Dose correction strategy for the optimization of volumetric modulated arc therapy Journal Article
| Authors: | Zhang, P.; Yang, J.; Hunt, M.; Mageras, G. |
| Article Title: | Dose correction strategy for the optimization of volumetric modulated arc therapy |
| Abstract: | Purpose: Dose calculation during optimization of volumetric modulated arc therapy (VMAT) is necessarily simplified to keep computation time manageably low; however the approximations used in the scatter dose calculation lead to discrepancy with more accurate dose calculation following optimization. The purpose of this study is to develop a dose correction strategy in optimization that can minimize the disagreement. Methods: VMAT delivery is modeled using a number of static equispaced beams. Dose correction factors (Cij) are associated with each beam i and point j inside the region of interest. Cij is calculated as the ratio of dose obtained from the full scatter dose calculation over that from the partial scatter dose calculation in optimization. VMAT optimization algorithm is a multiple resolution approach. The dose correction factors are calculated at the beginning of each resolution and applied as multiplicative corrections to the partial scatter dose during optimization. Clinical cases for brain, prostate, paraspinal, and esophagus are utilized to evaluate the method. Treatment plans created with and without the correction scheme are normalized such that the complication rates of organs at risk (OARs) are comparable. The resulting planning target volume (PTV) mean doses are used to compare plan quality. Results: The difference between the dose calculated at the end of optimization and at the end of the final forward dose calculation is reduced from 7% and 5% for the PTV and OAR mean doses without correction to approximately 1% with correction. Applying dose correction during optimization saves planners 2-4 h in average in treatment planning, and has a positive impact on plan quality, evidenced by a noticeably higher PTV mean dose: 2.1%, 2.4%, 0.5%, and 9.3% of the corresponding prescription dose in the brain, esophagus, prostate, and paraspinal cases, respectively. Conclusions: When dose correction is applied during optimization, dose discrepancies between optimization and full dose calculation are reduced. Integrating dose correction in VMAT optimization allows planners to adjust the optimization constraints more easily and confidently during optimization and has the potential to improve plan quality. © 2010 American Association of Physicists in Medicine. |
| Keywords: | treatment planning; pathophysiology; radiation dose; methodology; sensitivity and specificity; reproducibility; reproducibility of results; biological model; models, biological; radiotherapy dosage; evaluation; spinal cord tumor; spinal neoplasms; computer simulation; radiometry; radiotherapy planning, computer-assisted; radiotherapy, conformal; computer assisted radiotherapy; dose calculation; volumetric arc modulated therapy; peru tomato mosaic virus |
| Journal Title: | Medical Physics |
| Volume: | 37 |
| Issue: | 6 |
| ISSN: | 0094-2405 |
| Publisher: | American Association of Physicists in Medicine |
| Date Published: | 2010-06-01 |
| Start Page: | 2441 |
| End Page: | 2444 |
| Language: | English |
| DOI: | 10.1118/1.3426001 |
| PUBMED: | 20632554 |
| PROVIDER: | scopus |
| PMCID: | PMC8015868 |
| DOI/URL: | |
| Notes: | --- - "Cited By (since 1996): 1" - "Export Date: 20 April 2011" - "CODEN: MPHYA" - "Source: Scopus" |
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