基于虚拟现实技术的放疗CT模拟定位远程培训系统研发

目的 研发一种基于虚拟现实技术的放疗CT模拟定位的远程培训系统,探索一种医学培训的新方法。方法 使用3DMax与Maya进行3D建模,Unity3D引擎开发3D虚拟操作及交互系统;Java的SpringMvc架构作为系统后台服务,MySQL作为后台数据库系统;并将用户分为教师和学员两种角色,模式分为教学与考核模式。结果 系统功能涵盖CT模拟定位全过程,主要包括患者信息管理、CT模拟定位机认知、体位固定技术、CT定位扫描、处理突发事件等模块。自2018年投入使用以来,运行稳定,系统浏览量达14 920人次,培训通过率为86.66%。与传统培训相比,培训效率明显提升,并获得一致好评。结论 远程培训系统能有效提升学员的临床实践能力、人文关怀能力,具有良好的自主性、共享性、创新性。目前系统已上线且推广性较强,应用前景广阔。     

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。     

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。     

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.     

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。     

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.     

辅助体表标记摆位方法在胸腹部超重患者中的应用

目的 探讨辅助体表标记摆位方法是否可以减少胸腹部肿瘤超重患者放疗摆位误差。方法 入组2018年1-12月在福建医科大学附属第一医院行放疗的胸腹部肿瘤超重患者60例,随机均分成两组:A组用常规体表标记摆位,B组用常规体表标记+辅助体表标记摆位,均采用头体一体式体位固定板+热塑体膜固定;治疗前行锥形束CT扫描并在线自动匹配,记录各方向平移摆位误差数据,两组摆位误差比较采用t检验。结果 A组和B组在左右、头脚、腹背方向的摆位误差分别为(4.47±2.91) mm和(2.97±1.68) mm (P<0.001)、(5.43±2.61) mm和(3.21±1.62) mm (P<0.001)、(3.87±2.40) mm和(2.59±1.57) mm (P<0.001)。结论 采用辅助体表标记摆位方法可以减少胸腹部肿瘤超重患者的摆位误差,能提高治疗摆位重复性。     

Application of adjuvant skin-marker positioning in overweight patients with thoracic and abdominal tumors

Objective To investigate whether adjuvant skin-marker positioning can decrease the set-up errors in overweight patients with thoracic and abdominal tumors. Methods A total of 60 overweight patients with thoracic and abdominal tumors treated with radiotherapy in the First Affiliated of Fujian Medical University between January 2018 and December 2018 were randomly divided into two groups. In group A, conventional skin-marker positioning was adopted. In group B, conventional skin-marker positioning combined with adjuvant skin-marker position was employed. All patients were immobilized with thermoplastic positioning body membrane with head-body plate fixation. The set-up errors in the right-left, head-foot and dorsoventral directions were obtained from cone-beam CT (CBCT) scan system before radiation delivery. The set-up errors were statistically compared between two groups by using t-test. Results In group A, the set-up errors in the right-left, head-foot and dorsoventral directions were (4.47±2.91) mm,(5.43±2.61) mm and (3.87±2.40) mm, significantly higher compared with (2.97±1.68) mm,(3.21±1.62) mm and (2.59±1.57) mm, respectively (all P<0.001). Conclusion Adjuvant skin-marker positioning method can reduce the set-up errors and enhance the positioning repeatability in overweight patients with thoracic and abdominal tumors receiving radiotherapy.     

基于井型电离室源驻留位置和驻留时间检测方法研究

目的 研究利用井型电离室,以剂量学的方式,对后装治疗机源驻留位置和驻留时间精度进行验证,为后装治疗机的质控提供一种新方法。方法 基于井型电离室的硬件结构,分析井型电离室测量的原理,通过模拟测试和数据拟合分析其检测精度,并进行稳定性测试。通过与传统方法比较,总结优缺点。结果 源到位精度检测准确度较高,可以精确到0.07mm,驻留时间检测可以精确到0.09s。稳定性测试实验中测量值相对标准偏差<3%。结论 井型电离室方法可用于后装治疗机源驻留位置和驻留时间的快速相对验证,是一种精度较高、操作简便的方法。     

Experiences at the Paul Scherrer Institute with a remote patient positioning procedure for high-throughput proton radiation therapy

