三维适形与调强放疗技术在胃癌术后放疗中的剂量学比较

目的比较胃癌放疗中三维适形放疗(3DCRT)和调强放疗(IMRT)技术的剂量学差异,为临床应用提供参考。方法采用3DCRT治疗的5例胃癌术后患者,放疗时使用了主动呼吸门控技术,以减少呼吸引起的器官运动。IMRT计划采用7个共面等间距野,仅用于剂量学比较。患者靶区设定的处方剂量为至少95%计划靶体积(PTV)接受45.00 Gy,至少99%PTV接受42.75 Gy。根据积分剂量体积直方图(DVH)比较PTV受量和相关正常器官的受量差异和剂量分布。结果与IMRT相比3DCRT的剂量均匀性和适形度略差,但两者在PTV受量上剂量相似。对左、右肾受15 Gy剂量的体积百分比(V_(15))而言,3DCRT好于IMRT;从正常肝的平均受量及V_(30)上看,IMRT稍优于优势;在脊髓的受量上两者相似。结论3DCRT技术在主动呼吸门控辅助下,PTV和部分正常器官的受量上可接近或者达到采用相等野数的IMRT的结果。     

Conformal external beam radiotherapy in the treatment of anal canal carcinoma: A retrospective study of a genital organ sparing technique

To investigate and compare the dosimetric distribution of a conventional radiotherapy (CRT) technique and a genital organ sparing three‐dimensional conformal radiotherapy (3DCRT) technique for the treatment of anal canal cancer. Twenty‐four patients with anal canal cancer treated between January 2002 and December 2006 were investigated. Each patient was retrospectively planned with the CRT and 3DCRT techniques using the Eclipse planning system (version 7.3, Varian Medical Systems, Palo Alto, CA, USA). Planning target volumes (PTVs) and surrounding organs at risk were contoured. Organs at risk included the bladder, bowel, femoral head and neck, and external genitalia. The two planning approaches were compared using dose volume histograms. Dose volume histograms of the PTV pelvis and PTV inguinal showed comparable PTV coverage between the two techniques. The mean percentage volumes of the PTV pelvis and PTV inguinal receiving at least 95% of the prescribed dose was greater than 99% and 91.5%, respectively. Dose volume histograms of the external genitalia demonstrated that they were well spared by the 3DCRT technique with mean doses of 28.30 and 13.17 Gy for the CRT and 3DCRT techniques, respectively. The percentage volume of bowel and bladder receiving 35 Gy or less was reduced with the 3DCRT technique. The femoral head and neck doses were comparable between the two techniques, with average maximum doses recorded of 40.60 and 40.69 Gy. The results of this study demonstrate that the 3DCRT technique achieves significant sparing of surrounding organs at risk, particularly the external genitalia. This organ at risk sparing was accomplished while achieving comparable PTV coverage with a CRT technique.     

左乳腺癌保乳术后不同放疗方式的剂量学比较

目的:评价左乳腺癌保乳术后三种放疗方式（3DCRT,IMRT,VMAT）的剂量学特点。方法:选取本院2015年5月至2016年2月期间20例早期左乳腺癌保乳术后放疗患者,所有靶区及危及器官均由同一高级放疗医师勾画,包括临床靶区（CTV）、计划靶区（PTV）及危及器官（OAR）,并由同一高级放疗物理师分别设计3DCRT、IMRT、VMAT 三种治疗计划,处方剂量为50 Gy。比较三种计划的计划靶区（PTV）的靶区均匀性指数（HI）及适形度指数（CI）,最大剂量（Dmax）、平均剂量（Dmean）、最小剂量（Dmin）;肺、心脏的V5,V10,V20,V30,V40,Dmax,Dmean及Dmin等。结果:3DCRT、IMRT、VMAT三种放疗计划适形度指数（CI）分别为 0.75±0.08、0.84±0.04和0.89±0.04(P＜0.05),均匀性指数(HI)分别为 0.11±0.12、0.11±0.08 和0.10±0.09。VMAT与IMRT计划降低了危及器官高剂量区体积,但相应增加了低剂量区体积,尤其VMAT计划的心脏、患侧肺V5、V10明显增加(P＜0.05)。结论:IMRT计划不仅提高了靶区的适形度,而且降低了心脏和肺的低剂量受照体积及平均剂量。因此,IMRT计划更适用于左乳腺癌保乳术后的放射治疗。     

