Ghaseminezhad Seydeh Zahra, Sadremomtaz Alireza, Rajabi Hossein
Department of Physics, University of Guilan, Rasht, Iran.
Department of Medical Physics, School of Medical Sciences, Tarbiat Modares University, Tehran, Iran.
J Cancer Res Ther. 2018 Apr-Jun;14(3):647-650. doi: 10.4103/0973-1482.183191.
GATE/GEANT is a Monte Carlo code dedicated to nuclear medicine that allows calculation of the dose to organs (bone and bone marrow) of voxel phantoms. On the other hand, Medical Internal Radiation Dose (MIRD) is a well-developed system for estimation of the dose to human organs. In this study, results obtained from GATE/GEANT using leg of Snyder phantom is compared to published MIRD data.
For this, the mathematical leg of Snyder phantom was discretized and converted to a digital phantom of 100 × 100 × 200 voxels. The activity was considered uniformly distributed within bone and bone marrow. The GATE/GEANT Monte Carlo code was used to calculate the dose to the bone and bone marrow of the leg phantom from mono-energetic photons of 10, 15, 20, 30, 50, 100, 200, 500, and 1000 keV. The dose was converted into a specific absorbed fraction (SAF) and the results were compared to the corresponding published MIRD data.
On average, there was a good correlation between the two series of data for self-absorption (r = 0.99) and for cross-irradiation (r = 0.99). However, the GATE/GEANT data were on average 1.01 ± 0.79% higher than the corresponding MIRD data for self-absorption. As for cross-irradiation, the GATE/GEANT data were on average 8.11 ± 7.95% higher than the MIRD data.
In this study, the SAF values derived from GATE/GEANT and the corresponding MIRD published data were compared. On average, the SAF values derived with GATE/GEANT showed an acceptable correlation and agreement with the MIRD data for the photon energies of 50-1000 keV. For photons of 10-30 keV, there was an only poor agreement between the GATE/GEANT results and MIRD data.
GATE/GEANT是一款专门用于核医学的蒙特卡罗代码，可用于计算体素模型中各器官（骨骼和骨髓）的剂量。另一方面，医学内照射剂量（MIRD）是一个成熟的人体器官剂量估算系统。在本研究中，将使用斯奈德模型腿部得到的GATE/GEANT结果与已发表的MIRD数据进行比较。
为此，将斯奈德模型的数学腿部进行离散化处理，并转换为一个100×100×200体素的数字模型。假定放射性活度在骨骼和骨髓内均匀分布。使用GATE/GEANT蒙特卡罗代码计算腿部模型中骨骼和骨髓对能量分别为10、15、20、30、50、100、200、500和1000keV的单能光子的吸收剂量。将剂量转换为比吸收分数（SAF），并将结果与相应的已发表MIRD数据进行比较。
平均而言，两组关于自吸收的数据（r = 0.99）以及交叉照射的数据（r = 0.99）之间具有良好的相关性。然而，对于自吸收，GATE/GEANT数据平均比相应的MIRD数据高1.01±0.79%。对于交叉照射，GATE/GEANT数据平均比MIRD数据高8.11±7.95%。
在本研究中，对GATE/GEANT得出的SAF值与相应的已发表MIRD数据进行了比较。平均而言，对于50 - 1000keV的光子能量，GATE/GEANT得出的SAF值与MIRD数据显示出可接受的相关性和一致性。对于10 - 30keV的光子，GATE/GEANT结果与MIRD数据之间的一致性较差。
