Chapter 13- Management Of Imaging Personnel Radiation Dose During Diagnostic X-Ray Procedures

Front 1

What is a controlled area?

Back 1

areas where only radiology employees are allowed and not the public

Front 2

Weekly controlled area dose?

Back 2

1 mSv

Front 3

What is an uncontrolled area?

Back 3

areas of the radiology department where the public are allowed to occupy

Front 4

Weekly uncontrolled area dose?

Back 4

.02 mSv

Front 5

Workload (W)

Back 5

essentially the radiation output-weighted time the unit is actually delivering radiation during the week

Front 6

Inverse Square Law

Back 6

Intensity of an X-ray beam is lessened as the distance from source increases

Front 7

Use factor (U)

Back 7

quantity that was introduced to select the fractional contact time that most structures in diagnostic X-ray suite are struck by radiation to some degree for some fraction of the weekly beam-on time

Front 8

Another name for Use factor

Back 8

beam direction factor

Front 9

Occupancy factor (T)

Back 9

used to modify the shielding requirement for a particular barrier by taking into account the fraction of the work week during which the space beyond the barrier is occupied

Front 10

At a ___ degree angle to the primary x-ray beam at a distance of ___ m, the __________ x-ray intensity is generally approx __/_____ of the intensity of the primary x-ray beam.

Back 10

90, 1, scattered, 1/1000

Front 11

0.25 mm lead equivalent

Back 11

-mammo apron

-gloves

-spot film protective curtain

-bucky slot cover

Front 12

0.35 mm lead equivalent

Back 12

-glasses

Front 13

0.5 mm lead equivalent

Back 13

-aprons

-thyroid shields

-clear lead overhead barriers

Front 14

1.5 mm lead equivalent

Back 14

observation window

Front 15

primary protective barrier definition

Back 15

prevent direct, or unscattered, radiation from reaching personnel or members of the general public on the other side of the barrier

Front 16

primary protective barrier location

Back 16

perpendicular to undeflected line of travel of x-ray beam

Front 17

primary protective barrier specifications

Back 17

-1/16 inch (1.6 mm) lead

-7 feet (2.1 m) off ground

Front 18

secondary protective barrier definition

Back 18

protects against secondary radiation (leakage & scatter radiation)

Front 19

secondary protective barrier location

Back 19

any wall or barrier that is never struck by primary beam

Front 20

secondary protective barrier specifications

Back 20

-1/32 inch (0.8 mm) lead

-7 feet (2.1 m) off ground

- overlap primary by 1/2 inch (1.27 cm)

Front 21

poses the greatest occupational hazard in diagnostic radiology

Back 21

scattered radiation

Front 22

lead apron style that would afford the best protection

Back 22

wrap-around

Front 23

dose reduction methods & techniques (4)

Back 23

1.

-higher kVp (↑ mean energy photons in beam)

-lower mAs (↓ photon beam intensity)

2.

-avg energy beam ↑

-% radiation fwd scattered ↑

-less side-scatter to strike personnel

-EqD is reduced

3.

-use high-speed image receptor systems

4.

-require less mA

-fewer photons to produce compton scatter

-↓ personnel exposure

Front 24

Occupational annual dose limit

Back 24

50 mSv

Front 25

Occupational cumulative dose limit

Back 25

age x 10 mSv

Front 26

Occupational annual lens of eye dose limit

Back 26

150 mSv

Front 27

Occupational annual skin, hands, & feet dose limit

Back 27

500 mSv

Front 28

Nonoccupational annual frequent exposure dose limit

Back 28

1 mSv

Front 29

Nonoccupational annual infrequent exposure dose limit

Back 29

5 mSv

Front 30

Nonoccupational annual lens of eye dose limit

Back 30

15 mSv

Front 31

Nonoccupational annual skin, hands, & feet dose limit

Back 31

50 mSv

Front 32

Education and training annual dose limit

Back 32

1 mSv

Front 33

Education and training annual lens of eye dose limit

Back 33

15 mSv

Front 34

Education and training annual skin, hands, & feet dose limit

Back 34

50 mSv

Front 35

Embryo and fetus monthly dose limit

Back 35

0.5 mSv

Front 36

Embryo and fetus entire pregnancy dose limit

Back 36

5 mSv

Front 37

3 cardinal principles for personnel to minimize occupational radiation exposure

Back 37

time, distance, & shielding

Front 38

Time

Back 38

decrease length of time spent in room where x-radiation is being produced

Front 39

Distance

Back 39

standing at greatest distance possible from an energized x-ray beam

Front 40

Shielding

Back 40

interposing a radiation-absorbent shielding material between the radiation worker & the source of radiation

Front 41

most effective of the 3 cardinal principles for exposure

Back 41

distance

Front 42

Inverse Square Law

Back 42

intensity of radiation is inversely proportional to the square of the distance from the source

Front 43

2 times distance equals

Back 43

1/4 intensity

Front 44

3 times distance equals

Back 44

1/9 intensity

Front 45

4 times distance equals

Back 45

1/16 intensity

Front 46

effectiveness of shielding material depends on

Back 46

atomic number, density, thickness

Front 47

purpose of control booth barrier

Back 47

protect radiographer from secondary radiation (leakage & scatter)

Front 48

Diagnostic x-rays should scatter a minimum of how many times before reaching any area behind the control booth barrier?

Back 48

twice

Front 49

methods & devices for dose reduction during fluoroscopy

Back 49

-adequate beam collimation

-adequate filtration

-adequate gonadal shielding

-control of technical exposure factors

-use of high-speed IR systems

-appropriate SSD

-use of a cumulative timing device

-diagnostic-type protective x-ray tube housing

Front 50

Mobile x-ray units cord must be long enough to permit radiographer to stand how far from the patient?

Back 50

at least 2 m (6 feet)

Front 51

When doing mobile radiography, attempt to stand at what angle to the x-ray beam?

Back 51

right angle (90 degrees)

Front 52

For increased radiation safety it is best to place the x-ray tube of the C-arm ______ the table and the image intensifier ______ the table.

Back 52

under, over

Front 53

Exposure reduction for personnel during C-Arm Fluoroscopy

Back 53

-minimize beam-on time to reduce exposure

-set unit's cumulative time to 0 at the start

-image storage device (last image hold)

-image intensifier end close to patient as possible

-orient patient's anatomy correctly

-collimate beam to smallest area possible

-distance

-foot pedal/hand-held switch

-magnification feature sparingly

Front 54

3 categories of radiation sources from x-ray room

Back 54

primary radiation, scatter radiation, leakage radiation

Front 55

known collectively as secondary radiation

Back 55

scatter & leakage radiation

Front 56

"Caution Radiation Area" sign posted

Back 56

area where radiation levels could result in individual receiving a dose equivalent in excess of 0.05 mSv in 1 hour at 30 cm from source

Front 57

"Caution High Radiation Area" sign posted

Back 57

area where radiation levels could result in individual receiving a dose equivalent in excess of 1 mSv in 1 hour at 30 cm from source

Front 58

"Grave Danger, Very High Radiation Area" sign posted

Back 58

radiation levels could result in individual receiving an absorbed dose in excess of 5 Gy in 1 hour at 1 m from source