内镜下钛夹标记在早期食管癌精确放疗中应用

目的 介绍内镜下钛夹标记病变上、下界位置在早期食管癌精确放疗中的应用。方法 17例早期食管癌患者,通过内镜下钛夹标记病变上、下界,再行CT模拟定位勾画大体肿瘤体积(GTV),评估该项技术在精确放疗中的应用价值。结果 所有患者(包括13例初治、4例经内镜下切除后需放疗者)在CT和常规钡餐造影片上肿瘤显示不明显,无法准确确定GTV范围,内镜下在病变上下界均成功置入至少一个钛夹,标记肿瘤位置,在模拟定位CT上都能成功显示,并以此为依据准确勾画靶区,且未发生出血穿孔等3-4级不良反应。结论 早期食管癌在内镜下置入钛夹定位简便易行,对放疗靶区的确定有重要的临床价值。     

3D打印胸壁硅胶bolus制作及临床前研究

目的 探讨利用3D打印技术用于制作胸壁个性化硅胶组织补偿物与常规bolus及直接3D打印的PLA材料(3D-PLA材料) bolus的优势并验证其临床特性。方法 基于定位CT图像获取2例乳腺癌改良根治术后放疗患者的胸壁数据,使用3D打印硅胶倒模的设计方法,建立制作胸壁3D打印硅胶bolus (3D-SRB)。分别验证3D-SRB、常规bolus和3D-PLA与胸壁的贴合性,通过Eclipse计划系统比较虚拟计划和使用3种组织补偿物后的剂量学参数。结果 本研究成功设计并制作了一套硬度与常规bolus类似的3D-SRB。3D打印的组织补偿物(3D-SRB和3D-PLA)无论是在胸壁贴合性方面还是实际计划剂量分布方面均优于常规bolus;且3D-SRB在重复性、患者舒适性及胸壁贴合性方面优于3D-PLA。在剂量学方面,3D-SRB组与虚拟计划重复性最好,其次是3D-PLA,最后是常规bolus。结论 应用间接法3D打印的胸壁硅胶bolus在实际操作中是可行,具有较高的临床应用价值。     

放疗中基于超声形变场获取伪计算机断层扫描图像的研究

目的 提出一种改良的基于超声(US)形变场下获得伪CT图像(CTps)方法。方法 选用3例术后宫颈癌患者CT与三维US图像数据,包括模拟定位阶段获取的CT与US图像,以及治疗1周后摆位验证阶段获取的锥形束CT (CBCT)与US图像。制作基于两幅US图像全局成像重叠区域(OROW)的掩模和感兴趣区域重叠部分(OROI)的掩模,并分别应用于US图像间的配准中,得到两种形变场。分别将两种形变场应用于模拟CT图像得到两种CTps,比较不同CTps与CBCT的配准精度。结果 基于OROI、OROW及不加任何掩模下所得CTps与CBCT的相关系数(CC)的平均值分别为0.95、0.82及0.64,归一化灰度均方根误差(NMSE)平均值分别为0.12、0.42及0.57。结论 基于OROI所得掩模下获取的US形变场应用到CTsim时获得的CTps与CBCT的配准效果最好。     

应用4DCT技术确定食管癌放疗靶区及其剂量学研究

目的 比较胸中下段食管癌3D、4D放疗计划的靶区大小、靶区位移及相关剂量学差异,评估4D计划的临床价值。方法 2012年内 19例胸中下段食管癌患者分别在同次CT模拟定位时序贯行3D、4D扫描,模拟勾画二者靶区及OAR。设计3D计划和4D计划,比较3D计划与4D计划靶体积、中心点位移及OAR剂量学差异。在各项参数相同下将3D计划平移至4DCT形成3DC计划,并比较3DC计划与3D计划靶区剂量学差异。采用配对t检验或Wilcoxon符号秩检验两套计划差异。结果 全组4DCT的PTV大于3DCT (195.19 cm³∶175.67 cm³,P=0.001)。10例胸中段食管癌中心点位移仅左右方向不同(位移为0.25 cm,P=0.014)。9例胸下段食管癌中心点位移3个方向差异无统计学意义(P=0.722、0.307、0.208)。19例胸中下段食管癌3DC计划中 V₁₀₀、V₉₅、V₉₀均低于3D计划(88.62%∶95.69%,P=0.000;95.17%∶99.79%,P=0.001;97.19%∶99.99%,P=0.001)。全组4D计划两肺 V₅、V₂₀及心脏 D_mean均高于3D计划(39.49%∶37.44%,P=0.016;19.93%∶18.87%,P=0.018及2607.74 cGy∶2389.16 cGy,P=0.004),但均未超出剂量限制范围。结论 4DCT定位技术能准确确定胸中下段食管癌靶区个体化外扩边界,4D计划因靶区增大虽使肺受量增加但在剂量限制范围内,4D计划使心脏受量增加应引起注意。     

