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Proceedings Paper

Effects of collimator dependency and correction methods on I-123 SPECT images using x-ray-based attenuation map
Author(s): Yu-Wen Yang; Jyh-Cheng Chen; Chia-Jung Chang; Cheng-Yi Cheng; Wen-Sheng Huang
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Paper Abstract

Low energy (LE) collimator is generally used in I-123 SPECT imaging. However, the septal penetration and scattering of photons emitted with energy above 159 keV will affect the image contrast and quantitative accuracy of images. To reduce this effect, medium energy (ME) collimator has been used with the cost of lower counting statistics and spatial resolution. The effects of collimator dependency on the quantitative accuracy of attenuation corrected (AC) I-123 SPECT images using X-ray-based attenuation map was investigated. Both brain and heart/thorax phantoms were used to evaluate different degree of attenuation effect between brain and thorax. Experiments were performed at different target-to-background ratios to simulate different object contrast. Both photopeak and scatter projections were collected for dual-energy window scatter correction (SC). Images were reconstructed and compared using different reconstruction methods, which included FBP (filtered backprojection), and OSEM (ordered subset expectation maximization) without corrections, with AC, with SC, and with AC and SC. In both phantom studies, the image contrast and quantitative accuracy were both improved with the use of CT-based transmission map for AC. The image contrast provided by ME collimator was better than that of LE collimator, especially in the region with void activity of thorax phantom. From the results of phantom studies, medium energy collimator with CT-based transmission map showed improvements in image contrast and quantitative accuracy of I-123 SPECT images.

Paper Details

Date Published: 2 March 2006
PDF: 9 pages
Proc. SPIE 6142, Medical Imaging 2006: Physics of Medical Imaging, 61423Z (2 March 2006); doi: 10.1117/12.653007
Show Author Affiliations
Yu-Wen Yang, Tri-Service General Hospital (Taiwan)
National Yang-Ming Univ. (Taiwan)
Jyh-Cheng Chen, National Yang-Ming Univ. (Taiwan)
Chia-Jung Chang, Tri-Service General Hospital (Taiwan)
National Yang-Ming Univ. (Taiwan)
Cheng-Yi Cheng, Tri-Service General Hospital (Taiwan)
Wen-Sheng Huang, Tri-Service General Hospital (Taiwan)

Published in SPIE Proceedings Vol. 6142:
Medical Imaging 2006: Physics of Medical Imaging
Michael J. Flynn; Jiang Hsieh, Editor(s)

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