3D打印个体化施源器鼻咽癌腔内后装治疗应用初探

Preliminary exploration of 3D printed individualized applicator for 3D-image-guided intracavitary HDR-brachytherapy for nasopharyngeal carcinoma

目的初步探讨3D打印个体化施源器在鼻咽癌腔内后装放疗中应用的可行性。方法对1例rT1期复发鼻咽癌及1例T2期残留鼻咽癌患者进行定位CT扫描,传输至3D图像处理软件获得鼻咽腔几何轮廓参数,并设计管道走位使其靠近肿瘤区(rGTV)。按设计参数,使用3D打印机制造出个体化腔内施源器。用类似后鼻孔填塞技术将施源器置入鼻咽腔内。在施源器预设的管道中,插入后装施源管及假源,再次行定位CT并传入3D后装计划系统。勾画靶区和危及器官,设计优化治疗计划,完成首次治疗后取出施源器。再次治疗前复查定位CT并观察假源位置是否准确。结果施源器置入鼻咽腔后能与鼻咽壁完全贴合,并且自行固定无须额外的固定措施。治疗中多次复查CT并与计划CT比较假源位置误差≤1mm,患者治疗全程无明显不适。优化后三维治疗方案100%剂量曲线包全rGTV,脑干、脊髓最大剂量<30%。复发患者给予处方剂量40Gy分8次4周完成,残留患者12Gy分2次1周完成。2例患者后装治疗后3个月复查肿瘤均全消。结论使用3D打印技术制作的个体化鼻咽腔内施源器具有自行固定、位置准确、重复性好、患者耐受良好的优点,近期疗效确切,值得进一步研究。

Objective To explore the feasibility of 3D printed individualized applicator for the intracavitary HDR-brachytherapy for nasopharyngeal carcinoma.Methods CT scan was performed in 1 case of recurrent rT1 nasopharyngeal carcinoma and 1 case of T2 residual nasopharyngeal carcinoma and the obtained images were transmitted to 3D image processing software.The geometric contour parameters of the nasopharyngeal cavity were obtained and a pipeline was designed to make it close to the recurrent gross tumor volume(rGTV).Individualized cavity applicators were created by using 3D printer.The applicator was inserted into the patient′s nasopharyngeal cavity through oral cavity.The source tube and false source were inserted into the preset pipe of the applicator.CT scan was performed again and the images were transmitted to the 3D brachytherapy planning system.After delineating the target volume and organ at risk,treatment plan was optimized.After completing the first treatment,the applicator was removed.Before second treatment in a few days,CT scan was reviewed to confirm whether the position was correct.Results When the applicator was inserted into the nasopharyngeal cavity,it could be fully aligned with the nasopharyngeal wall and self-fixed without additional fixation measures.Comparing the location of false source in multiple reviews of CT scan,the error was≤1 mm.No significant discomfort was reported throughout the treatment.In optimized three-dimensional treatment,100%prescription dose curve included the full rGTV,maximum dose of the brain stem and spinal cord was<30%prescription dose.Recurrent patients were given with a prescription dose of DT 40Gy/8 fractions/4 weeks and patients with residual tumors were given with 12Gy/2 fractions/1 week.No tumor recurrence was observed at postoperative 3 months in two cases.Conclusions The 3D printed individualized nasopharyngeal intracavitary applicator has the advantages of self-fixation,accurate location,good repeatability and good patient tolerance.The short-term outcome is effective,whereas its long-term clinical effect and adverse reactions need to be further observed.