Implementation of a pre-calculated database approach for scatter correction in SPECT

In single photon emission computed tomography (SPECT), attenuation and scatter introduce important artefacts in the reconstructed images leading to mis diagnosis for patient's follow-up. Furthermore, by using Monte Carlo simulation (MCS), physical effects undergone by photons during the SPECT exam can be precisely modeled and accounted for during iterative reconstruction, which improves the quality of the image. However, MCS are time consuming and therefore inappropriate for the rate of daily exams performed in clinical routine. Our work is based on the assumption that patients are composed of identical biological tissues and that photon propagation in an element volume of a given tissue is similar and reproducible from one subject to another. We hence propose to accelerate modeling of the physical effects occurring in emission tomography making it adequate for daily exam by using the approach of scatter pre-calculated database. The developed efficient patient-dependent attenuation and scatter correction were implemented on a GPU architecture on a state-of-art single-processor workstation and yielded to a speed-up factor in time computing of four orders of magnitude. Results presented in this proof of concept study are in good agreement with full MCS.