Energy resolution enhancement in scintimammography. Deconvolution of ROI spectra by the mTSVD regularizing technique

The use of a dedicated gamma camera for scintimammography with breast under compression can improve the detection of sub centimeter cancers. Unfortunately, detectors based on PSPMT show a poor energy resolution that would not be able to discriminate tumors in the posterior portion of the breast where the scattering of photons, coming from the chest, is particularly prominent. In this paper we introduce the modified truncated SVD (mTSVD) based deconvolution as a numerical approach to enhance the energy resolution. Tc99m calibration spectra were used to numerically describe the detector response function; the degree of ill-posedness of the numerical problem was carefully study in order to perform the deconvolution of ROI, in different breast position, by a unique response function. Eight ROI spectra from breast phantom and two from a patient study were analyzed, respectively. For each or them the energy resolution, after the deconvolution, was about 1.7 times improved. The results shown that the mTSVD based deconvolution can represent an useful tool to increase the energy resolution in scintimammography, and to improve the image quality by further suppression of the Compton scattering