Geometry Calibration (Geocal); Description; Geometry Calibration Procedure - Philips CARDIOMD Service Manual

4.2.5

Geometry Calibration (GeoCal)

4.2.5.1

Description

Geometry calibration adjusts the image geometry for symmetry and uniform spatial registration
over the energy range.
Four multiple energy point sources are placed on the outer calibration marks on the crystal surface
and two images of the point sources are acquired in a dual energy setup. The position of the im-
ages of the point sources is calculated for both of the two energies. Based on the result, the nor-
malization table is modified to correct for any mismatch. With this normalization table applied,
another iteration of acquisition and calculation is run to check the result. The process is repeated
(typically 5 to 10 times) until the specification is met.
Note. If the CardioMD AC system is equipped with the AC option, the transmission scanners
must be removed before a GeoCal calibration can be performed.
Note. GeoCal must be preceded by HV, PMT and ECal calibration. When GeoCal has been com-
pleted, a PMT update must be performed.
Note. If GeoCal is required on one detector following high voltage calibration, perform a GeoCal
on the other detector, as well.
4.2.5.2

Geometry Calibration Procedure

To be performed:
Detector:
Source:
Source holders:
Total calibration time:
Calibration file created:
Procedure
1. Remove the collimators from the detector
to be calibrated. See the Operator's Man-
ual for instructions.
2. Ensure that the CardioMD system is in the
patient load position.
1MAN0158-H11 04-2005 CSIP Level 1
When the EDC board, X-E board, Y board or crystal is re-
placed.
One detector at a time with GeoCal mask (part of service
calibration kit).
4 sources, Ba-133, Ga-67 or Tl-201 of ~ 4 – 12 MBq or 0.1 –
0.3 mCi each.
4 pcs. with 4 bottles (part of service calibration kit).
Approximately 10 minutes per detector.
C:/Cardiocam/calibrations/geocal.det1
respectively.
Details
Calibration
and
det2
CardioMD Service Manual 4-17