Merkel细胞癌电子线放疗中3D打印补偿物的模拟应用

目的 探讨Merkel细胞癌电子线放疗中3D打印补偿物的设计制作过程,验证其在电子线放疗中的可行性。方法 CT采集仿真头模图像,在计划系统中模拟Merkel细胞癌的靶区勾画并添加补偿物制定放疗计划。用3D打印机打印补偿物后固定在头模上,再一次CT扫描设计出新治疗计划。对这2个计划选择若干与射束平行的层面,计算对应层面通量图的γ通过率。用免洗胶片测量实际剂量分布,计算胶片与计划系统两者剂量通量图的γ通过率。打印补偿物的计划与传统的等厚度的补偿物对比,分析靶区的剂量CI、HI值。对两种计划比较行配对t检验。结果 3D打印补偿物计划与虚拟补偿物计划的对应层面剂量分布γ通过率为(94.7±2.3)%。3D打印补偿物计划中的剂量与扫描胶片的γ通过率为96.6%。与传统的补偿物相比靶区CI值明显提高(0.85∶0.69,P=0.004),HI值有所改善(1.30∶1.26,P=0.011)。结论 3D打印电子线补偿物对不同深度肿瘤提供的适形剂量分布可以满足临床需要。     

不同扫描螺距对肺内孤立性病灶GTV构建的影响

目的 比较基于3DCT不同螺距下扫描图像构建的肺内孤立性病灶GTV大小及空间位置差异,探讨大螺距CT扫描在模拟定位中的可行性。方法 选取2014—2015年间肿瘤医院接受放疗的22例周围型肺癌或肺内孤立性转移瘤患者,根据肿瘤所在肺叶不同分为A、B组。在ABC下序贯完成常规螺距(0.938)、小螺距(0.438)及大螺距(1.188)条件下的模拟定位扫描,由同一位医生在相同的窗宽和窗位条件下勾画GTV,比较常规螺距条件下模拟定位所构建的GTVCON、小螺距条件下构建GTVS及大螺距条件下构建GTVB的大小、空间位置及匹配关系。采用Friedman M、Wilcoxon秩和检验。结果 3种螺距下构建的GTVCON、GTVS、GTVB大小分别为(11.58±16.42)、(11.63±17.73)、(12.09±17.46) cm³(P=0.11)。3种螺距下GTV中心点三维坐标比较均相近,A组Px=0.33、Py=0.81、Pz=0.39;B组Px=0.92、Py=0.05、Pz=0.37。GTVS、GTVB相对于GTVCON空间匹配指数与肿瘤所在肺叶的运动幅度有关。结论多层螺旋CT采用不同螺距模拟定位对GTV的大小及空间位置影响不大,适当增加螺距有利于提高扫描速度,缩短模拟定位时间,在肺内孤立性病灶模拟定位中具有可行性。     

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。     

基于UiBot软件实现治疗计划系统CT定位影像及轮廓自动导入功能探索

目的 实现CT定位影像和轮廓自动导入Eclipse和Monaco两套治疗计划系统(TPS)。方法 基于Eclipse和Monaco的TPS,利用流程自动化可编程程序UiBot,根据Eclipse和Monaco各自CT定位影像和轮廓导入流程,使用UiBot提供的窗口元素等功能开发出CT定位影像和轮廓自动导入的自动化脚本程序。结果 通过比较手动导入和自动导入的导入时间,自动化脚本程序不仅实现了从CT定位影像和轮廓到Eclipse和Monaco的TPS准确自动导入,而且也具有与手动导入相同的效率。大部分患者影像层数在 130~180之间,且手动导入时间与自动导入时间在此区间的平均时间为76s和75s。结论 通过利用脚本开发程序UiBot的自动化功能,结合放疗工作的实际问题和重复的工作流程可以开发出自动化的脚本,极大提高了放疗工作效率,节约了人力和时间成本,为放疗流程自动化提供了一种可选择的新方法。     

