CT-Based Evaluation of Tumor Volume After Intra-Arterial Chemotherapy of Locally Advanced Carcinoma of the Oral Cavity: Comparison with Clinical Remission Rates

Purpose To assess the volume of locally advanced tumors of the oral cavity and the oropharynx before and after intra-arterial (i.a.) chemotherapy by means of computed tomography and to compare these data with clinically determined treatment response of the same patient population. Methods Eighty-eight patients with histologically proven, advanced carcinoma of the oral cavity and/or the oropharynx (local tumor stages T3/4) received neoadjuvant i.a. chemotherapy with cisplatin as part of a multimodal therapeutic regimen, comprising (1) local chemotherapy, (2) surgery, and (3) combined radio-chemotherapy. Three weeks after the intervention, residual disease was evaluated radiologically by measurement of the tumor volume and clinically by inspection and palpation of the primary tumor according to WHO criteria. Results Comparison of treatment response according to radiological and clinical criteria respectively revealed complete remission in 5% vs. 8% (p < 0.05), partial remission in 30% vs. 31%, stable disease in 61% vs. 58%, and tumor progression in 5% vs. 2%. Conclusion Radiological volumetry and clinical evaluation found comparable response rates after local chemotherapy. However, in patients with good response after local treatment, volumetric measurement with CT may help to distinguish between partial and complete remission. Thus, radiological tumor volumetry provides precise and differentiated information about tumor response and should be used as an additional tool in treatment monitoring after local chemotherapy.     

宫颈癌调强放疗后骨盆衰竭骨折的发生率及影响因素分析

目的 探讨宫颈癌盆腔调强放疗后患者骨盆衰竭骨折（PIF）的发生率及影响因素。方法 收集2013年11月至2015年12月在本院行盆腔调强放疗的104例宫颈癌患者,回顾性分析随访过程中骨盆衰竭骨折的发生情况及其影响因素。结果 104例患者中,16例（31个部位）患者发生了骨盆衰竭骨折,发生率为15.4%;其中多发骨折患者10例（62.5%）。有症状的患者5例（31%）,经休息或止痛治疗后症状可缓解。骨折发生的时间是放疗结束后1~16个月（平均6.5个月）。发生的部位分别是骶骨16例（51.6%）、骶髂关节7例（22.6%）、髂骨6例（19.4%）、股骨头1例（3.2%）及耻骨1例（3.2%）。单因素和多因素分析显示,绝经后状态和低体重（≤ 55 kg）是宫颈癌盆腔调强放疗后骨盆衰竭骨折的危险因素（P<0.05）。亚组分析发现,对宫颈癌术后辅助调强放疗患者,绝经后状态是盆腔调强放疗后衰竭骨折的危险因素（P<0.05）。结论 绝经后状态和低体重（≤ 55 kg）是影响宫颈癌患者盆腔调强放疗后衰竭骨折发生的重要危险因素。     

膀胱充盈状态对宫颈癌调强放疗子宫及危及器官的影响

目的 通过研究膀胱充盈状态对子宫、宫颈的移位、靶区和危及器官（OAR）体积的影响,为宫颈癌调强放疗（IMRT）个体化内靶区（ITV）及临床靶区（CTV）到计划靶区（PTV）界定提供理论基础。方法 获取宁夏医科大学总医院27例局部进展期初治宫颈癌患者膀胱排空、膀胱充盈1.0 h、充盈1.5 h定位CT图像,分别勾画宫颈、宫体、OAR,以及膀胱充盈1.0 h的CTV、PTV,分析不同膀胱充盈间宫颈、宫体的移位,不同充盈状态下子宫、直肠、小肠、PTV内小肠、PTV内膀胱、PTV内直肠体积的差异;分析膀胱充盈与子宫移位及OAR体积的相关性。分析膀胱排空与充盈1.5 h靶区脱出PTV的体积。结果 膀胱充盈状态个体差异较大,子宫颈和子宫体随膀胱充盈状态变化引起的最大移动范围分别为0~3.04 cm、0~4.31 cm。不同充盈间子宫体在前方移位差异有统计学意义（F=7.818,P<0.05）;不同充盈状态下膀胱体积、PTV内膀胱及小肠体积差异有统计学意义（F=46.197、44.609、29.546,P<0.05）;膀胱的充盈状态与子宫体前缘的移位、小肠体积、PTV内膀胱体积、PTV内小肠体积间有相关性（r=-0.232、-0.298、0.915、-0.336,P<0.05）。在膀胱排空及充盈1.5 h时,宫颈、宫体脱出PTV的体积差异均具有统计学意义（t=-1.326、-1.559,P<0.05）。结论 膀胱充盈状态具有较大的个体差异,膀胱充盈状态对子宫前缘的影响较大,扩大CTV-PTV前方外放范围可能降低靶区的漏照,控制膀胱充盈状态的一致性对宫颈癌精确调强放疗是必要的。     

