射波刀同步追踪方式对头脚及左右运动肿瘤治疗的误差分析

目的：利用模体分析比较第四代射波刀同步追踪方式（Synchrony）对头脚及左右方向运动肿瘤的追踪照射误差.方法：对Synchrony模体采集CT影像,制定同步呼吸追踪的治疗计划.将装有EBT2胶片的球方模体放在治疗床上,球方在不同运动条件（头脚方向I/S、左右方向L/R）下执行模体验证计划,利用E2E软件对照射后的胶片进行分析,得出同步追踪的治疗误差.结果：Synchrony模体在头脚方向运动时E2E照射误差为0.358 mm,在左右方向运动时E2E照射误差为0.720 mm.结论：射波刀Synchrony同步追踪方式对于头脚及左右方向运动的肿瘤治疗误差均在AAPM允许范围之内,达到了实际临床治疗的精度要求.     

射波刀Synchrony同步追踪系统三维方向质量保证分析

目的:分析射波刀Synchrony同步追踪系统的质量保证验证方法是否符合临床肿瘤三维运动的要求,以保证射波刀临床治疗的质量。方法:利用改进的Synchrony模体采集CT影像信息,制订同步呼吸追踪的E2E(end to end)治疗验证计划。执行治疗计划,将装有EBT胶片的球方模体放在治疗床上,球方在不同运动条件下执行模拟验证计划,利用E2E软件对照射后的胶片进行分析,得出同步追踪的治疗误差。结果:射波刀Synchrony同步追踪系统在一维、二维、三维方向的治疗误差分别为0.91、1.03、0.90 mm。结论:射波刀Synchrony同步追踪系统的质量保证验证方法满足临床肿瘤精确治疗的要求。     

射波刀脊柱追踪仰卧与俯卧位照射精度的对比

目的 利用头颈、仿真人和肺部模体检测射波刀IGRT治疗脊柱追踪时仰卧与俯卧位照射精度并进行对比分析,为俯卧位脊柱追踪的应用提供参考数据。方法 用CT对装有胶片的头颈、仿真人和肺部模体分别进行仰卧和俯卧位扫描,然后利用治疗计划系统分别设计仰卧和俯卧位模体计划,执行模体计划。利用E2E软件分析照射精度,对比这种两种卧姿的照射精度。结果 仰卧与俯卧位精度检测结果,颈椎的追踪精度分别为0.77和0.87 mm,胸椎的为0.78和0.76 mm,腰椎的为0.89和0.80 mm,骶椎的为1.90和2.27 mm,4个不同椎体仰卧与俯卧位精度偏差分别为:0.01、0.02、0.09和0.37 mm。结论 对于这三种静态模体,颈椎、胸椎、腰椎和骶椎仰卧与俯卧位脊柱追踪精度偏差很小,可以认为具有同等的照射精度。     

射波刀治疗床修正值对六维颅骨追踪总体精度的影响

目的:探讨射波刀治疗床可修正值与六维颅骨(6D Skull)靶区追踪总体精度的关系.方法:通过影像引导将治疗床移至所需修正位置进行6D Skull球方模型定位精度测试,将测试结果与修正值为0相比较及分析.结果:治疗床3个平移方向修正值为0、3、6、10 mm,靶区追踪总体精度分别为0.23、0.32、0.53、0.55 mm;治疗床3个旋转方向修正值为(0.3、0.3、1°)、(0.6、0.6、2.)、(1、1、3°),靶区追踪总体精度分别为0.12、0.99、0.78 mm;治疗床3个平移方向和3个旋转方向修正值为(3、3、3 mm,0.3、0.3、1°)、(6、6、6mm,0.6、0.6、2°)、(10、10、10 mm,1、1、3°),靶区追踪总体精度分别为0.08、0.8、1.4 mm.结论:射波刀6D Skull靶区追踪总体精度随着治疗床3个平移方向或(和)3个旋转方向修正值的增加而增大,日常治疗摆位时应尽可能地减小治疗床的修正值.     

