Can you help me how to solve this is issue for our ct scan. here are the issues
1. when we do scanning we are getting a ring artifact on our image. To solve the artifact we do the fast calibration and the image will be ok, but after 4 hours or more is pass and we do scanning the artifact is back and we need to do the fastcal again. We try to leave the gantry turn on for 24hours but the problem still the same.
2. the ring artifact is not permanent sometimes we are getting it in the center and in different location. the artifact is about 5mm wide atleast
3. we also getting a solid line artifact during scout and it is in same location even we do fastcal but in the series images no artifact is present as long as you do fastcal.
4.I also notice that the fan in the gantry is turning on every minute. we maintain a 18 degrees in the room.
we have a ct/i base ct scan, 3.5MHu tube, a G5 collimator and an octane system with irix 6.5 version.
can you help us how to solve the problem.. thanks in advance
we already do the POR procedure and the 1mm and 10mm are in the center when you develop the scan image. what do you mean tired? the tube is manufactured 2010...is there any other possible problem except for the tube?
This problem is either detector or Das drift. You need to isolate what channel is failing. Swap the Das board for that channel with another elsewhere in the Das. If the ring moves, it's the Das pcb. If not, it is the detector.
since you have a solid line then you have one of the PCB's that amplify the detector signal is defective. There is a software in the service mode to check at what channel is this PCB. You have to run it. then change the PCB location to an outer channel perform the fast calibration and check the image. this will give you if the problem is in the PCB or from detector itself.
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Marivic Mendoza
ring artifact for ct scan
May 21, 2013 09:35
Can you help me how to solve this is issue for our ct scan. here are the issues
1. when we do scanning we are getting a ring artifact on our image. To solve the artifact we do the fast calibration and the image will be ok, but after 4 hours or more is pass and we do scanning the artifact is back and we need to do the fastcal again. We try to leave the gantry turn on for 24hours but the problem still the same.
2. the ring artifact is not permanent sometimes we are getting it in the center and in different location. the artifact is about 5mm wide atleast
3. we also getting a solid line artifact during scout and it is in same location even we do fastcal but in the series images no artifact is present as long as you do fastcal.
4.I also notice that the fan in the gantry is turning on every minute. we maintain a 18 degrees in the room.
we have a ct/i base ct scan, 3.5MHu tube, a G5 collimator and an octane system with irix 6.5 version.
can you help us how to solve the problem.. thanks in advance
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Marshall Shannon
re: ring artifact for ct scan
May 22, 2013 06:23
Sound like a detector in the DAS
Could be contrast in the detector cover as well but doubt that will cause it
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marivic
re: re: ring artifact for ct scan
May 22, 2013 11:31
how can i check the contrast in the detector can you help me how to do it
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Steven Ford
re: ring artifact for ct scan
May 22, 2013 06:23
sounds like possible tube problem, the focal spot moving or not in the right place. Is the tube tired?
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Marivic Mendoza
re: re: ring artifact for ct scan
May 22, 2013 08:53
we already do the POR procedure and the 1mm and 10mm are in the center when you develop the scan image. what do you mean tired? the tube is manufactured 2010...is there any other possible problem except for the tube?
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Kim Schofield
re: re: re: ring artifact for ct scan
May 23, 2013 08:22
This problem is either detector or Das drift. You need to isolate what channel is failing. Swap the Das board for that channel with another elsewhere in the Das. If the ring moves, it's the Das pcb. If not, it is the detector.
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Primco
re: ring artifact for ct scan
May 22, 2013 08:52
The solid line artifact only during scout could be a problem in your system board in the IRS. Pass the complete test.
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Borhan Kalash
re: re: ring artifact for ct scan
May 23, 2013 08:22
pls check the Das PS
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Juan de la Cruz Martinez
re: ring artifact for ct scan
May 23, 2013 08:22
Mark the spot of the artifact in the scout (a wire for example)and check the detector that is affecting your scout
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Mehedden Labban
re: ring artifact for ct scan
May 23, 2013 08:22
Dear Mr. Mendoza
since you have a solid line then you have one of the PCB's that amplify the detector signal is defective. There is a software in the service mode to check at what channel is this PCB. You have to run it. then change the PCB location to an outer channel perform the fast calibration and check the image. this will give you if the problem is in the PCB or from detector itself.
All the best,
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Tibor Ivanszky
re: ring artifact for ct scan
May 23, 2013 08:23
Try scout in different angles and see if lines change position.
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Wojciech Selwesiuk
re: ring artifact for ct scan
May 23, 2013 08:23
Hello,
I found that few weeks ago there was similar problem and here is a link. Maybe it can help?
https://www.dotmed.com/virtual-trade-show/category/Service-Technicians/Discussions/Forums/Ge-CtI-Ct-Scan-Ring-Artifact/42984?key=ring
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