Intraindividual Comparison of Conventional Three-Dimensional Radiotherapy and Intensity Modulated Radiotherapy in the Therapy of Locally Advanced Non-Small Cell Lung Cancer

BACKGROUND: Local failure is the one of the most frequent cause of tumor related death in locally advanced non-small cell lung cancer (LAD-NSCLC). Dose escalation has the promise of increased loco-regional tumor control but is limited by the tolerances of critical organs. PATIENTS AND METHODS: To evaluate the potential of IMRT in comparison to conventional three-dimensional conformal planning (3DCRT) dose constraints were defined: Maximum dose (D(max)) to spinal cord < 48 Gy, mean lung dose 70 Gy in not more than 5 cm of the total length. For ten patients two plans were compared: (1) 3DCRT with 5 weekly fractions (SD) of 2 Gy to a total dose (TD) of 50 Gy to the planning target volume of second order (PTV2). If the tolerance of the critical organs was not exceeded, patients get a boost plan with a higher TD to the PTV1. (2) IMRT: concomitant boost with 5 weekly SD of 2 Gy (PTV1) and 1.5 Gy to a partial (p)PTV (pPTV=PTV2 profile of a line PTV1) to a TD of 51 Gy to the pPTV and 68 Gy to the PTV1. If possible, patients get a boost plan to the PTV1 with 5 weekly SD of 2 Gy to the highest possibly TD. RESULTS: Using 3DCRT, 3/10 patients could not be treated with TD > 50 Gy, but 9/10 patients get higher TD by IMRT. TD to the PTV1 could be escalated by 16% on average. The use of non-coplanar fields in IMRT lead to a reduction of the irradiated lung volume. There is a strong correlation between physical and biological mean lung doses. CONCLUSION: IMRT gives the possibility of further dose escalation without an increasing mean lung dose especially in patients with large tumors.     

宫颈癌卵巢移位术后VMAT与IMRT卵巢放疗剂量的比较

目的:比较行卵巢移位术后的宫颈癌患者固定野调强(IMRT)和容积旋转调强(VMAT)计划中卵巢的剂量学差异。方法:31例接受宫颈癌根治术和卵巢移位术,术后需放射治疗的患者,设计9野均分IMRT计划和双弧VMAT计划,在保证靶区处方剂量及危及器官限量的情况下,尽量降低卵巢剂量。分析两种技术卵巢平均剂量的差异,以及卵巢-靶...     

