Characterization of a real-time surface image-guided stereotactic positioning system
Characterization of a real-time surface image-guided stereotactic positioning system
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DOI：
10.1118/1.3483783
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发表时间：
2010-10-01
期刊：
影响因子：
3.8
通讯作者：
Liu, Chihray
中科院分区：
文献类型：
--
作者：
Peng, Jean L.;Kahler, Darren;Liu, Chihray
目的：AlignRT(3C)系统是一种图像引导的立体定向定位系统(IGSPS)，可提供实时目标定位。这项研究涉及该系统的首次使用与三个相机吊舱。作者在临床环境中使用锥束计算机断层扫描(CBCT)系统和光学跟踪系统来评估其定位精度和跟踪能力。方法：使用改良的Rando头颈部模型和5名接受颅内立体定向放射治疗(SRT)的患者来评估AlignRT(3C)系统的校准、配准和位置跟踪精度，并研究表面重建的不确定性，包括分部间和分部内运动、肤色、房间光强、相机温度和图像配准感兴趣区域选择的影响。通过与Elekta KVCBCT系统(XVI)和瓦里安无框架声阵列(FSA)光学跟踪系统的比较，验证了系统的准确性。使用AlignRT(3C)每日采集表面图像数据集，以评估治疗前以及每个患者的股间和股内运动。结果：针对两组不同的参考图像集，规划CT表面轮廓(CT_S)和先前记录的AlignRT(3C)光学表面图像(ART_S)。结果：AlignRT(3C)和XVI系统的系统原点位移在1.3 mm和0.7度内一致。在AlignRT(3C)和FSA中也看到了类似的结果。对于沙发角为0度的体模移位，那些利用ART_S参考文献的体模位移导致相对于XVI的平均差为0.9 mm/0.4度，相对于FSA的平均差为0.3 mm/0.2度。对于超过+/-10 mm和+/-3度的体模位移，AlignRT与XVI和FSA系统之间的最大误差分别为3.0 mm和0.4 mm。对于最大为+/-90度的沙发角，平均值(最大)AlignRT(3C)与FSA之间的差值为1.2(2.3)分/0.7度(1.2度)。对于所有试验，使用CT_S参考获得的平均配准误差大约比使用ART_S参考获得的大1.3 mm/1.0度。在患者研究中，AlignRT(3C)和XVI系统治疗前位移的平均差异为0.3 mm/0.2度，FSA和XVI系统之间的平均位移差异为1.3 mm/1度。对于非共面治疗，使用ART_S和CT_S参考文献获得的分数间运动位移与FSA系统相比，分别导致了2.1 mm/0.8度和3.3 mm/0.3度范围内的第90个百分位数的差异。追踪最长14分钟的分数内移位与FSA系统获得的移位相差1 mm/1度。对于一名患者，咬盘带来的不确定度高达3 mm/2度。在CBCT采集过程中，机架、ASI探测器面板和X射线管堵塞效应的组合导致配准误差约为3 mm。结论：AlignRT(3C)可作为一种非电离IGSPS，其准确性可与目前基于图像/标记的系统相媲美。IGSPS和CBCT可以结合在一起进行高精度定位，而不需要患者附带的定位设备。(C)2010年美国医学物理学家协会。[DOI：10.1118/1.3483783]
Purpose: The AlignRT(3C) system is an image-guided stereotactic positioning system (IGSPS) that provides real-time target localization. This study involves the first use of this system with three camera pods. The authors have evaluated its localization accuracy and tracking ability using a cone-beam computed tomography (CBCT) system and an optical tracking system in a clinical setting.Methods: A modified Rando head-and-neck phantom and five patients receiving intracranial stereotactic radiotherapy (SRT) were used to evaluate the calibration, registration, and position-tracking accuracies of the AlignRT(3C) system and to study surface reconstruction uncertainties, including the effects due to interfractional and intrafractional motion, skin tone, room light level, camera temperature, and image registration region of interest selection. System accuracy was validated through comparison with the Elekta kV CBCT system (XVI) and the Varian frameless SonArray (FSA) optical tracking system. Surface-image data sets were acquired with the AlignRT(3C) daily for the evaluation of pretreatment and interfractional and intrafractional motion for each patient. Results for two different reference image sets, planning CT surface contours (CT_S) and previously recorded AlignRT(3C) optical surface images (ART_S), are reported.Results: The system origin displacements for the AlignRT(3C) and XVI systems agreed to within 1.3 mm and 0.7 degrees. Similar results were seen for AlignRT(3C) vs FSA. For the phantom displacements having couch angles of 0 degrees, those that utilized ART_S references resulted in a mean difference of 0.9 mm/0.4 degrees with respect to XVI and 0.3 mm/0.2 degrees with respect to FSA. For phantom displacements of more than +/- 10 mm and +/- 3 degrees, the maximum discrepancies between AlignRT and the XVI and FSA systems were 3.0 and 0.4 mm, respectively. For couch angles up to +/- 90 degrees, the mean (max.) difference between the AlignRT(3C) and FSA was 1.2 (2.3) min/0.7 degrees (1.2 degrees). For all tests, the mean registration errors obtained using the CT_S references were approximately 1.3 mm/1.0 degrees larger than those obtained using the ART_S references. For the patient study, the mean differences in the pretreatment displacements were 0.3 mm/0.2 degrees between the AlignRT(3C) and XVI systems and 1.3 mm/1 degrees between the FSA and XVI systems. For noncoplanar treatments, interfractional motion displacements obtained using the ART_S and CT_S references resulted in 90th percentile differences within 2.1 mm/0.8 degrees and 3.3 mm/0.3 degrees, respectively, compared to the FSA system. Intrafractional displacements that were tracked for a maximum of 14 min were within 1 mm/1 degrees of those obtained with the FSA system. Uncertainties introduced by the bite-tray were as high as 3 mm/2 degrees for one patient. The combination of gantry, aSi detector panel, and x-ray tube blockage effects during the CBCT acquisition resulted in a registration error of approximately 3 mm. No skin-tone or surface deformation effects were seen with the limited patient sample.Conclusions: AlignRT(3C) can be used as a nonionizing IGSPS with accuracy comparable to current image/marker-based systems. IGSPS and CBCT can be combined for high-precision positioning without the need for patient-attached localization devices. (C) 2010 American Association of Physicists in Medicine. [DOI: 10.1118/1.3483783]