Zibandeh-Gorji Mahmoud, Mowlavi Ali Asghar, Mohammadi Saeed
Physics Department of Payamnor University of Tehran, Tehran, Iran.
Physics Department of Sabsevar Tarbiat Moallem University, Sabzevar, Iran ; TRIL, ICTP, Trieste, Italy.
Rep Pract Oncol Radiother. 2012 Feb 9;17(2):110-4. doi: 10.1016/j.rpor.2012.01.003. eCollection 2012.
The purpose of this study is to calculate radiation dose around a brachytherapy source in a water phantom for different seed locations or rotation the sources by the matrix summation method.
Monte Carlo based codes like MCNP are widely used for performing radiation transport calculations and dose evaluation in brachytherapy. But for complicated situations, like using more than one source, moving or rotating the source, the routine Monte Carlo method for dose calculation needs a long time running.
The MCNPX code has been used to calculate radiation dose around a (192)Ir brachytherapy source and saved in a 3D matrix. Then, we used this matrix to evaluate the absorbed dose in any point due to some sources or a source which shifted or rotated in some places by the matrix summation method.
Three dimensional (3D) dose results and isodose curves were presented for (192)Ir source in a water cube phantom shifted for 10 steps and rotated for 45 and 90° based on the matrix summation method. Also, we applied this method for some arrays of sources.
The matrix summation method can be used for 3D dose calculations for any brachytherapy source which has moved or rotated. This simple method is very fast compared to routine Monte Carlo based methods. In addition, it can be applied for dose optimization study.
本研究的目的是通过矩阵求和法计算水模体中近距离放射治疗源周围不同籽源位置或源旋转时的辐射剂量。
基于蒙特卡罗的代码如MCNP被广泛用于近距离放射治疗中的辐射传输计算和剂量评估。但对于复杂情况，如使用多个源、移动或旋转源，常规的蒙特卡罗剂量计算方法需要很长的运行时间。
使用MCNPX代码计算（192）铱近距离放射治疗源周围的辐射剂量，并保存到一个三维矩阵中。然后，我们使用该矩阵通过矩阵求和法评估由于某些源或在某些位置移动或旋转的源在任意点的吸收剂量。
基于矩阵求和法，给出了（192）铱源在水立方模体中移动10步、旋转45°和90°时的三维剂量结果和等剂量曲线。此外，我们将该方法应用于一些源阵列。
矩阵求和法可用于任何移动或旋转的近距离放射治疗源的三维剂量计算。与常规的基于蒙特卡罗的方法相比，这种简单方法非常快速。此外，它可应用于剂量优化研究。