Varian定位系统与Topslane定位系统的比较

目的：探讨Varian金点定位法与Topslane数字床定位法的精度误差。方法：对同一患者,分别采用VarianEclipse金点定位法和Topslane头体集成定位床法定位,在模拟定位机下分别测量两种定位方式下得出的肿瘤中心坐标的偏差。结果：两种定位方法下,长度误差：1．7±0．3mm;宽度误差：0．5±0．4mm;高度误差：1．2±0．4mm。结论：结合两种定位方式的优点,将Topslane定位床应用到VarianEclipse计划系统上以改进定位方式,提高放射治疗疗效。     

射波刀Xsight患者六维方向数据分析

目的:分析30例Xsight追踪方式的患者治疗过程中所有曝光点生成的六维方向数据。方法:随机选择30例Xsight追踪方式的患者,在真空垫固定、CT-SIM定位,使用G3射波刀进行治疗,共采集1 358个曝光点图像,得到1 358组需要机械臂校准六维方向数据,其中包括患者移动超出射波刀机械臂校准范围的337个曝光点的数据,进行各个方向的平均值、标准差的比较。结果:在患者6个方向上的左右平移LET(+)/RIG(-)、前后平移ANT(+)/POS(-)、头脚平移NIF(+)/SUP(-)、左右旋转R(+)/L(-)、头高低Head-up(+)/Head-up(-)、逆顺时针CCW(+)/CW(-)上的最大值为2.3 mm、2.0 mm、1.7 mm、2.5°、1.6°、2.1°,最小值为-2.8 mm、-2.1 mm、-1.2 mm、-2.1°、-1.3°、-1.5°,中位值为-0.4 mm、0.3 mm、0.1 mm、0.6°、0.2°、0.4°,变化范围为5.1 mm、4.1 mm、2.9 mm、4.6°、2.9°、3.6°。结论:在射波刀立体定向精确放疗中,患者本身的运动呈现出对称运动,幅度相当,中位值接近于0,但是患者本身的运动变化范围超出了射波刀Xsight系统所要求的总误差不超过0.95 mm的要求,尤其是左右平移LET(+)/RIG(-)及左右旋转R(+)/L(-)(°),这充分说明了射波刀系统在出射束前进行机械臂校准的必要性和重要性。     

X刀系统等中心的验证和调整方法

立体定向放射外科(X刀)是颅脑肿瘤放射外科治疗的一种手段。X刀等中心的精度直接影响病人的治疗效果,X刀治疗时要求等中心的误差在1mm以内,每例病人治疗前都要进行验证。等中心校验和调整是X刀治疗质量保证工作的一项重要内容。等中心是机架旋转轴、治疗床旋转轴和准直器旋转轴     

螺旋断层调强放疗治疗宫颈癌误差分析

目的:探讨螺旋断层调强放疗治疗宫颈癌时MVCT引导下的治疗摆位误差。方法:2009年1月至2010年12月对30例宫颈癌术后的患者采用螺旋断层调强放疗治疗,每次治疗前实行靶区MVCT扫描,根据治疗计划的剂量分布对患者体位进行手动调节,获得治疗误差及分布规律。结果:30例患者共行MVCT扫描752次,X、Y、Z轴移动均数分别为(1.9+1.61)、(5.73+1.31)、(0.61+1.06)mm。结论:每次治疗前通过MVCT获得分次间摆位误差并对其加以纠正,这对提高宫颈癌放疗精度有积极意义。     

头颈肩面罩在鼻咽癌调强治疗中的摆位误差分析

目的探讨头颈肩面罩在鼻咽癌调强治疗中的固定效果及对摆位精度的影响。方法40例鼻咽癌患者均采用头颈肩面罩固定,在第一次治疗前和每周拍摄验证片,与DRR片进行比较,测量出X、Y、Z三方向的摆位误差,并查找误差原因。结果头颈肩面罩用于鼻咽癌调强治疗,重复性高,摆位误差小,系统误差和随机误差都控制在2 mm以内,左右方向X移动小些,头脚方向Y前后Z移动大些。结论在鼻咽癌调强治疗中,用头颈肩面罩固定效果好,摆位误差小,重复性高,值得广泛推广。但同时也存在着一定的摆位误差,为减少误差,应不要反复使用面罩,制作过程要紧贴患者体表部位,当患者消瘦、肿瘤缩小或面部肿胀的减轻时则需重新制作面罩和治疗计划。对于误差>2 mm者要进行实时摆位误差纠正,提高摆位精度,确保治疗效果。     

晚期妊娠合并子宫肌瘤193例临床分析

目的:研究分析193例晚期妊娠合并子宫肌瘤的临床特点.方法:自2014年12月到2015年11月间在我院分娩的193例晚期妊娠合并子宫肌瘤患者为研究对象,根据患者的肌瘤情况采用不同的方式进行分娩并采用不同方式治疗子宫肌瘤,并在治疗2个月后对评价指标内容进行统计分析.结果:采用手术方式治疗的总有效率为100%显著优于采用药物治疗的85.92%,P<0.05;采用肌瘤切除术的术中出血量优于采用子宫切除术的患者,P<0.05;采用子宫切除术的手术时间优于肌瘤切除术,P<0.05.均有差异统计学意义.结论:对晚期妊娠合并子宫肌瘤应根据肌瘤情况选择合适的治疗方式,在条件许可情况下采用手术方式具有较高的治疗有效率,对肌瘤较小的可采用药物方式进行治疗.     

