On prediction of cardio-pulmonary complications during hypofractionated versus conventional fractionated regimens of left breast radiation therapy using Monte Carlo and Collapsed Cone Convolution based algorithms

Document Type : Original Paper

Authors

1 Department of Medical Physics, University of Medical Sciences, Urmia, Iran

2 Omid Research and Treatment Center, Urmia, Iran

Abstract

Introduction: This study aimed to evaluate the dose calculation algorithms of Monte Carlo (MC) and Collapsed Cone Convolution (CCC) to compare the conventional fractionation radiotherapy (CFRT) and hypofractionation radiotherapy (HFRT) of the left breast cancer (BC) in the prediction of cardio-pulmonary complications and tumor control using two radiobiological indices, NTCP (normal tissue complication probability) and TCP (tumor control probability).

Materials and Methods: CT images of 19 female patients with early-stage left-sided breast cancer were used in this study. For each patient, two treatment regimens, CF (50Gy/25frs) vs. HF (42.5Gy/16frs), were simulated separately. Consequently, the TCP and NTCP values for each regimen using different radiobiological models were calculated via MC and CCC algorithms. The radiotherapy-induced cardiopulmonary complications are considered the radiobiological endpoint. Statistical significance was defined as p<0.05.

Results: The mean NTCP and TCP calculated in the CFRT and HFRT were as follows: cardiac mortality (MC: CFRT=0.0374±0.0031 vs. HFRT=0.0173±0.0015; p<0.001) and (CCC: CFRT=0.0373±0.0031 vs. HFRT=0.0168±0.0015; p<0.001), pneumonitis (MC: CFRT=0.1201±0.0074 vs. HFRT=0.0756±0.0051; p<0.001) and (CCC: CFRT=0.1131±0.0071 vs. HFRT=0.0697±0.0045; p<0.01), and TCP (MC: CFRT=0.9979±0.0020 vs. HFRT=0.9997±0.0002; p=0.593) and (CCC: CFRT=0.9982±0.0007 vs. HFRT=0.9986±0.0004; p=0.821).

Conclusion: The comparison of CFRT and HFRT treatment regimens using the MC and CCC algorithms showed that the risk of cardiac mortality and pneumonitis in the CFRT was significantly higher than in the HF regimen, and TCP was not significantly different in the two regimens. Applications of MC-based dose calculation algorithms along with suitable biological parameters can help physicists in the prediction of radiation-induced complications accurately and precisely.

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Articles in Press, Accepted Manuscript
Available Online from 02 July 2022
  • Receive Date: 13 January 2022
  • Revise Date: 10 June 2022
  • Accept Date: 02 July 2022
  • First Publish Date: 02 July 2022