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KMID : 0357520100330010031
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Journal of Radiological Science and Technology
2010 Volume.33 No. 1 p.31 ~ p.36
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A System Model of Iterative Image Reconstruction for High Sensitivity Collimator in SPECT
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Bae Seung-Bin
Lee Hak-Jae
Kim Yong-Kwon
Kim Yu-Hyun
Lee Ki-Sung
Joung Jin-Hun
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Abstract
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Low energy high resolution (LEHR) collimator is the most widely used collimator in SPECT imaging. LEHR has an advantage in terms of image resolution but has a difficulty in acquiring high sensitivity due to the narrow hole size and long septa height. Throughput in SPECT can be improved by increasing counts per second with the use of high sensitivity collimators. The purpose of this study is to develop a system model in iterative image reconstruction to recover the resolution degradation caused by high sensitivity collimators with bigger hole size. We used fan-beam model instead of parallel-beam model for calculation of detection probabilities to accurately model the high sensitivity collimator with wider holes. In addition the weight factors were calculated and applied onto the probabilities as a function of incident angle of incoming photons and distance from source to the collimator surface. The proposed system model resulted in the equivalent performance with the same counts (i.e. in shortened acquisition time) and improved image quality in the same acquisition time. The proposed method can be effectively applied for resolution improvement of pixel collimator of next generation solid state detectors.
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KEYWORD
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image reconstruction, system model, collimator, high sensitivity, SPECT
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