Oncology Institute of Southern Switzerland, Medical Physics Unit, Bellinzona, Switzerland.
Acta Oncol. 2013 Apr;52(3):545-52. doi: 10.3109/0284186X.2012.689853. Epub 2012 Jun 7.
To appraise the potential of volumetric modulated arc therapy (VMAT, RapidArc) and proton beams to simultaneously achieve target coverage and enhanced sparing of bone tissue in the treatment of soft-tissue sarcoma with adequate target coverage.
Ten patients presenting with soft-tissue sarcoma of the leg were collected for the study. Dose was prescribed to 66.5 Gy in 25 fractions to the planning target volume (PTV) while significant maximum dose to the bone was constrained to 50 Gy. Plans were optimised according to the RapidArc technique with 6 MV photon beams or for intensity modulated protons. RapidArc photon plans were computed with: 1) AAA; 2) Acuros XB as dose to medium; and 3) Acuros XB as dose to water.
All plans acceptably met the criteria of target coverage (V95% >90-95%) and bone sparing (D(1 cm3) <50 Gy). Significantly higher PTV dose homogeneity was found for proton plans. Near-to-maximum dose to bone was similar for RapidArc and protons, while volume receiving medium/low dose levels was minimised with protons. Similar results were obtained for the remaining normal tissue. Dose distributions calculated with the dose to water option resulted ~5% higher than corresponding ones computed as dose to medium.
High plan quality was demonstrated for both VMAT and proton techniques when applied to soft-tissue sarcoma.
评估容积旋转调强放疗（VMAT，RapidArc）和质子束在治疗腿部软组织肉瘤时，在充分覆盖靶区的同时，同时实现靶区覆盖和增强骨组织保护的潜力。
收集了 10 例腿部软组织肉瘤患者进行研究。计划靶区（PTV）的处方剂量为 66.5 Gy，共 25 次，同时将显著的最大骨剂量限制在 50 Gy。根据 RapidArc 技术，用 6 MV 光子束或调强质子进行优化。RapidArc 光子计划计算采用：1）AAA；2）Acuros XB 作为中剂量；3）Acuros XB 作为水剂量。
所有计划均能满足靶区覆盖（V95% >90-95%）和骨保护（D（1 cm3）<50 Gy）的标准。质子计划的 PTV 剂量均匀性明显更高。RapidArc 和质子的最大骨剂量相似，而质子可以使接受中/低剂量水平的体积最小化。其余正常组织也得到了类似的结果。用水剂量计算的剂量分布比用中剂量计算的结果高约 5%。
当应用于软组织肉瘤时，VMAT 和质子技术均表现出了较高的计划质量。
