3D打印个体化施源器鼻咽癌腔内后装治疗应用初探

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。     

鼻咽癌后装腔内放疗个体化施源器剂量学分析

目的:评估热塑面罩固定鼻咽个体化施源器剂量的准确性及其应用价值.方法:选择10例后装放疗患者,分别制作鼻咽个体化施源器并使用面罩固定.每次治疗前均行CT扫描,并在计划系统中重建出施源器位置,获取铱源驻留位点坐标,通过与计划CT比较,计算出施源器位移偏差,进而评估后装治疗剂量的准确性.结果:非面罩固定最远端源驻留位点(P1)平均偏差在X、Y、Z三个方向为(1.62士0.24)、(2.32士0.22)和(2.50士0.28)mm,近端(P5)为(1.13±0.11)、(1.22±0.20)和(1.80±0.15)mm.经面罩固定后个体化施源器最远端源驻留位点(P1)平均位移则分别为(0.82±0.06)、(0.70±0.07)和(0.94±0.08) mm,近端(P5)为(0.70士0.02)、(0.46土0.01)和(0.60土0.03)mm.面罩固定施源器位移偏差导致的感兴趣点(源旁2 cm)剂量误差＜1.2％.结论:使用热塑面罩固定个体化施源器剂量准确,适合鼻咽癌腔内后装治疗.     

HDR鼻咽癌腔内治疗的物理剂量参考点个体化设计的设置方法

目的 探讨鼻咽癌腔内治疗剂量参考点的个体化设置方法。方法 用模拟定位机摄接受HDR后装治疗病人的施源器正、侧位定位片,根据定位片结果预定治疗剂量及参考点,并使在定位片上预定的参考点在坐标系中坐标化。结果 从物理剂量学角度看,个体化设置处方参考点可以减小病人不必要的损伤。讨论 鼻咽癌腔内治疗需要考虑鼻咽腔的不规则立体性,病灶位置及施源器放置所呈现的多样化。     

一种新型可调充气式鼻咽后装施源器的研制和应用

背景与目的：鼻咽腔内近距离放疗施源器(以下简称施源器)在鼻咽腔内近距离放疗中起重要作用,直接影响治疗的效果。我们研制了一种新型施源器。方法：新型施源器用医用乳胶材料制成,在距施源器前端15mm处置一气囊,气囊边缘与管轴相切,紧贴于管壁一侧,令充气时管轴反向拱形隆起贴近治疗部位。使用时经中鼻道达后壁,通过旋转施源器可调节施源器方向和位置,经注气孔注入空气并固定。治疗前需复核定位证实。结果：共治疗221例鼻咽癌,初治病例中鼻咽肿物消退率92．6％,复发病例鼻咽肿物全部消退,鼻咽前壁或后壁粘膜坏死5例,鼻甲水肿及后鼻道粘连8例。结论：本施源器具有安全可靠,操作方便,患者无痛苦,剂量分布理想,固定性较好等优点。在治疗中出现鼻咽粘膜坏死可能与初期使用时单次剂量过高有关。     

3D打印技术在CT引导宫颈癌术后阴道残端肿瘤近距离治疗中应用

目的 探讨3D打印技术在腔内近距离治疗个体化施源器制作中的运用。方法 对1例宫颈癌术后阴道残端狭窄并规则实体肿瘤患者,用显影剂浸泡过的纱条对患者阴道进行填塞后进行CT扫描,获取阴道腔内三维几何轮廓。利用软件进行轮廓提取,在靠近病灶侧预留三根腔道,使用3D打印机、医用硅胶材料进行施源器打印。将该施源器重新置入患者阴道内,CT扫描并纠正施源器位置。将最终CT图像输出至TPS进行靶区及OAR勾画,完成剂量分布计算。结果 3D打印个体化阴道施源器可以和靶体积形成良好的贴合,弯曲处管道的曲率>1 cm,可保证放射源的顺利通过;通过对插植软管进行剪切,将总的出源长度统一设定为1 280 mm,可实现个体化施源器与后装机的精确连接;病灶达到处方剂量的同时,膀胱、直肠剂量D_{2 cm³}分别为320.4、331.5 cGy,不超过剂量限值。结论 利用3D打印技术制作个体化施源器适用于宫颈癌术后阴道残端狭窄并规则实体肿瘤的治疗,临床疗效与不良反应尚需进一步观察。     

鼻咽癌后装治疗鼻咽模施源器的制作方法

鼻咽癌后装治疗鼻咽模施源器的制作方法卢杰用后装治疗机进行鼻咽癌腔内照射时，需施源器作源的定位。本文介绍的是由我科设计并已在临床中使用的鼻咽模施源器的制作工艺及方法。１鼻咽模施源器的制作方法１．１依据鼻咽部Ｘ光片、ＣＴ片，以及尸体解剖上取得的鼻咽腔石膏...     

