Scintillator and photodetector array optimization for functional breast imaging

Nuclear Medicine methods have been proposed as a means of imaging primary breast lesions and regional metastatic involvement based on tumor physiology. Recently, the positive predictive value of scintimammography using 99Tc labelled SestaMIBI has been reported to be as high as 81%, with an associated negative predictive value of 97%. Visualization of small (<1 cm) lesions using scintimammography may be complicated, however, by the effects of overlying and underlying background uptake of MIBI in the breast soft tissue and the deterioration of lesion contrast with distance from the gamma camera. For these reasons dedicated compact gamma cameras have been proposed and successfully used. Nevertheless, the detection of very small tumors (<5–10 mm) is still very difficult. Many parameters affect the breast small tumors detection. The degree of pixellation of both the scintillator and photodetector is critical for the intrinsic position resolution of the detector and for the overall imaging performance. In this paper, we examine the basic imaging properties of systems using arrays of scintillators and pixellated photodetectors. The influence of readout systems is also taken into account. Simulations as well as preliminary experimental results are presented.