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Incorporating partial shining effects in proton pencil-beam dose calculation
Yupeng Li1, Xiaodong Zhang, Mingfwu Lii
1Department of Radiation Physics, University of Texas, MD Anderson Cancer Center, Houston, TX 77030, USA. yupli@mdanderson.org
Physics in Medicine and Biology
|January 18, 2008
Summary
A new algorithm models the partial shining effect on the range modulator wheel in proton therapy. This improves the accuracy of dose calculations, particularly at the spread-out Bragg peak
Area of Science:
- Medical Physics
- Radiation Oncology
Background:
- The range modulator wheel (RMW) is critical in passively scattered proton therapy.
- Current proton dose calculation algorithms often overlook the partial shining effect on the RMW.
Purpose of the Study:
- To develop and validate an algorithm for modeling the partial shining effect on the RMW.
- To improve the accuracy of dose calculations for passively scattered proton therapy.
Main Methods:
- Calculated apparent modulator weights without considering partial shining.
- Modeled proton beam spill as a uniform circular spot.
- Developed a weight-splitting process to incorporate the partial shining effect.
- Calculated spread-out Bragg peaks (SOBPs) using effective modulator weights.
Main Results:
- The developed algorithm significantly improved the fit of calculated SOBPs to measured data at proximal and entrance regions for eight different beam configurations.
- Dose calculations incorporating the partial shining effect showed better agreement with measurements compared to standard methods.
- In a prostate cancer patient, standard dose calculations underestimated femoral head and skin doses.
Conclusions:
- The developed algorithm accurately models the partial shining effect, enhancing dose calculation precision in proton therapy.
- Accounting for partial shining is crucial for accurate dose prediction, especially in the proximal shoulder and entrance regions of the SOBP.
- This improved accuracy can lead to better treatment planning and potentially reduce dose discrepancies in clinical scenarios.
