3. Description of the QABrowser
Real-time Display and Waveforms
2014-06/5.5C
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Piranha & QABrowser Reference Manual
Conditions - Compression paddle
For mammography, it is sometimes easier to do
measurements with the compression paddle in the field.
The compression paddle will however normally affect
the Piranha kV and dose reading. With this check box,
all the measured values (kV, dose and HVL) will be
corrected according to what the user has selected. The
default setting the first time you start the software is
without the compression paddle in the field.
When selected you will see the settings for Scatter
factor and Equivalent thickness. The thickness is given
in mm Al, if you do not know, ask the manufacturer or
make a comparison with Aluminium filters. When this
option is active, an indicator on the RTD screen
indicates that this feature is on.
If an ion chamber is positioned just below the compression paddle,
the measured dose will rise, because of side scattering from the
compression paddle material. The effect of this is depending on
the ion chambers angular dependence. Since the Piranha is
almost insensitive to this, you can put a number here to compare
readings from the Piranha with readings from an ion chamber.
See also section Average Glandular Dose, AGD (MGD) .
When this is activated a red compression paddle indicator will
show in the top right corner of the RTD screen ( ).
The given equivalent compression paddle thickness is used to
increase the accuracy of dose measurements when dose is
measured below the compression paddle. It is given in equivalent
thickness of aluminium.
This feature can also be used if you have additional
filtration in the beam. Add the equivalent thickness of aluminium.
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