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Title: Patient-specific radiation dose and cancer risk estimation in CT: Part II. Application to patients

Abstract

Purpose: Current methods for estimating and reporting radiation dose from CT examinations are largely patient-generic; the body size and hence dose variation from patient to patient is not reflected. Furthermore, the current protocol designs rely on dose as a surrogate for the risk of cancer incidence, neglecting the strong dependence of risk on age and gender. The purpose of this study was to develop a method for estimating patient-specific radiation dose and cancer risk from CT examinations. Methods: The study included two patients (a 5-week-old female patient and a 12-year-old male patient), who underwent 64-slice CT examinations (LightSpeed VCT, GE Healthcare) of the chest, abdomen, and pelvis at our institution in 2006. For each patient, a nonuniform rational B-spine (NURBS) based full-body computer model was created based on the patient's clinical CT data. Large organs and structures inside the image volume were individually segmented and modeled. Other organs were created by transforming an existing adult male or female full-body computer model (developed from visible human data) to match the framework defined by the segmented organs, referencing the organ volume and anthropometry data in ICRP Publication 89. A Monte Carlo program previously developed and validated for dose simulation on the LightSpeedmore » VCT scanner was used to estimate patient-specific organ dose, from which effective dose and risks of cancer incidence were derived. Patient-specific organ dose and effective dose were compared with patient-generic CT dose quantities in current clinical use: the volume-weighted CT dose index (CTDI{sub vol}) and the effective dose derived from the dose-length product (DLP). Results: The effective dose for the CT examination of the newborn patient (5.7 mSv) was higher but comparable to that for the CT examination of the teenager patient (4.9 mSv) due to the size-based clinical CT protocols at our institution, which employ lower scan techniques for smaller patients. However, the overall risk of cancer incidence attributable to the CT examination was much higher for the newborn (2.4 in 1000) than for the teenager (0.7 in 1000). For the two pediatric-aged patients in our study, CTDI{sub vol} underestimated dose to large organs in the scan coverage by 30%-48%. The effective dose derived from DLP using published conversion coefficients differed from that calculated using patient-specific organ dose values by -57% to 13%, when the tissue weighting factors of ICRP 60 were used, and by -63% to 28%, when the tissue weighting factors of ICRP 103 were used. Conclusions: It is possible to estimate patient-specific radiation dose and cancer risk from CT examinations by combining a validated Monte Carlo program with patient-specific anatomical models that are derived from the patients' clinical CT data and supplemented by transformed models of reference adults. With the construction of a large library of patient-specific computer models encompassing patients of all ages and weight percentiles, dose and risk can be estimated for any patient prior to or after a CT examination. Such information may aid in decisions for image utilization and can further guide the design and optimization of CT technologies and scan protocols.« less

Authors:
; ; ; ; ; ; ;  [1]
  1. Medical Physics Graduate Program, Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, Durham, North Carolina 27705 (United States)
Publication Date:
OSTI Identifier:
22096876
Resource Type:
Journal Article
Journal Name:
Medical Physics
Additional Journal Information:
Journal Volume: 38; Journal Issue: 1; Other Information: (c) 2011 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0094-2405
Country of Publication:
United States
Language:
English
Subject:
61 RADIATION PROTECTION AND DOSIMETRY; 60 APPLIED LIFE SCIENCES; ABDOMEN; CHEST; COMPUTERIZED SIMULATION; COMPUTERIZED TOMOGRAPHY; DOSIMETRY; HEALTH HAZARDS; IMAGE PROCESSING; MONTE CARLO METHOD; NEOPLASMS; OPTIMIZATION; PATIENTS; PEDIATRICS; PELVIS; RADIATION DOSES; VERTEBRAE

