Lecture 4

Question 1

What organizations are over radiation?

Answer 1

International commission on radiation protection (ICRP) and national council on radiation protection and measurements (NCRP)

Question 2

What do the ICRP and NCRp do?

Answer 2

Collect and analyze data regarding ionization radiation and put forth recommendations on radiation protection

Question 3

What are the different federal regulatory groups over radiation

Answer 3

NRC, FDA, FEMA, OSHA, EPA

Question 4

Which organization regulated radiation in AL?

Answer 4

Alabama Department of Public Health Office of Radiation

Question 5

Radiation interaction with matter

Answer 5

Water is key to radiation damage producing free radicals

Question 6

Indirect radiation damage

Answer 6

Inside cell HO- + HO- form hydrogen peroxide free radical (H2O2)
Migrates to nucleus and causes damage

Question 7

Direct radiation damage

Answer 7

Damage to DNA subsequent to impact from a high energy photon

Question 8

Deterministic effects of radiation exposure (non- stochastic)

Answer 8

Minimum threshold dose must be attained for the effect to occur (above causes deaths or degeneration of a large # of cells)
Ex: hair loss, cataract, skin, sterility

Question 9

Stochastic effects of radiation exposure

Answer 9

May occur after any amount of exposure (no threshold)
Ex: leukemia and genetic defects

Question 10

Early/ acute radiation injury reactions

Answer 10

In proliferating, renewing tissues (mm, skin, GI, BM) within days or weeks
Could be reversible

Question 11

Acute radiation syndrome

Answer 11

BM: @ lowest radiation dose, whole body dose 3-8Gy)
GI: whole body exposure (>10Gy)
CNS: whole body >100Gy

Question 12

Late effects of radiation injury

Answer 12

After months or years in slowly or non prolif. Tissues (CNS, kidney, liver, lung)
Improves but never repaired
Myelopathy and lung fibrosis

Question 13

Shielding

Answer 13

PPE equipment
Lead apron (0.5mm), gloves (0.25mm), thyroid shield (0.5mm), eyewear (0.35mm)

Question 14

Maximizing distance

Answer 14

Double the distance, 25% the exposure by a factor of 4

Question 15

Exposure

Answer 15

Total electrical charge per unit mass of dry air generated by x or gamma rays (energy)
Unit: roentgen (R)

Question 16

Absorbed dose

Answer 16

Amount of energy per unit mass, absorbed by the irradiated object
Unit: rad
SI unit: Gray (1gy = 100 rads)

Question 17

Dose equivalent

Answer 17

A measure of radiation specific biological damage (in humans)
Unit: rem
SI unit: Sievert (1 Sv=100 REM)

Question 18

Occupational dose limits for adults working radiation areas

Answer 18

NCRP guidelines state that 5rem per year is a maximum permissible dose

Question 19

Occupational dose limits for General public

Answer 19

The dog should not exceed 1mSv/ year

Question 20

Radiation exposure (in rem) for diagnostic exposures with small animal cases

Answer 20

Cervical spine: 0.002
Extremity : 0.001
Chest (2 views): 0.00007
Abdominal (multiple views): 0.245

Question 21

Occupational dose limits for embryo or fetus declared in pregnant individuals

Answer 21

The dose should not exceed 5 mSv

Question 22

Computed Tomography (CT) and Fluoroscopy (C-RAM)

Answer 22

Higher radiation doses
CT exams must be justified
Additional training required before use

Question 23

How id kVp determined?

Answer 23

Measure patient @ thickest pt. to be radiographed
kVp= (2 x cm) + 50
add 2 kVp for each cm up to 80 and add 3 after

Question 24

What happens if the image is overexposed?

Answer 24

↓ kVp by 10-15%
↓ mAs by 1/2