Document Detail


Interfraction liver shape variability and impact on GTV position during liver stereotactic radiotherapy using abdominal compression.
MedLine Citation:
PMID:  20947263     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
PURPOSE: For patients receiving liver stereotactic body radiotherapy (SBRT), abdominal compression can reduce organ motion, and daily image guidance can reduce setup error. The reproducibility of liver shape under compression may impact treatment delivery accuracy. The purpose of this study was to measure the interfractional variability in liver shape under compression, after best-fit rigid liver-to-liver registration from kilovoltage (kV) cone beam computed tomography (CBCT) scans to planning computed tomography (CT) scans and its impact on gross tumor volume (GTV) position.
METHODS AND MATERIALS: Evaluable patients were treated in a Research Ethics Board-approved SBRT six-fraction study with abdominal compression. Kilovoltage CBCT scans were acquired before treatment and reconstructed as respiratory sorted CBCT scans offline. Manual rigid liver-to-liver registrations were performed from exhale-phase CBCT scans to exhale planning CT scans. Each CBCT liver was contoured, exported, and compared with the planning CT scan for spatial differences, by use of in house-developed finite-element model-based deformable registration (MORFEUS).
RESULTS: We evaluated 83 CBCT scans from 16 patients with 30 GTVs. The mean volume of liver that deformed by greater than 3 mm was 21.7%. Excluding 1 outlier, the maximum volume that deformed by greater than 3 mm was 36.3% in a single patient. Over all patients, the absolute maximum deformations in the left-right (LR), anterior-posterior (AP), and superior-inferior directions were 10.5 mm (SD, 2.2), 12.9 mm (SD, 3.6), and 5.6 mm (SD, 2.7), respectively. The absolute mean predicted impact of liver volume displacements on GTV by use of center of mass displacements was 0.09 mm (SD, 0.13), 0.13 mm (SD, 0.18), and 0.08 mm (SD, 0.07) in the left-right, anterior-posterior, and superior-inferior directions, respectively.
CONCLUSIONS: Interfraction liver deformations in patients undergoing SBRT under abdominal compression after rigid liver-to-liver registrations on respiratory sorted CBCT scans were small in most patients (<5 mm).
Authors:
Cynthia L Eccles; Laura A Dawson; Joanne L Moseley; Kristy K Brock
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't     Date:  2010-10-13
Journal Detail:
Title:  International journal of radiation oncology, biology, physics     Volume:  80     ISSN:  1879-355X     ISO Abbreviation:  Int. J. Radiat. Oncol. Biol. Phys.     Publication Date:  2011 Jul 
Date Detail:
Created Date:  2011-05-30     Completed Date:  2011-07-27     Revised Date:  2011-09-26    
Medline Journal Info:
Nlm Unique ID:  7603616     Medline TA:  Int J Radiat Oncol Biol Phys     Country:  United States    
Other Details:
Languages:  eng     Pagination:  938-46     Citation Subset:  IM    
Copyright Information:
Copyright © 2011 Elsevier Inc. All rights reserved.
Affiliation:
Princess Margaret Hospital, and University of Toronto, Toronto, Ontario, Canada. cynthia.eccles@rob.ox.ac.uk
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MeSH Terms
Descriptor/Qualifier:
Abdomen
Aged
Aged, 80 and over
Cone-Beam Computed Tomography
Female
Finite Element Analysis
Humans
Immobilization / methods*
Liver / anatomy & histology,  radiography*
Liver Neoplasms / pathology,  radiography*,  surgery*
Male
Middle Aged
Movement
Organ Size
Pressure
Radiosurgery / methods*
Reproducibility of Results
Respiration
Tumor Burden*
Grant Support
ID/Acronym/Agency:
5R01CA124714/CA/NCI NIH HHS; R01 CA124714-01A2/CA/NCI NIH HHS

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