Optical imaging provides rapid verification of static small beams, radiosurgery, and VMAT plans with millimeter resolution
Optical imaging provides rapid verification of static small beams, radiosurgery, and VMAT plans with millimeter resolution
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DOI：
10.1002/mp.13797
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发表时间：
2019-11-01
期刊：
影响因子：
3.8
通讯作者：
Gladstone, David J.
中科院分区：
文献类型：
--
作者：
Ashraf, Muhammad Ramish;Bruza, Petr;Gladstone, David J.
PurposeWe证明了光学成像的可行性，作为一个质量保证工具，静态小波束，放射外科和体积调制弧治疗（VMAT）plannes.MethodsSmall静态光束和临床VMAT计划的预处理验证工具进行了模拟治疗计划系统（TPS），并提供到一个圆柱形的坦克充满了水基液体闪烁体。发射成像使用蓝色敏感，加强CMOS相机时间选通到直线加速器脉冲。对于静态光束，将投影强度分布的百分比深度和交叉光束轮廓与TPS数据进行比较。对所有临床计划进行了二维（2D）伽马分析，并通过在VMAT计划控制点中引入故意错误来测试该技术对常见错误（多叶准直器位置、机架角度）的灵敏度。还测试了该技术的空间分辨率检测限和可以可靠成像的最小控制点数量。常见的交付错误的灵敏度进行了比较，对商业2.5D二极管阵列dosemeter.ResultsA空间分辨率为1毫米，实现了与我们的成像设置。相对于小静态方形光束（5、10和50 mm（2））的TPS数据，光学投影百分比深度强度分布在2%以内。对于投影的横梁轮廓，对于3%/1 mm标准，伽马通过率>99%。所有临床计划均通过3%/3 mm标准，通过率>95%。可以测量具有20个监视器单元的静态5 mm光束，相对于TPS的平均百分比差异为5.5 3%。该技术是敏感的多叶准直器误差下降到1毫米和机架角度误差为1 degrees.ConclusionsOptical成像提供了足够的空间分辨率成像小光束。能够忠实地成像低至20 MU的5 mm、6 MV子束，证明了能够在动态计划中为每个控制点执行质量保证。该技术对机架角度和多叶准直器（MLC）叶片位置的小偏移误差敏感，并且在某些情况下，它表现出比商业2.5D二极管阵列更高的灵敏度。
PurposeWe demonstrate the feasibility of optical imaging as a quality assurance tool for static small beamlets, and pretreatment verification tool for radiosurgery and volumetric-modulated arc therapy (VMAT) plans.MethodsSmall static beams and clinical VMAT plans were simulated in a treatment planning system (TPS) and delivered to a cylindrical tank filled with water-based liquid scintillator. Emission was imaged using a blue-sensitive, intensified CMOS camera time-gated to the linac pulses. For static beams, percentage depth and cross beam profiles of projected intensity distribution were compared to TPS data. Two-dimensional (2D) gamma analysis was performed on all clinical plans, and the technique was tested for sensitivity against common errors (multileaf collimator position, gantry angle) by inducing deliberate errors in the VMAT plans control points. The technique's detection limits for spatial resolution and the smallest number of control points that could be imaged reliably were also tested. The sensitivity to common delivery errors was also compared against a commercial 2.5D diode array dosimeter.ResultsA spatial resolution of 1 mm was achieved with our imaging setup. The optical projected percentage depth intensity profiles agreed to within 2% relative to the TPS data for small static square beams (5, 10, and 50 mm(2)). For projected cross beam profiles, a gamma pass rate >99% was achieved for a 3%/1 mm criteria. All clinical plans passed the 3%/3 mm criteria with >95% passing rate. A static 5 mm beam with 20 Monitor Units could be measured with an average percent difference of 5.5 3% relative to the TPS. The technique was sensitive to multileaf collimator errors down to 1 mm and gantry angle errors of 1 degrees.ConclusionsOptical imaging provides ample spatial resolution for imaging small beams. The ability to faithfully image down to 20 MU of 5 mm, 6 MV beamlets prove the ability to perform quality assurance for each control point within dynamic plans. The technique is sensitive to small offset errors in gantry angles and multileaf collimator (MLC) leaf positions, and at certain scenario, it exhibits higher sensitivity than a commercial 2.5D diode array.