5. Measurements with the Piranha System
Radiography
2014-06/5.5C
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Piranha & QABrowser Reference Manual
However, if you really want to measure in fluoroscopy mode it is better to select
Fluoroscopy as type of measurement. The sensitivity is then automatically set to
"High".
To measure kVp only, select Tube voltage instead of All as parameter for type of
measure.
To be able to trust the reading it is always a good practice to first do a check
measurement, to verify that the whole detector area is uniformly irradiated. This is done
with the Position check that can verify the uniformity of the beam. The kV and radiation
waveform is always acquired together with the real-time display values and can be
displayed by tapping Wave. Applications and logging of the real-time values are
described earlier.
5.2.1 kVp, Time, Dose, and Dose Rate
To measure on radiographic units:
1. Set up the Piranha and the handheld computer according to the description in Setting
Up the Piranha .
2. Place the detector on the table at the distance that is clinically
relevant.
Place the Piranha in the direction indicated in the figure below
Adjust the collimator so the radiation clearly covers the
detector rectangle marked on the Piranha top panel, but try to
keep the field size inside the top panel size to minimize
scatter. Recommended field size is 20×40 mm. Furthermore
the Piranhasurface should optimally be placed perpendicular
to the focal spot, see also Angular Sensitivity, Piranha .
3. Selecting only one parameter enables you to see the measured values from a
distance of several meters.
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