Optimization of the acquisition parameters for a SPET system dedicated to breast imaging

This work is developed within the framework of a larger project, which aims to develop a multimodal CT-SPET system dedicated to breast imaging. The goal of this paper is to optimize the choice of the various parameters involved in the design of a SPET system dedicated to breast imaging. In particular, we simulated different collimators, different tumor to background (T/B) ratios for two different spherical tumors with diameters of 5 mm and 8 mm. The performance of the explored cameras were analyzed in terms of SNR and image contrast (IC) values, calculated on the reconstructed images. In addition, we investigated the visibility limits of the system, by modifying the tumor size, the T/B value, and the diameter of the breast phantom (8 cm, 10 cm, and 13 cm). As a general tendency, we found out that a high-resolution camera is preferable, in terms of image contrast. On the other hand, the general purpose collimator seems to give a smoother image, giving rise to SNR values comparable to those obtained with the high-resolution collimator, even with a reduced contrast. High-sensitivity collimators seem to give a worse response on the reconstructed images. The 8 mm tumor is clearly visible for all the simulated conditions, even if it could be very close to the visibility limit for the high-sensitivity collimator. The 5 mm tumor is close to the visibility limit for general purpose and high-resolution collimators, for a T/B ratio equal to 10:1 and is not visible with high-sensitivity collimator. The smaller tumor is almost obscured by the background with the thickest breast (13 cm diameter).