# Shared Flashcard Set

## Details

Equipment Specifications II
Protective barriers, apparel, fluoro and mobiles/portables
25
Physics
12/14/2008

Term
 What types of radiation are primary barriers and secondary barriers designed protect against?
Definition
 Primary: primary or useful beamSecondary: secondary (scatter + leakage)
Term
 Control booth walls are always designed to be what type of barriers?
Definition
 Secondary
Term
 How are primary barriers installed in relationship to the primary beam?
Definition
 Perpendicular to the CR.
Term
 What are the 5 factors in determining the thickness of protective barriers?
Definition
 1) Distance from x-ray source 2) Occupancy factor (T) 3) Workload (W) 4) Use factor (U) 5) Maximum kVp used in room
Term
 What is the relationship between distance from x-ray source and thickness of barrier?
Definition
 inverse (shorter distance, greater thickness)
Term
 The occupancy factor (T) is what?
Definition
 The amount of time the area behind the barrier is occupied.
Term
 What are the three types of occupancy factors?
Definition
 T=1 - 100% occupancy - any controlled areaT=1/4 - partial (25%) occupancyT=1/16 - occasional occupancy
Term
 What would the occupancy factor be for restrooms not routinely used by occupational workers, such as the bathroom attached to an x-ray room?
Definition
 T=1/4 or partial occupancy
Term
 What is the occupancy factor for restrooms NOT used by occupational workers?
Definition
 T=1/16 or occasional occupancy
Term
 What does workload measure? What unit is used?
Definition
 The amount of exposures and radiation output per week. The unit used is mA-minutes/week.
Term
 A busy room will have a workload of about _____ and require more shielding.
Definition
 1000 mA-minutes/week
Term
 Example problem for workload: A room is in operation 5 days a week, averaging 20 patients/day at 3 views per patient with average technique of 30 mAs/image. What is the workload?
Definition
 30 mAs/image x 5 days/week x 20 patients/day x 3 images/patient = 9,000 mAs/week divided by 60 seconds = 15 mA-minutes/week.
Term
 What is the use factor (U)?
Definition
 The percentage of time the x-ray beam is on and directed toward a particular barrier.
Term
 Another term for use factor is:
Definition
 Beam direction factor.
Term
 Which barriers are generally full use (U = 1)?
Definition
 Those routinely exposed to the useful (primary) beam - floors of x-ray rooms, doors, ceilings, and walls can all be full use, depending on the use of the room.
Term
 Which barriers are partial use (U = 1/4)?
Definition
 Doors and walls not routinely exposed to the primary beam, floor of a dental unit.
Term
 What type of barrier is occasional use (U = 1/16)?
Definition
 Ceilings of rooms not routinely exposed to primary beam.
Term
 What is the use factor for ALL secondary barriers?
Definition
 U = 1 (because scatter is constant.)
Term
 In a general purpose x-ray room, with the tube 5 to 7 feet from the barrier, how high should the primary barrier be?
Definition
 7.3 feet.
Term
 When must protective apparel be made available to be worn?
Definition
 When exposure rate could exceed 5 mR/hour.
Term
 Lead aprons must: Have a lead equivalence of _____ and cover _____% of active bone marrow
Definition
 Lead equivalence of 0.5 mm, cover 75% to 80% of active bone marrow.
Term
 Lead gloves must be what thickness?
Definition
 Required: 0.25 mm Pb equivalence. Preferred: 0.5 mm Pb equivalence
Term
 What is the requirement for thyroid shields?
Definition
 Must have 0.5 mm Pb equivalence. They are available in 1.0 mm thicknesses.
Term
 How much can wearing a thyroid shield reduce exposure to this gland?
Definition
 By 10 times or more.
Term
 What is the lead requirement for safety glasses?
Definition
 Must have 0.35 mm Pb equivalence.
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