鼻咽癌腔内近距离超分割推量照射的研究

目的 分析鼻咽癌腔内近距离超分割放射治疗的临床及效及适应证的选择。方法 体外照射＋腔内后装超分割推量放射治疗鼻咽癌128例，体外常规放射治疗50－66Gy后进行腔内近距离放射治疗，1996年6月以后由于经颌下鼻咽旁区插植术的开展，腔内后装的适应证的选择严格按肿瘤侵犯深度在鼻咽部粘膜下≤10mm。施源管技术采用个体化模块将施源管固定在鼻咽腔内，并将软腭推开，剂量分割采用超分割法2．5－3．0Gy／次，2次／d，间隔6h，总剂量12－24Gy，中位剂量18Gy。体外照射剂量分为3个组，即：56Gy组44例（其中37例为56Gy），60Gy组54例，66Gy组30例。结果 全组3、4年无瘤生存率分别为84．2％、74．9％，3、4年局部无复发生存率分别为97．1％、92．7％。体外照射56、60和66Gy组的3年无瘤生存率分别为83．6、88．4％和84．6％（X^6=0.92,P=0.63),3年局部无复发生存率分别为100％、90．9％、93．3％（X^2=0.25,P=0.88)，差异均无统计学意义。结论 腔内近距离治疗前应该进行CT或MRI影像评价并进行严格的适应证选择及后装技术的选择，腔内近距离治疗的适应证为病变厚度≤10mm的病例为好。在此基础上T1、T2期鼻咽癌计划外照射的剂量可以降低至56Gy。腔内近距离治疗超分割方法的晚期放射性反应少，患者可以耐受，具有可行性。     

3D打印多通道施源器在宫颈癌术后患者近距离治疗中研究北大核心CSCD

目的比较3D打印多通道施源器与常规阴道单通道施源器用于近距离治疗的剂量学差异,为宫颈癌术后患者的近距离治疗提供一定的指导依据。方法选取25例自2019年1月—2020年11月接受^(192)Ir高剂量率近距离治疗的宫颈癌术后合并阴道上皮内瘤变Ⅲ级的患者,每位患者均采用3D打印多通道施源器和常规阴道单通道施源器进行CT扫描定位,并制定相应计划及评估,运用逆向剂量优化算法计算后得出剂量体积直方图,比较两组施源器用于近距离治疗时的高危临床靶区、膀胱及直肠受照剂量的差异,选择最优计划实施治疗。结果采用3D打印个体化多通道施源设计计划的D_(90)%、D_(100)%、V_(100)%、V_(150)%与常规单通道施源器设计的计划相比,差异均无统计学意义(P>0.05);膀胱、直肠的D2cm3与常规相比均明显降低,差异有统计学意义(均为P<0.05)。结论采用3D打印技术制作的多通道个体化施源器靶区适形性好,可更好地保护膀胱和直肠,有一定的治疗优势。     