Geometric factors influencing dosimetric sparing of the parotid glands using IMRT

PURPOSE/OBJECTIVE: To determine the relationship between the parotid volume, parotid-planning target volume (PTV) overlap, and dosimetric sparing of the parotid with intensity-modulated radiation therapy (IMRT). METHODS AND MATERIALS: Parotid data were collected retrospectively for 51 patients treated with simultaneous boost IMRT. Unresectable patients received 54 or 59.4 Gy to subclinical disease, 70 Gy to gross disease. Patients treated postoperatively received 54, 60, and 66 Gy to low-risk, high-risk, and tumor bed regions. Volume and mean dose of each gland and gland segments outside of and overlapping the PTV were collected. Proximity of each gland to each PTV was recorded. RESULTS: Dosimetric sparing (mean dose 21% overlap (p = <0.0001). Among spared glands, the median mean dose in the overlap region was 55.0 Gy in glands with < or =21% overlap, but only 45.4 Gy when overlap >21%. Median mean dose was 25.9 Gy to glands overlapping PTV(54) or PTV(59) alone and 30.0 Gy to those abutting PTV(70) (p < 0.001). Although proximity to PTV(70) was associated with higher parotid dose, satisfactory sparing was achieved in 24 of 43 ipsilateral glands. CONCLUSIONS: Dosimetric sparing of the parotid is feasible when the parotid-PTV overlap is less than approximately 20%. With more overlap, sparing may result in low doses within the overlap region, possibly leading to inadequate PTV coverage. Gland proximity to the high-dose PTV is associated with higher mean dose but does not always preclude dosimetric sparing.     

日本京都大学前列腺癌三个外放疗计划比较

[目的]比较分析日本京都大学医院对局限性前列腺癌实施治疗的三个外放疗计划。[方法]从放疗计划数据库中调取5例局限性前列腺癌的定位CT影像资料，分别按先前的三维适形计划（old 3DCRT）、新的3DCRT（new 3DCRT）和调强放疗计划（IMRT）做计划，根据剂量体积直方图比较各计划剂量分布的差异。[结果]临床靶区（CTV，即前列腺）的剂量覆盖在三个计划中都基本相似并达到理想的剂量分布，但对于计划靶区（PTV），V95、D95和适形指数值在IMRT分别为99％、97％和0．88；在new 3DCRT为93．9％、94．5％和0．76；在old 3DCRT为59．6％、82．9％和0．6。在IMRT计划中PTV的剂量不均整值较new 3DCRT计划中的高；直肠壁接受大于40Gy剂量的体积百分数在IMRT和new 3DCRT中差异不大，在old 3DCRT中最低。[结论]局限性前列腺癌动态弧三维适形放疗计划可以实现和调强放疗计划相比拟的靶区覆盖及对直肠壁的保护，尽管调强放疗计划可以达到更适形的靶区剂量分布，但代价是更高的剂量不均整。先前的三维适形计划达不到目前对PTV靶区的充分覆盖。     

A treatment planning analysis of inverse-planned and forward-planned intensity-modulated radiation therapy in nasopharyngeal carcinoma

