基于XVI技术对IGRT中立体定向体架和热塑体膜固定重复摆位的精度分析

目的：研究IGRT（image guided radiotherapy,IGRT）时两种不同定位方法的重复摆位误差,分析两种定位方法的摆位精度。方法：选择经立体定位体架（A组,11例）和热塑体膜（B组,10例）方法定位,进行图像引导放射治疗,治疗前重复摆位后,利用XVI技术获取经两种不同定位方法的图像信息与治疗计划中的参考图像信息匹配,得到X（床的左右方向）、Y（床进退方向）、Z（床升降方向）方向的误差,对经两种定位方法106次摆位后X、Y、Z方向的摆位误差进行对照分析。结果：A组在X、Y、Z方向的误差分别为0．19±0．23cm、0．4±0．37cm、0．27±0．26cm;B组在X、Y、Z方向的误差分别为0．22±0．18cm、0．46±0．42cm、0．2±0．19cm。对两种定位方法的重复摆位误差分别在同一方向上两两比较结果：在X、Y方向上比较,两组误差均无差异（P〉0．05）,在Z方向上两组误差差异有统计学意义（P〈0．05）。立体定向体架定位在Z方向上误差大于热塑体膜定位,有统计学意义。结论：行IGRT时利用XVI（X-ray volume image,XVI）技术可以准确获取经两种不同的定位方法导致的摆位误差,热塑体膜定位精度高于立体定向体架,为医生确定在不同定位方法下勾画CTV（Clinical target volume,CTV）与门V（Planning target volume,PTV）之间的margin大小提供依据。     

C T模拟机及模拟定位机在头颈部肿瘤I MRT位置验证中的应用

目的：探讨GE LightSpeed RT型CT模拟机及Nucletron SIMULIX HQ型模拟定位机在头颈部肿瘤IMRT靶区治疗中心位置校正方法及各自优势。方法：抽取60例采取头颈肩热塑网膜固定的头颈部肿瘤IM-RT患者随机分成两组,利用DRR正侧位图像在模拟定位机下校正位置30例,利用中心层面的横断面图像在CT模拟机下复位30例。分别测量在X（左右）、Y（头脚）、Z（前后）三个方向上校位中心与治疗中心的位置差别,记录三个方向上的误差为Ex、Ey、Ez。结果：误差整理分为三个等级范围Ea≤±1mm,±1mm＜Eb≤±2mm,Ec ＞±2mm。CT模拟机校正中心时X方向上各误差等级范围例数依次为8（26．7％）、18（60．0％）、4（13．3％）;Y方向上为19（63．3％）、8（26．7％）、3（10．0％）;Z方向上为9（30．0％）、14（46．7％）、7（23．3％）。模拟定位机校正中心时X方向为6（20．0％）、19（63．3％）、5（16．7％）;Y方向上为9（30．0％）、18（60．0％）、3（10．0％）;Z方向上为8（26．7％）、14（46．7％）、8（26．7％）。三个方向上CT模拟机校正中心的平均误差分别为1．39mm、0．53mm、1．48mm;模拟定位机分别为1．51mm、1．43mm、1．66mm。60例患者首次治疗时按照校正后的中心进行摆位,经加速器治疗前IGRT验证其三维方向上的误差均控制在±2mm以内。结论：对于采取头颈肩热塑网膜固定的头颈部肿瘤IMRT患者,无论是采取CT模拟机复位还是模拟定位机复位,其三维方向上整体最高只有40％的患者位移精度在1 mm以内,所以为确保患者的治疗,IMRT计划出来后进行位置验证和修正是非常有必要的;三维方向上,CT模拟机和模拟定位机的复位平均精度都控制在2mm以内,所以两种设备都可以适用于IMRT计划的位置验证,有利于提高模拟机的使用率和工作效率;CT定位机复位方法在三维方向上平均精度高于模拟定位机的平均精度,主要是在Y方向上的差异明显。     

立体定向X射线全身治疗系统物理精度测试分析

目的：检测立体定向X射线全身治疗系统的物理精度。方法：通过用胶片和电离室测量法，测量出立体定向X射线全身治疗系统综合定位精度及X-TPS单靶点规划剂量误差。结果：综合定位误差1.91mm，单靶点剂量规划误差小于1%。结论：立体定向X射线全身治疗系统的物理精度符合临床要求。     

