Department of Radiation Oncology, The University of Alabama at Birmingham, Birmingham, Alabama, USA.
J Appl Clin Med Phys. 2021 Dec;22(12):203-210. doi: 10.1002/acm2.13438. Epub 2021 Nov 1.
To evaluate a two-dimensional diode array for patient-specific quality assurance of VMAT stereotactic radiosurgery (SRS) plans.
The diode array, an SRS MapCHECK (SRSMC), was composed of a 77 mm ×77 mm face-centered array having a spacing of 2.47 mm. Sixty SRS plans were selected from our clinical database, 30 for treatment of a single target and 30 for multiple targets. The target sizes ranged from 2.4 mm to 44.7 mm equivalent diameter (median 8.7 mm). The plans were delivered to the diode array. For multiple target plans, two measurements were obtained at two locations, one corresponding to the largest target and the other to the smallest target. Gamma using a 3%/1 mm criteria and the dose to the center diode were compared with radiochromic film (RCF). Dose to selected regions of the detector electronics was calculated.
The mean difference between the center diode and RCF was -1.2%. For a threshold of at least 95% of detectors/pixels having gamma < 1 for a 3%/1 mm criteria, SRSMC and RCF gave consistent results for 79 of the 90 measurements. For plans with an arc having a patient support angle of 90° or 270°, the median dose to the electronics was 0.65% of the prescription dose.
SRSMC is an efficient tool for accurate patient-specific quality assurance of VMAT single and multiple target radiosurgery, yielding similar clinical decisions as radiochromic film.
评估二维二极管阵列在 VMAT 立体定向放射外科（SRS）计划的患者特异性质量保证中的应用。
二极管阵列，即 SRS MapCHECK（SRSMC），由一个 77mm×77mm 的面心阵列组成，间距为 2.47mm。从我们的临床数据库中选择了 60 个 SRS 计划，其中 30 个用于治疗单个靶区，30 个用于多个靶区。靶区大小从 2.4mm 到 44.7mm 等效直径（中位数 8.7mm）不等。这些计划被传送到二极管阵列。对于多靶区计划，在两个位置进行了两次测量，一个对应于最大靶区，另一个对应于最小靶区。使用 3%/1mm 标准比较了伽马值和中心二极管的剂量与放射色膜（RCF）。计算了探测器电子元件选定区域的剂量。
中心二极管与 RCF 的平均差值为-1.2%。对于至少 95%的探测器/像素的阈值，当伽马值<1 时，3%/1mm 标准，SRSMC 和 RCF 在 90 次测量中的 79 次给出了一致的结果。对于具有 90°或 270°患者支撑角度的弧形计划，电子元件的中位剂量为处方剂量的 0.65%。
SRSMC 是一种用于 VMAT 单靶和多靶放射外科患者特异性质量保证的高效工具，与放射色膜相比，它能得出相似的临床决策。
