Area dose product measurement device
7
Siemens AG
SPR2-240.814.04
Page 7 of 10 POWERMOBIL/ARCOSKOP
Medical Engineering
Rev. 02
07.00
TD SD 24
Checking the accuracy of the area dose product measuring
device
1
Prerequisites
1
The calibration of the measuring device must already have been performed.
The X-iris is correctly set; the collimator blades are still just visible on the monitor screen.
Preparations
1
•
Attach the centering cross in the center of the I.I. (Fig. 3).
•
Select zoom format.
•
Select kV-mA-curve plateau IOD.
•
Release fluoroscopy briefly, adjusting the X-Iris on the radiation field to a format of
around 15 cm diameter.
•
Do not make any further adjustments to the X-Iris.
•
Record the inner diameter (key width, Fig. 5) of the octagonal area of the radiation field.
•
Remove the centering cross.
•
Attach the small (1cm
3
) dose measuring chamber in the center of the I.I. (Fig. 4).
Dose measurement
1
•
Press the "Next Pat" key to reset the area dose product display on the POWERMOBIL/
ARCOSKOP monitor to 0.
•
Select kV STOP and set 70 kV.
•
Reset the dose measuring device (Dali, Nomex ...) to 0.
•
Release fluoroscopy for approx. 20 seconds (~ 3mGy). The measured dose K
E
should
be high enough that the selected measurement range of the dose measuring device
(Dali, Nomex...) is fully utilized; if necessary, reset the area dose product display on the
POWERMOBIL/ ARCOSKOP and the dose measuring device and repeat the
measurement with a different fluoroscopic time. Select kV-Stop again and set 70 kV.
•
Record the measured dose K
E
.
•
Record the area dose product displayed on the POWERMOBIL/ ARCOSKOP (FDPa).
Calculating the area dose product
1
•
To calculate the measured area dose product: (measured area dose product FDPg) =
(measured dose K
E
) * (inner diameter d)
2
* 0.829.
The radiation field must cover the entire area of the dose measur-
ing chamber. If necessary, center the dose measuring chamber on
the II again.
NOTICE