局部晚期宫颈癌腔内放疗联合组织间插植的剂量学研究

目的 比较局部晚期宫颈癌单纯腔内放疗与腔内联合组织间插植放疗的剂量学差异。方法 2016年5月—2017年3月局部晚期宫颈癌患者共35例,均行根治性放疗,治疗方法为外照射+腔内联合组织间插植放疗。调强放射治疗处方剂量为46.8~50.4 Gy/26~28次,1.8 Gy/次。腔内联合组织间插植放疗剂量为7 Gy/次,1次/周,共4次。同一患者首先置入三管式后装放疗施源器,采集CT图像制定治疗计划,取出三管式施源器后,置入宫腔管并植入插植针,再次采集图像制定放疗计划。分别评价比较两组计划中靶区及危及器官的受照剂量差别。结果 共制定212次后装放疗计划,其中单纯腔内治疗计划106例,腔内联合组织间插植治疗计划106例。腔内联合组织间插植放疗组计划较单纯腔内放疗组的靶区剂量明显升高,高危临床靶区（CTV）的D₉₀、中危CTV的D₉₀均显著增高（t=-6.01、-2.73,P<0.05）,膀胱、直肠、乙状结肠的D_{2 cm³}显著降低（t=3.07、4.52、2.91,P<0.05）。结论 局部晚期宫颈癌应用腔内联合插植放疗可以明显提高靶区剂量,并降低危及器官膀胱、直肠和乙状结肠的受照剂量。     

宫颈癌腔内联合组织间插植近距离后装治疗中IPSA和HIPO逆向优化算法的比较分析

目的 比较宫颈癌腔内联合组织间插植三维后装计划中模拟退火逆向优化（IPSA）和混合逆向优化（HIPO）剂量分布的差异,为宫颈癌腔内联合组织间插植后装治疗逆向计划优化方法的选择提供依据。方法 选取2016年12月至2017年5月于河北省沧州中西医结合医院43例宫颈癌患者资料,所有患者原后装治疗计划采用IPSA优化,基于原图像信息,给定同样的初始约束条件,不进行手动优化,直接计算IPSA和HIPO计划,对高危靶区（HR-CTV）剂量体积参数D₉₀、D₁₀₀、V_100%,以及均匀性指数（HI）、适形指数（CI）、危及器官（OAR）（膀胱、直肠和乙状结肠）D_{2 cm³}的数据进行评价。结果 两组间HR-CTV的D₉₀、D₁₀₀以及CI剂量差异无统计学意义（P>0.05）,但HIPO组HR-CTV的V_100%为（87.72±0.49）%;HI为（0.51±0.08）,明显高于IPSA组的（85.01±0.55）%,HI（0.42±0.06）,差异具有统计学意义（t=2.54、3.02,P<0.05）。对于OAR,与IPSA计划相比,HIPO计划中膀胱的D_{2 cm³}（3.42±0.17）Gy,直肠的D_{2 cm³}（3.04±0.37）Gy,明显低于IPSA计划膀胱的D_{2 cm³}（3.57±0.28）Gy,直肠的D_{2 cm³}（3.21±0.48）Gy,差异具有统计学意义（t=0.27、0.19,P<0.05）。乙状结肠D_{2 cm³}剂量两者差异无统计学意义。结论 在宫颈癌腔内联合组织间插植后装治疗中,采用HIPO优化比IPSA优化可以获得更好的靶区HI以及减少膀胱和直肠的受照剂量。     

