Radiation Protection

Question 1

QA

Answer 1

human factor
repeat analysis
patient satisfaction

Question 2

QC

Answer 2

equipment operation

Question 3

genetically significant dose

Answer 3

EqD of population of childbearing age

Question 4

Annual effective dose for whole body as a radiation worker

Answer 4

50 mSv or 5 rem (5000 mrem)

Question 5

cumulative effective does of lifetime for radiation worker

Answer 5

Age x 10 mSv or 1 rem (1000 mrem)

Question 6

primary protective barrier

Answer 6

1.6mm (1/16 in) lead

Question 7

is lead shielding/glasses/etc considered primary or secondary protection?

Answer 7

secondary

Question 8

How do you protect yourself during fluoro, portables, OR?

Answer 8

distance from patient (6 feet)
wear lead
stand at right angle from pt

Question 9

Inadvertent radiation during early pregnancy - what dose is unlikely to affect embryo?

Answer 9

20 rad/0.2 Gy
studies say less than 1 rad/0.01 Gy

Question 10

What is the leakage radiation limit

Answer 10

100 mR/hr at 1 meter (3.3 ft) from the tube when tube is operated at highest kvp and mas

Question 11

how is tube housing benefit radiation protection

Answer 11

protects from off focus and leakage radiation
lead lined

Question 12

What is the air kerma rate?

Answer 12

0.88 mGy/hr

Question 13

How is the control panel helpful in radiation protection?

Answer 13

indicates when tube is energized by visual and audible tone
kvp and mas is visible on panel
located behind protection radiation absorbent barrier

Question 14

How is the exam table helpful in rad protection?

Answer 14

radiolucent material that absorbs minimal amount of radiation - reduces patient exposure
thickness is uniform - image quality

Question 15

How accurate does the SID indicator need to be?

Answer 15

Within 2% of SID in RAD room

Question 16

What is skin sparing?

Answer 16

keeping a safe distance between pt skin and the source of the primary beam

Question 17

What is the purpose of the spacer bars on the xray tube?

Answer 17

keeps tube from getting too close to the patient

Question 18

What is the minimum safe distance skin should be from the collimator box?

Answer 18

6 inches or 15cm

Question 19

What is PBL?

Answer 19

automatic collimation
collimation does not exceed the size of the IR

Question 20

What is the purpose of filtration?

Answer 20

hardens the beam
increases quality

Question 21

Inherent/intrinsic filtration is…

Answer 21

approx 1.5mm of AL filtration equivalent before leaving the collimator

Question 22

Added filtration is…

Answer 22

outside the glass housing above the first set of collimators

Question 23

Total Filtration = ___ + ____

Answer 23

inherent filtration
added filtration

Question 24

Total filtration is how thick?

Answer 24

2.5mm of AL equivalent for rooms using 70+ kvp
3-4 mm of AI or AL for fluoro rooms (higher kvp)

Question 25

What is HVL?

Answer 25

Half Value Layer
thickness of absorber that decreases primary beam intensity by 50%

Question 26

A higher the HVL, the ____ (higher/lower) the average kev of the beam

Answer 26

higher

Question 27

Define exposure reproducibility.

Answer 27

ability for xray unit to duplicate radiographic exposures for any given combo of kvp, ma, and time

Question 28

How do you test exposure reproducibility?

Answer 28

use the same techniques to make multiple exposures
variance of 5% or less

Question 29

Define exposure linearity.

Answer 29

measures how the radiation output in mR/mSv changes when mA and time combos change (but mAs stays the same)

Question 30

What is the range that radiation output can vary while keeping true exposure linearity?

Answer 30

+/- 10%

Question 31

What is the source to skin (SSD) distance for mobile radiography?

Answer 31

need at least 12 inches/30 cm from source (anode)