Citation Formats

Xiang, Li, Samei, Ehsan, Segars, W. Paul, Sturgeon, Gregory M., Colsher, James G., Toncheva, Greta, Yoshizumi, Terry T., Frush, Donald P., Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Medical Physics Graduate Program, Department of Physics, and Department of Biomedical Engineering, Duke University Medical Center, Durham, North Carolina 27705, Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Medical Physics Graduate Program, Duke University Medical Center, Durham, North Carolina 27705, Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, Durham, North Carolina 27705 and Department of Biomedical Engineering, University of North Carolina, Chapel Hill, North Carolina 27599, Department of Radiology, Duke University Medical Center, Durham, North Carolina 27705, Duke Radiation Dosimetry Laboratory, Department of Radiology, Duke University Medical Center, Durham, North Carolina 27705, Duke Radiation Dosimetry Laboratory, Department of Radiology, Medical Physics Graduate Program, Duke University Medical Center, Durham, North Carolina 27705, and Division of Pediatric Radiology, Department of Radiology, Medical Physics Graduate Program, Duke University Medical Center, Durham, North Carolina 27710. Patient-specific radiation dose and cancer risk estimation in CT: Part II. Application to patients. United States: N. p., 2011. Web. doi:10.1118/1.3515864.
Xiang, Li, Samei, Ehsan, Segars, W. Paul, Sturgeon, Gregory M., Colsher, James G., Toncheva, Greta, Yoshizumi, Terry T., Frush, Donald P., Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Medical Physics Graduate Program, Department of Physics, and Department of Biomedical Engineering, Duke University Medical Center, Durham, North Carolina 27705, Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Medical Physics Graduate Program, Duke University Medical Center, Durham, North Carolina 27705, Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, Durham, North Carolina 27705 and Department of Biomedical Engineering, University of North Carolina, Chapel Hill, North Carolina 27599, Department of Radiology, Duke University Medical Center, Durham, North Carolina 27705, Duke Radiation Dosimetry Laboratory, Department of Radiology, Duke University Medical Center, Durham, North Carolina 27705, Duke Radiation Dosimetry Laboratory, Department of Radiology, Medical Physics Graduate Program, Duke University Medical Center, Durham, North Carolina 27705, & Division of Pediatric Radiology, Department of Radiology, Medical Physics Graduate Program, Duke University Medical Center, Durham, North Carolina 27710. Patient-specific radiation dose and cancer risk estimation in CT: Part II. Application to patients. United States. https://doi.org/10.1118/1.3515864
Xiang, Li, Samei, Ehsan, Segars, W. Paul, Sturgeon, Gregory M., Colsher, James G., Toncheva, Greta, Yoshizumi, Terry T., Frush, Donald P., Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Medical Physics Graduate Program, Department of Physics, and Department of Biomedical Engineering, Duke University Medical Center, Durham, North Carolina 27705, Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Medical Physics Graduate Program, Duke University Medical Center, Durham, North Carolina 27705, Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, Durham, North Carolina 27705 and Department of Biomedical Engineering, University of North Carolina, Chapel Hill, North Carolina 27599, Department of Radiology, Duke University Medical Center, Durham, North Carolina 27705, Duke Radiation Dosimetry Laboratory, Department of Radiology, Duke University Medical Center, Durham, North Carolina 27705, Duke Radiation Dosimetry Laboratory, Department of Radiology, Medical Physics Graduate Program, Duke University Medical Center, Durham, North Carolina 27705, and Division of Pediatric Radiology, Department of Radiology, Medical Physics Graduate Program, Duke University Medical Center, Durham, North Carolina 27710. Sat . "Patient-specific radiation dose and cancer risk estimation in CT: Part II. Application to patients". United States. https://doi.org/10.1118/1.3515864.
@article{osti_22096876,
title = {Patient-specific radiation dose and cancer risk estimation in CT: Part II. Application to patients},
author = {Xiang, Li and Samei, Ehsan and Segars, W. Paul and Sturgeon, Gregory M. and Colsher, James G. and Toncheva, Greta and Yoshizumi, Terry T. and Frush, Donald P. and Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Medical Physics Graduate Program, Department of Physics, and Department of Biomedical Engineering, Duke University Medical Center, Durham, North Carolina 27705 and Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Medical Physics Graduate Program, Duke University Medical Center, Durham, North Carolina 27705 and Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, Durham, North Carolina 27705 and Department of Biomedical Engineering, University of North Carolina, Chapel Hill, North Carolina 27599 and Department of Radiology, Duke University Medical Center, Durham, North Carolina 27705 and Duke Radiation Dosimetry Laboratory, Department of Radiology, Duke University Medical Center, Durham, North Carolina 27705 and Duke Radiation Dosimetry Laboratory, Department of Radiology, Medical Physics Graduate Program, Duke University Medical Center, Durham, North Carolina 27705 and Division of Pediatric Radiology, Department of Radiology, Medical Physics Graduate Program, Duke University Medical Center, Durham, North Carolina 27710},
abstractNote = {Purpose: Current methods for estimating and reporting radiation dose from CT examinations are largely patient-generic; the body size and hence dose variation from patient to patient is not reflected. Furthermore, the current protocol designs rely on dose as a surrogate for the risk of cancer incidence, neglecting the strong dependence of risk on age and gender. The purpose of this study was to develop a method for estimating patient-specific radiation dose and cancer risk from CT examinations. Methods: The study included two patients (a 5-week-old female patient and a 12-year-old male patient), who underwent 64-slice CT examinations (LightSpeed VCT, GE Healthcare) of the chest, abdomen, and pelvis at our institution in 2006. For each patient, a nonuniform rational B-spine (NURBS) based full-body computer model was created based on the patient's clinical CT data. Large organs and structures inside the image volume were individually segmented and modeled. Other organs were created by transforming an existing adult male or female full-body computer model (developed from visible human data) to match the framework defined by the segmented organs, referencing the organ volume and anthropometry data in ICRP Publication 89. A Monte Carlo program previously developed and validated for dose simulation on the LightSpeed VCT scanner was used to estimate patient-specific organ dose, from which effective dose and risks of cancer incidence were derived. Patient-specific organ dose and effective dose were compared with patient-generic CT dose quantities in current clinical use: the volume-weighted CT dose index (CTDI{sub vol}) and the effective dose derived from the dose-length product (DLP). Results: The effective dose for the CT examination of the newborn patient (5.7 mSv) was higher but comparable to that for the CT examination of the teenager patient (4.9 mSv) due to the size-based clinical CT protocols at our institution, which employ lower scan techniques for smaller patients. However, the overall risk of cancer incidence attributable to the CT examination was much higher for the newborn (2.4 in 1000) than for the teenager (0.7 in 1000). For the two pediatric-aged patients in our study, CTDI{sub vol} underestimated dose to large organs in the scan coverage by 30%-48%. The effective dose derived from DLP using published conversion coefficients differed from that calculated using patient-specific organ dose values by -57% to 13%, when the tissue weighting factors of ICRP 60 were used, and by -63% to 28%, when the tissue weighting factors of ICRP 103 were used. Conclusions: It is possible to estimate patient-specific radiation dose and cancer risk from CT examinations by combining a validated Monte Carlo program with patient-specific anatomical models that are derived from the patients' clinical CT data and supplemented by transformed models of reference adults. With the construction of a large library of patient-specific computer models encompassing patients of all ages and weight percentiles, dose and risk can be estimated for any patient prior to or after a CT examination. Such information may aid in decisions for image utilization and can further guide the design and optimization of CT technologies and scan protocols.},
doi = {10.1118/1.3515864},
url = {https://www.osti.gov/biblio/22096876}, journal = {Medical Physics},
issn = {0094-2405},
number = 1,
volume = 38,
place = {United States},
year = {2011},
month = {1}
}