GE Healthcare
Senographe DS
Revision 1
Service Information and Procedures Class A 2385072-16-8EN
Job Card CAL A053 - mAs Non-linearity Calibration
Page no. 1725
Chapter 9
JC-CAL-A-053.fm
Job Card CAL A053 - mAs Non-linearity Calibration
Chapter 9
1
SUPPLIES
None
2
TOOLS
3
REQUIRED EFFORT
Personnel: 1 Field Engineer
Time: 10 minutes
4
SAFETY PRECAUTIONS
The procedures in this Job Card produce X-rays. Ensure that you take appropriate precautions when
operating with X-rays (for example, stay behind the radiation screen during an X-ray exposure).
5
PREREQUISITES
None
6
PROCEDURE
6-1
Presentation
The object of mAs non-linearity calibration is to compensate for the non-linearity of exposure delivered
by the Generator at low mAs values, as used in AOP pre-exposure operations.
This procedure measures pre-exposure linearity deviation, and stores a correction factor in the X-ray
Console menu, to be applied to the mAs value of all AOP exposures.
The correction factor is automatically calculated as:
MASPRE CORR = S
100
/ (25 x S
4)
, where
S
100
and
S
4
are the signals measured in the 100 mAs image and the 4 mAs image respectively.
6-2
Procedure
1. Install the Flat Field Phantom on the Bucky.
2. Install the paddle without compressing the phantom.
3. From the X-ray Console menu, enter the
SET UP/GENE/INSTAL/GENE/AOP/APOLLO/CALIB/
mAsPRE/CALIB
menu.
4. Press
CALIB
.
5. Press the Exposure button
on the X-ray Console and hold it down. Two exposures are taken
(about 20 seconds), then
CALIBRATION END
appears on the X-ray Console display. Release the
Exposure button
. Parameters for the two exposures are automatically set to MoMo/28 kV/4 mAs
and MoMo/28 kV/100 mAs.
6. Press SETUP once, then press PARAM.
7. Verify that the value displayed for MASPRE CORR is within the limits given below (
Acceptable val-
ues
).
8. Perform a checksum (
SETUP/SETUP/SETUP/SETUP/SETUP/SETUP/CKSUM/CKSUM
).
