(Sunday, 7/29/2018) 3:00 PM - 6:00 PM
Room: Exhibit Hall
Purpose: Clinical physics responsibilities include second check of treatment plans. Specifically, Radixact plans will benefit from a software solution for this need. Historically, phantom measurements provided only validation technique for such plans. Radcalcâ„¢ recently has provided for point dose calculation such a solution using simple dose deposition algorithms. The purpose of this study is to validate RadCalc as a second check for plans generated in Accuray Precisionâ„¢ TPS.
Methods: Thirty Precision plans were tested for accuracy. Point dose and treatment times calculated for various treatment sites were compared with those from Precision TPS. Points located in high-dose, low-gradient regions (inside the PTV) and those located in high-gradient regions were exported from Precision plans. Location of the points can be entered also manually in RadCalc or can be located by the program in the center of regions of interest (ROI) exported from Precision.
Results: Differences between dose calculated by Precision and RadCalc was less than 4% in all cases when points were located in high-dose, low-gradient regions. For points in high-gradient regions, the difference was found to be as high as 8%. The major difference was observed in prostate plans, when points were located inside the bladder when it was highly surrounded by bony structures. Differences in calculated treatment time in all cases was less than 3%. Results obtained for 30 cases, as a function of various treatment sites seen clinically, will be presented.
Conclusion: This study concentrated in evaluating RadCalc as a secondary check for Radixact plans generated by Precision TPS (both helical and Tomo-Direct plans). This type of software is mainly used for the validation of point dose calculation in high-dose, low-gradient regions and as a second check for treatment time. In this case, RadCalc performed as expected. Further study of the impact of heterogeneities corrections are underway.
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Taxonomy
TH- External beam- photons: Quality Assurance - IMRT
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