Document Detail


Dosimetric verification of a commercial Monte Carlo treatment planning system (VMC++) for a 9 MeV electron beam.
MedLine Citation:
PMID:  19544794     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The aim of this work was to evaluate the performance of the voxel-based Monte Carlo algorithm implemented in the commercial treatment planning system ONCENTRA MASTERPLAN for a 9 MeV electron beam produced by a linear accelerator Varian Clinac 2100 C/D. In order to realize an experimental verification of the computed data, three different groups of tests were planned. The first set was performed in a water phantom to investigate standard fields, custom inserts, and extended treatment distances. The second one concerned standard field, irregular entrance surface, and oblique incidence in a homogeneous PMMA phantom. The last group involved the introduction of inhomogeneities in a PMMA phantom to simulate high and low density materials such as bone and lung. Measurements in water were performed by means of cylindrical and plane-parallel ionization chambers, whereas measurements in PMMA were carried out by the use of radiochromic films. Point dose values were compared in terms of percentage difference, whereas the gamma index tool was used to perform the comparison between computed and measured dose profiles, considering different tolerances according to the test complexity. In the case of transverse scans, the agreement was searched in the plane formed by the intersection of beam axis and the profile (2D analysis), while for percentage depth dose curves, only the beam axis was explored (1D analysis). An excellent agreement was found for point dose evaluation in water (discrepancies smaller than 2%). Also the comparison between planned and measured dose profiles in homogeneous water and PMMA phantoms showed good results (agreement within 2%-2 mm). Profile evaluation in phantoms with internal inhomogeneities showed a good agreement in the case of "lung" insert, while in tests concerning a small "bone" inhomogeneity, a discrepancy was particularly evidenced in dose values on the beam axis. This is due to the inaccurate geometrical description of the phantom that is linked to the calculation voxel size, a feature over which the user has no control.
Authors:
P Schiapparelli; D Zefiro; G Taccini
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Publication Detail:
Type:  Evaluation Studies; Journal Article; Validation Studies    
Journal Detail:
Title:  Medical physics     Volume:  36     ISSN:  0094-2405     ISO Abbreviation:  Med Phys     Publication Date:  2009 May 
Date Detail:
Created Date:  2009-06-23     Completed Date:  2009-07-15     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0425746     Medline TA:  Med Phys     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1759-67     Citation Subset:  IM    
Affiliation:
S. C. Fisica Sanitaria, E. O. Ospedali Galliera, via A. Volta 8, 16128 Genova, Italy. piero.schiapparelli@galliera.it
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MeSH Terms
Descriptor/Qualifier:
Monte Carlo Method
Radiometry / methods*
Radiotherapy Dosage
Radiotherapy Planning, Computer-Assisted / methods*
Radiotherapy, High-Energy / methods*
Reproducibility of Results
Sensitivity and Specificity
Software*
Software Validation*

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


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