鼻咽癌外照射加腔内近距离超分割推量照射的远期疗效分析

背景与目的:鼻咽癌的后装治疗一般采用鼻咽腔内治疗的方法进行推量照射,适用于局部早期鼻咽癌.福建省肿瘤医院率先开展鼻咽旁插植技术,无颅底破坏的局部晚期鼻咽癌采用后装治疗推量照射.本文分析腔内后装推量照射的远期疗效,探讨常规外照射的合适剂量配合后程超分割后装推量照射的临床价值.方法:1998年1月～2002年12月体外照射加腔内后装超分割推量放射治疗鼻咽癌患者352例,体外常规放射治疗50～70 Gy后进行腔内近距离超分割推量照射,外照射后咽旁间隙肿瘤残留者配合咽旁区插植放疗.采用个体化鼻咽腔内施源器,超分割照射每次2.5～3.0 Gy,2次/天,间隔6 h,总剂量5～32 Gy,中位剂量17 Gy.结果:本组l、2、3、5年生存率分别为97.0%、91.3%、87.6%、84.7%.总体5年生存率Ⅰ、Ⅱ期88.2%,Ⅲ、Ⅳ期79.2%(log-rank检验,P=0.016);总体局控率Ⅰ、Ⅱ期94.1%,Ⅲ、Ⅳ期91.7%(log-rank检验,P＞0.05).后组颅神经损伤32例(9.4%).结论:鼻咽腔内后装联合咽旁间隙捅植近距离放射治疗鼻咽癌取得良好的局控率和生存率,局部晚期鼻咽癌取得与早期鼻咽癌类似的局控率,咽旁间隙受累者咽旁插植增加颈动脉鞘区照射剂量,后组颅神经损伤发生率较高.     

天津医科大学附属肿瘤医院研制出新型鼻咽癌施源器

一种鼻咽癌短距离放疗新型施源器由天津医科大学附属肿瘤医院研制成功。经２５例患者共６０例次应用 ,与旧施源器比较鼻咽顶部剂量提高了１３４．６ % ,鼻咽后壁提高６０．７ % ,鼻咽侧壁提高４０ %。软腭下降了７５．１ %。临床近期疗效很好 ,被专家们认为是目前放射治疗鼻咽癌理想的施源器。鼻咽癌的治疗 ,放射剂量直接影响着疗效 ,单用外放射治疗提高局部剂量受到周围重要器官和组织的限制 ,腔内短距离放疗可提高局部剂量 ,但施源器的结构直接影响着靶区受量。该施源器是按鼻咽腔轮廓制作 ,两根施源管附在模体背面的两侧 ,模体底部有一隆…     

鼻咽癌短距离放疗自制新型施源器的研制及应用

目的：为改善鼻咽癌原发或复发灶的局部控制。方法：新型鼻咽癌施源器完全地鼻咽腔的形状,先制成一个塑料模体,有两根管附在它的背面,紧贴鼻咽穹窿,模体腹面有一凸起可推开软腭,使其远离两根施源管。结果：新的鼻咽癌施源器操作简便,患者无痛苦。剂量分布合理,临床疗效满意。结论：新型鼻咽癌施源器的设计应用及临床效果,在提高靶区剂量改善局部控制的同时降低了正常组织放射剂量,值得进一步临床推广应用。     

PET-guided three-dimensional treatment planning of intracavitary gynecologic implants

PURPOSE: Positron emission tomography (PET) provides physiologic information that is not available from computed tomography (CT) or magnetic resonance studies. PET images may allow more accurate delineation of three-dimensional treatment planning target volumes of brachytherapy gynecologic (GYN) implants. This study evaluates the feasibility of using PET as the sole source of target, normal structure, and applicator delineation for intracavitary GYN implant treatment planning. MATERIALS AND METHODS: Standard Fletcher-Suit brachytherapy tandem and colpostat applicators were used for radiation delivery. After insertion of the applicator in the operating room, the patient was taken to a PET scanner, where 555 MBq (15 mCi) 18F-fluorodeoxyglucose (18F-FDG) was administered intravenously. Forty-five minutes later, three localization tubes containing 18F-FDG were inserted into the source afterloading compartments of the tandem and colpostat. A whole-pelvis scan was performed, and the images were transferred to a commercial brachytherapy three-dimensional treatment planning system. A Foley catheter was inserted into the urinary bladder while the patient was in the operating room. The regions of radioactivity in the three applicator tube image were contoured for reconstruction of the applicator, along with the bladder, rectum, and 18F-FDG-defined target volumes. A treatment plan was generated that included dose-volume histograms and three-dimensional dose distribution displays, allowing the physician an opportunity to determine if adequate target coverage and normal-tissue sparing had been obtained. For a more conservative approach, three-dimensional dose distributions and dose-volume histograms delivered with conventional source arrangements and loading could be observed. The accuracy of applicator localization from the PET images was verified using a water phantom containing two aluminum CT-compatible tandems. The PET-defined and CT scan applicator reconstructions were compared. RESULTS: Feasibility of using PET images for treatment planning of brachytherapy intracavitary GYN implants has been demonstrated. A phantom study demonstrated applicator reconstruction accuracy in the axial direction to be better than 2 mm. Reconstruction accuracy in the longitudinal direction (principally craniocaudal) was similar to the PET scanner's voxel size of 4.3 mm. CONCLUSIONS: Brachytherapy intracavitary GYN implant design has traditionally been based on patient tumor staging, palpation, and clinical experience. PET images have the potential to provide better spatial information about the relationship of tumor and normal structures to the applicator. This information can be used to optimize the delivery of radiation therapy treatments. Thus far, six patients have been scanned using this process.     

