organization that enforces radiation protection standards at the federal level related to use of radioactive material

Question 22

NCRP Report #102

Answer 22

makes recommendations on equipment design and protection regarding lead shielding and fluoroscopic and mobile exposure rates

Question 23

NCRP Report #116

Answer 23

defines annual exposure limits; makes recommendations pertaining to risk–benefit analysis of radiation exposure; states that somatic and genetic effects should be kept to a minimum when radiation is used for diagnostic imaging

Question 24

Effective dose limit

Answer 24

upper boundary dose that can be absorbed, either in a single exposure or annually, with a negligible risk of somatic or genetic damage to the individual; effective dose implies whole-body radiation exposure

Question 25

Cumulative effective dose

Answer 25

lifetime occupational exposure must not exceed the radiographer’s age multiplied by 10 mSv

Question 26

Equivalent dose

Answer 26

equal to the effective dose multiplied by the radiation weighting factor

Question 27

As low as reasonably achievable (ALARA)

Answer 27

concept of radiologic practice that encourages radiation users to adopt measures that keep the dose to the patient and themselves at minimal levels

Question 28

Dose-response curves

Answer 28

graphs that illustrate the relationship between radiation dose and the response of the organism to exposure; may be linear or nonlinear, threshold or nonthreshold

Question 29

Stochastic (probabilistic) effects

Answer 29

randomly occurring effects of radiation; the probability of such effects is proportional to the dose (increased dose equals increased probability, not severity, of effects)

Question 30

Tissue reactions (deterministic)

Answer 30

effects of radiation that become more severe at high levels of radiation exposure and do not occur below a certain threshold dose

Question 31

Linear energy transfer (LET)

Answer 31

amount of energy deposited by radiation per unit length of tissue

Question 32

Relative biological effectiveness (RBE)

Answer 32

ability to produce biological damage; varies with the LET

Question 32

Direct effect

Answer 32

effect that occurs when radiation directly strikes DNA in the cellular nucleus

Question 33

Indirect effect

Answer 33

effect that occurs when radiation strikes the water molecules in the cytoplasm of the cell

Question 34

Radiolysis of water

Answer 34

effect that occurs as radiation energy is deposited in the water of the cell; the result of radiolysis is an ion pair in the cell: a positively charged water molecule (HOH+) and a free electron

Question 35

Mutation

Answer 35

erroneous information passed to subsequent generations via cell division

Question 36

Law of Bergonié and Tribondeau

Answer 36

cells are most sensitive to radiation when they are immature, undifferentiated, and rapidly dividing

Question 37

Early somatic effects of radiation

Answer 37

hematopoietic syndrome; gastrointestinal (GI) syndrome; central nervous system syndrome

Question 38

Late somatic effects of radiation

Answer 38

carcinogenesis; cataractogenesis; embryologic effects; thyroid dysfunction; life span shortening

Question 39

Cardinal principles of radiation protection

Answer 39

distance, time, shielding

Question 40

Distance

Answer 40

best protection against radiation exposure

Question 41

Personnel monitoring devices

Answer 41

optically stimulated luminescence (OSL) badge, thermoluminescent dosimeter (TLD), digital ionization dosimeter