鼻咽癌的调强治疗剂量学比较研究

目的:应用三维治疗计划系统评价GTV大小不同的鼻咽癌调强治疗计划的剂量分布,以探讨GTV变化对调强治疗剂量分布的影响.材料和方法:38例鼻咽癌患者,按GTV/CTV比值分为3组,GTV/CTV＜10%为1组11例,10%＜GTV/CTV＜20%为2组15例,GTV/CTV＞20%为3组12例,应用三维治疗计划系统设计调强放射治疗计划,根据剂量体积直方图(DVH)计算各组鼻咽癌靶区和正常组织剂量均数,对组间均数行T检验.结果:各组鼻咽癌靶区剂量分布均能满足靶区剂量要求,随着GTV/CTV比值增大,CTV最高剂量逐渐增高,3组与1组经检验有显著差异;GTV最高剂量变化趋势与CTV最高剂量变化相似,3组与1组、2组比较均有显著差异;GTV最低剂量随着GTV/CTV的增大,剂量逐渐降低;95%的GTV体积剂量1组高于2组;各组鼻咽癌的50%腮腺、1%脑干和1%脊髓的受照剂量经检验无显著差异,50%患侧晶体、1%视神经、50%垂体受照剂量3组显著高于1组.结论:(1)GTV/CTV比值可以更好的反应GTV分布,其值可初步预测靶区IMRT剂量分布情况,当GTV/CTV＜10%时的剂量分布最均匀;(2)调强放射治疗适用于不同GTV的鼻咽癌患者,在满足靶区剂量要求的同时,减少了危及器官的受照剂量,使进一步提高靶区剂量成为可能;(3)当GTV/CTV＞20%时,对危及器官的保护优势减小.     

胰腺癌调强计划和三维适形计划剂量学比较与分析

目的：通过比较分析胰腺癌三维适形治疗计划（3DCRT）和调强治疗计划（IMRT）,确定患者选择合适的放射治疗方式。方法：对10例胰腺癌的病人分别制定三维适形和调强治疗计划,对它们计划的靶区剂量分布和危及器官的躲避进行评估。结果：IMRT放疗计划中十二指肠的V40、V30、V20分别比3DCRT降低44．51％、10．58％、15．53％,左肾的;V30、V20分别比3DCRT降低29．57％、16．18％,而小肠、脊髓、右肾、胃等危及器官的受量差别不大。结论：和三维适形治疗计划相比,调强治疗计划能有效地降低危及器官的高剂量区,有靶区剂量的提升空间。     

鼻咽癌调强放疗靶区剂量学研究及近期疗效观察

目的:分析鼻咽癌调强放疗和常规放疗中靶区和周围组织器官的剂量分布,观察鼻咽癌调强放疗的效果和副作用.方法:对63例初治鼻咽癌采用CT模拟定位,为每例患者制定2套放疗计划,即调强放疗计划和半开准直器常规放疗计划.63例患者非随机分为2组,调强组28例进行调强放射治疗,常规组35例进行常规放射治疗.结果:在IMRT和常规计划中,对肿瘤区(GTV)的靶区覆盖率(V95)分别为99.55%和98.41%,差异无显著性(P>0.05);对于临床靶区(CTV1)的靶区覆盖率(V95)分别为98.51%和87.26%,差异有显著性(P<0.05);颈淋巴结靶区的靶区(CTV2)覆盖率(V95)分别为98.71%和77.63%,差异有显著性(P<0.05),临床靶区(CTV1)和颈淋巴结靶区(CTV2)IMRT的V95优于常规放疗.对串联器官IMRT计划和常规计划均能比较好的保护脊髓、脑干和视交叉,对并联器官IMRT计划中腮腺和下颌骨受照剂量显著低于常规计划.调强组与常规组近期有效率分别为96.4%和97.1%,差异无显著性(P>0.05),放疗6个月后调强组口干症状明显轻于常规组.结论:调强放疗可以使各个靶区得到足够、均匀的剂量分布,周围正常组织得到较好的保护.     