图像融合技术在肺癌患者定位误差分析中应用初探

目的:应用图像融合技术比较肺癌患者三维放疗计划几何中心与经校对后中心的误差,明确误差方向,验证误差范围,提高放疗精度。方法:采用 Phlipis 16 排大孔径螺旋CT定位机对 30 例已行体膜固定的肺癌患者进行定位扫描,将图像传输入Eclipse 7.0三维治疗计划系统并设计放射治疗计划,确定几何中心后在 CT模拟机下校对中心并参照校对后中心进行图像扫描,传输图像进入Eclipse 7.0 三维治疗计划系统,应用图像融合技术对校对中心前后图像进行融合,比较两个图像中心点位置在三维方向上的误差并进行分析。结果:X 方向准确度为2.20 mm,X 方向精度为1.20 mm,平均误差2.20 ±1.20 mm;Y 方向准确度为2.36 mm,Y 方向精度为1.36 mm,平均误差2.30 ±1.95 mm;Z 方向准确度为3.12 mm,Z 方向精度为1.78 mm,平均误差3.50 ±3.48 mm;总的准确度为4.99 mm,精度为 1.34 mm。3 个方向平均误差间的差异采用多组比较的秩和检验分析有统计学意义（χ2=6.773,P=0.034）。结论:肺癌患者在定位阶段的误差在可接受范围内;三维方向误差主要来源于头脚方向。      

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。     

CT定位在IMRT中的应用价值

目的：通过对cT模拟定位在三维调强适形放疗（IMRT）中应用的总结研究。方法：对386例病理确诊的鼻咽癌患者采用螺旋cT模拟定位，经PACS网系统将扫描图像传输到TPS计划系统中，使用OTP计划系统进行设计，并将重建出的实际射野的图像与加速器下所拍摄的机下验证（END）片进行对照。结果：371例误差小于2mm，12例误差3—5mm因摆位而产生，5例误差达5—18mm因人为失误所致。即全部cT模拟定位资料均获得满意的结果。结论：cT模拟定位是开展IMRT技术的必要条件，cT模拟是否准确规范是IMRT成功与否的关键技术之一。     

眼内肿瘤X射线放射外科治疗精确度研究

背景与目的：眼内肿瘤X射线放射外科治疗受眼球旋转的限制,常规定位方法误差极大。本研究探讨用微真空角膜接触眼球固定器固定眼球进行放射外科治疗的精确度。方法：人体头颅模型内特定标记物测定CT定位的精确度;应用我院研制的微真空角膜接触眼球固定器固定眼球,进行眼内肿瘤CT扫描和验证扫描,测定眼球固定精确度和靶区定位精确度。结果：CT平均定位误差为0．65mm,最大误差为1．09mm。利用微真空角膜接触眼球固定器固定眼球,精确度为0．84mm,最大误差为1．17mm。眼内肿瘤定位精确度为0．87mm,最大误差为1．19mm。SRS 200治疗的摆位误差为0．22mm,最大误差为0．32mm。总治疗误差为1．40mm,95％置信概率为2．12mm。结论：利用微真空角膜接触眼球固定器进行眼内肿瘤放射外科治疗精确度高,可减少放射外科治疗时眼球旋转所产生的误差。     

CT图像三维重建在骨肿瘤诊治中的应用探讨

目的探讨螺旋CTN学图像三维重建在骨肿瘤诊断中的价值及其对手术的指导意义。方法对128例骨肿瘤患者采用螺旋CT进行薄层扫描和三维重建进行诊断。CT扫描全部采用SiemensSOMATOMSensation16型多排高速螺旋CT机,1．0mm层厚。扫描所得断层资料通过网络传送至计算机工作站进行处理。采用Window．NT3．51平合上Insight三维重建软件进行三维重建。结果三维CT图像能够围绕X轴和Z轴任意旋转、切割以从不同角度观察,能够清晰显示骨肿瘤与周围组织结构的解剖形态特点。结论三维CT重建在骨肿瘤的诊断及手术方案的制订方面具有很大的临床应用价值,有助于骨肿瘤的立体定位和肿瘤破坏范围的正确评估,并为手术入路的设计、重建和内固定选择提供客观依据。     

