Chapter 15: MANAGEMENT OF IMAGING PERSONNEL DOSE DURING DIAGNOSTIC X-RAY PROCEDURES

Question 1

Exposure to the technologist is from what type(s) of radiation?

Answer 1

scatter and leakage radiation

Question 2

The annual limit for occupationally exposed personnel set by the NCPR and enforced by the NRC is ______

Answer 2

50mSv
or
5 Rem

Question 3

how is lifetime effective dose calculated?

Answer 3

lifetime effective dose =10mSv x age in years

Question 4

nonoccupational effective dose limit
infrequent:
frequent:

Answer 4

frequent: 1mSv (0.1 rem = 100 millirem)

infrequent: 5mSv (0.5 rem = 500 millirem)

Question 5

what is genetically significant dose?

Answer 5

the average gonadal EqD to members of the population of childbearing age

Question 6

ALARA is also refered to as:

Answer 6

ORP optimization for radiation protection

Question 7

what are some dose reduction methods and techniques?

Answer 7

limiting repeats
using appropriate technique
proper positioning
checking index numbers and making adjustments
knowing where to stand to limit scatter radiation dose
collimation
filtration (inherent/added/total)
protective apparel
restraint/ immobilization

Question 8

What is used to limit the amount of photons available to scatter, and therefore reduces the technologist dose?

Answer 8

collimation / PBL

Question 9

What is used to remove non useful, “soft rays” that are low energy and only contribute to patient dose?

Answer 9

filtration

Question 10

What type of things are considered inherent filtration? how much inherent filtration is required?

Answer 10

tube housing, oil, 1st set of shutters

1.5mm Al Eq

Question 11

how much added filtration is required for units capable of 70kvp + ?

Answer 11

1mm Al Eq

Question 12

What are the 3 thicknesses of lead equivalent in lead aprons?

what are each used for?

Answer 12

.25mm, .5mm, 1mm

.25 is more for mammography and dx radiology

.5mm is the minimum to be used for fluoroscopy

1mm is heavy and more often used in interventional radiology/ cath lab

Question 13

How is pregnancy handled within the radiology field?

Answer 13

should be able to continue working with proper radiation protection

if a VOLUNTARY declaration is made- it is recognized by the apartment- there is acknowledgement of counseling w RSO where a form is signed- additional radiation dosimeter is worn at waist inside of lead apron.

Question 14

What is the monthly EqD for the pregnant radiation worker?
EqD for full gestation?

Answer 14

monthly: 0.5mSv (50 millirem)
gestation: 5 millisieverts (500millirem)

Question 15

what type of protective maternity apparel is worn in radiology?

Answer 15

specially designed maternity lead apron (0.5mm) and a width with panel of 1mm lead equivalent for embryo-fetus/ wraparound .5mm lead can be worn

Question 16

basic principles of radiation protection:

Answer 16

TIME
DISTANCE
SHIELDING

Question 17

prevents direct (unscattered) radiation from hitting personnel//
barriers are perpendicular to undeflected line of photon travel

Answer 17

primary protective barrier

Question 18

120 kVp units require ______ mm(inches) of lead extending ______ meters (inches) up when tube is ______ meters(feet) from the wall.

overlap with secondary barrier is _______ cm (inches).

Answer 18

1.6mm (1/16”)
2.1 meters (7 ft)
1.5-2.1 meters (5-7ft)

1.27cm (1/2”)

Question 19

secondary protective barriers are used for _____ and ______ radiation and must be _____ mm (inches) of lead thickness

Answer 19

scatter and leakage

.8 mm (1/32 inches)

Question 20

doors must be closed and contain _______ mm lead.

Answer 20

.8mm (1/32”)

Question 21

The control booth barrier must extend ______ meters (ft) and be permanently secured to the floor

Answer 21

2.1 meters (7 feet)

Question 22

The control booth is considered a _________ barrier.

Answer 22

secondary

Question 23

thickness of lead equivalent within the window of the control booth must be _______ mm (inch)

Answer 23

1.5mm (1/6 inch)

Question 24

exposure of the radiographer is not to exceed ______ mSv per week- and ideally should be _____ mSv per week.

Answer 24

1mSv
0.02mSv

Question 25

clear lead-acrylic secondary protective barriers are used for ___________ and ___________ studies.
____% lead by weight
_____ to _____ mm lead equivalency and ______ meters fro the floor.

overhead barrier : _____ mm lead equivalency.

Answer 25

cardiac and interventional studies

30%
0.3- 2mm
2.1 meters
0.5mm

Question 26

lead thickness for aprons and gloves

Answer 26

0.25 mm or 0.5mm

Question 27

lead thickness for neck and thyroid shields

Answer 27

minimum of 0.5mm lead equivalent

Question 28

lead thickness for protective eyeglasses

Answer 28

0.35 mm lead equivalent

Question 29

during fluoroscopy, the safest place to be is

Answer 29

by the image intensifier – exit side)

Question 30

routine fluoroscopy exposure rate maximum is ___________

Answer 30

0.88 cGy/ min (10R /min)

Question 31

HLC can be _____ - _______ cGy/min.

Answer 31

20-40

Question 32

extremity monitoring should be monitored for __________studies of physicians and assistants.
EqD limit to skin and hands is ______ mSv ( rem)

Answer 32

500mSv (50rem)

Question 33

radiation shielding categories:

Answer 33

primary radiation & secondary radiation

Question 34

emerges directly from x-ray tube and moves without deflection toward wall, door, or window
* require primary barriers

Answer 34

primary radiation
aka “direct radiation”

Question 35

Compton interaction produces scatter in all directions
*require secondary barriers

Answer 35

Scatter radiation

Question 36

penetrates from the housing, possibly sides of collimator/ is considered with secondary barriers

Answer 36

leakage radiation

Question 37

calculation considerations for minimum thickness include:

Answer 37

workload(W)
inverse square law
use factor (U)
Occupancy factor(T)
controlled and uncontrolled areas