ESTRO 2023 - Abstract Book

S1523

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ESTRO 2023

Conclusion Results of this work show that doses to organs at risk resulting from CBCT scans during IGRT procedures are affected by the patient . Some organs were influenced significantly, while less impact was found for organs that were located at edge of the scan field. The patient should be taken into account when doses of organs at risk are considered.

PO-1799 Validation of Beam Modeling and Dose Calculation of Proton Beam Therapy for Monaco TPS

S. Chen 1 , X. Li 1 , L. Zhao 1 , R. Deraniyagala 1 , W. Zheng 1 , A. Qin 1 , X. Ding 1

1 Beaumont Health, Radiation Oncology, Royal Oak, USA

Purpose or Objective To validate the physical beam modeling and the accuracy of proton dose calculation algorithms in Monaco treatment planning system (TPS) for proton therapy treatment. Materials and Methods Monaco TPS proton module (ver. 6.0, Elekta, Stockholm, Sweden) Pencil Beam Scanning (PBS) and Monte Carlo (MC) dose calculation algorithms were evaluated based on the IBA ProteusONE® system. The evaluations include:1) Pristine Bragg peak proton range in water comparison between Monaco and Raystation. Mono-energetic proton beams (10x10 field) with the energy of 70MeV, 100MeV, 150MeV, 200MeV, and 227.7MeV were evaluated, respectively; 2) physical beam model verification using 9 standard cube plans that were created to simulate different treatment sites, target volumes and positions. The dose calculated in Monaco was compared with the measurements for both PBS and MC dose calculation; 3) patient-specific dose distribution comparison was performed between Monaco and Raystation. Four intensity modulate proton therapy treatment plans including 1 prostate, 1 brain, 1 lung, and 1 head and neck patient were evaluated; 4) Dose calculation accuracy was verified using the IROC phantom of standard output check and phantoms of different treatment sites including prostate, spine, lung, brain, and liver. Results The deviation of percentage depth dose at midSOBP was within 0.8% for PBS and 2% for MC. The point doses were measured at the depth of 5 ~ 21cm and the deviation were -1.0% ~ 1.8% for PBS and -1.2% ~ 2.4% for MC. The dose discrepancy distributions and the DVHs for the 4 patients were shown in Figure 1. The dose discrepancies between the calculated dose and the measurements of different IROC phantoms with respect to the two TPS were shown in Figure 2.