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
1SUPPLIES
None
2TOOLS
Flat field phantom
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).
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