模拟退火逆向优化算法在宫腔管联合插植针的宫颈癌三维后装腔内放疗中的应用

目的 探讨模拟退火逆向优化算法（IPSA）在以插植针为施源器的宫颈癌三维后装腔内放疗中的应用效果。方法 以2016年10月至2018年7月接受根治性外照射及腔内联合组织间插植的局部晚期宫颈癌患者60例为研究对象,其中宫腔管联合1~4根插植针的患者各15例。在每例患者的同一套CT图像上,分别用正向的图形优化（GRO）方式和IPSA完成两种放疗计划,采用配对t检验分析两种计划方式的剂量学差异。结果 IPSA计划的D₉₀、V₁₀₀均高于GRO计划（t=-4.742、-4.823,P<0.05）,但靶区一致性指数（CI）和靶区适形指数（COIN）略低于GRO计划（t=9.642、8.783,P<0.05）。两组计划的靶区高量（V₁₅₀、V₂₀₀、V₃₀₀）比较,差异无统计学意义（P>0.05）。两组计划的膀胱、直肠D_{2 cm³}相近（P>0.05）。宫腔管联合1根插植针时,IPSA较GRO的平均D₉₀只提高了4 cGy （P>0.05）;但随着插植针管数的增加,IPSA相比于GRO,D₉₀提高的幅度也逐渐增加;当增加到4根插植针时,IPSA较GRO的平均D₉₀增加了14 cGy （t=-3.180,P<0.05）。与GRO相比,IPSA的V₁₀₀提高的幅度同样随着插植针管数的增加而逐渐增加。结论 在以宫腔管联合插植针为施源器的宫颈癌三维后装治疗中,相比于GRO计划,IPSA计划在未增加靶区高量和危及器官剂量的情况下,可以提高靶区的覆盖度（D₉₀、V₁₀₀）,且随着插植针管数的增多,IPSA较GRO在提高靶区覆盖度方面的优势也更为明显。     

乌德勒支施源器用于局部晚期宫颈癌三维近距离放疗的剂量学研究

目的 探讨在使用乌德勒支施源器治疗局部晚期宫颈癌时,不同的管道组合设计与靶区、危及器官（OAR）的剂量关系。方法 调取2017—2018年于河北省沧州中西医结合医院放疗科接受乌德勒支施源器进行近距离治疗的17例局部晚期宫颈癌患者数据,原计划为腔内联合组织间插植近距离放疗（IC/IS）,在原勾画轮廓与照射剂量不变的情况下,去除插植针完成腔内近距离放疗（IC）计划设计,对IC/IS计划和IC计划的剂量参数进行对比分析,并评价加入IS插植针对剂量的影响。结果 IC/IS和IC计划的高危临床靶区（HR-CTV）总的D₉₀分别（88.68±1.84）和（85.54±0.54）Gy,差异具有统计学意义（t=6.200,P<0.05）。此外,在靶区的CI指数上,IC/IS计划的明显高于IC计划（0.58±0.08,0.43±0.05）,差异具有统计学意义（t=1.010,P<0.05）。在两种计划中危及器官（OAR）的受照剂量差异无统计学意义（P>0.05）。结论 对于局部晚期宫颈癌的近距离治疗,使用乌德勒支施源器可满足其处方剂量覆盖,而加入IS针,提高了计划的优化空间,在满足OAR受照剂量限值的基础上,显著提高HR-CTV的受照剂量,且提升了剂量分布均匀性。     

鼻咽癌患者放疗后记忆功能及影像学改变的临床分析

目的 分析局部晚期鼻咽癌患者放疗前、后记忆功能及脑磁共振影像学的改变。方法 回顾性分析2015年11月至2016年8月于浙江省肿瘤医院就诊的14例鼻咽癌患者的一般临床资料及剂量学资料,其中T₂ 1例,T₃ 7例,T₄ 6例,均接受2~3疗程PF/TP方案诱导化疗,及单药铂类同步调强放疗或TOMO治疗。比较放疗前及放疗后3个月数字广度测试及脑磁共振影像学的改变。结果 剂量学可分析资料患者9例,均采用调强放疗,海马V_mean（15.17±2.17）cm³,颞叶V_mean（95.07±12.26）cm³,海马D_mean（1 154.06±771.63）cGy,颞叶D_mean（1 306.61±603.69）cGy,海马D_max（3 797.61±1 450.98）cGy,颞叶D_max（5 394.17±982.28）cGy。海马生物等效均衡剂量（equivalent uniform dose,EUD）（2 233.28±872.73）cGy,颞叶EUD（3 113.11±603.69）cGy。10例患者放疗前、后正背均值分别为8.8±1.8和8.1±1.59（P>0.05）,放疗前、后倒背均值分别为6.2±1.04和5.3±2.36（t=3.25,P<0.05）。9例患者在放疗前及放疗后3个月进行脑磁共振结构像扫描,双侧颞叶可观察到灰质体积萎缩（t=4.57,P<0.05）。结论 局部晚期鼻咽癌患者接受放疗,海马及颞叶均不可避免受到照射,放疗后,记忆功能部分受损,双侧颞叶灰质体积萎缩,两者间可能存在一定相关性,需进一步扩大样本量。     

