Genesis Care, Perth, Australia.
J Appl Clin Med Phys. 2023 Apr;24(4):e13934. doi: 10.1002/acm2.13934. Epub 2023 Mar 1.
The collimator radiation isocenter position determined in AQUA v3.0 [Elekta AB, Stockholm, Sweden] software test "MLC Leaf and Jaw Position" was independently validated using an in-house MATLAB [Natick, MA: The MathWorks Inc.] script.
The AQUA test determines radiation isocenter using the mean field center of nine 4 cm × 4 cm electronic portal imager (EPID) exposures at equidistant collimator angles. Impact of EPID image quality on AQUA reported isocenter for thirteen Elekta linear accelerators with Agility MLC heads were evaluated.
Of the thirteen, three had visually and quantitatively identifiable artifacts. For the ten good EPID's there was a systematic 0.25 mm offset of the MATLAB calculated mean field center relative to AQUA in the X-axis and Y-axis. This corresponds to one image pixel and was found to be due to differences in software co-ordinate convention. After subtracting this offset there was no significant difference in AQUA and MATLAB calculated isocenter.
For the three machines with poor image quality there was a demonstrated variation in AQUA calculated field center and therefore radiation isocenter relative to MATLAB. Restricting the region of interest (ROI) in AQUA software to only the irradiated section of the EPID brought AQUA and MATLAB result for these three machines into agreement.
在 Elekta AB（瑞典斯德哥尔摩）的 AQUA v3.0 软件测试“MLC 叶片和颌位置”中，通过独立验证使用内部 MATLAB（马萨诸塞州纳提克：The MathWorks Inc.）脚本确定准直器辐射等中心位置。
AQUA 测试使用九个 4 cm×4 cm 电子射野影像系统（EPID）在等距准直器角度的九次曝光的平均场中心来确定辐射等中心。评估了 EPID 图像质量对 Elekta 具有 Agility MLC 头的 13 台直线加速器的 AQUA 报告等中心的影响。
在这 13 台机器中，有 3 台存在视觉上和定量上可识别的伪影。对于 10 个良好的 EPID，MATLAB 计算的平均场中心相对于 AQUA 在 X 轴和 Y 轴上存在 0.25mm 的系统偏移。这相当于一个图像像素，是由于软件坐标约定的差异造成的。减去这个偏移量后，AQUA 和 MATLAB 计算的等中心没有显著差异。
对于图像质量较差的 3 台机器，AQUA 计算的场中心以及因此辐射等中心与 MATLAB 相比存在明显差异。在 AQUA 软件中将感兴趣区域（ROI）限制在 EPID 的照射部分，使这 3 台机器的 AQUA 和 MATLAB 结果达成一致。