直肠癌调强放疗计划中六维随机摆位误差的剂量学影响研究

目的 设计一种软件将随机六维摆位误差引入到直肠癌调强放疗(IMRT)计划中,并评估其剂量学影响。方法 随机选取21例直肠癌IMRT计划作为参考计划(单次剂量 2 Gy, 共50 Gy;PTV为CTV均匀外扩5 mm)。对参考计划的每个分次,通过调整射野几何参数的方法引入随机生成的六维摆位误差,并重新完成剂量计算。再将各分次剂量累加后得到存在摆位误差情况下的总剂量分布。基于美国瓦里安Eclipse脚本应用程序接口(ESAPI)开发能够自动完成上述流程的治疗模拟软件,将服从两种预设分布[分布1:平移误差服从N(0,4²),旋转误差服从N(0,2²);分布2:平移误差服从N(0,2²),旋转误差服从N(0,1²)]的六维摆位误差引入参考计划,并评估剂量学影响。结果 参考计划、误差分布1和误差分布2情况下,CTV的D_min分别为(49.4±0.41)、(47.56±0.76)和(49.17±0.64)Gy;CTV的D_98%分别为(50.23±0.07)、(49.98±0.10)和(50.27±0.09)Gy;主体靶区(靶区除去边缘后的内核部分)D_98%为(50.25±0.08)、(50.42±0.13)和(50.33±0.10)Gy;边缘靶区D_98%为(50.22±0.10)、(49.88±0.11) 和(50.26±0.10)Gy。另外,相比参考计划,误差分布1和2的情况下,膀胱和股骨头平均受量的变化差异均无统计学意义(P>0.05),剂量分布的适形指数虽有微弱降低,但临床意义有限。结论 本方法及据此开发的治疗模拟软件可以根据需要将服从不同分布的六维摆位误差引入到直肠癌IMRT计划中,并给出总体剂量学变化情况。     

乳腺癌术后胸壁大体积复发二野和六野调强放疗剂量学比较

目的 比较乳腺癌术后胸壁大体积复发2野和6野调强放疗的计划差异.方法 对8例乳腺切除术后胸壁大体积复发病例,Pinnacle计划系统上分别对PTV进行2野调强和6野调强放疗计划设计,PTV处方剂量为50 Gy/25次(GTV后续计划补量至66～70 Gy),比较2种计划95％处方剂量PTV适形指数(CI)、均匀性指数(HI)及心脏、同侧肺剂量.结果 6野IMRT计划的CI和HI均优于2野IMRT计划,6野和2野的CI分别为(0.66±0.08)和(0.53±0.10)(t=7.99,P＜0.05),HI分别为(1.36±0.08)和(2.19±0.78)(t=9.04,P＜0.05).2个计划中肺V5、V10、V20、V35和心脏Dmax、V35、Dmean值比较差异无统计学意义.结论 乳腺癌切除术后胸壁大体积复发患者行放疗,6野静态逆向调强放疗计划靶区覆盖优于2野,而心肺受量方面无明显差异.     

一种新型加速器的乳腺癌固定野调强放射治疗中计划质量和执行效率评价

目的 基于Halcyon加速器的乳腺癌固定野调强放射治疗（IMRT）计划质量和执行效率的研究。方法 回顾分析基于Trilogy平台治疗完成的10例左侧乳腺癌IMRT计划,将靶区和危及器官导入Eclipse 15.1版本计划系统,重新设计基于Halcyon治疗平台的IMRT计划,比较两种计划靶区和危及器官受量、机器跳数、子野面积和执行时间差异。结果 Halcyon左侧乳腺癌IMRT计划能够满足临床要求,靶区各剂量指标与Trilogy计划差异无统计学意义（P>0.05）。Halcyon计划中左肺的V₁₀、V₂₀、D_mean均低于Trilogy计划（Z=-2.22~-1.78,P<0.05）,Halcyon计划心脏的V₅为（27.80±7.66）%高于Trilogy计划的（23.18±8.19）%（Z=-0.71,P<0.05）,D_mean为（7.03±1.80）Gy低于Trilogy计划的（7.11±2.40）Gy,但差异无统计学意义（P>0.05）。Halcyon计划的机器跳数为1 770.5±383.9,Trilogy计划的机器跳数为1 526.2±227.7,差异有统计学意义（Z=-1.44,P<0.05）。Halcyon计划执行时间为（3.01±0.28）min,Trilogy计划执行时间为（12.38±1.49）min,差异有统计学意义（Z=-3.42,P<0.05）。结论 Halcyon加速器左侧乳腺癌IMRT在保证计划质量降低危及器官剂量的同时显著缩短了治疗时间。     