ArcherQA三维剂量验证系统在鼻咽癌调强放疗计划中的应用

目的 探讨ArcherQA三维剂量独立验证系统在鼻咽癌调强放疗计划验证中的可行性。方法 回顾性选取Eclipse治疗计划系统（TPS）制定的105例鼻咽癌患者调强放疗计划,分别利用ArcherQA与Portal dosimetry （PD）验证系统进行剂量验证。比较ArcherQA与PD的γ通过率（3 mm/3%,TH=10%）,以及ArcherQA与TPS在靶区剂量（D_mean、D_90%）与危及器官剂量（D_mean）上的差异,并分析ArcherQA结果中各危及器官的三维γ通过率情况。结果 ArcherQA计算得到的平均三维γ通过率为（99.04±1.01）%,PD测量结果的平均二维γ通过率为（99.49±0.78）%,二者差异具有统计学意义（t=-3.35,P<0.05）。ArcherQA与TPS在靶区的剂量学差异为：GTV：D_mean（0.57±0.48）%,D_90%（0.65±0.56）%;平均γ通过率：GTV （97.67±3.43）%,GTVnd-L （97.80±4.35）%,GTVnd-R （97.82±4.07）%,CTV1（97.88±2.44）%,CTV2（96.64±4.32）%;各靶区平均剂量差异为CTV1（0.57±0.46）%,GTVnd-L （0.85±0.55）%,GTVnd-R （0.73±0.55）%,CTV2（0.88±0.52）%;ArcherQA结果中各危及器官的平均γ通过率为脑干（99.93±0.22）%,视交叉（99.17±2.82）%,眼晶状体（100±0）%,脊髓（99.56±1.05）%,甲状腺（99.00±2.06）%,气管（87.86±10.42）%。各危及器官平均剂量,除左侧视神经、右侧海马、右侧腮腺外,差异均具有统计学意义（t=-14.62~4.82,P<0.05）。结论 ArcherQA基于高性能图形处理器平台,采用高精度蒙特卡罗算法,可根据患者CT图像快速并准确地计算出体内的三维剂量分布和γ通过率,并给出各感兴趣区域的剂量-体积直方图（DVH）指标参数比较,可用于鼻咽癌调强放疗计划验证,不占用加速器机时,有利于提高工作效率。     

3D打印非共面模板辅助CT引导125Ⅰ粒子植入治疗盆腔复发子宫颈癌的剂量学研究

目的 通过评估术前、术后治疗计划的物理剂量学参数,阐明利用3D打印非共面模板（3D-PNCT）辅助CT引导¹²⁵Ⅰ粒子植入治疗盆腔复发子宫颈癌的精确性。方法 盆腔复发宫颈癌患者9例,术前均行CT模拟机扫描定位图像传送粒子治疗计划系统（B-TPS）行术前计划,打印3D-PNCT,模板复位,插植粒子针并植入粒子,记录术前计划和术中实际植入针数和粒子数,比较计划靶区剂量学参数适形指数（CI）、均匀性指数（HI）和靶区外体积指数（EI）;90%靶区体积剂量（D₉₀）、匹配周边剂量（mPD,即D₁₀₀）,100%、150%和200%处方剂量体积百分比V₁₀₀、V₁₅₀和V₂₀₀。结果 患者GTV术前、术后平均体积差异无统计学意义（P>0.05）。术前粒子总数675颗,术后669颗。术前粒子针总数138根,术后132根。针道角度偏差平均1.99°±2.94°（0°~13°）。术前和术后CI、EI和HI、靶区D₉₀、MPD、V₁₀₀、V₁₅₀和V₂₀₀剂量参数差异均无统计学意义（P>0.05）。结论 3D-PNCT辅助CT引导¹²⁵Ⅰ粒子植入治疗盆腔复发宫颈癌可获得较好的术前、术后治疗计划匹配和植入精确性。     