保护颈动脉鞘的局部晚期鼻咽癌IMRT计划对靶区及危及器官剂量的影响

【摘 要】 目的:探讨保护颈动脉鞘的局部晚期鼻咽癌调强放疗（IMRT）计划对靶区及危及器官剂量的影响。 方法:对10例局部晚期鼻咽癌患者行回顾性分析,分别设计常规IMRT计划及保护颈动脉鞘的IMRT计划。对PGTVnx和PCTV1的平均剂量（Dmean）、D98%、D50%、D5%、D2%、适形度指数、均匀性指数,颈动脉鞘和危及器官剂量进行评价。 结果:与常规IMRT计划相比,保护颈动脉鞘的IMRT计划中PGTVnx的适形度指数、均匀性指数,PCTV1的D50%、Dmean,颈动脉鞘的Dmax、Dmean,脊髓的Dmean,以及脑干的V40、Dmean均有所降低,有统计学差异（P<0.05）;其它指标比较无统计学差异。 结论:保护颈动脉鞘的局部晚期鼻咽癌IMRT计划能保证靶区剂量覆盖,降低颈动脉鞘和脑干的剂量,同时,计划的剂量分布也更为合理     

胸腺瘤术后调强放射治疗和容积弧形调强放射治疗剂量学分析简

目的研究在胸腺瘤术后放射治疗中分别采取调强放射治疗（IMRT）技术和容积弧形调强放射治疗（VMAT）技术的剂量学特点,并进一步指导胸腺瘤的放射治疗计划设计。方法选择2012年9月至2013年2月10例行放射治疗的胸腺瘤术后的患者,其中男性7例,女性3例：年龄38-63岁。中位年龄56岁。分别在治疗计划系统（TPS）上勾画大体肿瘤靶区（GTV）、临床肿瘤靶区（CTV）和计划肿瘤靶区（P11V）。术后胸腺瘤放射治疗处方剂量为5000cGy,分别采取IMRT和VMAT技术设计治疗计划,由TPS得到正常组织、危及器官的受累剂量和靶区与处方剂量分布的一致性,并列表比较。结果IMRT的计划靶区的适形指数（CI）和均匀性指数（HI）分别为0．78和1．11,VMAT计划的CI和HI为O．87和1．07。VMAT相比较IMRT在靶区剂量的适形性和不均匀性均稍优于IMRT（P=0．012,P=0．047）。在并型器官如肺组织的低剂量体积（V5、V10）上,VMAT比IMRT对肺组织产生更大的损伤,分别为69．26％和64．68％（P〈0．05）、47．52％和44．93％（P〈0．05）。对于脊髓的最大剂量．VMAT为20.51Gy,IMRT为31．66Gy;心脏的V40和V50,VMAT和IMRT相应的值为10．64％和15．08％、4．39％和8．15％;食管的最大剂量,VMAT和IMRT相应的值为38．67Gv和44-30Gy。可以看出VMAT在保护正常器官方面均优于IMRT。结论对于肿瘤靶区偏中心、体积较小、压迫正常肺组织较小的患者,采取IMRT的治疗方式可以更好地保护正常和危及器官：但是对于肿瘤靶区体积较大、中心型、压迫正常肺组织较大的患者,采取照射范围较大的VMAT更加有优势。     

鼻咽癌调强放疗计划设计和优化方法

目的:讨论鼻咽癌调强放疗计划设计和优化方法.方法:随机选取24例鼻咽癌患者.在Eclips计划系统上对其进行调强放疗计划设计.对靶区和危及器官设定剂量体积限制条件和权重因子.并对凹形靶区对应的扇形正常组织、正常组织中的剂量热点和靶区中的剂量冷点定义剂量成形结构,对这三种剂量成形结构进行优化.最终得到一个现有条件下的最优化计划.结果:分析患者的剂量体积直方图,24例患者GTV1的最大剂量、最小剂量和平均剂量的平均值分别为73.46 Gy,、67.86 Gy和70.65 Gy,GTV2的最大剂量、最小剂量和平均剂量的平均值分别为68.83 Gy、64.67 Gy和66.29 Gy,CTV1的最小剂量为60.95 Gy,CTV2的最小剂量为51.37 Gy.1%体积的脊髓、脑干和视神经所接受的平均剂量为38.10 Gy、46.94 Gy和27.43 Gy,50%体积左侧和右侧腮腺所接受的剂量分别为36.03 Gy和35.88 Gy.结论:通过射野数目、方向的选择,剂量体积约束条件和权重因子合理的设定,以及对DSS的合理定义及优化,最终可以得到一个符合临床要求的较佳的调强治疗计划.靶区在各个断面都能得到较好的剂量覆盖,调强治疗能够提高靶区剂量的同时保护靶区周围的正常组织和重要器官.     

