RAD 260: Saftey

Question 1

Unit of absorbed dose

Answer 1

1.Amount of energy absorbed per unit mass of tissue
2.Unit of measurement of tissue is gray (Gy); normally expressed as Gyt (t indicates tissue)

Question 2

Mutation

Answer 2

Erroneous information passed to subsequent generations via cell division

Question 3

Free radicals

Answer 3

Highly reactive ions that have an unpaired electron in the outer shell

Question 4

Late tissue reactions (deterministic) include:

Answer 4

1.Cataractogenesis: Causes cataracts to form
2.Thyroid: cancer or cessation of function
3.Effect on fertility

Question 5

Two types of filtration:

Answer 5

inherent and added

Question 6

Added Filtration

Answer 6

1.Aluminum sheets placed in the path of the beam near the x-ray tube window
2.Mirror placed in the collimator head

Question 7

Inherent filtration

Answer 7

1.Glass envelope of the x-ray tube
2.Insulating oil around the tube
3.Diagonal mirror used for positioning light

Question 8

Measuring patient dose

Answer 8

Skin entrance dose
2.Mean marrow dose (MMD)

Question 9

Mean Marrow Dose (MMD)

Answer 9

Average dose to active bone marrow

Question 10

Three Cardinal Principals

Answer 10

Time, Distance, Shielding

Question 11

Primary protective barriers

Answer 11

Must be at least -inch lead equivalent and extend from the floor to a height of 7 feet

Question 12

Secondary protective barriers

Answer 12

Must be at least -inch lead equivalent and extend from the primary protective barrier to the ceiling with a ½-inch overlap

Question 13

Determinants of barrier thickness

Answer 13

Distance, occupancy, workload, use

Question 14

Handheld ionization chamber:

Answer 14

Used to measure radiation in an area; measures doses of 10 μGya per hour

Question 15

Geiger-Mueller detector:

Answer 15

Used to detect radioactive particles; meter reads in counts per minute

Question 16

Air Kerma
(units of exposure)

Answer 16

Used to define radiation exposure or radiation delivered to a specific point, measured in Gy

Question 17

Coloumbs/kilograms
(units of exposure)

Answer 17

Sometimes used to measure exposure, but preferred unit is air kerma

Question 18

General types of radiation damage

Answer 18

Somatic and Genetic

Question 19

Somatic

Answer 19

damage to the exposed individual

Question 20

Genetic

Answer 20

Damage to the genetic code of the germ cell contained in the DNA; may be passed to the next generation

Question 21

Natural background radiation

Answer 21

1. Contributes 3.0 mSv
2. Approx. 48%

Question 22

Largest source of natural background

Answer 22

radiation

Question 23

Medical background radiation

Answer 23

1. Contributes 3.2 mSv
2. Approximately 50% of total radiation dose

Question 24

Pair Production

Answer 24

Does not occur with radiography

Question 25

Linear-nonthreshold relationship

Answer 25

 Indicates that no level of radiation can be considered completely safe b. A response occurs at every dose c. The degree of response to exposure is directly proportional to the amount of radiation received

Question 26

 Linear-threshold relationship

Answer 26

a. Indicates that at lower doses of radiation exposure (to the left of the line intersecting the x-axis), no response is expected b. When the threshold dose is exceeded, the response is directly proportional to the dose received c. As an example, cataractogenesis does not occur at low levels of radiation exposure; there is a threshold dose below which cataractogenesis does not occur

Question 27

 Nonlinear-threshold relationship

Answer 27

a. Indicates that at lower doses of radiation exposure (to the left of the curve intersecting the x-axis), no response is expected b. When the threshold dose is exceeded, the response is not directly proportional to the dose received and is increasingly effective per unit dose

Question 28

 Nonlinear-nonthreshold relationship

Answer 28

 Indicates that no level of radiation can be considered completely safe b. A response occurs at every dose c. The degree of the response is not directly proportional to the dose received d. The effect is large even with a small increase in dose

Question 29

 Stochastic effects

Answer 29

Randomly occurring effects of radiation; the probability of such effects is proportional to the dose

Question 30

Tissue reactions

Answer 30

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