左侧乳腺癌调强放疗中心跳对左心室肌及左前降支剂量评估的影响

目的 研究左侧乳腺癌调强放射治疗（IMRT）中,心跳对左心室肌（mLV）及左前降支（LAD）剂量评估的影响。方法 选取15例女性患者平静吸气屏气下的心电门控（ECG-gated）4D-CT图像,参照心动周期以5%间隔进行图像重建,重建0~95%共20个时相的图像。分别勾画mLV及LAD。基于0%时相的图像进行左侧乳腺癌IMRT计划设计。统计各时相mLV的体积并计算相似性指数（dice similarity coefficient,DSC）;计算LAD及mLV剂量-体积指标的变化范围。结果 mLV的DSC变化率最大可达472.07%,其平均变化率约为体积变化率的8倍。mLV的体积与DSC在最大、最小值之间差异均具有统计学意义（t=-6.585、-28.870,P<0.05）。mLV的平均剂量（D_mean）变化率最高可达41.95%。mLV的D_mean、V₁₀、V₂₀、V₃₀、V₄₀在最大、最小值之间差异均有统计学意义（t=-5.260、-4.084、-3.592、-3.273、-2.566,P<0.05）。LAD的D_mean平均变化率最高可达130.14%。LAD的D_mean、V₁₀、V₂₀、V₃₀、V₄₀在最大、最小值之间差异均有统计学意义（t=-9.758、-8.810、-8.682、-7.853、-6.205,P<0.05）。结论 左侧乳腺癌放疗中,心跳对mLV和LAD的剂量评估影响不容忽视。     

支气管动脉灌注结合放疗治疗中晚期非小细胞肺癌的临床观察

目的　观察支气管动脉灌注结合放疗治疗中晚期非小细胞肺癌的临床疗效。方法　本组共 2 6例 ,首先经支气管动脉灌注化疗药物 ,再行放射治疗 ,半量后 (40Gry)再行灌注治疗 ,最后进行完剩余的放疗量。灌注化疗药物为DDP 80～ 12 0mg ,ADM40～ 80mg ,VP -162 0 0～ 40 0mg ,羟基喜树碱 2 0～ 40mg ,放射治疗量 60Gry。 结果　近期疗效CR 9例 ,PR 14例 ,SD 3例 ,PD 0例 ,总有效率 88.5%。结论　支气管动脉灌注结合放疗治疗中晚期肺癌是一种有效的方法     

Intraindividual Comparison of Conventional Three-Dimensional Radiotherapy and Intensity Modulated Radiotherapy in the Therapy of Locally Advanced Non-Small Cell Lung Cancer A Planning Study