胸中段食管癌根治性放疗三维适形放疗与调强放疗剂量学比较

目的：比较食管癌根治性放疗三维适形放射治疗（3D-CRT）与调强放射治疗（IMRT）的剂量分布,探讨IMRT在胸中段食管癌放疗的价值。方法：对10例胸中段食管癌病例分别行3D-CRT和IMRT计划设计,应用剂量体积直方图（DVH）比较两种计划靶区剂量、适形度指数（CI）、不均匀度指数（HI）及正常器官受量。结果：在食管癌根治放疗中,IMRT在靶区剂量分布上与3D-CRT各有优劣;IMRT在正常器官的保护上优势明显;肺V5、V10、V20以及全肺平均剂量IMRT均明显优于3D-CRT;心脏V30IMRT低于3D-CRT;脊髓剂量没差别。结论：食管癌根治放疗中IMRT计划在靶区剂量分布上没有明显优势。但可更好保护正常组织。     

鼻咽癌放射治疗正向调强计划设计方法

目的利用正向调强计划实现鼻咽癌放射治疗计划设计,总结出适合笔者单位的计划设计方案。方法选择2009年1月至2010年5月40例鼻咽癌患者,其中男性26例,女性14例,年龄30～70岁,平均年龄45岁。进行鼻咽癌治疗计划设计,讨论鼻咽癌计划设计的技巧。根据靶区和危及器官的形态和位置、预设射野方向,人工设置射野形状,根据处方剂量做射野权重的优化,再人为增加子野并调整子野形状,再优化,循环调整和优化,最后得到合适的计划。结果在所有病例中,一般预设7个大野,角度是210°、260°、300°、0°、60°、100°、150°,实际射野角度可以在预设方向附近做调整。根据处方剂量设计计划,大体靶体积(GTV1)为(6636.45±126.43)cGy,均匀度为1.0660±0.0217;临床靶体积(CTV1)为(6396.08±106.01)cGy,均匀度为1.1440±0.0306;CTV2为(5647.16±197.53)cGy,均匀度为(1.0860±0.0456)。并且所有计划基本满足90%CTV达到100%处方剂量,95%以上GTV达到100%处方剂量。结论调强放射治疗(IMRT)是先进的放射治疗技术,但正向调强计划的优劣很大程度上取决于操作者的经验,掌握合适技巧,运用合理方案,才可以得到符合要求的计划,总体说来鼻咽癌的正向调强计划比逆向调强计划有更加灵活的射野形状设置和权重给予,更有助于满足临床要求。     

颈段及胸上段食管癌调强放射治疗计划的比较

目的：射野数目的多少在调强放射计划中直接影响着靶区的适形性（conformity）,均匀度（uniformity）以及对周围危及器官（organs at risk,OAR）的保护。本文就颈段及胸上段食管癌,对不同射野数目进行调强放射治疗计划的比较。方法：回顾继往颈段及胸上段食管癌病例,从中挑选5位患者,运用5,7,9个射野的调强放射治疗计划,同时对IMRT的靶区运用200 cGy/fx,30fx总共60 Gy剂量,比较在这个给定相同的剂量的条件下,通过剂量体积直方图（dose volumehistograms,DVH）,等剂量曲线分布（iso-dose distributions）以及靶区的适形指数（conformity index,CI）等来比较各个计划中计划靶区（planning target volume,PTV）,以及危及器官（OARs）的剂量学差异。结果：随着射野数目的增加靶区适形度以及等剂量线分布越来越好。7、9个射野对肺的损伤也不像想象中那么大。甚至7、9野的IMRT在肺的V20更低。结论：相比5个射野的IMRT计划,7个射野能提供更好的适形度和均匀性,以及对肺组织的保护;而相比9野计划,7个射野能运用更短的治疗时间和更少的加速器跳数（monitor unite,MU）,减少器官运动对靶区剂量的影响。     

