Chapter 6 second half Flashcards
How tall must primary protective barriers be?
at least 7 ft tall
Leakage radiation from the x-ray tube housing shall not exceed ____ mR/hr at a distance of 1 meter from the tube
100
Lead aprons worn during a mobile exam must have a lead equivalency of at least _____ mm.
0.5
The cardinal rules of radiation protection include
- time
- distance
- shielding
When wearing a lead apron, a pregnant radiographer is required to wear their fetal dosimeter
at the waist level, inside the lead apron
Factors which determine protective barrier thickness include:
- time occupancy
- workload
- use
Applying the inverse square law, if we double our distance from the source, the intensity at our new distance is _____ as much as the original intensity
1/4
define primary protective barriers
- located perpendicular to the line of travel of the primary x-ray beam
- up to 140 kVp
- should consist of 1/16 in lead (Pb) or equivalent
define secondary protective barriers
- parallel to the line of travel of the x-ray tube
- cover areas exposed to scatter or leakage radiation
- require 1/32 inch lead (Pb) or equivalent
what are some examples of secondary protective barriers?
- plaster
- concrete
what is the average glass shielding?
- 1.5 mm Pb equivalent
define time of occupancy
- denotes the amount of time a hospital is occupied by people
- consists of controlled and uncontrolled
define controlled area (T)
- an area occupied by radiation personnel
- given a factor of 1
- a radiation worker is always present
define uncontrolled area (T)
- occupied by the general public (non-radiation personnel)
- designated as full, partial or orccasional
- hallway factor if 1/4
- stairways and elevators a factor of 1/16
what are some examples of uncontrolled areas?
- stairways
- unattended elevators
- outside areas
Uncontrolled area design limits require barriers to reduce the exposure rate to less than ____ mrem/week.
10
controlled area design limits require barriers to reduce the expo- sure rate to less than ____ mrem/week
100
define workload (W)
- which takes into account weekly average tube current and tube operating time,
- measured in milliampere-minutes/week (mA-min/wk)
define use factor (U)
- the percentage of time that the X-ray beam is energized and directed toward a particular wall.
define HVL
- half value layer
- lead thickness that will reduce the intensity of radiation by 50%
what causes a lead apron to be heavy?
- the lead equivalency of the apron
where should the personnel monitor be worn?
- at the collar level, outside of the lead apron
what type of aprons do pregnant women wear?
- long aprons that run from the xiphoid process (bottom portion of the sternum) to the pubic symphysis
how many personnel monitors do pregnant women wear? where are they placed?
- 2
- 1 is at the collar level, outside of the apron
- 1 is at the waist level, INSIDE the apron
how far is it recommended for the radiographer to stand away from the x-ray tube?
6 ft
what’s the formula for inverse square law?
I1/!2 = D2^2/D1^2
what are some examples of immobilizations?
- tape
- angle sponges
- sandbags
- foam pads
