Department of Radiation Oncology, Division of Medical Physics, Rajiv Gandhi Cancer Institute and Research Centre, New Delhi; Department of Physics, Amity School of Applied Sciences, Amity University, Noida, Uttar Pradesh, India.
Department of Physics, Amity School of Applied Sciences, Amity University, Noida, Uttar Pradesh, India.
J Cancer Res Ther. 2022 Oct-Dec;18(6):1504-1512. doi: 10.4103/jcrt.JCRT_835_20.
The number of patients for carcinoma cervix with implanted hip prostheses has been increasing worldwide during the past several decades. Technological advancements are useful for delivering higher doses, i.e., dose escalation to the target, but the presence of high-density implanted hip prosthesis creates challenges for the planner.
A population of 25 patients was selected for the study. Plans were generated using the MONACO treatment planning system keeping the isocenter same. The parameters evaluated for planning target volume (PTV) were D, D, D, D, D, V and V. Similarly, the parameters D, D, and D were evaluated for the delineated critical organs. Average monitor units (TMU) were also assessed.
D of PTV was 44.51 (standard deviation [SD]: 0.13) Gy, 44.41 (SD: 0.38) Gy, 44.58 (SD: 0.14) Gy, 44.08 (SD: 0.41) Gy and 44.46 (SD: 0.32) Gy for 4F, intensity-modulated radiation therapy (IMRT), IMRT_WP, volumetric-modulated arc therapy (VMAT), and VMAT_WP techniques, respectively, where WP stands for "without prosthesis". Volume of bowel receiving 45 Gy was 86.82 (SD: 66.38) cm, 6.97 (SD: 5.77) cm, 14.11 (SD: 14.29) cm, 13.31 (SD: 6.57) cm, and 10.31 (SD: 10.94) cm for 4F, IMRT, IMRT_WP, VMAT and VMAT_WP techniques, respectively.
Radiotherapy is standard care of practice for known cases of cervical malignancies. As per our investigations, VMAT has generated comparable plans in terms of target coverage (D) as compared to IMRT and 4F techniques (P = 0.015 and P = 0.002) and with prosthesis also (P = 0.024). The mean dose to the bladder was significantly lesser with IMRT and VMAT. Our results highlight that VMAT has reduced the mean dose to the rectum (P = 0.001) in presence of high-density implant. The mean dose to femoral heads was also reduced when compared with the 4-field technique.
VMAT has an edge over other techniques in terms of target coverage and sparing of critical organs in the presence of metallic prosthesis. Information about the geometry and density of prosthesis will be beneficial for treatment planning.
在过去几十年中，全球范围内宫颈癌合并植入髋关节假体的患者数量一直在增加。技术进步有助于提供更高的剂量，即提高靶区剂量，但高密度植入髋关节假体的存在给规划师带来了挑战。
选择了 25 名患者进行研究。使用 MONACO 治疗计划系统生成计划，保持等中心不变。评估计划靶区（PTV）的参数为 Dmean、D98、D100、D2 和 V95、V100。同样，评估勾画的关键器官的参数 Dmean、Dmax 和 Dmin。还评估了平均监测单位（TMU）。
PTV 的 Dmean 分别为 44.51（标准差 [SD]：0.13）Gy、44.41（SD：0.38）Gy、44.58（SD：0.14）Gy、44.08（SD：0.41）Gy 和 44.46（SD：0.32）Gy，用于 4F、调强放疗（IMRT）、无假体的 IMRT_WP、容积调强弧形治疗（VMAT）和 VMAT_WP 技术，其中 WP 代表“无假体”。4F、IMRT、IMRT_WP、VMAT 和 VMAT_WP 技术的直肠接受 45 Gy 的体积分别为 86.82（SD：66.38）cm、6.97（SD：5.77）cm、14.11（SD：14.29）cm、13.31（SD：6.57）cm 和 10.31（SD：10.94）cm。
放疗是已知宫颈癌病例的标准治疗方法。根据我们的研究，VMAT 在靶区覆盖（Dmean）方面与 IMRT 和 4F 技术相当（P=0.015 和 P=0.002），并且与假体也相当（P=0.024）。IMRT 和 VMAT 技术的膀胱平均剂量明显较低。我们的结果表明，VMAT 降低了高密度植入物存在时直肠的平均剂量（P=0.001）。与 4 野技术相比，股骨头的平均剂量也降低了。
VMAT 在存在金属假体时在靶区覆盖和保护关键器官方面优于其他技术。有关假体的几何形状和密度的信息将有助于治疗计划。