容积旋转调强在局部晚期鼻咽癌放疗中的剂量学特点

目的:研究容积旋转调强（VMAT）放射治疗技术在局部晚期鼻咽癌放疗中的剂量学特点。方法:选取70例局部晚期鼻咽癌患者,分别对入组患者进行等效均匀剂量优化+双弧VMAT计划设计（EUD组）和剂量-体积优化+双弧VMAT计划设计（DV组）,比较两种计划的靶区和部分危及器官（OAR）剂量参数和截面剂量分布情况。结果:EUD组均匀性指数和适形度指数均显著低于DV组,靶区和OAR剂量参数显著低于DV组（P<0.05）,尤其是EUD组脑干区域最高剂量在52 Gy以下,显著降低了治疗中损伤脑干的风险;EUD组靶区剂量分布更加均匀,能够减少靶区外高剂量分布和颈部高剂量体积。结论:将VMAT技术应用于局部晚期鼻咽癌放疗中时,采取等效均匀剂量优化方法,能够提升靶区均匀性与适形度,有助于改善肿瘤局部控制率,并且能够降低OAR接受剂量,保护作用更加显著。     

肿瘤腹主动脉旁淋巴结转移三维适形和调强放射治疗计划的剂量学比较

目的：比较腹主动脉旁淋巴结肿瘤转移的3D—CRT和IMRT放射治疗计划的剂量学差异。方法：设计常规四野（3D-CRT）和调强放疗（IMRT）计划，通过剂量-体积直方图比较二者的放射物理参数。并评价其应用价值。结果：IMRT计划中靶区最大剂量明显低于3D—CRT计划中的相应值，其靶区适形度也明显占优。同时。IMRT计划中的肾脏高剂量区明显低于3D—CRT计划中的高剂量区，并且其肠道剂量D5、D10、D20、D30和平均剂量均明显低于3D—CRT计划中的相应值，差异有统计学意义。结论：就腹主动脉旁淋巴结肿瘤转移的放射治疗。IMRT技术有效地将肿瘤靶区与周围正常危险器官分割开，从而在提高肿瘤放射剂量的同时最大限度减少危险器官的照射剂量，应该更广泛地应用于临床。     

Energy modulated electron therapy using a few leaf electron collimator in combination with IMRT and 3D-CRT: Monte Carlo-based planning and dosimetric evaluation

Energy modulated electron therapy (EMET) based on Monte Carlo dose calculation is a promising technique that enhances the treatment planning and delivery of superficially located tumors. This study investigated the application of EMET using a novel few-leaf electron collimator (FLEC) in head and neck and breast sites in comparison with three-dimensional conventional radiation therapy (3D-CRT) and intensity modulated radiation therapy (IMRT) techniques. Treatment planning was performed for two parotid cases and one breast case. Four plans were compared for each case: 3D-CRT, IMRT, 3D-CRT in conjunction with EMET (EMET-CRT), and IMRT in conjunction with EMET (EMET-IMRT), all of which were performed and calculated with Monte Carlo techniques. For all patients, dose volume histograms (DVHs) were obtained for all organs of interest and the DVHs were used as a means of comparing the plans. Homogeneity and conformity of dose distributions were calculated, as well as a sparing index that compares the effect of the low isodose lines. In addition, the whole-body dose equivalent (WBDE) was estimated for each plan. Adding EMET delivered with the FLEC to 3D-CRT improves sparing of normal tissues. For the two head and neck cases, the mean dose to the contralateral parotid and brain stem was reduced relative to IMRT by 43% and 84%, and by 57% and 71%, respectively. Improved normal tissue sparing was quantified as an increase in sparing index of 47% and 30% for the head and neck and the breast cases, respectively. Adding EMET to either 3D-CRT or IMRT results in preservation of target conformity and dose homogeneity. When adding EMET to the treatment plan, the WBDE was reduced by between 6% and 19% for 3D-CRT and by between 21% and 33% for IMRT, while WBDE for EMET-CRT was reduced by up to 72% when compared with IMRT. FLEC offers a practical means of delivering modulated electron therapy. Although adding EMET delivered using the FLEC results in perturbation of target conformity when compared to IMRT, it significantly improves normal tissue sparing while offering enhanced target conformity to the 3D-CRT planning. The addition of EMET systematically leads to a reduction in WBDE especially when compared with IMRT.     

