Application of volume rotary intensity modulated radiotherapy and static intensity modulated radiotherapy in nasopharyngeal carcinoma and their effects on thyroid function
YANG Na1 SUN Yi2 ZHANG Jianqing1
1.Department of Radiotherapy Center, Xinjiang Uygur Autonomous Region People’s Hospital, Xinjiang Uygur Autonomous Region, Urumqi 830000, China; 2.Cancer Center, the First Affiliated Hospital of Xinjiang Medical University, Xinjiang Uygur Autonomous Region, Urumqi 830000, China
Abstract Objective To compare the application of volume rotary intensity modulated radiotherapy (VMAT) and static intensity modulated radiotherapy (s-IMRT) in nasopharyngeal carcinoma (NPC) and their effects on thyroid function. Methods A total of 62 NPC patients admitted to Xinjiang Uygur Autonomous Region People’s Hospital from June 2015 to June 2019 were prospectively selected and divided into VMAT group and s-IMTR group by random number table method, with 31 cases in each group. The VMAT group received VMAT, and the s-IMRT group received s-IMRT. The dose parameters of plan gross tumor volume (PGTV), plan gross tumor volume of the cervical lymph node (PGTVnd), plan tumor volume (PTV1, 2), and organs at risk, and radiotherapy efficiency (machine hop number, beam out time) were compared between the two groups. The changes of thyroid function [free triiodothyronine (FT3) and serum thyroid-stimulating hormone (TSH)] were compared between the two groups before and 3, 6 months after radiotherapy. The effects of radiotherapy on oral mucosa and normal tissue of oral salivary glands in two groups were recorded. Results The conformance indexes of PGTV, PGTVnd, PTV1, and PTV2 in VMAT group were higher than those in s-IMRT group, the mean doses of PTVnd, PTV1, and PTV2 were lower than those of s-IMRT group (P＜0.05). The mean doses of bilateral parotid gland, lens, and optic nerve, the V30 of bilateral parotid gland, the maximum doses of bilateral lens, and the V40 of the left temporomandibular joint in VMAT group were all lower than those in s-IMRT group (P＜0.05). The machine hop number of VMAT group was lower than that of s-IMRT group, and the beam out time was shorter than that of s-IMRT group (P＜0.05). In both groups, serum FT3 levels at 3, 6 months after radiotherapy was lower than those before radiotherapy, and TSH level was higher han those before radiotherapy, and serum FT3 level at six months after radiotherapy was lower than that at three months after radiotherapy, and TSH level was higher than that at three months after radiotherapy (P＜0.05). Serum FT3 levels at 3, 6 months after radiotherapy in VMAT group were higher than those in s-IMRT group at the same time, and serum TSH levels were lower than those in s-IMRT group at the same time (P＜0.05). The incidence of oral mucosal injury in VMAT group was lower than that in s-IMRT group (P＜0.05). Conclusion Comparing with s-IMRT, VMAT in NPC patients can help regulate the dose of target area, control the dose of organs at risk, improve the efficiency of treatment, and reduce the influence on thyroid function and normal tissues of oral mucosa.
YANG Na1 SUN Yi2 ZHANG Jianqing1. Application of volume rotary intensity modulated radiotherapy and static intensity modulated radiotherapy in nasopharyngeal carcinoma and their effects on thyroid function[J]. 中国医药导报, 2022, 19(34): 134-139.