PURPOSE: To compare dose-volume histograms of target volumes and organs at risk in 57 patients with nasopharyngeal carcinoma (NPC) with inverse- (IP) or forward-planned (FP) intensity-modulated radiation treatment (IMRT). METHODS AND MATERIALS: The DVHs of 57 patients with NPC with IMRT with or without chemotherapy were reviewed. Thirty-one patients underwent IP IMRT, and 26 patients underwent FP IMRT. Treatment goals were to prescribe a minimum dose of 66-70 Gy for gross tumor volume and 59.4 Gy for planning target volume to greater than 95% of the volume. Multiple selected end points were used to compare dose-volume histograms of the targets, including minimum, mean, and maximum doses; percentage of target volume receiving less than 90% (1-V90%), less than 95% (1-V95%), and greater than 105% (1-V105%). Dose-volume histograms of organs at risk were evaluated with characteristic end points. RESULTS: Both planning methods provided excellent target coverage with no statistically significant differences found, although a trend was suggested in favor of improved target coverage with IP IMRT in patients with T3/T4 NPC (p = 0.10). Overall, IP IMRT statistically decreased the dose to the parotid gland, temporomandibular joint, brain stem, and spinal cord overall, whereas IP led to a dose decrease to the middle/inner ear in only the T1/T2 subgroup. CONCLUSIONS: Use of IP and FP IMRT can lead to good target coverage while maintaining critical structures within tolerance. The IP IMRT selectively spared these critical organs to a greater degree and should be considered the standard of treatment in patients with NPC, particularly those with T3/T4. The FP IMRT is an effective second option in centers with limited IP IMRT capacity. As a modification of conformal techniques, the human/departmental resources to incorporate FP-IMRT should be nominal.     

鼻咽癌螺旋断层放疗与常规加速器调强放疗的剂量学比较

目的 通过比较鼻咽癌螺旋断层放疗与常规直线加速器静态调强治疗计划,研究其剂量学特性.方法 选10例鼻咽癌患者的CT图像,统一勾画靶区及正常器官后,分别传输至螺旋断层放疗、常规调强放疗逆向调强计划系统.统一给予肿瘤靶区(pGTV、PTVnd)处方剂量70 Gy分33次,亚临床病灶区(PTV1)60 Gy分33次,预防照射区(PTV2)54 Gy分33次.正常器官限制体积与剂量为腮腺V35＜50%,脑干＜54 Gy,脊髓＜45 Gy,晶体＜9 Gy等.对两组数据进行配对t检验.结果 两组计划均有较好靶区处方剂量分布,但螺旋断层放疗组的均匀性好于常规调强放疗组;PTV1平均剂量(63.84 Gy)也显著低于常规调强放疗组(70.30 Gy);腮腺平均剂量较常规常规调强放疗组低5.3Gy,V30及V35显著低于常规调强放疗组;喉-气管-食管的最大剂量也较常规调强放疗组明显降低.结论 在鼻咽癌调强放疗中,螺旋断层放疗较常规直线加速器静态调强放疗有更好的剂量均匀性及更陡峭的剂量梯度,并可更好地保护正常器官.     

肺癌合并纵隔淋巴结转移的三维适形放疗和调强放疗的剂量学研究

目的比较肺癌合并纵隔淋巴结转移的三维适形放疗（3 DCRT）和调强放疗（IMRT）的剂量学差异,为临床应用提供参考。方法选择2007年8月至2008年2月行IMRT放射治疗的11例肺癌纵隔转移患者,利用其CT模拟定位图像分别设计IMRT计划和3DCRT计划,结合等剂量曲线以及剂量体积直方图（DVH）对IMRT计划和3 DCRT计划进行适形性、靶区均匀性和对各关键器官受量进行比较。处方剂量66Gy／33次,治疗时间6周;要求95％靶区体积达到95％以上的处方剂量。SPSS14．0统计软件进行t检验。结果IMRT靶区的适形度优于3DCRT（P〈0．05）,IMRT靶区内超过处方剂量110％体积相比3DCRT放疗靶区内超过处方剂量110％体积减小;在对肺组织的保护上,IMRT肺V20、V30、V40数值均明显小于3 DCRT（P〈0．05）。结论对临床靶区体积大、形状不规则的肺癌合并纵隔淋巴结转移患者,IMRT治疗是较好的选择。     

