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The quad-HIDAC positron camera, designed for laboratory animal imaging, has been evaluated as a potential positron emission mammography system. With a detection efficiency for 511 keV photons of ~1.6% for a centrally placed line source and an intrinsic spatial resolution of 1.25 mm FWHM the camera has many of the attributes needed for PEM. Small spherical 'lesions' with volumes between 0.04ml and 0.46ml were imaged in a small 'breast' phantom filled with 68Ga. Results were compared to those obtained from a similar study carried out previously with the VUBPET system which had an average spatial resolution of ~3.5 mm. The data show that the HIDAC system was able to detect the smallest (4 mm diameter, 0.04 ml) lesion at a tumour to background (T/B) ratio of 5:1. The VUBPET system could just detect the 6 mm diameter lesion at a T/B ratio of 8:1. We conclude that for mammography an MWPC-based detector with high resolution would be fine and could be achieved by reducing the frame thicknesses of the MWPC on the side closest to the chest wall.