lesson 3 Flashcards
- not exceed (21mGYA/min)(2.1R/min)
- for each mA operation at 80kVp
tabletop
- not exceed (100mGya/min)(10R/min)
- max table top dose
no optional high level control
- (200mGya/min)(20Rmin)
- boost fluoroscopy
with optional high level control
no limit on x-ray intensity when image is recorded
Cineradiography or videography
- energy deposited locally
- the quantity that best reflects the potential for injury to that tissue
tissue radiation dose
- this radiation is the most intense, hazardous and difficult to shield
- useful beam
primary beam (other is secondary radiation)
when beam intercepts any objects causing some x-ray to scatter
scatter radiation
radiation emitted from the x-ray tube housing in all direction other than that of the useful beam
leakage radiation
assist for the design of proper radiation shielding
medical physicist
any wall to which the useful beam can be directed
primary barrier
examples of primary barrier
- lead bonded
- sheetrock
- wood paneling
designed to shield areas from secondary radiation
- operating console
- barrier
- ceiling
- walls
secondary protective barrier
examples of less thick than primary radiation barrier
- gypsum board
- glass
- lead acrylic
factors that affect barrier thickness
- distance
- occupancy
- control, workload
- use factor
- kVp
distance between the source of radiation and the barrier
distance
must be positioned in the middle of the room
x-ray imaging system
the use of the area that is being protected is of principal importance
(40 hours per week = more shielding, office, and lab)
occupancy
length of time that the area being protected is used
time occupancy factor (T)
an area occupied primarily by radiology personnel and patient
controlled area or CONTROL
area that is occupied by anyone
uncontrolled area
- express in 9mAmin/week) milliAmpere-minutes per week
level of radiation activity in the room
workload (W)
percentage of time during which the x-ray beam is on and directed toward a particular protective barrier
use factor (U)
- used as a measurement of penetrability
- final consideration in the design of the protective barrier
kVp
kVp of the ff:
- general radiography
- mammography
- modern x-ray
- most examination
- 100kVp
- 30kVp
- 150kVp
- 75kVp