头颈肿瘤立体定向分次照射靶区定位的误差分析

背景与目的:明确靶区定位的精确度是立体定向分次照射质量保证的基本要求。本文主要分析头颈肿瘤立体定向分次照射(fractionatedstereotacticradiotherapy,FSRT)中机械等中心、CT定位、治疗摆位以及CT图像误差等可能引起的靶区定位误差。方法:使用立体定向治疗计划系统、靶点模拟器、头部定位框架检查各个治疗阶段靶区定位的误差。设置任意5个参考点,使用靶点模拟器检查CT定位误差;选取7个不同机器臂架/治疗床角度,定期用胶片检验使用的PhilipsSL-18直线加速器等中心误差大小;用验证片检查治疗摆位误差;对自制模体行CT扫描,分析CT图像伪影可能引起的图像误差。结果:CT定位误差约为(1.5±0.4)mm;在检查的不同机器臂架/治疗床角度中机械等中心最大误差为(1.0±0.6)mm;患者摆位的距离误差为(1.0±0.3)mm;整个治疗过程中靶区定位误差约为(2.1±0.8)mm。结论:立体定向分次照射中需要综合考虑各个阶段中可能对治疗靶区定位产生的影响,误差分析结果可用来确定治疗的计划靶区。     

食管癌三维适形放射治疗精确定位研究

目的：探讨提高食管癌三维适形放射治疗CT模拟精确定位的方法。方法：未经治疗的食管癌患者25例先X线透视,在体表用铅珠标记病变上下缘,然后经体位固定、模拟机定位、体膜上标记射野中心后进行CT扫描,通过局域网将扫描图像传送到治疗计划系统,另8例未经X线透视标记病变上下缘直接CT模拟定位。根据食管造影、纤维食管镜和CT勾画GTV、CTV。当照射剂量达30Gy时,重新行CT扫描定位,勾画靶区。观察扫描后GTV长度、两次扫描后GTV最大横径、最大前后径、GTV几何中心点坐标及靶区移位情况。结果：不同定位方法肿瘤长度（8．23±2．43）cm与（6．48±1．73）cm有显著差异;两次定位后GTV最大横径及最大前后径比较有显著差异;二次定位靶中心复查移位率达60．0％;二次定位等中心点位置在X、Y、Z3个轴上分别相差（0．394±0．194）cm、（0．5872±0．3097）cm和（0．213±0．073）cm。结论：CT模拟定位能更充分显示肿瘤外侵范围并反映其非对称生长,但在确定病灶长度时不如钡餐透视,用CT定位时常规食管吞钡X射线仍有重要的参考价值,可将二者结合,对提高定位精度有重要帮助。同时食管癌放射治疗中二次定位,可纠正靶中心的误差,提高照射剂量准确性。     

肺部肿瘤的影像学,支纤镜检及病理学对照分析（附80例报告）

目的：评价Ｘ线影像、ＣＴ、痰检、支纤镜检、针吸细胞学、冰冻切片等对肺部肿瘤的诊断价值。方法：对８０例肺部肿瘤的Ｘ线影像与ＣＴ、痰检、支纤镜、针吸细胞学、冰冻切征组织学进行对照分析。结果：Ｘ线一般能对肺部肿物作出诊断并初步定们；ＣＴ具有Ｘ线优点外，对显示某些特殊部位肿物以及纵隔、肺门等淋巴结肿大或转移优于Ｘ线；痰检适用于肺癌特别是中央型肺癌；支纤镜检适用于中央型肺部肿瘤；针吸细胞学适用于肺部肿瘤特别     

改进的三维可视化用光线投射算法

把图像处理、光线投射与包围体技术有机结合，提出了一种提高成像质量和速度的三维可视化新方法。该方法利用物体空间的包围体算法来减少追踪光线的数量，加快了绘制速度。通过实际的医学胸部CT图像的三维重建实验，取得了较好的三维显示效果和速度，验证了改进的光线投射算法对胸部CT图像的快速三维可视化问题的有效性。     

3D optoelectronic analysis of interfractional patient setup variability in frameless extracranial stereotactic radiotherapy

PURPOSE: To investigate size and frequency of interfractional patient setup variability in hypofractionated stereotactic extracranial radiotherapy. METHODS AND MATERIALS: Infrared optical 3D tracking of surface markers was applied to quantify setup variability on 51 patients. Isocenter position repeatability was assessed by means of frameless anatomic calibration and was compared with portal image evaluation. Specific data analysis allowed for compensation of patients' breathing movements and for separation of the effects of operator-dependent misalignments and respiration-induced displacements. Effects of patient position (supine vs. prone) and treatment table configuration were investigated. RESULTS: Patient positioning assisted by the optical tracking device allowed reducing displacements of surface control points within the 3-mm range. Errors in isocenter localization were in the range of a few millimeters. This was in agreement with the portal image evaluation. Breathing motion introduced appreciable errors, which increased control points and isocenter 3D variability. This effect was significantly higher than those related to other investigated factors. CONCLUSIONS: The role of infrared optical tracking devices for patient positioning is assessed on a large patient population. Their use in the frame of high-precision radiotherapy is emphasized by the application of related methodologies for breathing phase detection and frameless isocenter localization.     

