Simple method to measure gamma camera energy resolution

- We present a simple method of measuring gamma camera energy resolution.
- We used static images taken using separated narrow windows.
- Gaussian fitting was used to estimate the energy resolution.
- The two detectors of the dual head gamma camera had similar energy resolution.
- This method can be easily implemented within routine quality assurance.

PurposeEnergy resolution is one of the major limitations of gamma camera performance, mainly affecting image contrast and resolution. There is a need for a simple method of measuring gamma camera energy resolution, which is practical for technology students as well as for routine quality control.Materials and methodsA 37 MBq (1 mCi) MBq 99Tcm point source was prepared and positioned 1.5 m away from the gamma camera. Eleven static images were acquired with the same acquisition time (60 s), using 1 keV windows at intervals of 5 keV from 115 to 165 keV. The counts for each image were recorded and plotted graphically (counts vs. energy). Gaussian fitting was used to estimate the full-width-at-half-maximum height (FWHM), and the energy resolution (FWHM%) was calculated as a percentage of the photopeak (∼140 keV).ResultsThe FWHM% of the energy peak was measured to be ∼7%. Most values for the energy resolution (FWHM%) of our system were significantly lower (i.e., higher energy resolution) than the commissioning measurement, and were comparable to the recent preventive maintenance values. There were no significant energy resolution differences between the two detectors of the dual head gamma camera.ConclusionsThis simple method for the evaluation of the energy resolution of a gamma camera system can be easily implemented within routine quality assurance. The measure will help prevent image deterioration through early detection of serious energy resolution issues which can be resolved in routine gamma camera corrective maintenance.