MR加速器呼吸导航引导肝癌SBRT的初步临床应用研究

目的 初步探讨MR加速器呼吸导航引导肝癌立体定向体部放疗（SBRT）的流程、可行性及应用优势。方法 回顾分析2021年9—12月10例使用MR加速器接受呼吸导航引导,行SBRT的肝癌患者临床数据。所有患者均行CT模拟定位和Unity MR定位,采集平扫、增强和4D CT,及T₁ 3D、T₂ 3D MR影像。选择4D CT呼气末端图像设计参考计划,治疗前采集呼吸导航（呼气末端）T₂ Navigator MR图像,并结合实时监控2D MR影像调整或修改靶区位置和形状,选择合适的在线自适应计划流程。目测定位CT、T₂ 3D MR和T₂ 3D Navigator MR图像显示肿瘤的清晰度;统计靶区体积变化;比较自适应计划和参考计划的剂量学差异;评估患者疗效和不良反应。结果 在自由呼吸状态下,T₂ 3D Navigator MR图像质量明显优于常规T₂ 3D MR图像,可更清楚显示肿瘤及其边界。10例患者采用位置适应（ATP）和形状适应（ATS）自适应计划分别为37分次和22分次,3例患者肿瘤消退明显。自适应计划的靶区平均适形指数（CI）与参考计划无差异,但靶区外剂量跌落稍慢（P<0.05）,尤其是ATS计划较明显。ATP自适应计划的正常肝平均受量与参考计划基本一致,但平均机器跳数明显增加,且差异有统计学意义（P<0.05）。ATS自适应计划的平均机器跳数、平均子野数和正常肝D_mean和V_{10 Gy}比参考计划有所降低,V_{5 Gy}轻微增加,但均无显著差异。7例患者进行放疗后1个月和3个月疗效评价,野内病灶控制较好,放疗不良反应轻微,未见≥3级不良反应。结论 MR加速器的呼吸导航提高了自由呼吸状态下肿瘤和MR影像的目测清晰度,在肝脏肿瘤的精准自适应放疗特别是立体定向自适应放疗中展现了优势。     

125I放射性粒子植入治疗乏氧肿瘤近期疗效的临床研究

目的 研究¹²⁵I放射性粒子在CT引导下植入治疗乏氧性肿瘤的近期疗效。方法 通过多普勒彩色超声仪检测实体瘤内血流信号,将2014—2016年于我科行¹²⁵I放射性粒子植入治疗22例肿瘤患者分为少血供组(乏氧组)12例和多血供组(非乏氧组)10例。经增强CT定位扫描后将影像学数据传输至三维粒子植入TPS上设计术前计划,然后行¹²⁵I粒子植入治疗。术后剂量学验证靶区剂量D90为106~128 cGy;术后1~3个月按照WHO标准评价病灶缓解情况。结果 两组术后3个月总有效率为82%;乏氧组和非乏氧组有效率(CR+PR)相近,术后1个月P=0.840,术后2个月P=0.696,术后3个月P=0.840。结论 ¹²⁵I放射性粒子植入治疗实体恶性肿瘤可以克服乏氧性肿瘤体外放疗的抗拒性并获得满意近期疗效。     

Research and development of remote training system for radiotherapy CT simulation based on virtual reality technology

Objective To develop a remote training system for CT simulation positioning of radiotherapy using virtual reality technology, and to explore a new method of medical training. Methods The 3DMax and Maya were employed to establish the 3D model. The unity3D engine was adopted to develop 3D virtual operation and interaction system. Java spring MVC architecture was utilized as the system background service. MySQL was used as the background database system. The users were assigned into two roles:teacher and student, and the modes were divided into teaching and assessment modes. Results The function of the system covered the whole process of CT simulation positioning, mainly including modules of patient information management, CT simulation positioning machine cognition, body position fixation technology, CT positioning scanning, and emergency handling, etc. Since it was put into use in 2018, the system has been running stably, with 14920 pages views and an 86.66% pass rate. Compared with the traditional training, the training efficiency has been significantly improved and has received unanimous recognition. Conclusions The remote training system can effectively improve the clinical practice ability and humanistic care ability of the trainees, which has good autonomy, sharing, and innovation. At present, the system has been put online and has strong popularization with prospects for broad application.     

An alternative mantle irradiation technique using 3D CT- based treatment planning for female patients with Hodgkin's disease

