Ap-Spine Image Problems: Probable Causes; Broken Signal Cable; Loss Of Tube Head Current; X-Ray Relay Failure - GE Medical Systems PRODIGY Service Manual

Most image discontinuity problems occur in femur images performed at 3 mA
on thin or osteoporotic subjects. These lines usually occur in the trochanter
area where the x-ray beam is least attenuated by tissue.
These lines are caused by Automatic Gain Stabilizer (AGS) trying to adjust
the input signal which is at an excessively high count rate. However, the AGS
is not at fault, and the correct action is for the customer to attenuate the x-ray
beam. Lunar normally recommends placing a rice bag (on its side to create 12
cm of patient thickness in the x-ray beam) along the side of the patient's thigh
for thin or osteoporotic patients.

4.11.3 AP-Spine Image Problems: Probable causes

4.11.4 Broken Signal Cable

The cables which carry the voltage to the detector and return the signal from
the detector array are part of the upper and lower cable bundle assemblies.
Any break or significant pinch of the cable can cause reduction in counts in
either or both channels. This could result in horizontal artifacts which effect all
16 detectors at once.

4.11.5 Loss of tube head current

The tube head control cable contains the wires which provide power to the
filament transformer. If the wire to the transformer center tap breaks, the x-
rays will stop, the orange lamp will go off, and the end-of-exposure alarm will
sound. If either of the other two wires break, the MAX board fuse will blow.
Always ask the operator if a "ping" sound (the end of exposure alarm) is
heard, and whether the Shutter Open or X-Ray On lamp turns off. In the case
of a tube head current problem, the X-Ray On light will turn off.

4.11.6 X-Ray Relay Failure

DPX-NT Service Manual (Rev A- 1999)
• the shutter closes (causes the shutter open lamp to go out, and the End
of Exposure Alarm to sound).
• increase or reduction of high voltage to the detector (causes horizontal
artifacts in the image).
• loss of the signal from the detector (this effects all 16 detectors at once)
• loss of current to the x-ray insert filament (28 volt power supply error
message, the orange lamp to go out, and the End of Exposure Alarm to
sound).
• bad x-ray relay contacts (providing power to tube head power supplies)
• reduction in AC Line voltage
• loss of proper high voltage on the x-ray tube
• faulty operation of the AGS system (white lines are short and found only
where scan lines move from air into tissue).
• arcing (may cause vertical artifacts in the image)
Troubleshooting 4-137