Kats Chapter 36
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Leakage radiation must be less than ____ mR/hr (__mGya/hr) at a distance of 1 m from the protective housing.
The SID indicator must be accurate to within ___% of the indicated SID
PBL stands for
positive-beam–limiting (PBL) devices
All general purpose diagnostic x-ray beams must have a total filtration (inherent plus added) of at least ____ mm Al when operated above 70 kVp.
Radiographic tubes operated between 50 and 70 kVp must have at least ___mm Al. Below 50 kVp, a minimum of ___ mm Al total filtration is required.
The SSD must be not less than ___ cm on stationary fluoroscopes and not less than __ cm on mobile fluoroscopes.
A protective curtain or panel of at least ___mm Pb equivalent should be positioned between the fluoroscopist and the patient
DAP stands for
Dose area product (DAP)
what is the regulatory limit of Leakage radiation is that radiation emitted from the x-ray tube housing
1 mGya/hr (100 mR/hr) at 1 m.
The percentage of time during which the x-ray beam is on and directed toward a particular protective barrier is called the ____ for that barrier.
use factor (U)
Most modern x-ray imaging systems are designed to operate at up to ____ kVp. Most examinations, however, are conducted at an average of ___ kVp.
Three types of gas-filled radiation detectors are?
- 1-ionization chambers,
- 2-proportional counters,
- 3-Geiger-Muller detectors
The use factor for secondary barriers is always?
keep radiation exposure as low as reasonably achievable.
Patient dose from diagnostic x-rays usually is reported in what three ways
- gonadal dose
- entrance skin dose
- bone marrow dose
ESD in fluoroscopy is much more difficult to estimate because ?
the x-ray field moves and sometimes varies in size.
Be able to apply
ALARA and the three cardinal rules of time, distance and shielding for both the
occupational worker and patient in both radiography and fluoroscopy exams.
Time is short, distance is long, and shielding isused
Define primary radiation.
The useful beam
Define a primary protective barrier.
Any wall to which the useful beam CAN be directed
and lead equivalency requirements.
1/6 inch lead or 4 inch of concrete, 7 feet high
and lead equivalency requirements.
1/6 inch lead or 4inch of concrete, 7 feet hi
is scatter & leakage radiation first or secondary radiation
Be able to discuss
unnecessary exams /
reduction of repeat exams / communications
- Conformation of the correct exam and making sure this exam has not been completed at another facility.
- If previous images can be obtained the second exam should be skipped.
patients – always in the
path of the primary beam so it is ___ mm lead equivalent (equal to 2 HVL)
How much lead
equivalent for the fluoro protective curtain?
. The best place to stand during fluoro is
- 2 steps back, one step to the side, while behind the radiologist. The further
- away from the fluoro table the better.
The worst place to stand during fluoro is (fixed unit)?
- The worst place
- to stand is right next to the patient.
What is the purpose of beam limiting devices? Why
are they important?
To keep radiation within receptor/cassette limits, also to collimate down as muchas possible to lower the amount or radiation output.
is inherent filtration?
Filtration of useful x-raybeams provided by the permanently installed components of an x-ray tube housingassembly and the glass window of an x-ray tube
What is added
Addingfiltration to the useful x-ray beam reduces x-ray beam intensity whileincreasing the average energy
variation cannot exceed what %? The
variation in x-ray intensity should not exceed
maximum acceptable variation in linearity is % from one mA station to an
adjacent mA station
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