Document Detail


MRI-guided prostate radiation therapy planning: Investigation of dosimetric accuracy of MRI-based dose planning.
MedLine Citation:
PMID:  21339009     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
BACKGROUND AND PURPOSE: Dose planning requires a CT scan which provides the electron density distribution for dose calculation. MR provides superior soft tissue contrast compared to CT and the use of MR-alone for prostate planning would provide further benefits such as lower cost to the patient. This study compares the accuracy of MR-alone based dose calculations with bulk electron density assignment to CT-based dose calculations for prostate radiotherapy.
MATERIALS AND METHODS: CT and whole pelvis MR images were contoured for 39 prostate patients. Plans with uniform density and plans with bulk density values assigned to bone and tissue were compared to the patient's gold standard full density CT plan. The optimal bulk density for bone was calculated using effective depth measurements. The plans were evaluated using ICRU point doses, dose volume histograms, and Chi comparisons. Differences in spatial uniformity were investigated for the CT and MR scans.
RESULTS: The calculated dose for CT bulk bone and tissue density plans was 0.1±0.6% (mean±1 SD) higher than the corresponding full density CT plan. MR bulk bone and tissue density plans were 1.3±0.8% lower than the full density CT plan. CT uniform density plans and MR uniform density plans were 1.4±0.9% and 2.6±0.9% lower, respectively. Paired t-tests performed on specific points on the DVH graphs showed that points on DVHs for all bulk electron density plans were equivalent with two exceptions. There was no significant difference between doses calculated on Pinnacle and Eclipse. The dose distributions of six patients produced Chi values outside the acceptable range of values when MR-based plans were compared to the full density plan.
CONCLUSIONS: MR-alone bulk density planning is feasible provided bone is assigned a density, however, manual segmentation of bone on MR images will have to be replaced with automatic methods. The major dose differences for MR bulk density plans are due to differences in patient external contours introduced by the MR couch-top and pelvic coil.
Authors:
Jonathan Lambert; Peter B Greer; Fred Menk; Jackie Patterson; Joel Parker; Kara Dahl; Sanjiv Gupta; Anne Capp; Chris Wratten; Colin Tang; Mahesh Kumar; Jason Dowling; Sarah Hauville; Cynthia Hughes; Kristen Fisher; Peter Lau; James W Denham; Olivier Salvado
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2011-02-19
Journal Detail:
Title:  Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology     Volume:  98     ISSN:  1879-0887     ISO Abbreviation:  Radiother Oncol     Publication Date:  2011 Mar 
Date Detail:
Created Date:  2011-03-08     Completed Date:  2011-08-03     Revised Date:  2012-02-02    
Medline Journal Info:
Nlm Unique ID:  8407192     Medline TA:  Radiother Oncol     Country:  Ireland    
Other Details:
Languages:  eng     Pagination:  330-4     Citation Subset:  IM    
Copyright Information:
Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.
Affiliation:
School of Mathematical and Physical Sciences, University of Newcastle, University Drive, Callaghan, NSW 2308, Australia. Jonathan.Lambert@uon.edu.au
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MeSH Terms
Descriptor/Qualifier:
Aged
Clinical Protocols
Humans
Magnetic Resonance Imaging*
Male
Middle Aged
Prostatic Neoplasms / radiography,  radiotherapy*
Radiometry*
Radiotherapy Planning, Computer-Assisted* / standards
Tomography, X-Ray Computed
Comments/Corrections
Comment In:
Radiother Oncol. 2012 Jan;102(1):163   [PMID:  21704415 ]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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