A novel flood source used for the MTF determination in SPECT systems

Abstract

The Modulation Transfer Function (MTF) is an important parameter for the characterization of the signal transfer properties and image quality of a single photon emission computed tomography (SPECT) system. MTF can be derived by determining the line spread function (LSF) from images of a flood source. The method presented here is novel and easy to implement, requires materials commonly found in clinical practice, is robust to aliasing. Furthermore, since this technique is based on the LSF method, reduces measurement noise levels due to greater data averaging than conventional Point Spread Function (PSF)-integration techniques. In an effort to prepare easily, cheaply and reproducibly a Tc-99m-based flood source (Eγ=140 keV), various combinations of films and radiopharmaceuticals were tried. Excellent results were obtained by immersing an Agfa MammoRay HDR Medical X-ray film in a solution of dithiothreitol (DTT, 10-3 M)/Tc-99m(III)-DMSA (DMSA:Trivalent Technetium-99m-dimercapto-succinic acid, 40 mCi/40 mL) for 30-45 min in the dark. These films exhibited high integral uniformity (CV <1.9%). All imaging experiments were performed in a Siemens e-Cam γ-camera