直肠癌术后调强放疗和三维适形放疗剂量学比较研究

目的比较研究直肠癌术后调强放疗（IMRT）和三维适形放疗（3DCRT）时靶区及其周围危及器官受照剂量的差异。方法随机选择6例直肠癌术后患者,进行CT扫描、靶区和危及器官的勾画,用三维治疗计划系统进行3DCRT和IMRT计划设计,并对结果进行比较分析。结果IMRT计划PTV的均匀性（1．09±0．02）和适形度（0．81±0．08）均优于3DCRT计划（1．17±0．01,0．66±0．05）,差异具有统计学意义（P〈0．05）。IMRT与3DCRT相比,在50Gy的高剂量区,膀胱的V50下降了10％,小肠的V50下降了4％,差异具有统计学意义（P〈0．05）,而左、右股骨头的差异无统计学意义。结论在直肠癌术后放疗中,IMRT技术较3DCRT技术有剂量学方面的优越性。     

Dosimetric Evaluation of 3-D Conformal and Intensitymodulated Radiotherapy for Breast Cancer after Conservative Surgery

Background: Breast cancers are becoming more frequently diagnosed at early stages with improved longterm outcomes. Late normal tissue complications induced by radiotherapy must be avoided with new breastradiotherapy techniques being developed. The aim of the study was to compare dosimetric parameters of planningtarget volume (PTV) and organs at risk between conformal (CRT) and intensity-modulated radiation therapy(IMRT) after breast-conserving surgery. Materials and Methods: A total of 20 patients with early stage leftbreast cancer received adjuvant radiotherapy after conservative surgery, 10 by 3D-CRT and 10 by IMRT, witha dose of 50 Gy in 25 sessions. Plans were compared according to dose-volume histogram analyses in terms ofPTV homogeneity and conformity indices as well as organs at risk dose and volume parameters. Results: The HIand CI of PTV showed no difference between 3D-CRT and IMRT, V95 gave 9.8% coverage for 3D-CRT versus99% for IMRT, V107 volumes were recorded 11% and 1.3%, respectively. Tangential beam IMRT increasedvolume of ipsilateral lung V5 average of 90%, ipsilateral V20 lung volume was 13%, 19% with IMRT and3D-CRT respectively. Patients treated with IMRT, heart volume encompassed by 60% isodose (30 Gy) reducedby average 42% (4% versus 7% with 3D-CRT), mean heart dose by average 35% (495cGy versus 1400 cGywith 3D-CRT). In IMRT minimal heart dose average is 356 cGy versus 90cGy in 3D-CRT. Conclusions: IMRTreduces irradiated volumes of heart and ipsilateral lung in high-dose areas but increases irradiated volumes inlow-dose areas in breast cancer patients treated on the left side.     

鼻咽癌调强放疗后近期腮腺功能影响因素分析

[目的]总结鼻咽癌调强放疗后腮腺功能影响因素。[方法]收集2008年7月至2009年8月初治的20例鼻咽癌调强放疗靶区及腮腺剂量学参数,随访其放疗后3个月口干情况,分析腮腺受照剂量与口干分级之间的关系。[结果]20例接受调强放疗鼻咽癌腮腺平均剂量41.25Gy,患侧腮腺V20：96.77%,V30：80.56%,V40：52.43%,健侧腮腺V20：971.47%,V30：69.95%,V40：40.85%。放疗后3个月轻度、中度、重度口干发生率分别为15%、55%、30%,口干分级与腮腺平均剂量、患侧及健侧腮腺V20、V30、V40呈正相关。[结论]鼻咽癌调强放疗后腮腺功能与腮腺受照体积、剂量显著相关。     

