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Conference Proceeding

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Publication Title

Medical Physics


Purpose: To improve the dose and LET distribution in the IMPTLET, we introduce a new optimization algorithm to search for the optimal beam orientation and count through the arc trajectory (BOC-IMPTLET). Methods: We introduce kmeans clustering analysis in the BOC-IMPTLET algorithm by analyzing the distribution of LET in the target from the full arc trajectory. The optimal of cluster count was used as beam count, which was determined based on the SSE (Sum of Square Error) value and the angle of the corresponding centroid of each cluster was used as beam orientation, respectively. The BOC-IMPTLET algorithm was implemented in the open-source platform matRad (Department of Medical Physics in Radiation Oncology, German Cancer Research Center-DKFZ). Three different disease sites, head and neck, brain and liver were used for testing purpose by comparing the dose and LET distribution target and OARs between the BOC-IMPTLET and IMPTLET using clinical beam angles (clinical-IMPTLET). Results: With the same number of beam angles or counts, the dose and LET distribution were improved using BOC-IMPTLET compared to the clinical-IMPTLET. More specifically, for the brain case, the dose conformity index increased from 0.84 to 0.85, and the mean LET in the target increased from 4.57 keV/m to 4.70 keV/m. The maximum LET of brainstem and optic chiasm decreased by a factor of 8.5% and 70.94%, from 8.00 keV/m and 25.84 keV/m in the clinical-IMPTLET, to 7.32 keV/m and 7.51 keV/m in the plan with BOC-IMPTLET, respectively. The improvement was similar in other cases. Conclusion: The BOC-IMPTLET is capable of improving both dose and LET distribution compared to the clinical-IMPTLET making it more effective than manual beam assignment from the clinical plan.





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American Association of Physicists in Medicine 65th Annual Meeting & Exhibition, July 23-27, 2023, Houston, TX