Marshall Emily L, Borrego David, Fudge James C, Rajderkar Dhanashree, Bolch Wesley E
J. Crayton Pruitt Family, Department of Biomedical Engineering, University of Florida, Gainesville, FL, USA.
Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA.
Med Phys. 2018 Jun 13. doi: 10.1002/mp.13044.
To assess various computational phantom alignment techniques within Monte Carlo radiation transport models of pediatric fluoroscopically guided cardiac interventional studies.
Logfiles, including all procedure radiation and machine data, were extracted from a Toshiba infinix-I unit in the University of Florida Pediatric Catheterization Laboratory for a cohort of 10 patients. Two different alignment methods were then tested against a ground truth standard based upon identification of a unique anatomic reference point within images co-registered to specific irradiation events within each procedure. The first alignment method required measurement of the distance from the edge of the exam table to the top of the patient's head (table alignment method). The second alignment method fixed the anatomic reference point to be the geometric center of the heart muscle, as all 10 studies were cardiac in nature. Monte Carlo radiation transport simulations were performed for each patient and intervention using morphometry-matched hybrid computational phantoms for the reference and two tested alignment methods. For each combination, absorbed doses were computed for 28 organs and root mean square organ doses were assessed and compared across the alignment methods.
The percent error in root mean square organ dose ranged from -57% to +41% for the table alignment method, and from -27% to +22% for the heart geometric centroid alignment method. Absorbed doses to specific organs, such as the heart and lungs, demonstrated higher accuracy in the heart geometric centroid alignment method, with average percent errors of 10% and 1.4%, respectively, compared to average percent errors of -32% and 24%, respectively, using the table alignment method.
Of the two phantom alignment methods investigated in this study, the use of an anatomical reference point - in this case the geometric centroid of the heart - provided a reliable method for radiation transport simulations of organ dose in pediatric interventional cardiac studies. This alignment method provides the added benefit of requiring no physician input, making retrospective calculations possible. Moving forward, additional anatomical reference methods can be tested to assess the reliability of anatomical reference points beyond cardiac centered procedures.
在儿科荧光镜引导下心脏介入研究的蒙特卡罗辐射传输模型中评估各种计算体模对准技术。
从佛罗里达大学儿科导管实验室的一台东芝Infinix - I设备中提取了包括所有程序辐射和机器数据的日志文件，涉及10名患者。然后，基于在与每个程序中的特定照射事件配准的图像中识别出一个独特的解剖参考点，针对一个地面真值标准测试了两种不同的对准方法。第一种对准方法需要测量检查台边缘到患者头顶的距离（台面对准方法）。第二种对准方法将解剖参考点固定为心肌的几何中心，因为所有10项研究本质上都是心脏相关的。对于每位患者和干预操作，使用形态测量匹配的混合计算体模针对参考方法以及两种测试的对准方法进行了蒙特卡罗辐射传输模拟。对于每种组合，计算了28个器官的吸收剂量，并评估了均方根器官剂量，并在不同对准方法之间进行了比较。
台面对准方法的均方根器官剂量百分比误差范围为 - 57%至 + 41%，心脏几何质心对准方法的百分比误差范围为 - 27%至 + 22%。心脏和肺部等特定器官的吸收剂量在心脏几何质心对准方法中显示出更高的准确性，平均百分比误差分别为10%和1.4%，而使用台面对准方法时平均百分比误差分别为 - 32%和24%。
在本研究中研究的两种体模对准方法中，使用解剖参考点——在这种情况下是心脏的几何质心——为儿科介入心脏研究中器官剂量的辐射传输模拟提供了一种可靠的方法。这种对准方法的额外好处是不需要医生输入，使得回顾性计算成为可能。展望未来，可以测试其他解剖参考方法，以评估除心脏中心程序之外的解剖参考点的可靠性。
