mammo equipment 2 Flashcards
1
Q
what are advantages of using Tungsten (W) target
A
increased XR output and more heat capacity adn reduced image noise
2
Q
what do rotating anodes allow
A
- allow higher tube loading capacity
- increase mA allows for shorter exposure times
3
Q
what do stationary anodes use
A
- produce less off-focus radiation resulting in less image noise
- tube tilted 25 degrees
4
Q
why is the stationary anode tube tilted 25 degrees
A
- gives beam coverage equal to rotating anode design and effective focal spot size
5
Q
what is AEC
A
automatic exposure control
6
Q
what is AEC designed for
A
to automatically adjust exposure parameters such as tube current and exposure time based on the characteristics of the breast
7
Q
how is the AEC achieved
A
achieved by 5mAs pre-pulse that is taken to determine exposure and XR tube target combo required based on breast density and compressed thickness
8
Q
how are the correct exposure parameters chosen for mammo
A
- based on breast characteristics (thickness and density- thicker = longer exposure)
- AEC
- patient positioning = aligned and compressed
- ALARA
9
Q
typical mAs range
A
20 to 300 mAs
9
Q
radiation dose reduction
A
- AED reduce risk of repeat exposures
- strict field collimation
- optimized XR spectrum for each patient
- optimum compression of breast
- XR tilted away from patients body so chest wall is projected and thyroid protected
- interlocks
10
Q
QA
A
- quality assurance
- QA is overall management on actions taken to attan IQ consistently
to ensure unnecessary radiation is minimised - efficiency maximised
- standards maintained
11
Q
what are the 5 tests performed during a flat field test
A
- brightness uniformity
- high frequency spatial modulation
- signal to noise ratio uniformity
- bad pixel verification