Technique for verifying treatment fields using portal images with diagnostic quality

The image quality of portal films for megavoltage photon beams, when using the double-exposure technique, is poor compared to diagnostic quality, X ray images. A technique is described to record on a single film a megavoltage portal image superimposed upon a diagnostic X ray image, which provides the radiotherapist with "diagnostic quality" portal images. The technique uses a commercially available X ray tube mounted on the head of a 60Co unit. The alignment procedure, which uses a leveling device to ensure that the X ray focal spot and 60Co source are at the same location for each exposure, is confirmed by registering on film the image of an alignment marker. An evaluation of film-screen combination showed therapy verification film in a rare earth intensifying screen cassette to be best suited for this technique. The relationship between off-axis dose and the penumbral region of the portal image has been evaluated and should be useful in the interpretation of portal verification film relative to the treatment volume.     

4D-CBCT reconstruction using MV portal imaging during volumetric modulated arc therapy

Background

Recording target motion during treatment is important for verifying the irradiated region. Recently, cone-beam computed tomography (CBCT) reconstruction from portal images acquired during volumetric modulated arc therapy (VMAT), known as VMAT-CBCT, has been investigated. In this study, we developed a four-dimensional (4D) version of the VMAT-CBCT.

Materials and methods

The MV portal images were sequentially acquired from an electronic portal imaging device. The flex, background, monitor unit, field size, and multi-leaf collimator masking corrections were considered during image reconstruction. A 4D VMAT-CBCT requires a respiratory signal during image acquisition. An image-based phase recognition (IBPR) method was performed using normalised cross correlation to extract a respiratory signal from the series of portal images.

Results

Our original IBPR method enabled us to reconstruct 4D VMAT-CBCT with no external devices. We confirmed that 4D VMAT-CBCT was feasible for two patients and in good agreement with in-treatment 4D kV-CBCT.

Conclusion

The visibility of the anatomy in 4D VMAT-CBCT reconstruction for lung cancer patients has the potential of using 4D VMAT-CBCT as a tool for verifying relative positions of tumour for each respiratory phase.     

全数字化X线摄影与彩色多普勒超声诊断乳腺癌的对比研究

目的：探讨全数字化 X 线摄影与彩色多普勒超声诊断乳腺癌的对比研究。方法：对2013年1月至2013年12月期间接受治疗的66例乳腺癌患者及34例乳腺良性肿瘤患者进行回顾分析,患者均使用全数字化 X 线摄影法与彩色多普勒超声诊断法进行检查。将患者术后的病理情况与检查结果进行对比,对两种方法的确诊率进行判定,并对两组方法联合后的准确率进行研究。结果：100例患者中,单发病灶81例,多发病灶19例。经全数字化 X 线摄影诊断后,诊断符合率为81.33%,经彩色多普勒超声诊断后,诊断符合率90.52%。结论：全数字化 X 线摄影与彩色多普勒超声诊断在乳腺癌诊断上均有较高诊断率,相比之下,彩色多普勒超声诊断的诊断率稍大于全数字化 X 线摄影,若将两者联用,可明显增大诊断符合率,为医护人员对乳腺癌患者的治疗奠定基础。     

用于颅颌面种植外科的三维立体可视化系统

目的论文对在个人PC机上对颅颌面医学图像的可视化进行研究,开发出用于颅颌面种植外科的CT断层图像三维可视化系统。方法应用3D纹理映射的方法对颅颌面CT断层图像进行三维重建,并得到其XYZ方向上的切面图像。然后利用边缘检测的方法得到眼眶的位置,并在眼眶位置进行扇形切割,得到18幅扇形切割图像。结果该系统可以帮助医生进行手术前的骨质、骨量分析,设计种植手术的过程及模拟、预测手术的种植效果。结论建立的颅颌面种植外科三维可视化系统以其硬件配置合理、软件设计新颖、多维视角、便捷快速精确等为特色。具有较强的应用价值。     