Background: Local failure is the one of the most frequent cause of tumor related death in locally advanced non-small cell lung cancer (LAD-NSCLC). Dose escalation has the promise of increased loco-regional tumor control but is limited by the tolerances of critical organs. Patients and Methods: To evaluate the potential of IMRT in comparison to conventional three-dimensional conformal planning (3DCRT) dose constraints were defined: Maximum dose (D_max) to spinal cord < 48 Gy, mean lung dose h 24 Gy, D_max esophagus > 70 Gy in not more than 5 cm of the total length. For ten patients two plans were compared: (1) 3DCRT with 5 weekly fractions (SD) of 2 Gy to a total dose (TD) of 50 Gy to the planning target volume of second order (PTV2). If the tolerance of the critical organs was not exceeded, patients get a boost plan with a higher TD to the PTV1. (2) IMRT: concomitant boost with 5 weekly SD of 2 Gy (PTV1) and 1.5 Gy to a partial (p)PTV (pPTV=PTV2 š PTV1) to a TD of 51 Gy to the pPTV and 68 Gy to the PTV1. If possible, patients get a boost plan to the PTV1 with 5 weekly SD of 2 Gy to the highest possibly TD. Results: Using 3DCRT, 3/10 patients could not be treated with TD > 50 Gy, but 9/10 patients get higher TD by IMRT. TD to the PTV1 could be escalated by 16% on average. The use of non-coplanar fields in IMRT lead to a reduction of the irradiated lung volume. There is a strong correlation between physical and biological mean lung doses. Conclusion: IMRT gives the possibility of further dose escalation without an increasing mean lung dose especially in patients with large tumors. Hintergrund: Lokale Rezidive sind eine häufige Todesursache bei Patienten mit lokal fortgeschrittenen nichtkleinzelligen Bronchialkarzinomen (LAD-NSCLC). Dosiseskalation verspricht hier eine Verbesserung der lokalen Kontrolle, ist aber limitiert durch die Toleranz der Nachbarstrukturen. Patienten und Methoden: Um das Potential der IMRT im Vergleich zur konventionellen 3-D-Planung herauszuarbeiten, wurden folgende Dosis-Volumen-Vorgaben definiert: Maximale Dosis (D_max) des Myelons < 48 Gy, mittlere Lungendosis (MLD) h 24 Gy, D_max des Ösophagus > 70 Gy in h 5 cm der Gesamtlänge. Für zehn Patienten mit LAD-NSCLC wurden verglichen: 1. 3DCRT mit fünf wöchentlichen Einzeldosen (ED) von 2 Gy bis zu einer Gesamtdosis (GD) von 50 Gy für das Planungszielvolumen zweiter Ordnung (PTV2). Wenn die Toleranz der umliegenden Gewebe dies zuließ, erhielten die Patienten einen Boostplan für das PTV1. 2. IMRT: Concomitant Boost mit fünf söchentlichen ED von 2 Gy für das PTV1 und 1,5 Gy für das partielle PTV (pPTV=PTV2 š PTV1) bis zu einer GD von 51 Gy im pPTV und 68 Gy im PTV1. Falls die Belastung des Normalgewebes dies erlaubte, erfolgte ein Boostplan für das PTV1 mit fünf wöchentlichen ED von 2 Gy bis zur höchstmöglichen GD. Ergebnisse: Konventionell konnten 3/10 Patienten mit GD > 50 Gy behandelt werden - mittels IMRT konnten bei 9/10 Patienten höhere Dosen appliziert werden. Im PTV1 konnte im Mittel eine Dosiseskalation von 16% erreicht werden. Besonders Patienten mit großen Tumoren profitierten von der IMRT. Die Verwendung nonkoplanarer Techniken führte zur Verringerung der Dosis innerhalb des kritischen Lungenvolumens. Die physikalischen mittleren Lungendosen waren hoch korreliert mit den biologisch gewichteten mittleren Lungendosen. Schlussfolgerung: Im Vergleich zur 3DCRT ermöglicht die IMRT eine Dosiseskalation in der Behandlung von LAD-NSCLC ohne Erhöhung der mittleren Lungendosis. Von der Technik profitieren insbesondere Patienten mit größeren Tumoren.     

乳腺癌保乳术后两野与多野动态调强的剂量学研究

目的 比较早期乳腺癌保乳术后切线2野动态调强与非共面多野调强放疗治疗靶区和危及器官的剂量学差异。方法 选取40例接受保乳术后放疗的左侧乳腺癌患者,在同一患者CT影像上,利用相同优化条件分别进行切线2野和非共面3、4、5野4种调强治疗计划设计。比较4种计划的靶区剂量分布、心脏、左肺及右侧乳腺受照剂量和体积,以及机器跳数的差异。结果 非共面4、5野调强计划适形度指数（CI）和均匀性指数（HI）均优于切线2野调强计划（P<0.05）,临床靶区（PTV）最大剂量（D_max）小于2野调强计划（P<0.05）,PTV最小剂量（D_min）大于2野调强计划（P<0.05）。3野与2野计划间无明显差异。4种计划的右乳接受5 Gy照射的百分体积（V₅）、心脏接受30 Gy照射的百分体积（V₃₀）及平均剂量（D_mean）、左肺接受20和5 Gy照射的百分体积（V₂₀、V₅）、平均剂量（D_mean）无明显差异,而机器跳数间差异有统计学意义（F=25.63,P<0.05）,2野调强跳数最少,5野最多。结论 保乳术后非共面4、5野调强计划与切线2野调强计划相比,靶区剂量分布更好,不明显增加正常组织、器官的受照射剂量,但机器跳数明显增加。     

Oral cancer from the perspective of wide-field optical fluorescence: Diagnosis,tumor evolution and post-treatment follow up

In this communication, we present that wide-field optical fluorescence might be useful for: the screening of oral lesions that are imperceptible to the naked eye, determination of biopsy area, better definition of treatment, and previous and post-treatment follow-up.     

