Chapter 11, 12, 15 Flashcards
Every diagnostic imaging system MUST have:
Protective tube housing
A correctly functioning control panel
In equipment design, leakage:
Leakage cannot exceed 100 mR/hr at a distance of 1 meter
Control panel (console):
Must indicate condition of exposure and have light or audible c-ray indicator
a Table is:
Radiolucent- absorbs only minimal amount of radiation
Commonly carbon filter
SID
Must have a means of measurement from anode focal spot to IR
Beam Limiting devices
Devices that limit the x-ray beam before it enters the patient
In scatter radiation, tight collimation:
Decreases patient dose
To minimize skin exposure in Skin Sparing:
the patients skin surface should be at least 15 cm below collimator for fixed equipment
Positive Beam Limitation:
Automatic collimation
Purpose is to restrict the size and shape, so it does not exceed the size and shape of the IR
Effects of filtration:
Increases quality of the beam
Decreases quantity of x-rays by absorbing some low energy beams- fewer overall beams are left
2 types of filtration?
Inherent- original filtration
Added- any filtration occurring outside the tube housing and before the IR
Half Value Layer (HVL)
Decreases the intensity of the primary beam by 1/2 (50%) of its original value
Types of compensating filters:
Wedge: bone and joint- T spine, feet (thicker part towards toes)
Trough (bilateral wedge): CXR- PA (thin center)
Reproducibility
Consistent output in radiation intensity for identical generator setting from one exposure to the next
Automatic Exposure Control (AEC)
Back up timer is set at 150%
For Mobile Radiographic Units:
Minimum SSD of at least 30 cm (12 inches)
Exposure factors for children:
Decrease kVp by 25% of adult
Filtration
Minimum 2.5 mm total Al
Permanently installed