TY - GEN
T1 - Compensation for the response function of medium energy collimator in 67Ga planar and SPECT imaging
AU - Tocharoenchai, C.
AU - Tsui, B. M.W.
AU - Lewis, D. P.
AU - Frey, E. C.
AU - Zhao, X.
N1 - Copyright:
Copyright 2004 Elsevier Science B.V., Amsterdam. All rights reserved.
PY - 1999
Y1 - 1999
N2 - This preliminary study is to improve 67Ga planar and SPECT images by compensating for the response function of a medium energy (ME) collimator. The point response functions (PRFs) of a GE ME collimator for the 93, 185 and 300 keV photons of 67Ga at 5, 10, 15 and 20 cm from the collimator face were experimentally determined. For small pixel sizes, the PRFs for all distances showed hole pattern effects. Images from the higher energy photopeaks showed increased penetration fractions. For a specified source distance, a Butterworth filter can be designed to eliminate the collimator hole pattern with minimal degradation of the spatial resolution. Compensation for the distance-dependent collimator-detector response was accomplished using iterative reconstruction methods. To evaluate the compensation methods, planar images and SPECT projection data were acquired from a phantom consisting of 3 hot spheres with diameters of 1, 1.3 and 1.6 cm inside a cylindrical phantom. The iterative reconstruction-based compensation method provided improved resolution and fewer artifacts than in images reconstructed with filtered backprojection. We conclude that degradation caused by ME collimator in 67Ga imaging can be effectively compensated for using these techniques.
AB - This preliminary study is to improve 67Ga planar and SPECT images by compensating for the response function of a medium energy (ME) collimator. The point response functions (PRFs) of a GE ME collimator for the 93, 185 and 300 keV photons of 67Ga at 5, 10, 15 and 20 cm from the collimator face were experimentally determined. For small pixel sizes, the PRFs for all distances showed hole pattern effects. Images from the higher energy photopeaks showed increased penetration fractions. For a specified source distance, a Butterworth filter can be designed to eliminate the collimator hole pattern with minimal degradation of the spatial resolution. Compensation for the distance-dependent collimator-detector response was accomplished using iterative reconstruction methods. To evaluate the compensation methods, planar images and SPECT projection data were acquired from a phantom consisting of 3 hot spheres with diameters of 1, 1.3 and 1.6 cm inside a cylindrical phantom. The iterative reconstruction-based compensation method provided improved resolution and fewer artifacts than in images reconstructed with filtered backprojection. We conclude that degradation caused by ME collimator in 67Ga imaging can be effectively compensated for using these techniques.
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M3 - Conference contribution
AN - SCOPUS:0032597057
SN - 0780350227
T3 - IEEE Nuclear Science Symposium and Medical Imaging Conference
SP - 1405
EP - 1408
BT - IEEE Nuclear Science Symposium and Medical Imaging Conference
PB - IEEE
T2 - Proceedings of the 1998 IEEE Nuclear Science Symposium Conference Record
Y2 - 8 November 1998 through 14 November 1998
ER -