宫颈癌调强放疗和三维适形放疗剂量对比研究

目的:研究宫颈癌调强放疗(IMRT)和三维适形放疗(3D-CRT)时靶区及其周围正常组织受照剂量的差异.材料方法:用拓能公司生产的WiMRT三维适形调强放疗计划系统分别进行6～9个照射角度的3D-CRT和IMRT计划设计,肿瘤量45Gy,计算出正常组织和靶区的剂量—体积直方图以及所需照射的总跳数.用Siemens生产的Primart电子直线加速器(X射线能量6MV,MLC叶片29对)实施放疗计划,测量出10 cm×10cm射野外漏射线和散射线剂量率,估算放疗时正常组织所受辐射剂量随距离的变化关系.结果:照射野数和照射角度一致,IMRT时膀胱、直肠、阴道所受平均剂量分别只有3D-CRT时的19.5％(29.3/150.3)、64.5％(538.0/833.0)和61.0％(1553.6/2546.3),靶区平均受照剂量略高于3D-CRT.IMRT病人正常组织所受散射线和漏射线剂量约为3D-CRT病人的1.5倍.结论:宫颈癌IMRT剂量分布优于3D-CRT.     

A two isocenter IMRT technique with a controlled junction dose for long volume targets

Most IMRT techniques have been designed to treat targets smaller than the field size of conventional linac accelerators. In order to overcome the field size restrictions in applying IMRT, we developed a two isocenter IMRT technique to treat long volume targets. The technique exploits an extended dose gradient throughout a junction region of 4-6 cm to minimize the impact of field match errors on a junction dose and manipulates the inverse planning and IMRT segments to fill in the dose gradient and achieve dose uniformity. Techniques for abutting both conventional fields with IMRT ('Static + IMRT') and IMRT fields ('IMRT + IMRT') using two separate isocenters have been developed. Five long volume sarcoma cases have been planned in Pinnacle (Philips, Madison, USA) using Elekta Synergy and Varian 2100EX linacs; two of the cases were clinically treated with this technique. Advantages were demonstrated with well-controlled junction target uniformity and tolerance to setup uncertainties. The junction target dose heterogeneity was controlled at a level of +/-5%; for 3 mm setup errors at the field edges, the junction target dose changed less than 5% and the dose sparing to organs at risk (OARs) was maintained. Film measurements confirmed the treatment planning results.     

On-line re-optimization of prostate IMRT plans for adaptive radiation therapy

For intermediate and high risk prostate cancer, both the prostate gland and seminal vesicles are included in the clinical target volume. Internal motion patterns of these two organs vary, presenting a challenge for adaptive treatment. Adaptive techniques such as isocenter repositioning and soft tissue alignment are effective when tumor volumes only exhibit translational shift, while direct re-optimization of the intensity-modulated radiation therapy (IMRT) plan maybe more desirable when extreme deformation or differential positioning changes of the organs occur. Currently, direct re-optimization of the IMRT plan using beamlet (or fluence map) has not been reported. In this study, we report a novel on-line re-optimization technique that can accomplish plan adjustment on-line. Deformable image registration is used to provide position variation information on each voxel along the three dimensions. The original planned dose distribution is used as the 'goal' dose distribution for adaptation and to ensure planning quality. Fluence maps are re-optimized via linear programming, and a plan solution can be achieved within 2 min. The feasibility of this technique is demonstrated with a clinical case with large deformation. Such on-line ART process can be highly valuable with hypo-fractionated prostate IMRT treatment.     

