New daily detector uniformity quality control methodology for cardiac SPECT using solid-state detectors

Abstract

Detector non-uniformity can potentially introduce detectable artifacts into SPECT images. The degree of nonuniformity and the position of the non-uniform area on the detector surface determine the position and severity of the introduced artifacts. The commonly used daily uniformity quality control (QC) procedure follows the NEMA methodology but acquires fewer counts than the latter specifies. It has three major drawbacks: (1) it does not report the locations and extension of the non-uniform areas on the detector surface; (2) it may report a non-uniformity value that is lower than the true value due to the use of a 9-point filter, and it makes the reported non-uniformity value vary with the extension of the nonuniform area. These two drawbacks are inherited from the NEMA methodology. The third drawback is that the noise due to the relatively low counts collected in daily uniformity QC does not allow the measurement of certain degrees of nonuniformity with adequate statistical significance, yet such nonuniformity can potentially introduce observable artifacts. In this work we propose a new methodology for daily uniformity QC for cardiac SPECT imaging using solid-state detectors. The new QC largely overcomes the above drawbacks of NEMA QC. In addition, the new procedure (1) can catch some detectors that pass the NEMA-based daily uniformity QC but can be nonuniform enough to introduce detectable artifacts and (2) reports the locations and extension of the non-uniform areas of the detectors, therefore, may allow a detector that fails the NEMAbased daily QC to be used for imaging without introducing artifacts in certain situations.