原发性支气管肺癌MRI相对信号强度与PCNA相关性的研究

目的 探讨肺癌组织的ＭＲＩ相对信号强度与增殖细胞核抗原（ＰＣＮＡ）之间的关系。材料与方法 ２６例肺癌患者,术前用Ｒｅｓｏｎｅｘ ０．３８Ｔ磁共振成像系统,行横断而ＳＥ Ｔ１ＷＩ,ＧＲ序列成像,增强后行ＳＥ Ｔ１ＭＩ。术后标本采用ＡＢＣ免疫组化技术,观察ＰＣＮＡ在２６例肺癌中的表达。结果 Ｇｄ－ＤＴＰＡ增强后增殖活性较低的肿瘤细胞（５％〈ＰＣＮＡ≤５０％）,其ＭＲＩ相对信号强度啬值明显瘤细胞吸收Ｇｄ     

不同调强方式在胸中上段食管癌放疗中的剂量学研究

目的 对胸中上段食管癌患者进行静态调强（IMRT）和容积旋转调强（VMAT）两种放疗方式的剂量学对比研究。方法 对20例IMRT治疗的食管癌患者行VMAT（单弧和双弧）计划的重新设计。在单弧的VMAT计划中,对其中5例患者行不同子野间隔（4°、3°、2°）以及不同计划系统（Monaco和MasterPlan）的计划设计。比较靶区和危及器官（OAR）的剂量学差异及治疗参数。结果 双弧VMAT计划各项靶区剂量学参数明显好于IMRT计划和单弧VMAT计划（P<0.05）,靶区均匀性（HI）（P<0.05）和适形度（CI）（P<0.05）最好。危及器官参数VMAT可在一定程度上降低OAR的受照剂量,但是IMRT对肺组织和正常组织（E-P）的低剂量保护要优于VMAT（P<0.05）;不同子野间隔的VMAT计划中,2°相对于3°和4°其OAR的受照剂量是减小的（P<0.05）,除了心脏的D_mean;不同计划系统设计的VMAT计划,以Monaco对OAR的保护为最优（P<0.05）;VMAT的机器跳数少于IMRT,而且有效节省了治疗时间。 结论 VMAT方式相对于IMRT能够实现更好的靶区覆盖、均匀性和适形度,同时能降低脊髓、肺组织、心脏和E-P的受照剂量;对于VMAT来说,双弧技术、小子野角度间隔能够进一步地改善靶区和OAR的受照剂量;此外,在物理参数和优化参数一致的前提下,Monaco可以更好地保护OAR。     

The role of palliative interventional radiotherapy (brachytherapy) in esophageal cancer: An AIRO (Italian Association of Radiotherapy and Clinical Oncology) systematic review focused on dysphagia-free survival

PurposeThe aim of this review was to examine efficacy of palliative interventional radiotherapy (IRT) in esophageal cancer compared with other treatment in terms of dysphagia-free survival (DyFS) and safety.Methods and MaterialA systematic research using PubMed, Scopus, and Cochrane library was performed to identify full articles evaluating the efficacy of IRT as palliation in patients with esophageal cancer. ClinicalTrials.gov was searched for ongoing or recently completed trials, and PROSPERO was searched for ongoing or recently completed systematic reviews. We analyzed only clinical study as full text of patients with symptomatic esophageal cancer treated with IRT alone or in combination with other treatment. Conference paper, survey, letter, editorial, book chapter, and review were excluded. Time restriction (1990–2018) as concerns the years of the publication was considered. The primary outcome was the duration of dysphagia relief (DyFS) after brachytherapy vs. other treatment (external-beam radiotherapy, photodynamic therapy, argon plasma coagulation, stent, and laser) during followup. Secondary outcomes included overall survival and adverse event rates.ResultsThe literature search resulted in 554 articles. Sixty-six articles were assessed via full text for eligibility. Of these, 59 articles were excluded for various reasons, leaving seven randomized studies. The number of evaluated patients was 905 patients, and median age was 70.5 years. In the IRT group, the median DyFS was 99 days, the most relevant G3–G4 toxicity were fistula development and stenosis reported, respectively, in 8.3% and 12.2%; the overall median survival was 175.5 days.ConclusionIn conclusion, we provided evidence-based support that IRT is an effective and safe treatment option; therefore, its underuse is no longer justified.     

