Modern irradiation techniques for optimized conformal TBI can be realized by Helical Tomotherapy (HT) or Volumetric Modulated Arc Therapy (VMAT), depending on the availability of suitable specialized equipment. In this dosimetric planning study, we compared both modalities and addressed the question of whether VMAT with small field sizes is also suitable as a backup in case of HT equipment malfunctions. For this purpose, we retrospectively used planning computed tomography (CT) data from 10 patients treated with HT with a total dose of 8 Gy (n = 5) or 12 Gy (n = 5) for treatment planning for VMAT with a small field size (36 × 22 cm). The target volume coverage, dose homogeneity at target volume, and dose reduction in organs at risk (OAR) (lungs, kidneys, lenses) were analyzed and compared. One patient was irradiated with both modalities due to a device failure of the HT equipment during the study, which facilitated a comparison in a real clinical setting. The findings indicate that in addition to a higher mean dose to the lenses in the 12 Gy group for VMAT and a better dose homogeneity in the target volume for HT, comparably good and adequate target dose coverage and dose reduction in the other OAR could be achieved for both modalities, with significantly longer treatment times for VMAT. In conclusion, after appropriate optimization of the treatment times, VMAT using linear accelerator radiosurgery technology can be used both as a backup in addition to HT and in clinical routines to perform optimized conformal TBI.
现代优化的适形全身照射技术可通过螺旋断层放疗或容积旋转调强放疗实现，具体取决于专业设备的可用性。在本剂量计划研究中，我们比较了这两种技术，并探讨了小射野VMAT是否适合作为HT设备故障时的备用方案。为此，我们回顾性使用10例接受HT治疗患者的计划计算机断层扫描数据（总剂量8 Gy组5例，12 Gy组5例），为小射野（36×22 cm）VMAT制定治疗计划。分析比较了靶区覆盖度、靶区剂量均匀性及危险器官（肺、肾、晶状体）的剂量降低情况。研究中因HT设备故障，一例患者同时接受两种技术照射，为真实临床场景下的比较提供了条件。研究结果显示，除12 Gy组VMAT晶状体平均剂量较高及HT靶区剂量均匀性更优外，两种技术在其他危险器官的靶区剂量覆盖和剂量降低方面均能达到相当良好且适宜的水平，但VMAT治疗时间显著更长。综上所述，经适当优化治疗时间后，采用直线加速器放射外科技术的VMAT既可作为HT的备用方案，也可在临床常规中用于实施优化的适形全身照射。
肿瘤(癌症)患者之家