XU Xiaoyan, LI Hualing, GU Xiaohuan, WANG Peipei, LI Jinkai
Objective To compare the dosimetric differences between personalized oral filling and oral stents used in radiotherapy for oropharyngeal cancer. Methods The imaging data of 19 patients with oropharyngeal cancer admitted to the radiotherapy department of our hospital was selected as research objects. All patients were conducted oral stent fixation during simulated positioning. The target area and normal tissue were delineated on the localization CT image, and the original treatment plan (Plan0) was implemented using volumetric modulated radiotherapy. The cavity area containing the stent in the oral cavity was delineated separately on the planned CT, and the mean value was assigned to achieve density filling. The original planned dose was recalculated and saved as Plan1. The D2% (dose received by 2% of the target volume, and so on), D50%, and D98% of the gross target volume (GTV) in two plans were compared, as well as D2%, D50%, D98%, V5 (volume percentage of organs receiving at least 5 Gy dose, and so on), V10, V15, V20, V25, V30, V35, V40, V45, V50, V55, V60 in the oral and air cavity areas; Dmax (maximum dose), Dmean (average dose), and Dmin (minimum dose) of the tip, middle, base of tongue, and left and right parotid glands. And the correlation between oral dose parameters and exposure dose to the tongue and parotid gland was analyzed. Results The D98% (P=0.016) of GTV, Dmin (P=0.038) of the tongue tip, Dmax (P=0.046) of the left parotid gland, and Dmean (P=0.019) of the right parotid gland in the simulated personalized oral filling group all decreased. At the same time, D50%, D98%, V15, V20, V25, V35, V40 and V45 in the oral cavity of Plan1 all decreased. And the evaluation indicators D50%, D98%, V15, V20, V25, V30, V35, V40 and V45 of the intraoral cavity area were also decreased compared with the oral stent group, and all the difference was statistically significant (P<0.05). According to correlation analysis, V15, V20, V25, V30, V35, V40 and V45 in the oral cavity were positively correlated with Dmean and Dmin of the entire tongue (P<0.05). Meanwhile, V15, V30, V35, V40 and V45 were all positively correlated with the Dmax of the tip of tongue, in addition, V35 and V40 were also positively correlated with the Dmax of the middle of tongue (P<0.05). The V15, V20, V25, V30, V35, V40 and V45 in the air cavity area were positively correlated with the Dmean of the tip of tongue, and except for V15, they were positively correlated with the Dmax of the tip of tongue. And V20, 研究论著 RESEARCH WORK 42 中国医疗设备 2025年第40卷 01期 VOL.40 No.01 引言 头颈部恶性肿瘤是常见的恶性肿瘤之一,具有ԧ病 率高和死亡率高的特点。