ClearPEM scanners: Performance results and studies in preclinical environment

The ClearPEM detector is a dual planar Positron Emission Mammography (PEM) scanner that was developed within the framework of the international Crystal Clear Collaboration at CERN. The scanner is being used for preclinical studies and the new phase of the clinical trials will start on the second half of November. A second prototype was build and installed (ClearPEM-Sonic). The main results presented in this paper were obtained with the first prototype. The scanner image performance was evaluated using gelatin phantoms. The methodology included the quantification of the homogeneity (BV) and statistical noise (COV). Lesion detectability was evaluated using parameters such as lesion to background noise (LTBN) and lesion contrast recovery coefficient (CRC). Results indicate BV and COV of the order of 5-9% and 20-24%, respectively. ClearPEM images have been found globally homogeneous showing no artifacts. Small lesion to background ratio (LTB) and lesions of dimensions smaller than 3 mm showed less good contrast, but in most cases we report CRC values between 80% and 100%. The detection of lesions is feasible down to 2-3 mm in diameter.