Acquisition and Processing Methods for a Bedside Cardiac SPECT Imaging System

Abstract

We have developed a compact and mobile gamma imaging system that is designed for both PET and SPECT acquisitions within a bedside environment, such as an intensive care unit, surgical suite, or emergency room. This paper describes the SPECT performance evaluation of the system for cardiac imaging, including both Tc-99m and F-18 radionuclides. For cardiac F-18 imaging in a bedside environment, the 511 keV SPECT approach using high energy collimation and anterior 180 degree acquisition has the advantages of not requiring a detector to be positioned beneath the bed and greatly reducing attenuation effects. In this study, we evaluated SPECT reconstructed image quality using an anthropomorphic dynamic cardiac phantom filled with Tc-99m and F-18 separately. The specific issues that were addressed in this study included the following: 1) mitigating septal penetration effects with the 511 keV photons using de-convolution filtering, 2) reducing truncation effects due to the relatively small field-of-view of the camera using angle-dependent center-of-rotation shifts, and 3) investigating the effects of reduced angular sampling and angular range. We found that reducing angular sampling to 28 projections through 135 degrees with Tc-99m and 25 projections through 180 degrees with F-18 showed all features of the myocardium.