Medical Physics Seminar – Monday, April 8, 2013
Patient-specific CT Dose Determination from CT images
Qing Liang (student of Dr. Larry DeWerd)
Research Assistant, Department of Medical Physics, UW-School of Medicine & Public Health, Madison, WI - USA -
The radiation dose received by patients from computed tomography (CT) scans has become a major public concern. The current CT dose index (CTDI) and size-specific dose estimates (SSDE) do not provide patient-specific organ dose from CT scans. A promising approach for individual CT dose determination is to use Monte Carlo simulations to calculate the dose to a patient based on their CT images. In this work, the Monte Carlo model of a CT scanner, including spectrum generation and bowtie filter estimation, was established and verified. Image extrapolation methods were proposed to improve dose accuracy by providing scatter to the scan region from the adjacent region that is not covered by the CT scan. Real patient study showed that for some cases, SSDE method fails to predict patient-specific CT dose. This work demonstrates a feasible patient-specific dose calculation solution, which could be utilized in clinic to provide organ dose based on patient CT image.