Peak Test; Tests Performed In The Secondary Calibration - GE Medical Systems PRODIGY Service Manual

2.17.3 Tests Performed in the Secondary Calibration

Detector Mother Board Self Test
Find Block

Peak Test

Beam Stop test
Motor motion and limit switches
Spillover test
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2-92 System Overview
The DACs and Flash RAM of the Detector Mother Board are tested.
The scanner performs a scout scan to find the block. If block is not properly
positioned, the scanner will prompt the user to Reposition standard more
accurately.
The software automatically finds landmarks within the secondary phantom.
This reduces the need for exact positioning on the table top.
During this test, the shutter opens with the x-rays on.
This test adjusts the sensitivity of the photon counting electronics. The test
determines the optimal voltage setting for the detector amplifier so the
maximum number of photons are detected. With the shutter open the software
adjusts the voltage setting for the detector amplifier, acquiring counts at the
different amplifier settings.
The detector peak test then determines the optimal voltage setting for the
detector amplifiers based on the results. The actual peak setting is taken from
the high energy count rates, the low energy channel is essentially blocked by
the brass spillover piece in the QA standard.
Measures the movement of the source shutter. A functional test checks the
shutter LSW and ensures the shutter stops all photons.
OMI Interrupt function - the OMI signal is tested by verifying the OMI Interpol
signal is present when the scan arm is stationary.
Each motor (transverse, longitudinal) will be run between hard limits and back
to home position. If the hard limits do not engage, this is a failure. Also
compare steps against predetermined scan window size.
If a failure occurs the number of steps taken, the expected value and the
direction the arm was traveling is noted in the error log.
PRODIGY Service Manual (Rev C - 2000)