The performance of the progressive resolution optimizer (PRO) for RapidArc planning in targets with low‐density media

A new version of progressive resolution optimizer (PRO) with an option of air cavity correction has been implemented for RapidArc volumetric‐modulated arc therapy (RA). The purpose of this study was to compare the performance of this new PRO with the use of air cavity correction option (PRO10_air) a...

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Bibliographic Details
Published in:Journal of applied clinical medical physics 2013-11, Vol.14 (6), p.205-221
Main Authors: Kan, Monica W.K., Leung, Lucullus H.T., Yu, Peter K.N.
Format: Article
Language:English
Subjects:
Acuros XB algorithm
air cavity correction
Algorithms
Carcinoma
Carcinoma, Non-Small-Cell Lung - pathology
Carcinoma, Non-Small-Cell Lung - radiotherapy
Humans
low‐density media
Lung cancer
Lung Neoplasms - pathology
Lung Neoplasms - radiotherapy
Nasopharyngeal Carcinoma
Nasopharyngeal Neoplasms - pathology
Nasopharyngeal Neoplasms - radiotherapy
Neoplasm Staging
Optimization
optimization algorithm
Organs at Risk
Phantoms, Imaging
Planning
Quality
Radiation therapy
Radiotherapy Dosage
Radiotherapy Planning, Computer-Assisted
Radiotherapy, Intensity-Modulated
RapidArc
Studies
Tumors
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Summary:A new version of progressive resolution optimizer (PRO) with an option of air cavity correction has been implemented for RapidArc volumetric‐modulated arc therapy (RA). The purpose of this study was to compare the performance of this new PRO with the use of air cavity correction option (PRO10_air) against the one without the use of the air cavity correction option (PRO10_no‐air) for RapidArc planning in targets with low‐density media of different sizes and complexities. The performance of PRO10_no‐air and PRO10_air was initially compared using single‐arc plans created for four different simple heterogeneous phantoms with virtual targets and organs at risk. Multiple‐arc planning of 12 real patients having nasopharyngeal carcinomas (NPC) and ten patients having non‐small cell lung cancer (NSCLC) were then performed using the above two options for further comparison. Dose calculations were performed using both the Acuros XB (AXB) algorithm with the dose to medium option and the analytical anisotropic algorithm (AAA). The effect of using intermediate dose option after the first optimization cycle in PRO10_air and PRO10_no‐air was also investigated and compared. Plans were evaluated and compared using target dose coverage, critical organ sparing, conformity index, and dose homogeneity index. For NSCLC cases or cases for which large volumes of low‐density media were present in or adjacent to the target volume, the use of the air cavity correction option in PROIO was shown to be beneficial. For NPC cases or cases for which small volumes of both low‐ and high‐density media existed in the target volume, the use of air cavity correction in PRO10 did not improve the plan quality. Based on the AXB dose calculation results, the use of PRO10_air could produce up to 18% less coverage to the bony structures of the planning target volumes for NPC cases. When the intermediate dose option in PRO10 was used, there was negligible difference observed in plan quality between optimizations with and without using the air cavity correction option. PACS number: 87.55.D‐, 87.55.de, 87.56.N‐
ISSN:1526-9914
1526-9914
DOI:10.1120/jacmp.v14i6.4382