应用CTVision图像引导分析胸部肿瘤在放疗中的摆位误差

目的应用西门子CTVision图像引导分析校正胸部肿瘤在放疗中的摆位误差,为制定胸部肿瘤放疗计划时从临床靶区（CTV）到计划靶区（PTV）的外扩边界提供参考。方法选取我科2011年1～9月应用西门子ONCOR直线加速器行根治性放疗的胸部恶性肿瘤患者20例,每周行CTVisinn图像引导放射治疗分析1次,对摆位误差超过3inltl的患者进行在线校正,分析患者校正前和校正后的摆位误差。结果20例患者共获得三维方向上校正前后的摆位误差数据194组。校正前患者在前后（AnteriorPosterior,AP）、上下（SuperiorInferior,SI）和左右（LeftRight,LR）3个方向上的摆位误差分别是：（-0．57±1．28）mm、（-0．81±4．39）mm、（0．94±1．25）mm,校正后AP、SI、LR3个方向的摆位误差值分别为：（-0．24±0．40）mm、（0．31±1．29）mm、（-0．02±0．41）mm,采用Van等人的摆位外扩边界（MPT,）推理公式Mptv=2．5∑＋0．76计算,校正前cTv到门V需外扩MPTV值应为11mm．校正后为3mm。结论采用CTVision图像引导系统在线引导放疗技术,可以有效地减少患者在治疗实施过程的误差,提高治疗精度。     

ExacTrac X线图像引导系统在非小细胞肺癌立体定向体部放射治疗中的应用

目的 探讨ExacTrac X线(ETX)图像引导系统在非小细胞肺癌(NSCLC)立体定向体部放射治疗(SBRT)中的应用价值.方法 选择2020年5—10月于医院接受SBRT的NSCLC患者24例,治疗前均采用ETX图像引导系统获取六维治疗床校正前、后的误差,并利用锥形束CT(CBCT)获取验证误差,比较上述3组误差...     

Investigation on effect of image lag in fluoroscopic images obtained with a dynamic flat-panel detector (FPD) on accuracy of target tracking in radiotherapy

Real-time tumor tracking in external radiotherapy can be achieved by diagnostic (kV) X-ray imaging with a dynamic flat-panel detector (FPD). The purpose of this study was to address image lag in target tracking and its influence on the accuracy of tumor tracking. Fluoroscopic images were obtained using a direct type of dynamic FPD. Image lag properties were measured without test devices according to IEC 62220-1. Modulation transfer function (MTF) and profile curves were measured on the edges of a moving tungsten plate at movement rate of 10 and 20 mm/s, covering lung tumor movement of normal breathing. A lung tumor and metal sphere with blurred edge due to image lag was simulated using the results and then superimposed on breathing chest radiographs of a patient. The moving target with and without image lag was traced using a template-matching technique. In the results, the image lag for the first frame after X-ray cutoff was 2.0% and decreased to less than 0.1% in the fifth frame. In the measurement of profile curves on the edges of static and moving tungsten material plates, the effect of image lag was seen as blurred edges of the plate. The blurred edges of a moving target were indicated as reduction of MTF. However, the target could be traced within an error of ± 5 mm. The results indicated that there was no effect of image lag on target tracking in usual breathing speed in a radiotherapy situation.     

Development of fast patient position verification software using 2D-3D image registration and its clinical experience

To improve treatment workflow, we developed a graphic processing unit (GPU)-based patient positional verification software application and integrated it into carbon-ion scanning beam treatment. Here, we evaluated the basic performance of the software. The algorithm provides 2D/3D registration matching using CT and orthogonal X-ray flat panel detector (FPD) images. The participants were 53 patients with tumors of the head and neck, prostate or lung receiving carbon-ion beam treatment. 2D/3D-ITchi-Gime (ITG) calculation accuracy was evaluated in terms of computation time and registration accuracy. Registration calculation was determined using the similarity measurement metrics gradient difference (GD), normalized mutual information (NMI), zero-mean normalized cross-correlation (ZNCC), and their combination. Registration accuracy was dependent on the particular metric used. Representative examples were determined to have target registration error (TRE) = 0.45 ± 0.23 mm and angular error (AE) = 0.35 ± 0.18° with ZNCC + GD for a head and neck tumor; TRE = 0.12 ± 0.07 mm and AE = 0.16 ± 0.07° with ZNCC for a pelvic tumor; and TRE = 1.19 ± 0.78 mm and AE = 0.83 ± 0.61° with ZNCC for lung tumor. Calculation time was less than 7.26 s.The new registration software has been successfully installed and implemented in our treatment process. We expect that it will improve both treatment workflow and treatment accuracy.     