乳腺癌放疗中两种不同摆位方式的剂量分布及摆位误差比较

目的 比较研究乳腺癌放射治疗成角度胸前板（ABB）和平板胸前板（PBB）两种摆位方法治疗计划的剂量学参数及摆位误差。方法 选取2017年3月至2018年1月在浙江大学医学院附属第一医院就诊的20例左侧乳腺癌术后患者病例资料,按不同摆位方法分ABB组和PBB组,每组10例,在定位扫描的CT图像上勾画靶区、心脏和肺等结构。计划设计采用切线野中野（FIF）技术,比较两种摆位方法治疗计划的计划靶区体积（PTV）、肺、心脏的剂量学参数及摆位误差。结果 两种摆位方式治疗计划在肿瘤靶区覆盖方面差异无统计学意义（P>0.05）。患侧肺V₂₀ ABB组和PBB组分别为（11.2±3.2）%和（15.9±5.3）%,两组比较差异有统计学意义（t=-2,47,P<0.05）,V₃₀ ABB组和PBB组分别为（9.8±1.5）%和（12.9±2.2）%,两组比较差异有统计学意义（t=-4.46,P<0.05）。心脏剂量V₂₅ ABB组和PBB组分别为（1.9±0.2）%和（2.8±0.4）%,两组比较差异有统计学意义（t=-8.28,P<0.05）,V₃₀ ABB组和PBB组分别为（1.8±0.1）%和（2.7±0.3）%,两组比较差异有统计学意义（t=-8.34,P<0.05）,心脏平均剂量D_mean ABB组和PBB组分别为（3.0±0.5）和（5.3±1.2）Gy,两组比较差异有统计学意义（t=5.58,P<0.05）。ABB摆位在左右（LR）、上下（SI）、前后（AP）的平移误差分别为（3.23±2.63）、（5.42±3.22）、（4.58±2.30）mm,在θ、Φ、ψ方向的旋转误差分别为（1.60±0.56）°、（3.40±1.65）°、（2.50±1.72）°。PBB摆位误差在LR、SI、AP的平移误差分别为（2.35±1.22）、（2.17±1.29）、（2.27±1.58）mm,在θ、Φ、ψ方向的旋转误差分别为（1.37±0.43）°、（1.79±0.71）°、（2.06±0.63）°,且进出SI、前后AP、侧翻Φ误差,两组比较差异均有统计学意义（t=3.06,2.80,3.33,P<0.05）。结论 两种摆位方式治疗计划在肿瘤靶区覆盖方面差异无统计学意义,ABB摆位方式对正常组织的保护效果优于PBB摆位方式。但摆位精度PBB比ABB摆位方式更具优势。     

