Hansen Anders T, Rose Hanne K, Yates Esben S, Hansen Jolanta, Petersen Jørgen B B
Department of Medical Physics, Aarhus University Hospital, Aarhus, Denmark.
Department of Oncology, Aarhus University Hospital, Aarhus, Denmark.
Tech Innov Patient Support Radiat Oncol. 2021 Dec 14;21:1-7. doi: 10.1016/j.tipsro.2021.11.006. eCollection 2022 Mar.
Total body irradiation (TBI) is an important treatment modality that is used in combination with chemotherapy in many stem cell transplantation protocols. Therefore, the quality of the irradiation is important. Two techniques for planning and delivering TBI are presented and compared.
The technique named ExIMRT is a combination of manually shaped conventional fields from an extended SSD and isocentric IMRT fields. The technique named ExVMAT is a combination of conventional and IMRT fields from an extended SSD and isocentric VMAT fields. Dosimetric data from 32 patients who were planned and treated according to one of the two techniques were compared.
When comparing the two techniques, it is determined that the ExVMAT technique is able to significantly reduce the mean total volume overdosed by 120% from 408 to 12 cm. The dose covering 98% of the total lung volume is significantly increased by this technique from a mean of 9.7 Gy to 10.3 Gy. Additionally, the dose covering 2% of the total kidney volume is significantly decreased from a mean of 12.8 to 12.5 Gy. Furthermore, the population-based variance of the median dose to the total lung volume, the heart and the volume of the body prescribed to 12.5 Gy is significantly reduced. The results are obtained without compromising overall treatment quality as treatment time or dose rate to the lungs.
Using the ExVMAT technique, a superior dose distribution can be delivered both from a patient and a population perspective compared to the ExIMRT technique.
全身照射（TBI）是一种重要的治疗方式，在许多干细胞移植方案中与化疗联合使用。因此，照射质量很重要。本文介绍并比较了两种用于全身照射计划和实施的技术。
名为ExIMRT的技术是一种将来自扩展源皮距（SSD）的手动塑形常规射野与等中心调强放疗（IMRT）射野相结合的技术。名为ExVMAT的技术是一种将来自扩展SSD的常规和IMRT射野与等中心容积调强弧形放疗（VMAT）射野相结合的技术。比较了根据这两种技术之一进行计划和治疗的32例患者的剂量学数据。
比较这两种技术时发现，ExVMAT技术能够显著降低平均总过量照射体积，从408立方厘米降至12立方厘米，降幅达120%。该技术使覆盖98%全肺体积的剂量从平均9.7 Gy显著增加到10.3 Gy。此外，覆盖2%全肾体积的剂量从平均12.8 Gy显著降至12.5 Gy。而且，全肺体积、心脏以及处方剂量为12.5 Gy的身体体积的基于总体的中位剂量方差显著降低。在不影响总体治疗质量（如治疗时间或肺部剂量率）的情况下获得了这些结果。
与ExIMRT技术相比，从患者个体和总体角度来看，使用ExVMAT技术均可实现更优的剂量分布。
