5. Measurements with the Barracuda System
CT
Barracuda & QABrowser Reference Manual
2012-10/4.3A
158
7. Set up the CT to make a topogram.
8. Start the topogram program. If the procedure
includes more than one topogram you may
abort after the one taken with the tube in the
top position.
If the MPD is positioned in a correct way, the position is accepted and the real-time
display is shown again. If not check the position of the MPD and/or increase the slice
width if possible.
9. You are now ready to measure. Repeat the
topogram program to measure kVp.
The exposure time you measure is not related
to the actual "radiation time". It is the time it
takes for the detector to "pass through" the CT
X-ray field when the table moves when it is
acquiring the topogram.
5.8.2 CT Dose and CT Dose Index (CTDI)
This topic will show how to measure CT dose
and the CTDI. Measurements of CTDI are
performed parallel to the axis of rotation during
one or several complete gantry rotations while
the table position remains stationary. It is
normally measured in a phantom but can also be
measured free in air. In this example we will use
a five hole head phantom and a 10 cm CT ion
chamber.
We will use the QABrowser application CTDI to measure and calculate CTDI. Read the
topic Definition of CTDI to get information on how it is calculated.
To measure CTDI:
164
To Next Page
Loading...
Need help?
General