经阴道3D打印个体化模板在宫颈癌后装治疗中的应用价值研究

目的 介绍一种经阴道3D打印后装腔内联合插植治疗个体化模板设计方法,比较该方法和徒手插植方法的剂量学和操作安全性差异。方法 研究选取40例行¹⁹²Ir高剂量率腔内联合插植后装治疗计划。实验组为20例使用经阴道3D后装个体化模板设计方法,用基于CT影像的预计划方法设计插植针路径,用3D打印技术创建个体化模板实体和插植针路径,最后在CT引导下置入模板。对照组选取20例腔内联合徒手插植治疗计划,徒手插植方法不做预计划并且插植针方向由操作医生经验决定。结果 两组计划HR-CTV的分次D90相近,实验组正常组织D2cm³的剂量有较显著改善,且肿瘤靶区内高剂量区体积和剂量适形性指数均有改善。实验组共使用273次插植针,脱靶次数为1次,未出现插植针刺穿正常组织事件。对照组共使用203次插植针,脱靶次数4次,且观察到3次刺穿正常组织事件。结论 3D打印后装腔内联合插植治疗个体化模板方法对比徒手插植方法有剂量学优势,并且操作更安全,实际治疗可达到预计划剂量设计要求。     

局部晚期宫颈癌CT图像引导下192Ir三维腔内后装治疗剂量体积参数与疗效关系

目的 观察CT图像引导下192Ir三维腔内后装治疗的肿瘤靶区及危及器官受照射体积剂量参数与肿瘤局部控制率及晚期副反应之间关系.方法 10例局部晚期宫颈癌患者在完成盆腔外照射40 Gy及同期化疗后开始每周1次的CT图像引导下192Ir三维腔内后装治疗,每次治疗前进行CT扫描定位,勾画肿瘤靶区(GTV、CTV)和危及器官,利用PLATO治疗计划系统进行逆向治疗计划设计及优化,CTV单次处方剂量为6 Gy,治疗5～7次.结果 1年盆腔控制率为90%,1～2级放射性肠炎发生率为50%,无≥3级副反应.90%CTV等效生物剂量(BED)和相当于2 Gy分次的等效剂量(EQD2)分别为(95.50±7.81)Gy和(79.73±6.57)Gy(α/β=10).90%GTV的BED和EQD2分别为(101.86±7.27)Gy和(84.95±6.1)Gy(α/β=10).90%处方剂量对GTV、CTV的覆盖率分别为92%±4%、87%±7%.直肠、乙状结肠2 cm3体积受到的最小照射剂量分别为(74.97±1.64)、(67.93±4.30)Gy(EQD2,α/β=3).与二维治疗计划相比,三维治疗计划在没有改变A点剂量、直肠参考点剂量情况下提高了GTV、CTV的90%体积受照射剂量及90%处方剂量对GTV、CTV的覆盖率.结论 CT图像引导下192Ir三维腔内后装治疗提高了处方剂量对肿瘤靶区的覆盖率,1年盆腔控制率为90%且无严重副反应,远期疗效观察中.

