Wu Anna K, Damico Nicholas J, Healy Erin, Kharouta Michael Z, Khandel Ghazal, Deshane Alok, Sipos Jennifer, Eckstein Jacob, Zoller Wesley, Ewing Ashlee, Ling Stella, Wobb Jessica, Mitchell Darrion, Grecula John, Jhawar Sachin, Miller Eric, Gamez Mauricio, Diavolitsis Virginia, Blakaj Dukagjin, Bhatt Aashish D
Case Western Reserve University School of Medicine, Cleveland, OH, USA.
Department of Radiation Oncology, University Hospitals Seidman Cancer Center, Cleveland, OH, USA.
Tech Innov Patient Support Radiat Oncol. 2021 Nov 1;20:28-34. doi: 10.1016/j.tipsro.2021.10.003. eCollection 2021 Dec.
Radiation-induced hypothyroidism is a common toxicity of head and neck radiation. Our re-planning study aimed to reduce thyroid dose while maintaining target coverage with IMRT.
We retrospectively identified patients with oral-cavity (n = 5) and oropharyngeal cancer (n = 5). Treatment plans were re-optimized with 45 Gy thyroid mean dose constraint, then we cropped the thyroid out of PTVs and further reduced thyroid dose. Target coverage was delivering 100% dose to ≥ 93% of PTV and 95% of dose to > 99% of PTV.
Originally, average mean dose to thyroid was 5580 cGy. In model I, this dropped to 4325 cGy (p < 0.0001). In model II, average mean dose was reduced to 3154 cGy (p < 0.0001). For PTV low and PTV int, all had acceptable target coverage.
In patients with oral-cavity and oropharyngeal cancers, mean dose could be significantly reduced using a thyroid-optimized or thyroid-sparing IMRT technique with adequate coverage.
放射性甲状腺功能减退是头颈部放疗常见的毒性反应。我们的重新计划研究旨在降低甲状腺剂量，同时通过调强放疗（IMRT）维持靶区覆盖。
我们回顾性纳入了口腔癌患者（n = 5）和口咽癌患者（n = 5）。治疗计划重新优化，将甲状腺平均剂量限制在45 Gy，然后我们将甲状腺从计划靶体积（PTV）中裁剪出来，进一步降低甲状腺剂量。靶区覆盖要求为PTV的≥ 93%接受100%剂量，PTV的> 99%接受95%剂量。
最初，甲状腺的平均剂量为5580 cGy。在模型I中，该剂量降至4325 cGy（p < 0.0001）。在模型II中，平均剂量降至3154 cGy（p < 0.0001）。对于PTV低危区和PTV高危区，所有病例的靶区覆盖均达到可接受标准。
对于口腔癌和口咽癌患者，采用甲状腺优化或甲状腺 sparing的IMRT技术，在保证足够靶区覆盖的同时，可显著降低平均剂量。