胸中段食管癌三维适形放疗、调强放疗及旋转调强放疗的剂量学研究

 目的　研究胸中段食管癌三维适形放疗（3DCRT）、调强放疗（IMRT）、旋转调强放疗（IMAT）3种放疗计划的剂量差异。方法　选取胸中段食管癌患者15例,以Varian Eclipse 8.6计划系统分别设计3DCRT、IMRT、IMAT 3种放疗计划,其中3DCRT采用5～8个共面射野,IMRT采用7个共面射野,IMAT采用2个弧度。比较3种计划的剂量学差异。结果　IMRT、IMRT的靶区均匀指数（HI）、适形指数（CI）、95 % 计划靶体积（PTV）体积剂量均优于3DCRT,全肺V5、V20、V35、心脏V30受照剂量低于3DCRT（t＝2.531,P＜0.05）,而在全肺V10、V15、V25、V30、全肺平均、心脏平均、脊髓Dmax剂量之间三者的差异均无统计学意义（t＝1.325,P＞0.05）。结论　IMAT与IMRT在胸中段食管癌放疗靶区体积剂量覆盖和危及器官保护方面相似,二者均优于3DCRT。IMAT的机器跳数和照射时间均少于IMRT。     

食管癌常规放疗与三维适形放疗剂量分布的比较

目的比较食管癌常规三野照射和三维适形放射治疗2种不同的治疗方法,不同设野方法的计划中靶区及正常组织的受量。方法应用三维治疗计划系统(TPS)在28例食管癌患者的CT虚拟图像上分别设计2种外照射计划(A:常规三野;B:三维适形三野),应用剂量体积直方图比较2种计划肺、心脏等正常组织受量及肺正常组织并发症发生概率(NTCP)的区别。根据肺的NTCP来估计放射性肺炎的发生概率。结果常规三野照射和适形放射治疗的比较:PTV各项指标无显著性差异,心脏受照的体积百分比(V40、V50)及左右肺及双肺受照的体积百分比(V20、V30)等有明显的差异(P=0)。结论食管癌三野常规照射与适形放射治疗比较:三野的适形放射治疗有利于保护心脏及正常肺组织,可降低放射性肺炎的发生概率。     

Dosimetric Comparison between Intensity Modulated Radiotherapy and 3 Dimensional Conformal Radiotherapy in the Treatment of Rectal Cancer

Objective: To compare dosimetric parameters of 3 dimensional conformal radiotherapy (3 DCRT) and intensity modulated radiotherapy (IMRT) in terms of target coverage and doses to organs at risk (OAR) in the management of rectal carcinoma. Methods: In this prospective study, conducted between August 2014 and March 2016, all patients underwent CT simulation along with a bladder protocol and target contouring according to the Radiation Therapy Oncology Group (RTOG) guidelines. Two plans were made for each patient (3 DCRT and IMRT) for comparison of target coverage and OAR. Result: A total of 43 patients were recruited into this study. While there were no significant differences in mean Planning Target Volume (PTV) D95% and mean PTV D98% between 3 DCRT and IMRT, mean PTV D2% and mean PTV D50% were significantly higher in 3 DCRT plans. Compared to IMRT, 3 DCRT resulted in significantly higher volumes of hot spots, lower volumes of cold spots, and higher doses to the entire OAR. Conclusion: This study demonstrated that IMRT achieves superior normal tissue avoidance (bladder and bowel) compared to 3 DCRT, with comparable target dose coverage.     

Neck Node Bolus Technique in the Treatment of Nasopharyngeal Carcinoma with Intensity-modulated Radiotherapy

Purpose: To study the effect of bolus versus no bolus in the coverage of the nodal tumour volume withintensity-modulated radiotherapy (IMRT) for the treatment of nasopharyngeal carcinoma (NPC). Methods andMaterials: This retrospective study used data from 5 consecutive patients with NPC who were treated with bolusfor large neck nodes using IMRT from November 2011-January 2012 in our institute. All these patients weretreated radically with IMRT according to our institution’s protocol. Re-planning with IMRT without bolus forthese patients with exactly the same target volumes were done for comparison. Comparison of the plans was doneby comparing the V70 of PTV70-N, V66.5 of PTV70-N, V65.1 of PTV70-N and the surface dose of the PTV70-N.Results: The mean size of the largest diameter of the enlarged lymph nodes for the 5 patients was 3.9 cm. Themean distance of the GTV-N to the skin surface was 0.6 cm. The mean V70 of PTV70-N for the 5 patients showedan absolute advantage of 10.8% (92.4% vs. 81.6%) for the plan with bolus while the V66.5 of PTV70-N had anadvantage of 8.1% (97.0% vs. 88.9%). The mean V65.1 also had an advantage of 7.1% (97.6% vs. 90.5%). Themean surface dose for the PTV70-N was also much higher at 61.1 Gy for the plans with bolus compared to only23.5 Gy for the plans without bolus. Conclusion: Neck node bolus technique should be strongly considered inthe treatment of NPC with enlarged lymph nodes treated with IMRT. It yields a superior dosimetry comparedt o non-bolus plans with acceptable skin toxicity.     

