Patel Pooja Nandwani, Goyal Sumit, Shah Anand, Gohel Mehul, Suryanarayana Unnikrishnan
Department of Radiotherapy, Gujarat Cancer and Research Institute, Ahmedabad, Gujarat, India.
Department of Community Oncology, Gujarat Cancer and Research Institute, Ahmedabad, Gujarat, India.
South Asian J Cancer. 2018 Jan-Mar;7(1):55-57. doi: 10.4103/sajc.sajc_183_17.
During course of radiation therapy, anatomical variations occur risking overdose of parotid gland. We tried to quantify volume of parotid gland and mean dose to parotid gland after every 10 fractions (#).
We conducted the prospective study from July 2016 to May 2017 in 25 patients of early-stage oropharyngeal carcinoma. Patients had Karnofsy Performance Score of 80-100, median age was 54 years, and 18 patients were males. Patients were planned with intensity-modulated radiation therapy planning with dose as 66 Gy/30# to planning target volume (PTV) including primary and 54 Gy/30# to PTV-nodal including elective neck irradiation. After each 10#, replanning was done, and variations in parotid volume were studied including D (mean dose to parotids) and D (the dose delivered to 50% of volume). Other tumor characteristic like PTV of primary was also assessed and minimum PTV volume covered by 95% isodose line was kept as 95%.
Average parotid volumes decreased by the mean value of 10% and 6% for the left and right parotids, respectively, and PTV of primary target decreased by mean of 13%. The difference in D doses to parotid glands was 32% and 42% and difference in D dose was 30% and 35% on the left and right side, respectively.
The parotid volumes differ considerably during adaptive planning done after every ten fractions. These differences in parotid volumes and doses received to parotid glands play a significant role in the risk of xerostomia observed during later follow-up.
在放射治疗过程中，解剖结构会发生变化，存在腮腺过量照射的风险。我们试图量化腮腺体积以及每10次分割照射（#）后腮腺的平均剂量。
2016年7月至2017年5月，我们对25例早期口咽癌患者进行了前瞻性研究。患者的卡氏评分在80 - 100分之间，中位年龄为54岁，其中18例为男性。患者采用调强放射治疗计划，计划靶区（PTV）包括原发灶的剂量为66 Gy/30#，包括选择性颈部照射的PTV-淋巴结剂量为54 Gy/30#。每10次分割照射后进行重新计划，并研究腮腺体积的变化，包括D（腮腺平均剂量）和D（50%体积所接受的剂量）。还评估了其他肿瘤特征，如原发灶的PTV，95%等剂量线覆盖的最小PTV体积保持为95%。
左、右腮腺的平均体积分别下降了10%和6%，原发靶区的PTV平均下降了13%。左侧和右侧腮腺的D剂量差异分别为32%和42%，D剂量差异分别为30%和35%。
在每10次分割照射后的适应性计划中，腮腺体积有显著差异。这些腮腺体积和接受剂量的差异在后期随访中观察到的口干风险中起重要作用。
