A NEW PHANTOM FOR FAST DETERMINATION OF THE SCATTER RESPONSE OF A GAMMA-CAMERA

A triangular phantom is proposed which enables the determination and p arameterization of the depth dependent scatter response function (SRF) in uniformly attenuating objects for Single Photon Emission Computed Tomography (SPECT) by means of a single line source measurement. This approach replaces a tedious measurement series with line sources at va rious depths in slab phantoms. The method is evaluated for Tc-99m. Mon te Carlo simulations of SRFs and scatter-to-primary ratios (SPRs) of t he triangular phantom are compared with those of slabs. It is found th at both the SPRs and the shapes of the SRFs from the slab and triangul ar phantoms are in excellent agreement. In addition, the data obtained from a single measurement using the triangular phantom can be used in the parameterization of the slab phantom SRF and can be described by an analytical expression of the line source response function. This in formation can be combined with knowledge of the geometric detector res ponse and the shape of the object to compute the full scatter response function in convex shaped objects. This method for estimating scatter can serve as the basis for accurate scatter compensation in SPECT.