基于脚本的乳腺癌切线野机架角度设置

目的 通过脚本寻找乳腺癌保乳术后正向调强放疗计划（fIMRT）中最优的切线野机架角度,以降低危及器官的受量。方法 采用脚本对手动布置切线野的46例（左、右两侧病例分别为26和20例）已治疗的保乳术后正向调强放疗计划进行重新设计,脚本程序由Pinnacle³计划系统内置的脚本功能配合Python语言编写。脚本程序统计保乳术后放疗患者在不同切线野角度下患侧肺V₂₀、健侧乳腺D₁和心脏V₁₀等剂量学指数,采用罚分函数计算不同机架角度下各个危及器官的罚分值,以选取最优的切线野角度。结果 对于26例左侧乳腺癌计划,手动和脚本设置切线野患侧肺V₂₀分别为（18.2±3.4）%和（18.1±3.4）%（P>0.05）,健侧乳腺D₁分别为（249.2±88.4）和（230.4±80.2）cGy（t=2.27,P<0.05）,心脏V₁₀分别为（13.7±5.7）%和（13.1±5.7）%（t=2.82,P<0.05）。对于20例右侧乳腺癌计划,患侧肺的V₂₀分别为（19.8±3.8）%和（19.8±3.9）%（P>0.05）,健侧乳腺D₁分别为（340.0±286.2）和（298.0±239.7）cGy（t=2.53,P<0.05）。结论 与手动相比,脚本能个性化、量化地评估切线野机架角度对乳腺癌危及器官受量的影响,更好地平衡各个危及器官间的受量,进一步提升计划质量。     

深吸气屏气技术在左侧乳腺癌保乳术后放疗中的应用

目的 比较3种呼吸模式在左侧乳腺癌保乳术后全乳放疗中的剂量学差异,以探索能最大程度地减少靶区周围重要组织器官照射体积和剂量的呼吸模式。方法 前瞻性选取18例左侧早期乳腺癌保乳术后需行放疗的患者,采集自由呼吸（FB）、胸式深吸气屏气（T-DIBH）及腹式深吸气屏气（A-DIBH）3种呼吸模式下的CT图像,随后行适形放疗计划设计,比较3种呼吸模式下的剂量学参数,包括剂量-体积直方图、靶区平均剂量及靶区剂量均匀指数、危及器官平均剂量等。结果 3种呼吸模式下,计划靶区体积、计划靶区平均剂量及计划靶区剂量均匀指数等差异均无统计学意义（P>0.05）;FB、T-DIBH及A-DIBH3种模式下的危及器官受量在心脏D_mean分别为（3.21±1.02）、（1.74±0.51）及（1.31±0.41） Gy,差异有统计学意义（W=171,P<0.05）;冠状动脉左前降支（LAD）D_mean分别为（34.61±13.51）、（14.38±10.20）及（9.21±6.53） Gy,差异有统计学意义（W=171,P<0.05）;左侧肺D_mean分别为（8.31±2.75）、（7.46±1.96）及（6.89±1.79） Gy,差异有统计学意义（W=171,P<0.05）。结论 两种深吸气屏气技术（T-DIBH或A-DIBH）可显著降低心脏、LAD及左肺等危及器官的照射剂量,且不影响放疗靶区剂量;而A-DIBH比T-DIBH在降低各危及器官的照射剂量方面更具优势。     

MRI-guided brachytherapy for locally advanced cervical cancer: Program initiation,learning curve and dose delivery results in Kuopio University Hospital

Background and purposeImage guided adaptive brachytherapy, the standard treatment for locally advanced cervical cancer (LACC), is a complex medical procedure that requires an experienced multidisciplinary team. The aims of this analysis were to assess (1) the learning curve of brachytherapy team, (2) dose-volume parameters, (3) the use of an interstitial component, and (4) the overall treatment time (OTT).Materials and methodsOur study cohort comprised 117 LACC patients treated in Kuopio University Hospital with magnetic resonance imaging guided intracavitary (IC) or combined intracavitary/interstitial (IC/IS) high dose rate brachytherapy during 2009-2018. Target volumes and organs at risk (OAR) were contoured according to ICRU/GEC-ESTRO recommendations. Treatment plans were optimized individually without using standard loading patterns.ResultsMean dose to 90% of the high-risk clinical target volume (HR-CTV D90) improved after the first 15 patients, however the team's learning curve to reliably fulfill the main planning aim (PA) of 85 Gy required a total 43 patients and more than 10 patients annually. Significant difference was detected between IC and IC/IS brachytherapy in achieving the PA of HR-CTV D90. Especially, HR-CTV volumes >30 cm³ benefitted from IS needles. Needle insertion did not cause serious complications. With the brachytherapy program, the OTT of patients from outside institutions was reduced to the same level as our own patients.ConclusionBrachytherapy requires good experience of multidisciplinary team and the continuous development of the program to fulfill PA and to avoid OTT prolongation. The use of IS needles is safe and improves the fulfillment of PA to target volume.     