PURPOSE: For female patients, radiotherapy treatment for Hodgkin's disease invariably results in the irradiation of breast tissue that may lead to radiation induced secondary cancers. The risk for secondary breast cancer is correlated with dose. We have developed a technique in an attempt to increase breast sparing during mantle field irradiation for female patients. MATERIAL AND METHODS: To minimize the irradiated breast volume, a virtual simulation technique making use of a Styrofoam breast immobilization board has been developed whereby the patient lies prone with the breasts positioned in grooves within the board. The breast position is adjusted using Styrofoam wedges, and breast placement is verified using an AP CT-pilot view. A CT scan of the neck and thoracic regions is taken, and the lymph nodes, breast volume and critical structures are outlined. Virtual simulation of the mantle fields (typically AP/PA isocentric beams) is performed, and beam blocks are drawn on the digitally reconstructed radiographs (DRR) generated by the virtual simulation package. The shielding is designed to allow adequate margins around the lymph nodes while maximizing shielding of the lung and breast tissues. The para-aortic fields are also easily determined through virtual simulation, where multi-planar reconstructions (MPR) and 3D renderings of the patient's CT data are used to determine the field limits and beam gaps. In addition to allowing for the geometric optimization of the positioning of the breasts under the lung shields, the virtual simulation technique provides the necessary information for a 3D dosimetric analysis, including dose-volume histograms (DVHs) of the irradiated breast volume. RESULTS: The 3D breast sparing technique was qualitatively and quantitatively compared to non-CT-based techniques and other 3D techniques currently available to assess the protection of the breasts. In a preliminary analysis, virtual simulation images (DRRs, 3D rendering and multi-planar reconstruction) demonstrated the advantage of using the breast sparing technique. A further analysis of DVHs showed a reduction of at least 50% in the volume of breast tissue irradiated when using the breast positioning board and virtual simulation as compared to the conventional simulation techniques where a breast immobilization board was not used. CONCLUSIONS: The use of a breast immobilization board and of a virtual simulation technique is recommended for the planning and treatment of female patients with Hodgkin's disease. DVH analysis has shown that this leads to a decrease in the volume of breast irradiated. It is hoped that this approach will reduce the risk of secondary breast malignancies in female patients with Hodgkin's disease.     

PET/CT模拟定位系统在放射治疗中的初步应用

目的:评价PET/CT模拟定位系统在放射治疗中的作用。方法:将PET/CT、三维激光定位系统和Focus3.2.1三维计划系统通过网络连接,形成放疗科专用的三维PET/CT模拟定位计划系统,分别对62例肿瘤患者进行PET/CT模拟定位和治疗计划。结果:通过改造组成的PET/CT模拟定位系统,比CT模拟定位提供更丰富和准确的图像信息,指导靶区GTV的勾画和放疗效果的评价。结论:PET/CT模拟定位系统明显提高放疗的定位精度,是未来放疗治疗定位的发展趋势。     

三维CT模拟定位计划系统的临床应用研究

[目的]通过三维CT模拟定位计划系统的临床应用研究。评价其在放疗听作用。[方法]将螺旋CT,三维激光定位系统和Focus9200三维计划系统通过网络连接,形成放疗科专用的,集影像诊断,图像传送,肿瘤定位和三维计划为一体的三维CT模拟定位计划系统。分别对143例肿瘤病人进行CT模拟定位和治疗计划。[结果]CT模拟定位和X线模拟定位一样可完成从定位到体表标记的全过程,利用CT进行定位,可为靶区的确定,复杂多野照射,适形调强放疗以及立体定向放疗提供更多的图像信息和更高的定位精度,使治疗中心和实际靶中心的重复误差小于1mm。[结论]CT模拟定位可用于大多数肿瘤病人的定位,是实现高精度放疗的必备设备之一。     

虚拟现实技术在放疗技术教学中的应用

目的 基于现有的放疗技术课程教学模式理论与实践的矛盾,探讨虚拟现实(VR)技术在放疗技术创新课程中应用的必要性和可行性。方法 在深入分析现有学科教学模式的特点下,引入VR技术,基于VR设计软件、眼镜、操作手柄等搭建专用的可交互平台,可通过手机端增强现实(AR)、头盔端AR、触摸屏、PC虚拟仿真以及VR虚拟仿真等多种形式的课程学习,并进行放疗六大流程的实训测试,分析该技术在放疗技术人才培养中的可行性。结果 经过软硬件的设计及测试结果分析,线上教学可应用编写交互程序,搭建虚拟体验场景,制作课程资源库,构建实训类课程和教学体系等实现;线下实践测试可应用在反馈整个流程的模拟学习,具有可行性及开发价值,可应用于放疗技术的理论和实践教学中,使教学更加简便、生动直观。结论 VR技术与放疗技术的人才培养相结合,可通过平面及虚拟仿真技术进行线上及线下课程的理论和实践教学,具有方便快捷,效率高的优点,值得大力推广。     

