Lightspeed Ultra w/MDAS16 getting ringy images. Does not appear to be DAS related, not a specific ring. Passes all tests in DAS tools. Air cals do not affect problem but will CAL out by doing phantom cals. Problem starts reappearing within 1 or 2 days. Re - did all tube alignments - same problem. No temp errors in logs & checked DAS power supplies. Dont know where to go from here.
In all third generation CT's, the only way to get a ring is in the acquisition area between the collimator and the DAS. Since this cals out and then comes back, it must be electronic drift.
Set up an overnight DAS diag sequence and see if you get errors. Also, try varying the room temp to see if things change.
Marty Bennett
GE LIGHTSPEED 4.X IMAGE QUALITY PROBLEM
November 19, 2007 07:13
Lightspeed Ultra w/MDAS16 getting ringy images. Does not appear to be DAS related, not a specific ring. Passes all tests in DAS tools. Air cals do not affect problem but will CAL out by doing phantom cals. Problem starts reappearing within 1 or 2 days. Re - did all tube alignments - same problem. No temp errors in logs & checked DAS power supplies. Dont know where to go from here.
Thanks
to rate and post a comment
Elliot Marcus
Re: GE LIGHTSPEED 4.X IMAGE QUALITY PROBLEM
November 19, 2007 04:45
Marty,
Does the Detector feel warm? Can you tell if the Detector heater cycles on/off?
to rate and post a comment
Marty Bennett
Re: GE LIGHTSPEED 4.X IMAGE QUALITY PROBLEM
November 20, 2007 03:10
Detector temps are staying within specs. It does feel warm but not too warm and there are no log entries relating to temp.
to rate and post a comment
Ralph Childs
Re: GE LIGHTSPEED 4.X IMAGE QUALITY PROBLEM
November 21, 2007 12:11
Marty,
In all third generation CT's, the only way to get a ring is in the acquisition area between the collimator and the DAS. Since this cals out and then comes back, it must be electronic drift.
Set up an overnight DAS diag sequence and see if you get errors. Also, try varying the room temp to see if things change.
This is the tough kind to locate.
Good luck.
Scooter
scanner1@eim.ae
to rate and post a comment