Three-dimensional image-guided combined intracavitary and interstitial high-dose-rate brachytherapy in cervical cancer: A systematic review

PurposeTo evaluate the local control and toxicities of three-dimensional image-guided combined intracavitary and interstitial (IC/IS) high-dose-rate brachytherapy (BT) in cervical cancer through a systematic review.Methods and MaterialsA systematic review of relevant studies was performed through the PubMed, Web of Science, and Cochrane Library databases through May 10, 2020. Articles reporting on IC/IS technology, volumetric doses to high-risk clinical target volume (HR-CTV) and organs at risk (OARs), tumor control and/or treatment-related side effects were identified. The key information, including the type of applicator, implantation technology, characteristics of implantation, volumetric doses, tumor control, and/or treatment-related side effects, was extracted. A probit model analysis between HR-CTV D90 and tumor local control was performed.ResultsTwelve studies encompassing 520 patients were included in the probit model between HR-CTV D90 and the local control rate. The probit model showed a significant relationship between the HR-CTV D90 value and the local control probability, p = 0.003. The prescribed dose of 85 Gy_EQD2,10 would in theory warrant an 87.4% (95% confidence interval 82.5%–90.5%) local control rate.ConclusionIC/IS BT is an appropriate method to achieve a high therapeutic ratio for tumors with large volumes or poor responses after external irradiation in cervical cancer. The probit model showed that the dose escalation of HR-CTV D90 was helpful to improve the local tumor control rate.     

不同HR-CTV下单纯腔内治疗与腔内联合组织间插植治疗在宫颈癌三维后装治疗中的对比研究

目的 研究不同高危临床靶体积（HR-CTV）下单纯腔内治疗与腔内联合组织间插植（腔内+插植）治疗技术在宫颈癌三维后装治疗中的剂量学差异,并探讨HR-CTV是否存在阈值。 方法 回顾性分析2019年10月至2021年2月于广西医科大学第四附属医院接受根治性放疗的100例中晚期宫颈癌患者的临床资料,年龄35~63岁,中位年龄51岁。根据后装治疗技术不同将患者分为单纯腔内治疗组（45例）、腔内+插植治疗组（55例）。按患者每个计划的HR-CTV大小分为6个体积范围进行分析,即HR-CTV≤40 cm3、40 cm380 cm3。 采用独立样本t检验比较2种后装治疗技术在不同体积范围内的靶区和危及器官（OAR）的剂量学参数。 结果 当HR-CTV≤40 cm3时,单纯腔内治疗组的靶区剂量（D₉₀、D₁₀₀）、靶区覆盖度（V₁₀₀）及靶区高量（D₅₀、V₁₅₀、V₂₀₀）均高于腔内+插植治疗组,且差异均有统计学意义（t=2.826~3.927,均P<0.05）,但靶区适形指数（CI）、OAR膀胱和直肠D_{2 cm3}（2 cm3的OAR体积接受的最低照射剂量）的差异均无统计学意义（t=0.186、1.871、0.258,均P>0.05）。当70 cm380 cm3时,腔内+插植治疗组的靶区剂量（D₉₀、D₁₀₀）、靶区覆盖度（V₁₀₀）、CI、OAR直肠和膀胱D_{2 cm3}剂量均显著优于单纯腔内治疗组,且差异均有统计学意义（t=?6.872~3.782,均P<0.05）,而2种治疗技术的靶区高量（D₅₀、V₁₅₀、V₂₀₀）相近,差异无统计学意义（t=0.613~1.918,均P>0.05）。当40 cm390、D₁₀₀）、靶区覆盖度（V₁₀₀ ）以及直肠D_{2 cm3}的差异均无统计学意义（t=?1.759~0.710,均P>0.05）,但腔内+插植治疗组的CI显著优于单纯腔内治疗组,且差异均有统计学意义（t=?2.590、?4.577、?3.144,均P<0.05）。 结论 对于小体积靶区（≤40 cm3）,单纯腔内治疗技术在不增加OAR剂量的情况下能更好地提高靶区剂量和靶区内高剂量体积;当靶区体积较大特别是>70 cm3时,腔内+插植治疗技术能在显著提高靶区处方剂量和适形度的同时更好地保护OAR。     