子宫颈癌术后盆腔不同体外照射方法的剂量学研究

目的 比较常规放疗(CRT)、三维适形放疗(3DCRT)及调强放疗(IMRT)方法在子宫颈癌靶体积剂量覆盖及危及器官(OAR)保护方面的差异,探讨子宫颈癌患者术后盆腔体外照射的合理方法.方法 对10例子宫颈癌术后患者进行模拟CT增强扫描,在计划系统内勾画临床靶体积(CTV),CTV均匀外扩1.0 cm生成计划靶体积(PTV),同时勾画小肠、直肠、膀胱、骨髓、卵巢及股骨头作为OAR.进而设计出CRT、3DCRT及IMRT的3种治疗计划,对CRT要求参考点达到处方剂量45 Gy,对3DCRT及IMRT要求95%的PTV达45 Gy.应用等剂量曲线及剂量体积直方图对3种计划的CTV及OAR的剂量分布进行比较.结果 CRT计划中CTV达45 Gy的平均体积显著低于3DCRT、IMRT计划(Q=8.27、8.37,P值均＜0.01),而3DCRT和IMRT计划之间相似(Q=0.10,P＞0.05).3DCRT和IMRT计划中小肠达30、45 Gy的体积明显低于CRT.IMRT计划中直肠、膀胱达30、45 Gy的体积均显著低于CRT,而3DCRT中仅直肠、膀胱达45 Gy的体积显著低于CRT.3DCRT和IMRT使骨髓达30、45 Gy剂量的体积明显低于CRT.4例卵巢移位者中2例在3DCRT及IMRT计划中,另2例在3种计划中卵巢平均受量全部超过300 cGy.结论 IMRT和3DCRT在提高靶体积内剂量及其均匀度,以及保护小肠、直肠和膀胱方面较CRT具备明显优势,以IMRT为最佳.在高剂量范围内,IMRT和3DCRT对骨髓的保护优势确定.对于移位悬吊的卵巢,IMRT、3DCRT及CRT均不能对其形成有效保护.     

Rectal dose reduction with IMRT for prostate radiotherapy

Dose escalation in radiation therapy has led to increased control rates with some clinical trial evidence that rectal toxicity may be reduced when using intensity-modulated radiotherapy (IMRT) over 3D conformal radiotherapy (3DCRT) for dose-escalated prostate radiotherapy. However, IMRT for prostate patients is not yet standard in many Australian radiation oncology centres. This study investigates dosimetric changes that can be observed between IMRT and 3DCRT in prostate radiotherapy. Fifteen patients were selected for analysis. Two target definitions were investigated – prostate-only and prostate plus seminal vesicles (p + SVs). A five-field 3DCRT and seven-field IMRT plan were created for each patient and target definition. The planning target volume coverage was matched for both plans. Doses to the rectum, bladder and femoral heads were compared using dose volume histograms. The rectal normal tissue complication probabilities (NTCPs) were calculated and compared for the 3DCRT and IMRT plans. The delivery efficiency was investigated. The IMRT plans resulted in reductions in the V25, V50, V60, V70 and V75 Gy values for both the prostate-only and p + SVs targets. Rectal NTCP was reduced with IMRT for three different sets of model parameters. The reductions in rectal dose and NTCP were much larger for the p + SVs target. Delivery of IMRT plans was less efficient than for 3DCRT plans. IMRT resulted in superior plans based on dosimetric and biological endpoints. The dosimetric gains with IMRT were greater for the more complex p + SVs target. The gains made came at the cost of decreased delivery efficiency.