PURPOSE: To describe a remote positioning system for accurate and efficient proton radiotherapy treatments. METHODS AND MATERIALS: To minimize positioning time in the treatment room (and thereby maximize beam utility), we have adopted a method for remote patient positioning, with patients positioned and imaged outside the treatment room. Using a CT scanner, positioning is performed using orthogonal topograms with the measured differences to the reference images being used to define daily corrections to the patient table in the treatment room. Possible patient movements during transport and irradiation were analyzed through periodic acquisition of posttreatment topograms. Systematic and random errors were calculated for this daily positioning protocol and for two off-line protocols. The potential time advantage of remote positioning was assessed by computer simulation. RESULTS: Applying the daily correction protocol, systematic errors calculated over all patients (n = 94) were below 0.6 mm, whereas random errors were below 1.5 mm and 2.5 mm, respectively, for bite-block and for mask immobilization. Differences between pre- and posttreatment images were below 2.8 mm (SD) in abdominal/pelvic region, and below 2.4 mm (SD) in the head. Retrospective data analysis for a subset of patients revealed that off-line protocols would be significantly less accurate. Computer simulations showed that remote positioning can increase patient throughput up to 30%. CONCLUSIONS: The use of a daily imaging and correction protocol based on a "remote" CT could reduce positioning errors to below 2.5 mm and increase beam utility in the treatment room. Patient motion between imaging and treatment were not significant.     

Computed tomographic simulation of craniospinal fields in pediatric patients: improved treatment accuracy and patient comfort

Purpose: To reduce the time required for planning and simulating craniospinal fields through the use of a computed tomography (CT) simulator and virtual simulation, and to improve the accuracy of field and shielding placement.

Methods and Materials: A CT simulation planning technique was developed. Localization of critical anatomic features such as the eyes, cribriform plate region, and caudal extent of the thecal sac are enhanced by this technique. Over a 2-month period, nine consecutive pediatric patients were simulated and planned for craniospinal irradiation. Four patients underwent both conventional simulation and CT simulation. Five were planned using CT simulation only. The accuracy of CT simulation was assessed by comparing digitally reconstructed radiographs (DRRs) to portal films for all patients and to conventional simulation films as well in the first four patients.

Results: Time spent by patients in the CT simulation suite was 20 min on average and 40 min maximally for those who were noncompliant. Image acquisition time was <10 min in all cases. In the absence of the patient, virtual simulation of all fields took 20 min. The DRRs were in agreement with portal and/or simulation films to within 5 mm in five of the eight cases. Discrepancies of ≥5 mm in the positioning of the inferior border of the cranial fields in the first three patients were due to a systematic error in CT scan acquisition and marker contouring which was corrected by modifying the technique after the fourth patient. In one patient, the facial shield had to be moved 0.75 cm inferiorly owing to an error in shield construction.

Conclusions: Our analysis showed that CT simulation of craniospinal fields was accurate. It resulted in a significant reduction in the time the patient must be immobilized during the planning process. This technique can improve accuracy in field placement and shielding by using three-dimensional CT-aided localization of critical and target structures. Overall, it has improved staff efficiency and resource utilization.     

肺部肿瘤大分割放疗分次内体位移动影响因素分析

目的 应用IGRT技术,探讨肺部恶性肿瘤患者大分割放疗过程中分次内体位移动情况及相关影响因素。方法 选择江苏省肿瘤医院收治的 96例肺部恶性肿瘤接受大分割治疗的患者。每次治疗前常规行千伏级CBCT扫描并在线配准,校正误差后进行治疗。治疗后再次行CBCT扫描并配准,记录治疗后患者左右、上下、前后方向上的体位变化,应用多元线性回归分析相关影响因素与治疗后体位偏差的关系。结果 上下和前后方向随着分割序数增大分次内体位偏差减小(P=0.000);左右方向随治疗时间延长则分次内移动度增大(P=0.010),体重较大者则移动度较小(P=0.003)。相对于真空体膜,采用热塑网膜固定分次内左右移动度明显增大(P=0.009)。结论 肺部肿瘤大分割放疗分次内存在一定体位误差;这种误差不同方向上有不同的影响因素。改进相关因素,可减少分次内体位误差,提高治疗精度。     