Analysis of dose-effect relationship between DVH parameters and clinical prognosis of definitive radio(chemo)therapy combined with intracavitary/interstitial brachytherapy in patients with locally advanced cervical cancer: A single-center retrospective study

PurposeThe purpose of the study was to explore the dose-effect relationship between dose-volume histogram parameters and clinical prognosis of definitive radio(chemo)therapy followed by intracavitary/interstitial brachytherapy in locally advanced cervical cancer.Methods and MaterialsA retrospective analysis was performed on 110 patients with locally advanced cervical cancer who underwent external beam radiotherapy combined with intracavitary/interstitial brachytherapy with or without chemotherapy from July 2010 to September 2018. We reported D₁₀₀, D₉₈, and D₉₀ for high-risk clinical target volume (HR-CTV) and intermediate-risk clinical target volume, D_2cm³ for organs at risk. Multivariate Cox regression was used to screen independent factors. Dose-volume parameters screened by the Cox regression were incorporated into the probit model for investigating its relationship with survival.ResultsThe median followup time was 72.33 months. Multivariate Cox regression analysis showed that HR-CTV D₁₀₀, HR-CTV D₉₈, and HR-CTV D₉₀ were independent factors, affecting the 5-year overall survival (OS), cancer-specific survival (CSS), and local control (LC) rates. The probit model showed that HR-CTV D₉₈ had predictive values for the 5-year OS, CSS, and LC, and HR-CTV D₁₀₀ had predictive values for the 5-year OS, CSS, whereas HR-CTV D₉₀ had a predictive value only for the 5-year OS. The HR-CTV D₉₈ corresponding to OS _ED90, CSS _ED90, and LC _ED90 was 86.8, 85.6, and 78.6 Gy, respectively.ConclusionsA significant dependence of OS, CSS, and LC on D₉₈ for HR-CTV was found. When the long-term OS, CSS, and LC rate of the patient was >90%, HR-CTV D₉₈ > 86.8 Gy _EQD2, 85.6 Gy _EQD2, and 78.6 Gy _EQD2 were required.     

Novel use of ViewRay MRI guidance for high-dose-rate brachytherapy in the treatment of cervical cancer

PurposeTo characterize image quality and feasibility of using ViewRay MRI (VR)–guided brachytherapy planning for cervical cancer.Methods and MaterialsCervical cancer patients receiving intracavitary brachytherapy with tandem and ovoids, planned using 0.35T VR MRI at our institution, were included in this series. The high-risk clinical target volume (HR-CTV), visible gross tumor volume, bladder, sigmoid, bowel, and rectum contours for each fraction of brachytherapy were evaluated for dosimetric parameters. Typically, five brachytherapy treatments were planned using the T2 sequence on diagnostic MRI for the first and third fractions, and a noncontrast true fast imaging with steady-state precession sequence on VR or CT scan for the remaining fractions. Most patients received 5.5 Gy × 5 fractions using high-dose-rate Ir-192 following 45 Gy of whole-pelvis radiotherapy. The plan was initiated at 5.5 Gy to point A and subsequently optimized and prescribed to the HR-CTV. The goal equivalent dose in 2 Gy fractions for the combined external beam and brachytherapy dose was 85 Gy. Soft-tissue visualization using contrast-to-noise ratios to distinguish normal tissues from tumor at their interface was compared between diagnostic MRI, CT, and VR.ResultsOne hundred and forty-two fractions of intracavitary brachytherapy were performed from April 2015 to January 2017 on 29 cervical cancer patients, ranging from stages IB1 to IVA. The median HR-CTV was 27.78 cc, with median D₉₀ HR-CTV of 6.1 Gy. The median time from instrument placement to start of treatment using VR was 65 min (scan time 2 min), compared to 105 min using diagnostic MRI (scan time 11 min) (t-test, p < 0.01). The contrast-to-noise ratio of tumor to cervix in both diagnostic MRI and VR had significantly higher values compared to CT (ANOVA and t-tests, p < 0.01).ConclusionsWe report the first clinical use of VR-guided brachytherapy. Time to treatment using this approach was shorter compared to diagnostic MRI. VR also provided significant advantage in visualizing the tumor and cervix compared to CT. This presents a feasible and reliable manner to image and plan gynecologic brachytherapy.     

