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Title: Estimation of organ doses from kilovoltage cone-beam CT imaging used during radiotherapy patient position verification

Abstract

Purpose: The purpose of this study was to develop a practical method for estimating organ doses from kilovoltage cone-beam CT (CBCT) that can be performed with readily available phantoms and dosimeters. The accuracy of organ dose estimates made using the ImPACT patient dose calculator was also evaluated. Methods: A 100 mm pencil chamber and standard CT dose index (CTDI) phantoms were used to measure the cone-beam dose index (CBDI). A weighted CBDI (CBDI{sup w}) was then calculated from these measurements to represent the average volumetric dose in the CTDI phantom. By comparing CBDI{sup w} to the previously published organ doses, organ dose conversion coefficients were developed. The measured CBDI values were also used as inputs for the ImPACT calculator to estimate organ doses. All CBDI dose measurements were performed on both the Elekta XVI and Varian OBI at three clinically relevant locations: Head, chest, and pelvis. Results: The head, chest, and pelvis protocols yielded CBDI{sup w} values of 0.98, 16.62, and 24.13 mGy for the XVI system and 5.17, 6.14, and 21.57 mGy for the OBI system, respectively. Organ doses estimated with the ImPACT CT dose calculator showed a large range of variation from the previously measured organ doses, demonstratingmore » its limitations for use with CBCT. Conclusions: The organ dose conversion coefficients developed in this work relate CBDI{sup w} values to organ doses previously measured using the same clinical protocols. Ultimately, these coefficients will allow for the quick estimation of organ doses from routine measurements performed using standard CTDI phantoms and pencil chambers.« less

Authors:
;  [1]
  1. Department of Radiation Oncology, University of Iowa Hospitals and Clinics, 200 Hawkins Drive, Iowa City, Iowa 52242 (United States)
Publication Date:
OSTI Identifier:
22098526
Resource Type:
Journal Article
Journal Name:
Medical Physics
Additional Journal Information:
Journal Volume: 37; Journal Issue: 9; Other Information: (c) 2010 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; ACCURACY; CHEST; COMPUTERIZED TOMOGRAPHY; DOSEMETERS; DOSIMETRY; HEAD; IMAGES; PATIENTS; PELVIS; PHANTOMS; RADIATION DOSES; RADIOTHERAPY; STANDARDS; VERIFICATION

Citation Formats

Hyer, Daniel E., Hintenlang, David E., and University of Florida, 202 Nuclear Sciences Center, P.O. Box 118300, Gainesville, Florida 32611. Estimation of organ doses from kilovoltage cone-beam CT imaging used during radiotherapy patient position verification. United States: N. p., 2010. Web. doi:10.1118/1.3476459.
Hyer, Daniel E., Hintenlang, David E., & University of Florida, 202 Nuclear Sciences Center, P.O. Box 118300, Gainesville, Florida 32611. Estimation of organ doses from kilovoltage cone-beam CT imaging used during radiotherapy patient position verification. United States. https://doi.org/10.1118/1.3476459
Hyer, Daniel E., Hintenlang, David E., and University of Florida, 202 Nuclear Sciences Center, P.O. Box 118300, Gainesville, Florida 32611. 2010. "Estimation of organ doses from kilovoltage cone-beam CT imaging used during radiotherapy patient position verification". United States. https://doi.org/10.1118/1.3476459.
@article{osti_22098526,
title = {Estimation of organ doses from kilovoltage cone-beam CT imaging used during radiotherapy patient position verification},
author = {Hyer, Daniel E. and Hintenlang, David E. and University of Florida, 202 Nuclear Sciences Center, P.O. Box 118300, Gainesville, Florida 32611},
abstractNote = {Purpose: The purpose of this study was to develop a practical method for estimating organ doses from kilovoltage cone-beam CT (CBCT) that can be performed with readily available phantoms and dosimeters. The accuracy of organ dose estimates made using the ImPACT patient dose calculator was also evaluated. Methods: A 100 mm pencil chamber and standard CT dose index (CTDI) phantoms were used to measure the cone-beam dose index (CBDI). A weighted CBDI (CBDI{sup w}) was then calculated from these measurements to represent the average volumetric dose in the CTDI phantom. By comparing CBDI{sup w} to the previously published organ doses, organ dose conversion coefficients were developed. The measured CBDI values were also used as inputs for the ImPACT calculator to estimate organ doses. All CBDI dose measurements were performed on both the Elekta XVI and Varian OBI at three clinically relevant locations: Head, chest, and pelvis. Results: The head, chest, and pelvis protocols yielded CBDI{sup w} values of 0.98, 16.62, and 24.13 mGy for the XVI system and 5.17, 6.14, and 21.57 mGy for the OBI system, respectively. Organ doses estimated with the ImPACT CT dose calculator showed a large range of variation from the previously measured organ doses, demonstrating its limitations for use with CBCT. Conclusions: The organ dose conversion coefficients developed in this work relate CBDI{sup w} values to organ doses previously measured using the same clinical protocols. Ultimately, these coefficients will allow for the quick estimation of organ doses from routine measurements performed using standard CTDI phantoms and pencil chambers.},
doi = {10.1118/1.3476459},
url = {https://www.osti.gov/biblio/22098526}, journal = {Medical Physics},
issn = {0094-2405},
number = 9,
volume = 37,
place = {United States},
year = {Wed Sep 15 00:00:00 EDT 2010},
month = {Wed Sep 15 00:00:00 EDT 2010}
}