Abstract：

Objective To investigate the correlation between dose volume histogram(DVH)of tumor targets and organs at risk(OAR)at CT-image based 192Ir brachytherapy and effects and complications for patients with locally advanced cervical cancer. Methods Ten patients with FIGO stage ⅢB cervical cancer received CT image-based 192Ir intracavitary brachytherapy after 54 Gy of three-dimentional four-field pelvic external beam radiotherapy and concurrent weekly cisplatin chemotherapy. Before each brachytherapy,CT images were acquired with applicators in place. Gross tumor volume(GTV), clinical target volume (CTV)and OAR were contoured and inverse treatment planning was designed and optimized by using PLATO treatment planning system. Conventional two-dimensional plans were also designed for comparison.The total intracavitary brachytherapy dose was 30 -42 Gy in 5 -7 fractions. The patients were followed, and the local control and complications were analyzed. The biologically equivalent dose(BED)and biologically equivalent dose in 2 Gy fractions(BED2)for GTV, CTV and OAR were calculated. The minimum dose in the most irradiated tissue volume 2 cm3(D2 cm3)adjacent to the applicator of the sigmoid colon, rectum,bladder and small bowel was determined from the DVH. Results The 1-year local pelvic control rate was 90% and grade 1-2 late complication of sigmoid colon and rectum was 50%. No grade 3 or more complications developed. On CT-image based planning, the BED and BED2 to 90% of the CTV(D90)were 95.50 Gy ± 7. 81 Gy and 79. 73 Gy ± 6. 57 Gy. The BED and BED2 to 90% of the GTV(D90)were 101.86 Gy ± 7.27 Gy and 84. 95 Gy ± 6. 1 Gy. The volume enclosed by 90% of prescribed dose(V90)for GTV and CTV were 92% ±4% and 87% ±7% respectively. The D2cm3 for rectum and sigmoid colon were 74. 97 Gy ±1.64 Gy and 67. 93 Gy ± 4. 30 Gy(EQD2, α/β = 3). Comparing with 2D brachytherapy plans , CT - image based planning has improved D90 and V90 for GTV and CTV with similar dose at point A and rectum reference point. Conclusions Computer tomography-image based 192Ir brachytherapy has resulted in the better dose distribution to the tumor targets with excellent tumor control and acceptable toxicity.     

鼻咽癌调强放疗中肿瘤和正常组织体积-剂量变化的研究

目的:研究鼻咽癌在调强放射治疗过程中,肿瘤和正常组织的体积、形态变化对各自剂量受量的影响。方法:2009年1月-2010年6月间初诊经病理明确诊断的鼻咽癌患者42例,所有患者经头颈肩膜固定行模拟CT,在CT图像上逐层勾画治疗靶区和正常组织,采用6MV X线9野共面调强放射治疗计划（IMRT）。鼻咽原发灶及颈部转移淋巴结照射剂量66Gy/30f/6w,鼻咽部和颈部淋巴引流区亚临床病灶照射剂量60Gy/30f/6w。治疗设备为西门子ONCOR直线加速器。治疗期间每日采集患者治疗体位0度和90度正交二维摄片图像,同原始计划DRR图像对比,在三维方向对患者进行摆位误差校正,然后实施放射治疗。每周采集一次患者治疗体位头颈部CT图像,把治疗计划按照标记点移植到每周CT上,重新进行计量计算,分析患者在治疗期间靶区及正常组织剂量分布变化。同步化疗采用多西他赛加顺铂方案,每三周一次,在放疗开始前1周内开始同步治疗。结果:所有患者放疗前GTV1平均体积39.19cc,GTV2平均体积16.59cc,放疗第4周及第6周GTV1平均退缩分别为26.41%、62.68%,GTV2平均退缩分别为28.43%、53.93%。治疗前双侧腮腺体积平均为24.16cc,放射治疗第4周,平均腮腺体积为19.04cc,第6周平均腮腺体积为17.54cc。正常组织计量受量方面,脊髓（D1%）、脑干（D1%）、颞叶（D1%）、内耳（Dmean）、腮腺（V30）,原计划计量分别为:（41.2±0.98）Gy、（51.26±1.57）Gy、（59.95±2.11）Gy、（45.02±1.98）Gy、（47.87±18.05）%。照射第4周分别为:（44.09±1.88）Gy、（52.81±2.47）Gy、（62.04±2.43）Gy、（47.24±3.68）Gy、（49.03±15.68）%。第六周（44.44±2.7）Gy、（54.14±2.51）Gy、（62.34±2.86）Gy、（48.37±5.37）Gy、（52.19±15.51）%。结论:随着鼻咽癌调强放射治疗的进行,照射肿瘤靶区同原始计划剂量分布会有一定差异,除1例淋巴结退缩及病人消瘦等原因而造成外轮廓内收较大的患者以外,其余CTV实际照射剂量为处方剂量95%以上。正常组织在整个治疗过程所受照射剂量同原始计划比较有所增加。     

Uncertainties when using only one MRI-based treatment plan for subsequent high-dose-rate tandem and ring applications in brachytherapy of cervix cancer.

