Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
8248176 | Medical Dosimetry | 2018 | 7 Pages |
Abstract
To provide a modified formula consistent with the Monte Carlo (MC) algorithm for dose calculations during stereotactic ablative body radiotherapy for non-small cell lung cancer. Seventy CyberKnife treatment plans were calculated and analyzed by MC and ray-tracing (RT) algorithms, separately. Parameters of treatment plans were compared, and those associated with differences of dose distributions were analyzed to establish a modified formula. Gross tumor volume and tumor tracking volume (TTV) were defined as the evident disease on the sequences of the window width and level of the lung and the mediastinum. Additionally, the formula was validated by another 20 plans. The prescription dose of the 90 patients was 60âGy/5f. The RT algorithm overestimated the planning target volume (PTV) D95 by an average of 8.59âGy and the gross tumor volume D99 by an average of 5.84âGy. The homogeneity index of PTV was underestimated by 0.11 on average, whereas the conformity index and new conformity index was underestimated by 0.05. The RT algorithm overestimated the dose distribution to the spinal cord by 2.23âGy, the esophagus by 1.96âGy, the trachea by 1.89âGy, the left-sided bronchus by 1.77âGy, the right-sided bronchus by 1.64âGy, and the heart by 2.16âGy. The average whole-lung dose volumes of lung tissues and dose volumes of V5 were overestimated by 2.69âGy and 7.52%, respectively. A power function distribution (R2â=â0.8626) was confirmed between PTV D95 and TTV volumes. PTV D95 calculated by the MC algorithm could be computed easily with TTV and PTV D95 calculated by the RT algorithm based on the formula. The modified equation was more consistent with MC algorithm than with other formula, which could be a reference to those not accessible to the MC algorithm.
Keywords
Related Topics
Physical Sciences and Engineering
Physics and Astronomy
Radiation
Authors
Yangsen MD, Xiaofei MD, Yu MD, Chunshan MD, Yongming MD, Yongjian MD, Zhitao MD, Xueling MD, Xiaoping MD, Huojun MD,