Multimodality nuclear medicine imaging in three-dimensional radiation treatment planning for lung cancer: challenges and prospects

The purpose of this study was to determine the utility of quantitative single photon emission computed tomography (SPECT) lung perfusion scans and F-18 fluorodeoxyglucose positron emission computed tomography (PET) during X-ray computed tomography (CT)-based treatment planning for patients with lung cancer. Pre-radiotherapy SPECT (n = 104) and PET (n = 35) images were available to the clinician to assist in radiation field design for patients with bronchogenic cancer. The SPECT and PET scans were registered with anatomic information derived from CT. The information from SPECT and PET provides the treatment planner with functional data not seen with CT. SPECT yields three-dimensional (3D) lung perfusion maps. PET provides 3D metabolic images that assist in tumor localization. The impact of the nuclear medicine images on the treatment planning process was assessed by determining the frequency, type, and extent of changes to plans. Pre-radiotherapy SPECT scans were used to modify 11 (11%) treatment plans; primarily altering beam angles to avoid highly functioning tissue. Fifty (48%) SPECT datasets were judged to be 'potentially useful' due to the detection of hypoperfused regions of the lungs, but were not used during treatment planning. PET data influenced 34% (12 of 35) of the treatment plans examined, and resulted in enlarging portions of the beam aperture (margins) up to 15 mm. Challenges associated with image quality and registration arise when utilizing nuclear medicine data in the treatment planning process. Initial implementation of advanced SPECT image reconstruction techniques that are not typically used in the clinic suggests that the reconstruction method may influence dose response data derived from the SPECT images and improve image registration with CT. The use of nuclear medicine transmission computed tomography (TCT) for both SPECT and PET is presented as a possible tool to reconstruct more accurate emission images and to aid in the registration of emission data with the planning CT. Nuclear medicine imaging techniques appear to be a potentially valuable tool during radiotherapy treatment planning for patients with lung cancer. The utilization of accurate nuclear medicine image reconstruction techniques and TCT may improve the treatment planning process.     

Accuracy and inter-observer variability of 3D versus 4D cone-beam CT based image-guidance in SBRT for lung tumors

ABSTRACT: BACKGROUND: To analyze the accuracy and inter-observer variability of image-guidance (IG) using 3D or 4D cone-beam CT (CBCT) technology in stereotactic body radiotherapy (SBRT) for lung tumors. Materials and methods Twenty-one consecutive patients treated with image-guided SBRT for primary and secondary lung tumors were basis for this study. A respiration correlated 4D-CT and planning contours served as reference for all IG techniques. Three IG techniques were performed independently by three radiation oncologists (ROs) and three radiotherapy technicians (RTTs). Imageguidance using respiration correlated 4D-CBCT (IG-4D) with automatic registration of the planning 4D-CT and the verification 4D-CBCT was considered gold-standard. Results were compared with two IG techniques using 3D-CBCT: 1) manual registration of the planning internal target volume (ITV) contour and the motion blurred tumor in the 3D-CBCT (IGITV); 2) automatic registration of the planning reference CT image and the verification 3DCBCT (IG-3D). Image quality of 3D-CBCT and 4D-CBCT images was scored on a scale of 1-3, with 1 being best and 3 being worst quality for visual verification of the IGRT results. RESULTS: Image quality was scored significantly worse for 3D-CBCT compared to 4D-CBCT: the worst score of 3 was given in 19 % and 7.1 % observations, respectively. Significant differences in target localization were observed between 4D-CBCT and 3D-CBCT based IG: compared to the reference of IG-4D, tumor positions differed by 1.9 mm +/- 0.9 mm (3D vector) on average using IG-ITV and by 3.6 mm +/- 3.2 mm using IG-3D; results of IG-ITV were significantly closer to the reference IG-4D compared to IG-3D. Differences between the 4D-CBCT and 3D-CBCT techniques increased significantly with larger motion amplitude of the tumor; analogously, differences increased with worse 3D-CBCT image quality scores. Inter-observer variability was largest in SI direction and was significantly larger in IG using 3D-CBCT compared to 4D-CBCT: 0.6 mm versus 1.5 mm (one standard deviation). Interobserver variability was not different between the three ROs compared to the three RTTs. CONCLUSIONS: Respiration correlated 4D-CBCT improves the accuracy of image-guidance by more precise target localization in the presence of breathing induced target motion and by reduced interobserver variability.