Simulation approach for the evaluation of tracking accuracy in radiotherapy: a preliminary study

Real-time tumor tracking in external radiotherapy can be achieved by diagnostic (kV) X-ray imaging with a dynamic flat-panel detector (FPD). It is important to keep the patient dose as low as possible while maintaining tracking accuracy. A simulation approach would be helpful to optimize the imaging conditions. This study was performed to develop a computer simulation platform based on a noise property of the imaging system for the evaluation of tracking accuracy at any noise level. Flat-field images were obtained using a direct-type dynamic FPD, and noise power spectrum (NPS) analysis was performed. The relationship between incident quantum number and pixel value was addressed, and a conversion function was created. The pixel values were converted into a map of quantum number using the conversion function, and the map was then input into the random number generator to simulate image noise. Simulation images were provided at different noise levels by changing the incident quantum numbers. Subsequently, an implanted marker was tracked automatically and the maximum tracking errors were calculated at different noise levels. The results indicated that the maximum tracking error increased with decreasing incident quantum number in flat-field images with an implanted marker. In addition, the range of errors increased with decreasing incident quantum number. The present method could be used to determine the relationship between image noise and tracking accuracy. The results indicated that the simulation approach would aid in determining exposure dose conditions according to the necessary tracking accuracy.     

新型TiGRT IVS系统引导肺癌调强放射治疗摆位研究

目的:以锥形束CT(cone beam CT,CBCT)配准结果为参考,验证TiGRT IVS系统的在线校位精度,从而验证其临床有效性及可行性.方法:选择2019年10月至2020年2月在陆军军医大学第二附属医院全军肿瘤研究所放疗中心接受调强放射治疗的30例肺癌患者.首次摆位时行TiGRT IVS系统和CBCT位置验证...     

A method for patient set-up guidance in radiotherapy using augmented reality

A system for patient set-up in external beam radiotherapy was developed using Augmented Reality (AR). Live images of the linac treatment couch and patient were obtained with video cameras and displayed on a nearby monitor. A 3D model of the patient’s external contour was obtained from planning CT data, and AR tracking software was used to superimpose the model onto the video images in the correct position for treatment. Throughout set-up and treatment, the user can view the monitor and visually confirm that the patient is positioned correctly. To ensure that the virtual contour was displayed in the correct position, a process was devised to register the coordinates of the linac with the camera images. A cube with AR tracking markers attached to its faces was constructed for alignment with the isocentre using room lasers or conebeam CT. The performance of the system was investigated in a clinical environment by using it to position an anthropomorphic phantom without the aid of additional set-up methods. The positioning errors were determined by means of CBCT and image registration. The translational set-up errors were found to be less than 2.4 mm and the rotational errors less than 0.3°. This proof-of-principle study has demonstrated the feasibility of using AR for patient position and pose guidance.     

First clinical experience in carbon ion scanning beam therapy: retrospective analysis of patient positional accuracy

Our institute has constructed a new treatment facility for carbon ion scanning beam therapy. The first clinical trials were successfully completed at the end of November 2011. To evaluate patient setup accuracy, positional errors between the reference Computed Tomography (CT) scan and final patient setup images were calculated using 2D-3D registration software. Eleven patients with tumors of the head and neck, prostate and pelvis receiving carbon ion scanning beam treatment participated. The patient setup process takes orthogonal X-ray flat panel detector (FPD) images and the therapists adjust the patient table position in six degrees of freedom to register the reference position by manual or auto- (or both) registration functions. We calculated residual positional errors with the 2D-3D auto-registration function using the final patient setup orthogonal FPD images and treatment planning CT data. Residual error averaged over all patients in each fraction decreased from the initial to the last treatment fraction [1.09 mm/0.76° (averaged in the 1st and 2nd fractions) to 0.77 mm/0.61° (averaged in the 15th and 16th fractions)]. 2D-3D registration calculation time was 8.0 s on average throughout the treatment course. Residual errors in translation and rotation averaged over all patients as a function of date decreased with the passage of time (1.6 mm/1.2° in May 2011 to 0.4 mm/0.2° in December 2011). This retrospective residual positional error analysis shows that the accuracy of patient setup during the first clinical trials of carbon ion beam scanning therapy was good and improved with increasing therapist experience.