Assessment of DOI resolution in a fully mounted PEM scanner

The ClearPEM scanner is a dedicated system to perform breast imaging with the ability of measuring DOI, allowing an image spatial resolution close to 1.5 mm. The DOI is measured by calculating the amplitude asymmetry between the signals produced by two APD, one in the top and other in the bottom of the crystal. The DOI resolution measured in laboratory tests is 2.0 mm. In this paper we present a method to periodically confirm this value with the scanner fully mounted. The DOI resolution obtained with this method was 2.8 mm, which is consistent with the resolution measured during the laboratory tests.