A clinical study of lung cancer dose calculation accuracy with Monte Carlo simulation

Radiation Oncology

Xiongfei Liao¹  Shengwei Kang¹  Jie Li¹  Mingyong Xiao¹  Jian Li¹  Pei Wang¹  Xianliang Wang¹  Gang Yin¹  Guohai Qi¹  Yanqun Zhao¹ 

[1] Department of Radiation Oncology, Sichuan Provincial Cancer Hospital, Chengdu 610041, Sichuan, China

关键词: Intensity-modulated radiation therapy;    Monte Carlo;    Lung cancer;    Pencil beam convolution;    Collapsed cone convolution;    3-Dimensional conformal radiation therapy;   

Others  :  1150578
DOI  :  10.1186/s13014-014-0287-2

 received in 2014-07-03, accepted in 2014-12-04,  发布年份 2014

【 摘 要 】

Background

The accuracy of dose calculation is crucial to the quality of treatment planning and, consequently, to the dose delivered to patients undergoing radiation therapy. Current general calculation algorithms such as Pencil Beam Convolution (PBC) and Collapsed Cone Convolution (CCC) have shortcomings in regard to severe inhomogeneities, particularly in those regions where charged particle equilibrium does not hold. The aim of this study was to evaluate the accuracy of the PBC and CCC algorithms in lung cancer radiotherapy using Monte Carlo (MC) technology.

Methods and materials

Four treatment plans were designed using Oncentra Masterplan TPS for each patient. Two intensity-modulated radiation therapy (IMRT) plans were developed using the PBC and CCC algorithms, and two three-dimensional conformal therapy (3DCRT) plans were developed using the PBC and CCC algorithms. The DICOM-RT files of the treatment plans were exported to the Monte Carlo system to recalculate. The dose distributions of GTV, PTV and ipsilateral lung calculated by the TPS and MC were compared.

Result

For 3DCRT and IMRT plans, the mean dose differences for GTV between the CCC and MC increased with decreasing of the GTV volume. For IMRT, the mean dose differences were found to be higher than that of 3DCRT. The CCC algorithm overestimated the GTV mean dose by approximately 3% for IMRT. For 3DCRT plans, when the volume of the GTV was greater than 100 cm³, the mean doses calculated by CCC and MC almost have no difference. PBC shows large deviations from the MC algorithm. For the dose to the ipsilateral lung, the CCC algorithm overestimated the dose to the entire lung, and the PBC algorithm overestimated V₂₀ but underestimated V₅; the difference in V₁₀ was not statistically significant.

Conclusions

PBC substantially overestimates the dose to the tumour, but the CCC is similar to the MC simulation. It is recommended that the treatment plans for lung cancer be developed using an advanced dose calculation algorithm other than PBC. MC can accurately calculate the dose distribution in lung cancer and can provide a notably effective tool for benchmarking the performance of other dose calculation algorithms within patients.

【 授权许可】

   
2014 Zhao et al.; licensee BioMed Central.

【 图 表 】

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