锥形束CT生成伪CT的深度学习方法

目的针对前列腺癌放疗, 研究锥形束CT(CBCT)生成伪CT的深度学习方法, 以满足自适应放疗的需要。方法纳入瓦里安On-Board Imager采集的74例前列腺癌患者的CBCT图像及其模拟定位CT图像, 并使用MIM软件进行形变配准。将数据按简单随机法分为训练集(59例)和测试集(15例)。使用U-net、Pix2PixGAN和CycleGAN学习CBCT到模拟定位CT的映射。以形变配准后CT作为参考图像, 评价平均绝对误差(MAE)、结构相似指数(SSIM)和峰值信噪比(PSNR)。另外单独分析了图像质量, 包括软组织分辨率、图像噪声和伪影等。结果使用U-net、Pix2PixGAN和CycleGAN生成图像的MAE分别为(29.4±16.1)、(37.1±14.4)、(34.3±17.3)HU。在图像质量方面, U-net和Pix2PixGAN生成的图像存在过度模糊的问题, 导致了图像失真;而CycleGAN生成的图像保留了CBCT图像结构且改善了图像质量。结论 CycleGAN能有效地提高CBCT图像质量, 有更大的潜力应用于自适应放疗中。     

Dosimetric validation of compensator for their use in clinical routine, in conformation radiotherapy]

PURPOSE: The aim of this work was to establish the acquisition, calculation and 3D compensator manufacturing optimum parameters. This methodology is based on virtual simulation and 3D dosimetry. MATERIALS AND METHODS: The material used is a helicoidal CT (PQ 5000-Marconi), a virtual simulation system (AcQsim version 4-Marconi), a Treatment Planning System (Dosigray), a linear accelerator Saturne 43 (Varian, CGR), an automated milling system for compensator filters (Autimo 2.5 D-HEK), a water tank phantom (wellhofer) and an homogeneous phantom with simple patterns in order to simulate the obliquity surface of patient body. The compensator was composed by granulate tin because this material ensures a good profile modulation. The compensation plane has been calculated at 80% to dose profile. The compensator thickness profile has been calculated with different acquisition (slice thickness, pitch factor), calculation (attenuation coefficient, bixel) and fabrication parameters (drill diameter, specification of milling system). RESULTS: After this preliminary study, we have defined the optimum parameters for the compensator realization. We have observed that the slice thickness, bixel size and drill diameter are the parameters that mainly affect the profiles homogeneity. The choice of parameters with smaller dimensions S = 3 mm; B = 3 mm, F = 3 mm, improve the profiles homogeneity. Though, for manufacture times compatible with the clinical routine, the selected parameters are S = 5 mm, B = 6 mm and F = 6 mm. Compensator can be used for any type of Linac. However, one must pay attention on their realization and their positioning on the beam central axis.     

基于Dense V-Network神经网络的女性肠道自动分割研究

目的 用精准自动勾画女性肠道器官的Dense V-Network模型对宫颈癌患者进行训练并评估。方法 将Dense Net与V-Net2个网络模型进行融合,形成一种用于三维CT图像自动分割的Dense V-Network算法。160例宫颈癌患者CT数据被随机分为训练集130例用于调整模型参数,测试集30例用于评估自动分割效果。采用戴斯相似性系数(DSC)等8个参数定量评估分割效果。结果 小肠DSC、杰卡德距离、体积差异性系数、敏感性指数、包容性指数、豪斯多夫距离、轮廓平均差异、质心偏差分别为0.86±0.03、0.25±0.04、0.10±0.07、0.88±0.05、0.85±0.05、(2.98±0.61) cm、(2.40±0.45) mm、(4.13±1.74) mm,结果优于单一算法(均P<0.05)。结论 Dense V-Network算法可较为准确地分割肠道器官,医生修改审查简单易行,可用于临床。     

Research on automatic segmentation of female bowel based on Dense V-Network neural network

Objective To resolve the issue of poor automatic segmentation of the bowel in women with pelvic tumors, a Dense V-Network model was established, trained and evaluated to accurately and automatically delineate the bowel of female patients with pelvic tumors. Methods Dense Net and V-Net network models were combined to develop a Dense V-Network algorithm for automatic segmentation of 3D CT images. CT data were collected from 160 patients with cervical cancer, 130 of which were randomly selected as the training set to adjust the model parameters, and the remaining 30 were used as test set to evaluate the effect of automatic segmentation. Results Eight parameters including Dice similarity coefficient (DSC) were utilized to quantitatively evaluate the segmentation effect. The DSC value, JD,ΔV, SI, IncI, HD (cm), MDA (mm), and DC (mm) of the small intestine were 0.86±0.03,0.25±0.04,0.10±0.07,0.88±0.05,0.85±0.05,2.98±0.61,2.40±0.45 and 4.13±1.74, which were better than those of any other single algorithm. Conclusion Dense V-Network algorithm proposed in this paper can deliver accurate segmentation of the bowel organs. It can be applied in clinical practice after slight revision by physicians.