BACKGROUND AND PURPOSE: This retrospective study compares individual MRI based 3D treatment planning for each intracavitary applicator insertion and the use of only one MRI treatment plan for cervical cancer brachytherapy. MATERIALS AND METHODS: GTV, high risk (HR) CTV and OAR were delineated and analysed for 14 patients. Data using the individual approach were taken from the actual irradiated plans. The "single plan procedure" was simulated by matching the dose distribution of the first plan to the MRI datasets of each subsequent implantation. Total doses from brachytherapy were added up and normalized to 2Gy fractionation (EQD2). RESULTS: The mean D90 for HR CTV was 6Gy higher when using one plan than when using individual treatment plans. The D(2cc) increased 3.5Gy for the bladder, 4.2Gy for the rectum and 5.8Gy for the sigmoid. The use of only one treatment plan would have resulted in 2, 1 and 5 extra cases exceeding total D(2cc) constraints for bladder (90Gy), rectum (75Gy) and sigmoid (75Gy), respectively. CONCLUSION: The use of only one treatment plan for several applications results in higher dose to target and OAR structures. CT, clinical examination and X-ray findings can help to reduce certain situations of overdosage, when individual MRI based treatment planning is not available for each fraction.     

Three-dimensional conformal radiotherapy versus intracavitary brachytherapy for salvage treatment of locally persistent nasopharyngeal carcinoma

PURPOSE: To compare the outcomes of three-dimensional conformal radiotherapy (3D-CRT) and intracavitary brachytherapy (ICBT) as salvage treatment for locally persistent nasopharyngeal carcinoma. METHODS AND MATERIALS: Between March 1994 and November 2001, a total of 117 patients with locally persistent nasopharyngeal carcinoma received salvage treatment for 2-8 weeks (median, 4 weeks) after a full course of conventional external beam RT. Of the 117 patients, 54 were salvaged with 3D-CRT (3D group) and 63 with ICBT (BT group). No statistically significant differences were found in the patient characteristics between the two groups (p >0.05). In the 3D group, the planning target volume for 3D-CRT was defined as the persistent disease plus a 5-mm margin; three to seven static conformal coplanar or noncoplanar portals were delivered for each fraction. The median salvage dose was 24 Gy (range, 18-38 Gy), with fraction size of 2.0 Gy/d. In the BT group, a median salvage dose of 20 Gy (range, 15-30 Gy) was delivered with a (192)Ir source, at 5 Gy/fraction, twice weekly. The brachytherapy dose was prescribed at a distance of 1 cm from the center of the surface as defined by the sources, irrespective of the extent of persistent disease. The actuarial rates of survival were estimated using the Kaplan-Meier method. Potential differences in the actuarial outcomes between groups were evaluated using the Mantel log-rank test. Multivariate analyses were performed with the Cox regression proportional hazards model. RESULTS: The 5-year actuarial rates of overall survival, disease-specific survival, and local failure-free survival for the 3D group and BT group were 64.50% vs. 55.78% (p = 0.33), 70.03% vs. 59.56% (p = 0.11), and 88.93% vs. 76.28% (p = 0.07), respectively. Subgroup analysis showed that the 5-year actuarial local failure-free survival rate of patients with initially diagnosed T3-T4 disease for the 3D group and BT group was 84.01% vs. 60.50% (p = 0.03). The incidence of Grade 3-4 late complications was comparable between the two groups. Multivariate analyses performed in the whole group showed that T stage at initial diagnosis and the salvage technique (3D-CRT or ICBT) were the statistically significant, independent prognostic factors for local failure-free survival (p = 0.00 and p = 0.02, respectively). CONCLUSION: 3D-CRT seemed to provide better local control than ICBT as a salvage treatment for locally persistent nasopharyngeal carcinoma, especially in patients with initially diagnosed T3-T4 disease. CT/MRI evaluation of the extent of persistent disease is recommended for technique selection of salvage RT. Patients should be cautioned about the potentially increased complications. The optional time for salvage treatment remains controversial.