三种局部补量技术在晚期宫颈癌放疗中的应用研究

目的 探讨三维腔内联合组织间插植（IC/IS BT）、三维腔内（ICBT）联合调强 （ICBT+IMRT）以及单纯IMRT技术在局部晚期宫颈癌治疗中的剂量学差异。方法 选取16例接受三维近距离治疗的局部晚期宫颈癌患者,在原IC/IS BT计划的基础上分别设计ICBT+IMRT和单纯 IMRT计划,研究3种计划中肿瘤靶区和危及器官（OARs）的剂量学差异。结果 共制定75个后装治疗计划,其中IC/IS BT、ICBT+IMRT和单纯 IMRT各25个。 ICBT+IMRT与IC/IS BT计划的靶区体积剂量D₉₀差异无统计学意义（P>0.05）, OARs的剂量比较低。单纯IMRT计划中OARs受量相对较大,且V₆₀明显偏高（与IC/IS BT相比,t=6.77、10.37、4.61、2.83,P<0.05）。结论 ICBT+IMRT计划的肿瘤靶区剂量覆盖较好且OARs受剂量低,可以作为IC/IS BT替代治疗手段。单纯 IMRT技术虽然靶区覆盖度较好,但OARs保护差,不适用于晚期宫颈癌的局部补量治疗。     

Comparative analysis of rectal dose parameters in image-guided high-dose-rate brachytherapy for cervical cancer with and without a rectal retractor

PurposeThe objective of this study was to determine if use of a rectal retractor (RR) in high-dose-rate intracavitary brachytherapy for cervical cancer reduces rectal dose parameters.Methods and MaterialsWe reviewed data obtained from patients treated with intracavitary brachytherapy for cervical cancer with and without an RR. Treatment plans for each brachytherapy fraction were separated into two groups; R group with use of an RR and P group with use of vaginal packing. Dose–volume parameters for high-risk clinical target volume (HR-CTV), rectum, sigmoid, small bowel, and vaginal surface were collected for each fraction. Rectal D_2cc and International Commission on Radiation Units & Measurements (ICRU) rectal point doses were compared between groups using Student's t tests. Predictors of higher rectal D_2cc were determined by univariate and multivariate regression analyses.ResultsFour hundred sixty-three brachytherapy fractions from 114 patients were used for analysis, 377 fractions with a RR (R group) and 86 with vaginal packing only (P group). Both groups were similar except for slightly higher mean HR-CTV and mean bladder volume in P group. Both mean ICRU rectal point dose (241.1 vs. 269.9 cGy, p = 0.006) and rectal D_2cc (240.6 vs. 283.6 cGy, p < 0.001) were significantly higher in P group. Point A dose, HR-CTV, stage, and use of an RR were significant predictors of rectal D_2cc on multivariate analysis.ConclusionsOur data show that use of an RR leads to lower rectal dose parameters compared with vaginal packing. Further study is needed to determine if this will lead to less long-term toxicity.