Xiong Zhenyu, Vijayan Sarath, Rana Vijay, Jain Amit, Rudin Stephen, Bednarek Daniel R
Toshiba Stroke and Vascular Research Center, University at Buffalo, Buffalo, New York.
Proc SPIE Int Soc Opt Eng. 2016 Feb 27;9783. doi: 10.1117/12.2216504. Epub 2016 Mar 22.
The aim of this work is to develop a method to calculate lens dose for fluoroscopically-guided neuro-interventional procedures and for CBCT scans of the head. EGSnrc Monte Carlo software is used to determine the dose to the lens of the eye for the projection geometry and exposure parameters used in these procedures. This information is provided by a digital CAN bus on the Toshiba Infinix C-Arm system which is saved in a log file by the real-time skin-dose tracking system (DTS) we previously developed. The x-ray beam spectra on this machine were simulated using BEAMnrc. These spectra were compared to those determined by SpekCalc and validated through measured percent-depth-dose (PDD) curves and half-value-layer (HVL) measurements. We simulated CBCT procedures in DOSXYZnrc for a CTDI head phantom and compared the surface dose distribution with that measured with Gafchromic film, and also for an SK150 head phantom and compared the lens dose with that measured with an ionization chamber. Both methods demonstrated good agreement. Organ dose calculated for a simulated neuro-interventional-procedure using DOSXYZnrc with the Zubal CT voxel phantom agreed within 10% with that calculated by PCXMC code for most organs. To calculate the lens dose in a neuro-interventional procedure, we developed a library of normalized lens dose values for different projection angles and kVp's. The total lens dose is then calculated by summing the values over all beam projections and can be included on the DTS report at the end of the procedure.
这项工作的目的是开发一种方法，用于计算荧光透视引导下神经介入手术以及头部CBCT扫描时晶状体的剂量。使用EGSnrc蒙特卡罗软件，根据这些手术中使用的投影几何形状和曝光参数，确定眼睛晶状体的剂量。此信息由东芝Infinix C型臂系统上的数字CAN总线提供，并由我们之前开发的实时皮肤剂量跟踪系统（DTS）保存在日志文件中。使用BEAMnrc模拟了该机器上的X射线束光谱。将这些光谱与SpekCalc确定的光谱进行比较，并通过测量的百分深度剂量（PDD）曲线和半值层（HVL）测量进行验证。我们在DOSXYZnrc中针对CTDI头部体模模拟了CBCT程序，并将表面剂量分布与用Gafchromic胶片测量的结果进行比较，还针对SK150头部体模模拟了CBCT程序，并将晶状体剂量与用电离室测量的结果进行比较。两种方法都显示出良好的一致性。使用带有Zubal CT体素模型的DOSXYZnrc为模拟神经介入手术计算的器官剂量，与使用PCXMC代码为大多数器官计算的剂量相差在10%以内。为了计算神经介入手术中的晶状体剂量值，我们针对不同的投影角度和千伏峰值开发了一个归一化晶状体剂量值库。然后，通过对所有射束投影的值求和来计算晶状体的总剂量，并且该剂量可以包含在手术结束时的DTS报告中。