Dosimetric Comparison Between 2-Dimensional Radiation Therapy and Intensity Modulated Radiation Therapy in Treatment of Advanced T-Stage Nasopharyngeal Carcinoma: To Treat Less or More in the Planning Organ-At-Risk Volume of the Brainstem and Spinal Cord

The aim of this study is to evaluate the deficiencies in target coverage and organ protection of 2-dimensional radiation therapy (2DRT) in the treatment of advanced T-stage (T3-4) nasopharyngeal carcinoma (NPC), and assess the extent of improvement that could be achieved with intensity modulated radiation therapy (IMRT), with special reference to of the dose to the planning organ-at-risk volume (PRV) of the brainstem and spinal cord. A dosimetric study was performed on 10 patients with advanced T-stage (T3-4 and N0-2) NPC. Computer tomography (CT) images of 2.5-mm slice thickness of the head and neck were acquired with the patient immobilized in semi-extended-head position. A 2D plan based on Ho’s technique, and an IMRT plan based on a 7-coplanar portals arrangement, were established for each patient. 2DRT was planned with the field borders and shielding drawn on the simulator radiograph with reference to bony landmarks, digitized, and entered into a planning computer for reconstruction of the 3D dose distribution. The 2DRT and IMRT treatment plans were evaluated and compared with respect to the dose-volume histograms (DVHs) of the targets and the organs-at-risk (OARs), tumor control probability (TCP), and normal tissue complication probabilities (NTCPs). With IMRT, the dose coverage of the target was superior to that of 2DRT. The mean minimum dose of the GTV and PTV were increased from 33.7 Gy (2DRT) to 62.6 Gy (IMRT), and 11.9 Gy (2DRT) to 47.8 Gy (IMRT), respectively. The D₉₅ of the GTV and PTV were also increased from 57.1 Gy (2DRT) to 67 Gy (IMRT), and 45 Gy (2DRT) to 63.6 Gy (IMRT), respectively. The TCP was substantially increased to 78.5% in IMRT. Better protection of the critical normal organs was also achieved with IMRT. The mean maximum dose delivered to the brainstem and spinal cord were reduced significantly from 61.8 Gy (2DRT) to 52.8 Gy (IMRT) and 56 Gy (2DRT) to 43.6 Gy (IMRT), respectively, which were within the conventional dose limits of 54 Gy for brainstem and of 45 Gy for spinal cord. The mean maximum doses deposited on the PRV of the brainstem and spinal cord were 60.7 Gy and 51.6 Gy respectively, which were above the conventional dose limits. For the chiasm, the mean dose maximum and the dose to 5% of its volume were reduced from 64.3 Gy (2DRT) to 53.7 Gy (IMRT) and from 62.8 Gy (2DRT) to 48.7 Gy (IMRT), respectively, and the corresponding NTCP was reduced from 18.4% to 2.1%. For the temporal lobes, the mean dose to 10% of its volume (about 4.6 cc) was reduced from 63.8 Gy (2DRT) to 55.4 Gy (IMRT) and the NTCP was decreased from 11.7% to 3.4%. The therapeutic ratio for T3-4 NPC tumors can be significantly improved with IMRT treatment technique due to improvement both in target coverage and the sparing of the critical normal organ. Although the maximum doses delivered to the brainstem and spinal cord in IMRT can be kept at or below their conventional dose limits, the maximum doses deposited on the PRV often exceed these limits due to the close proximity between the target and OARs. In other words, ideal dosimetric considerations cannot be fulfilled in IMRT planning for T3-4 NPC tumors. A compromise of the maximal dose limit to the PRV of the brainstem and spinal cord would need be accepted if dose coverage to the targets is not to be unacceptably compromised. Dosimetric comparison with 2DRT plans show that these dose limits to PRV were also frequently exceeded in 2DRT plans for locally advanced NPC. A dedicated retrospective study on the incidence of clinical injury to neurological organs in a large series of patients with T3-4 NPC treated by 2DRT may provide useful reference data in exploring how far the PRV dose constraints may be relaxed, to maximize the target coverage without compromising the normal organ function.