Department of Radiation Oncology, Cancer Research Institute, Himalayan Institute of Medical Sciences, Swami Rama Himalayan University, Dehradun, Uttarakhand, India.
J Cancer Res Ther. 2021 Jan-Mar;17(1):235-241. doi: 10.4103/jcrt.JCRT_350_20.
The assessment of volumetric and dosimetric changes in the head-and-neck cancer during fractionated radiotherapy by intensity-modulated radiotherapy (IMRT) technique.
A single-center prospective observational hospital-based study with a sample size of 20 cases of the head-and--neck squamous cell carcinoma over 1 year treated with chemoradiotherapy 66-70 Gy/33-35#@2 Gy/fraction with weekly cisplatin 35 mg/m. After contouring of target volumes (TVs) and organs at risk (OARs) in initial computed tomography (CT) scan, all patients were planned and treated by the IMRT technique. We re-delineated the TVs and OARs in the second (CT15#) and third (CT30#) planning CT scan, and the initial plan was implemented in the re-CT scan dataset with the same optimization and doses. The volumetric and dosimetric changes during fractionated radiotherapy of TVs and OARs were evaluated and compared. Nonparametric Wilcoxon-signed-rank test was used to compare the means between each plan.
For all 20 patients, plans were compared for volumetric and dosimetric parameters on repeat CT scans. The mean variation in gross tumor volume (GTV) and planning TV (PTV) was significant after 15 and 30 fractions of radiotherapy. On dosimetric evaluation, there was a significant increase in doses to GTV and OARs (parotid, spinal cord, and cochlea) with a significant P value. However, doses to the OARs were not exceeded the maximum tolerance limit.
This prospective single-center study concluded that two repeat imaging, along with re-planning improved TV coverage and decreased doses to the normal tissue. Larger studies with more sample sizes are required to set the criteria for replanning.
评估头颈部癌症在分次放射治疗中通过调强放射治疗（IMRT）技术的容积和剂量变化。
一项为期 1 年的单中心前瞻性观察性医院基础研究，样本量为 20 例头颈部鳞状细胞癌患者，接受了 66-70 Gy/33-35#@2 Gy/fraction 的放化疗，每周给予顺铂 35 mg/m。在初始计算机断层扫描（CT）扫描中对靶区（TVs）和危及器官（OARs）进行轮廓勾画后，所有患者均采用 IMRT 技术进行计划和治疗。我们在第二次（CT15#）和第三次（CT30#）计划 CT 扫描中重新勾画了 TVs 和 OARs，并在相同的优化和剂量下将初始计划实施到重新 CT 扫描数据集中。评估和比较了 TVs 和 OARs 在分次放射治疗过程中的容积和剂量变化。采用非参数 Wilcoxon 符号秩检验比较每个计划之间的平均值。
对于所有 20 例患者，在重复 CT 扫描上比较了计划的容积和剂量参数。在接受 15 和 30 次放射治疗后，GTV 和计划靶区（PTV）的平均变化具有统计学意义。在剂量评估方面，GTV 和 OARs（腮腺、脊髓和耳蜗）的剂量显著增加，具有显著的 P 值。然而，OARs 的剂量未超过最大耐受限度。
这项前瞻性单中心研究得出结论，两次重复成像和重新计划可以提高 TV 覆盖范围，并降低正常组织的剂量。需要进行更大规模、更多样本量的研究，以确定重新计划的标准。
