Position-dependent scatter response functions: will they make a difference in SPECT conducted with homogeneous cylindrical phantoms?
This paper explains why it is possible to perform accurate quantitative SPECT when scatter correction is based on stationary and non-stationary scatter functions. This is achieved by comparing the variations of scatter parameters as a function of phantom thickness. The results show that the decrease of scatter fraction with phantom thickness and the decrease of values of scatter kernel inside the field of view are about equal. The deviation of the position-dependent slope from the average value is small for central distributions. These observations explain why estimations of scatter projection by non-stationary convolution and by stationary convolution are comparable when SPECT measurements are conducted with uniform cylindrical phantoms. It is concluded that investigations on the perceived superiority of non-stationary over stationary scatter subtraction in SPECT should be conducted with elliptic phantoms that deviate appreciably from cylindrical shape.
Msaki
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Department of Nuclear Medicine and Radiobiology, University of Sherbrooke, Sherbrooke, Quebec, Canada J1H 5N4.
D000465:Algorithms; D006801:Humans; D007089:Image Enhancement; D007091:Image Processing, Computer-Assisted; D008962:Models, Theoretical; D019047:Phantoms, Imaging; D049268:Positron-Emission Tomography / Q000295:instrumentation* / Q000379:methods*; D012542:Scattering, Radiation; D015899:Tomography, Emission-Computed, Single-Photon / Q000295:instrumentation* / Q000379:methods*