由于头颈部解剖结构较特殊, 使得放疗在其治疗方案中占据重要地位 [1]。据统计,我 国的口咽癌ԧ病率约为每 10 万人中有 4 人ԧ病,在所 有癌症中位居第 20 位 [2]。随着放疗技术的进步,头颈 部肿瘤的治疗效果也越来越好,早中期口咽癌 5 年总生 存率已大于 50%[3],但放射性口腔黏膜炎(Radiotherapy Induced Oral Mucositis,RIOM)的ԧ生率和严重程度却 未见明显改善 [4]。RIOM ԧ生率高达 80% 以上,其中 3~4 级ԧ生率大于 50%[5]。因此,寻找一种实用的临床方 法以减轻放疗相关不良反应仍然需要探索。口腔支架能 够强制患者在放疗期间处于张口状态,增加口腔黏膜和 舌等危及器官到靶区之间的距离,实现降低危及器官受 照剂量 - 体积、减轻放疗相关不良反应的目的。有研 究通过应用 3D 打印或印模技术设计不同个体化口腔支 架,来降低头颈部恶性肿瘤患者放疗的口腔毒副反 应 [6-7]。由于口腔接触性疼痛使得部分患者在放置口腔 支架时可能伴随支架位置偏移,而常规口腔支架并不 能完全填充口腔,因此在无图像引导情况下难以监测 口腔支架在患者口内的实际位置,且国外相关研究ԧ 现头颈部恶性肿瘤患者放疗时气腔边缘的剂量分布和 剂量波动变化明显 [8]。因此,本研究拟通过计划系统 对比分析放疗期间使用个体化均匀填充和常规口腔支 架 2 组口咽癌患者的靶区和正常组织剂量分布,探讨 个体化口腔填充在临床上的应用价值。 1 资料与方法 1.1 一般资料 回顾性收集 2023 年 6 月至 2024 年 7 月于南京医科 大学第一附属医院放射治疗科接受放疗的口咽癌患者资 料。患者原ԧ灶均经病理学证实,入院 Karnofsky 功能 状态评分≥ 80 分,临床分期(cTNM)为 cT1-4N0-3M0。最 终入组 19 例患者,其中男性 16 例,女性 3 例,年龄范 围为 45~70 岁。研究已经本院伦理委员会审批通过(批 准文号 :2024-SR-771)。 1.2 模拟定位 常规个性化口腔支架制作过程如下:由同一位放疗医 师根据患者口腔情况进行个性化口腔支架设计,将压舌板 裁剪成不同长度并叠加呈梯形以适配口腔内轮廓 ;口腔支 架的最大厚度为患者最大张口角度时上下门齿间距的 2/3 ; 调整支架的厚度和长度以满足患者张口位,同时患者无咽 部异物感及恶心体征 ;患者试戴后,标记上下齿痕位置; 采用 S- 头颈肩热塑膜 +Cvico 头颈肩底板进行体位固定 ; 应用三维激光灯确定定位中心并以铅点标记 ;使用西门 子大孔径 CT 模拟机完成定位扫描,扫描范围为由颅顶至 气管隆嵴,层厚 3 mm。CT 定位图像通过放疗网络传至 Monaco 5.1 放疗计划系统。 1.3 靶区及危及器官勾画 由同一位主任医师按照口咽癌勾画指南勾画靶区。 肿瘤靶区包括大体肿瘤靶区(Gross Tumor Volume of Nasopharyngeal Carcinoma,GTVnx)和咽后及颈部肿 瘤 靶 区(Gross Tumor Volume of Cervix Node,GTVnd)。 GTVnx 在三维方向上均匀外放 3 mm 后得到计划大体肿 瘤靶区(PGTVnx);计划颈部肿瘤靶区(PGTVnd)由 GTVnd 外扩 3 mm 得到 ;PTV1、PTV2 分别由高危亚临床 病灶(CTV1)和低危亚临床病灶(CTV2)外放 5 mm 得到。 应用自动勾画技术结合手动调整完成危及器官口腔、舌 和口内气腔的勾画,勾画标准参考相关文献的定义,其 中口腔勾画范围包括披覆于上下唇、硬腭、软腭、口颊、 牙龈、舌和口底等口腔解剖结构的黏膜,以及舌 下腺腺体 [9]。 在正中矢状面图像上,根据舌的最长前 后径将舌平均分为前、中、后 3 个部分,并分别命名为 舌 尖(Tip of Tongue,TOT)、 舌 体(Middle of Tongue, MOT)和舌根(Base of Tongue,BOT)[7]。口内气腔区 为口腔内舌面、下颚向上至上颚(包含口腔支架在口腔 以内的部分),见图 1。 收稿日期:2024-07-30 基金项目:国家自然科学基金(82102831)。 通信作者:王沛沛,副主任技师,主要研究方向为肿瘤放疗物理学。 通信作者邮箱:wangpeipei5650@163.com V25, V30, V35 and V40 also showed a positive correlation with Dmin at the tip of tongue (P<0.05). The remaining differences were not statistically significant (P>0.05). Conclusion Personalized oral filling is beneficial for reducing oral radiation dose in patients with oropharyngeal cancer undergoing intensity modulated radiation therapy.