Segmentation of the Body and Lungs from Compton Scatter and Photopeak Window Images in SPECT: A Monte Carlo Investigation

Research output: Contribution to journalArticle

Abstract

In SPECT imaging of the chest, nonuniform attenuation
correction requires use of a patient specific attenuation (p)map. Such a map can be obtained by estimating the regions of 1)the lungs and 2) the soft tissues and bones, and then assigning an appropriate value of attenuation coefficient (p) to each region. We proposed a method to segment such regions from the Compton scatter and photopeak window SPECT slices of Tc-99m Sestamibi
studies. The Compton scatter slices are used to segment the body outline and to estimate the regions of the lungs. Locations of the back bone and sternum are estimated from the photopeak window slices to assist in the segmentation. To investigate the accuracy of using Compton scatter slices in estimating the regions of the body and the lungs, a Monte-Carlo SPECT simulation of an anthropomorphic phantom with an activity distribution and noise characteristics similar to patient data was conducted. Energy windows of various widths were simulated for use in locating a suitable Compton scatter window for imaging. The effects of attenuation correction using a p map based on segmentation were also studied. The results demonstrated for the activity and p maps studied herein that: 1) reasonable contrast could be obtained from Compton scatter data for the segmentation of the lung regions, 2) true positive rates of 99% and 89% for
determining the body and lung regions, respectively, with total error rates of 4% and 29%, could be achieved, 3) usage of a p map based on segmentation for attenuation correction improved relative quantification over filtered backprojection, 4) variations in the assigned p value of 40% smaller or 40% larger in the lung regions had an insignificant impact on the results of relative quantification, 5) a wide energy window away from the photopeak window for recording scattered events could benefit both the segmentation of the lung regions and the attenuation correction of the activity in the myocardium region, and 6) usage of a smaller than true p value in the lung regions of an assigned p map might
benefit attenuation correction for absolute quantification.

Details

Authors
Organisations
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Radiology, Nuclear Medicine and Medical Imaging
Original languageEnglish
Pages (from-to)13-24
JournalIEEE Transactions on Medical Imaging
Volume15
Issue number1
Publication statusPublished - 1996
Publication categoryResearch
Peer-reviewedYes