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目的：评价局部复发鼻咽癌多方位固定适形野立体定向放射治疗的剂量分布优势。方法：局部复发鼻咽癌１２ 例，在ＣＴ 定位并确定计划靶区（Ｐｌａｎｎｉｎｇ Ｔａｒｇｅｔ Ｖｏｌｕｍｅ ，ＰＴＶ ） 后，采用三维ＴＰＳ，按照“以尽可能小的治疗区（Ｔｒｅａｔｅｄ Ｖｏｌｕｍｅ ，ＴＶ） 完全包绕ＰＴＶ 的原则”设计多方位固定适形野立体定向照射计划。利用三维ＴＰＳ 的剂量、体积计算功能评价本组病例多方位固定适形野立体定向放射治疗的剂量分布特点和优势。结果：１２ 例患者ＰＴＶ内平均最大剂量为（１１６－５ ±６－８） ％ 、最小剂量为（８１－２ ±２－７） ％ 、平均剂量为（１０５－６±２－７） ％ ；ＰＴＶ 相应节段脑干脊髓、颞颌关节、下颌骨等邻近正常重要结构的平均最大剂量分别为（４１－１ ±６－１） ％ 、（８０－８±３－２） ％ 、（７６－９ ±３－８） ％ ，平均剂量分别为（２２－０ ±３－１） ％ 、（６０－３ ±５－２） ％ 、（３１－６ ±２－３） ％ ；（ＴＶ－ ＰＴＶ）／ＴＶ 值为（９－４ ±１－７） ％ 。结论：采用多方位固定适形野立体定向放射治疗局部复发鼻咽癌，可使其ＴＶ 高度适形ＰＴＶ，从而使ＰＴＶ 受到高剂量照射的同时大大减少了邻近正常结构受照?
Objective: To evaluate the dose distribution advantage of stereotactic radiotherapy for locally recurrent nasopharyngeal carcinoma with multi-azimuth fixation. METHODS: Twelve patients with local recurrence of nasopharyngeal carcinoma were treated with three-dimensional TPS after CT positioning and planning target volume (PTV), according to “completely surrounding the PTV with the smallest possible treatment area (TV). ”The principle of" design multidimensional fixed stereo field stereotactic irradiation program. The dose distribution and volume calculation of three-dimensional TPS were used to evaluate the dose distribution characteristics and advantages of stereotactic radiotherapy with multi-azimuth fixed conformal field in this group of patients. Results: In 12 patients, the average maximum dose in PTV was (116-5 ± 6-8) %, the minimum dose was (81-2 ± 2-7) %, and the average dose was (105-6 ± 2-7) %; The average maximum doses of normal adjacent structures such as brainstem spinal cord, temporomandibular joint and mandible in corresponding segments of PTV were (41-1 ±6-1)%, (80-8±3-2) %, (76- 9 ± 3-8) %, with an average dose of (22-0 ±3-1)%, (60-3 ±5-2)%, (31-6 ±2-3)%; (TV-PTV) The /TV value is (9-4 ±1-7) %. Conclusion: The use of multi-azimuth fixed stereoscopic stereotactic radiotherapy for local recurrence of nasopharyngeal carcinoma can make TV highly conforming to PTV, which results in high exposure to PTV and greatly reduces the exposure to adjacent normal structures.