简化调强技术在脑转移瘤外照射中应用的剂量学研究

目的：通过比较脑转移瘤三维适形放疗（3D-CRT）、调强放疗（IMRT）和简化调强放疗（sIMRT）技术靶区剂量分布均匀性、适形度,危及器官受照体积、剂量,以及实施治疗的机器跳数,对比三者放疗技术的剂量学差异,探讨sIMRT应用于脑转移瘤治疗的可行性。方法：针对10例脑转移瘤患者分别设计3种放疗计划：三维适形放疗、调强放疗和简化调强放疗。保证靶区和危及器官满足临床要求前提下,分别比较3种计划的靶区剂量分布、靶区均匀指数和适形指数、危及器官受照剂量、机器跳数（MU）等,探讨其剂量学差异。结果：3种照射技术均满足临床要求,靶区（PGTV）均匀指数三者没有差异。靶区（PTV）均匀指数sIMRT逊于IMRT,但与3D-CRT无差异。靶区（PGTV、PTV）适形指数sIMRT逊于IMRT而强于3D-CRT。危及器官的保护例如左、右晶体和脑干,sIMRT优于3D-CRT但与IMRT无区别,对左、右视神经和视交叉的保护,IMRT最好,sIMRT和3D-CRT差异不大。机器跳数（MU）以IMRT最多,sIMRT居中,3D-CRT最少,但3D-CRT二程计划增加照射次数,提示实际治疗时间以sIMRT最优。结论：sIMRT可减轻工作人员劳动强度,缩短治疗时间,节省资源,是一种性价比较高的放疗技术,适用于脑转移瘤放疗。     

Evaluation of dose coverage to target volume and normal tissue sparing in the adjuvant radiotherapy of gastric cancers: 3D-CRT compared with dynamic IMRT

Purpose:

To assess the potential advantage of intensity-modulated radiotherapy (IMRT) over 3D-conformal radiotherapy (3D-CRT) planning in postoperative adjuvant radiotherapy for patients with gastric carcinoma.

Methods and materials:

In a retrospective study, for plan comparison, dose distribution was recalculated in 15 patients treated with 3D-CRT on the contoured structures of same CT images using an IMRT technique. 3D-conformal plans with three fields and four-fields were compared with seven-field dynamic IMRT plans. The different plans were compared by analyzing the dose coverage of planning target volume using TV₉₅, D_mean, uniformity index, conformity index and homogeneity index parameters. To assess critical organ sparing, D_mean, D_max, dose to one-third and two-third volumes of the OARs and percentage of volumes receiving more than their tolerance doses were compared.

Results:

The average dose coverage values of PTV with 3F-CRT and 4F-CRT plans were comparable, where as IMRT plans achieved better target coverage(p<0.001) with higher conformity index value of 0.81±0.07 compared to both the 3D-CRT plans. The doses to the liver and bowel reduced significantly (p<0.001) with IMRT plans compared to other 3D-CRT plans. For all OARs the percentage of volumes receiving more than their tolerance doses were reduced with the IMRT plans.

Conclusion:

This study showed that a better target coverage and significant dose reduction to OARs could be achieved with the IMRT plans. The IMRT can be preferred with caution for organ motion. The authors are currently studying organ motion in the upper abdomen to use IMRT for patient treatment.     

Potential for dose-escalation and reduction of risk in pancreatic cancer using IMRT optimization with lexicographic ordering and gEUD-based cost functions

Radiotherapy for pancreatic cancer is limited by the tolerance of local organs at risk (OARs) and frequent overlap of the planning target volume (PTV) and OAR volumes. Using lexicographic ordering (LO), a hierarchical optimization technique, with generalized equivalent uniform dose (gEUD) cost functions, we studied the potential of intensity modulated radiation therapy (IMRT) to increase the dose to pancreatic tumors and to areas of vascular involvement that preclude surgical resection [surgical boost volume (SBV)]. We compared 15 forward planned three-dimensional conformal (3DCRT) and IMRT treatment plans for locally advanced unresectable pancreatic cancer. We created IMRT plans optimized using LO with gEUD-based cost functions that account for the contribution of each part of the resulting inhomogeneous dose distribution. LO-IMRT plans allowed substantial PTV dose escalation compared with 3DCRT; median increase from 52 Gy to 66 Gy (a=-5,p<0.005) and median increase from 50 Gy to 59 Gy (a=-15,p<0.005). LO-IMRT also allowed increases to 85 Gy in the SBV, regardless of a value, along with significant dose reductions in OARs. We conclude that LO-IMRT with gEUD cost functions could allow dose escalation in pancreas tumors with concomitant reduction in doses to organs at risk as compared with traditional 3DCRT.