Presentation Transcript
Quality Control of a Geiger-Mueller Detector :Quality Control of a Geiger-Mueller Detector Tim Marshel R.T., CNMT
Quality Control :Quality Control The routine assessment of instrument performance in nuclear medicine
Extremely important part of Nuclear Medicine
Commonly referred to as “QC”
Geiger-Mueller detector :Geiger-Mueller detector Laboratory and personal survey instrument
Detector used to measure and locate radiation and contamination
Most sensitive gas filled detector
Geiger-Mueller detector :Geiger-Mueller detector Pancake Probe Side Window Probe
“QC” for Accuracy :“QC” for Accuracy NRC requires that GM counters be calibrated for accuracy at least annually
Calibration must also be performed following any type of repair to the instrument
“QC” for Accuracy :“QC” for Accuracy Calibration is performed at two different operating points on the instruments scale
The points are usually 1/3 and 2/3 of the full scale
Standard used must be traceable to within 5% of the NIST limits
“QC” for Constancy :“QC” for Constancy GM detectors must be checked for constancy on a daily basis
Constancy tests are done with a long lived reference source usually located on the instrument
“QC” for Constancy :“QC” for Constancy When checking for constancy the results should always fall within 10% of the expected reading
If results exceed 10% after a battery change and any type of repair the instrument must be recalibrated
The End :The End