不同三维探测器对鼻咽癌VMAT计划MLC位置误差探测灵敏度的研究

目的 研究鼻咽癌容积旋转调强(VMAT)计划剂量验证中,Delta⁴和ArcCHECK两种三维探测器对多叶准直器(MLC)叶片位置误差检测的灵敏度。方法 选取10例鼻咽癌VMAT计划,对原始文件中每个MLC子野的叶片分别引入0.5~4.0 mm的位置误差,使子野整体扩大、缩小或偏向一侧平移,模拟VMAT治疗中MLC可能出现的位置误差。分别用Delta⁴和ArcCHECK进行验证测量,比较计划系统计算值与测量结果的γ通过率并行配对t检验。结果 当评价标准取3 mm/3%时,两种探测器所有患者的原计划验证绝对剂量γ通过率均>95%,Delta⁴和ArcCHECK可以检测出的MLC外扩、内收以及平移误差分别是1.5、1.0、2.0 mm和3.0、1.0、3.0 mm;而取2 mm/2%评价标准时,患者原计划验证绝对剂量γ通过率有较大幅度下降,此时Delta⁴和ArcCHECK能检出的MLC外扩、内收和平移误差分别是1.0、1.0、2.0 mm和1.5、0.5、2.0 mm。结论 Delta⁴和ArcCHECK鼻咽癌VMAT计划的剂量验证可以检测出不同类型和大小的MLC位置误差,但两者的检测灵敏性略有差异,而对<1.0 mm微小误差的检测都不够敏感,日常工作中仍需加强MLC的质量保证。     

自制“倾倒式”治疗床减小胸腹部肿瘤放疗摆位误差可行性与有效性

目的 CT模拟定位和放疗过程中均使用自制“倾倒式”治疗床进行摆位,探讨其减小摆位误差的可行性和有效性。方法 选取 2016年3-9月于肿瘤医院进行放疗的 22例胸腹部肿瘤患者,根据是否使用“倾倒式”治疗床随机分为2个组,每组 11例。试验组使用“倾倒式”治疗床实现患者由直立位转换至仰卧位,对照组采用常规的患者自主仰卧位。所有患者均在自主呼吸的状态下接受定位CT扫描,根据IGRT协作组的规范化建议进行图像配准。记录并分析CBCT扫描平移误差和旋转误差配准数据,根据“四参数模型”计算2个组摆位误差。结果 试验组x、y、z轴向平移误差和范围分别为(-0.012±0.128)、(0.272±0.123)、(0.089±0.105) cm和 0.29~0.70、0.23~0.70、0.14~0.53 cm,对照组的分别为(0.006±0.198)、(-0.108±0.396)、(-0.096±0.176) cm和 0.27~0.75、0.56~2.08、0.34~0.89 cm。结论 自制“倾倒式”治疗床可以提高胸腹部肿瘤放疗的摆位重复性,减少摆位误差,尤其是y轴向上的摆位误差。     

Quality assurance of a virtual simulation software: application to IMAgo and SIMAgo (ISOgray)]

PURPOSE: Virtual simulation process is often used to prepare three dimensional conformal radiation therapy treatments. As the quality of the treatment is widely dependent on this step, it is mandatory to perform extensive controls on this software before clinical use. The tests presented in this work have been carried out on the treatment planning system ISOgray (DOSIsoft), including the delineation module IMAgo and the virtual simulation module SIMAgo. MATERIAL AND METHODS: According to our experience, the most relevant controls of international protocols have been selected. These tests mainly focused on measuring and delineation tools, virtual simulation functionalities, and have been performed with three phantoms: the Quasar Multi-Purpose Body Phantom, the Quasar MLC Beam Geometry Phantom (Modus Medical Devices Inc.) and a phantom developed at Hospital Tenon. RESULTS: No major issues have been identified while performing the tests. These controls have emphasized the necessity for the user to consider with a critical eye the results displayed by a virtual simulation software. The contrast of visualisation, the slice thickness, the calculation and display mode of 3D structures used by the software are many factors of uncertainties. CONCLUSION: A virtual simulation software quality assurance procedure has been written and applied on a set of CT images. Similar tests have to be performed periodically and at minimum at each change of major version.     

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。