ACRF Image X Institute, The University of Sydney, Sydney, New South Wales, Australia.
Danish Center for Particle Therapy and Department of Oncology, Aarhus University Hospital, Aarhus, Denmark.
Med Phys. 2022 Feb;49(2):1161-1180. doi: 10.1002/mp.15418. Epub 2021 Dec 29.
Lung stereotactic ablative body radiotherapy (SABR) is a radiation therapy success story with level 1 evidence demonstrating its efficacy. To provide real-time respiratory motion management for lung SABR, several commercial and preclinical markerless lung target tracking (MLTT) approaches have been developed. However, these approaches have yet to be benchmarked using a common measurement methodology. This knowledge gap motivated the MArkerless lung target Tracking CHallenge (MATCH). The aim was to localize lung targets accurately and precisely in a retrospective in silico study and a prospective experimental study.
MATCH was an American Association of Physicists in Medicine sponsored Grand Challenge. Common materials for the in silico and experimental studies were the experiment setup including an anthropomorphic thorax phantom with two targets within the lungs, and a lung SABR planning protocol. The phantom was moved rigidly with patient-measured lung target motion traces, which also acted as ground truth motion. In the retrospective in silico study a volumetric modulated arc therapy treatment was simulated and a dataset consisting of treatment planning data and intra-treatment kilovoltage (kV) and megavoltage (MV) images for four blinded lung motion traces was provided to the participants. The participants used their MLTT approach to localize the moving target based on the dataset. In the experimental study, the participants received the phantom experiment setup and five patient-measured lung motion traces. The participants used their MLTT approach to localize the moving target during an experimental SABR phantom treatment. The challenge was open to any participant, and participants could complete either one or both parts of the challenge. For both the in silico and experimental studies the MLTT results were analyzed and ranked using the prospectively defined metric of the percentage of the tracked target position being within 2 mm of the ground truth.
A total of 30 institutions registered and 15 result submissions were received, four for the in silico study and 11 for the experimental study. The participating MLTT approaches were: Accuray CyberKnife (2), Accuray Radixact (2), BrainLab Vero, C-RAD, and preclinical MLTT (5) on a conventional linear accelerator (Varian TrueBeam). For the in silico study the percentage of the 3D tracking error within 2 mm ranged from 50% to 92%. For the experimental study, the percentage of the 3D tracking error within 2 mm ranged from 39% to 96%.
A common methodology for measuring the accuracy of MLTT approaches has been developed and used to benchmark preclinical and commercial approaches retrospectively and prospectively. Several MLTT approaches were able to track the target with sub-millimeter accuracy and precision. The study outcome paves the way for broader clinical implementation of MLTT. MATCH is live, with datasets and analysis software being available online at https://www.aapm.org/GrandChallenge/MATCH/ to support future research.
立体定向消融体放射治疗（SABR）是放射治疗的一个成功案例，具有 1 级证据证明其疗效。为了对肺部 SABR 进行实时呼吸运动管理，已经开发了几种商业和临床前无标记肺部目标跟踪（MLTT）方法。然而，这些方法尚未使用共同的测量方法进行基准测试。这一知识差距促使开展了 MArkerless lung target Tracking CHallenge（MATCH）。目的是在回顾性的模拟研究和前瞻性的实验研究中准确、精确地定位肺部目标。
MATCH 是美国医学物理学家协会赞助的一项大型挑战赛。模拟研究和实验研究的共同材料包括实验设置，包括一个带有两个肺部目标的拟人化胸部体模，以及一个肺部 SABR 计划方案。体模随患者测量的肺部目标运动轨迹刚性移动，这些轨迹也作为地面真实运动。在回顾性的模拟研究中，模拟了容积调强弧形治疗，并向参与者提供了一个包含治疗计划数据以及治疗过程中千伏（kV）和兆伏（MV）图像的数据集，这些数据用于四个盲目的肺部运动轨迹。参与者使用他们的 MLTT 方法根据数据集定位移动的目标。在实验研究中，参与者收到了体模实验设置和五个患者测量的肺部运动轨迹。参与者在实验 SABR 体模治疗过程中使用他们的 MLTT 方法定位移动的目标。挑战赛向任何参与者开放，参与者可以完成挑战赛的一个或两个部分。对于模拟研究和实验研究，使用前瞻性定义的跟踪目标位置在 2mm 内的百分比的度量标准对 MLTT 结果进行分析和排名。
共有 30 个机构注册，收到了 15 份参赛结果，其中 4 份来自模拟研究，11 份来自实验研究。参赛的 MLTT 方法有：Accuray CyberKnife（2）、Accuray Radixact（2）、BrainLab Vero、C-RAD 和临床前 MLTT（5），使用的是常规线性加速器（Varian TrueBeam）。对于模拟研究，3D 跟踪误差在 2mm 内的百分比范围为 50%至 92%。对于实验研究，3D 跟踪误差在 2mm 内的百分比范围为 39%至 96%。
已经开发了一种用于测量 MLTT 方法准确性的通用方法，并使用该方法对临床前和商业方法进行了回顾性和前瞻性的基准测试。几种 MLTT 方法能够以亚毫米的精度跟踪目标。该研究结果为更广泛地将 MLTT 应用于临床铺平了道路。MATCH 正在进行中，数据集和分析软件可在 https://www.aapm.org/GrandChallenge/MATCH/ 在线获取，以支持未来的研究。
