Papadimitroulas Panagiotis, Loudos George, Nikiforidis George C, Kagadis George C
Department of Medical Physics, School of Medicine, University of Patras, Rion, GR 265 04, Greece.
Med Phys. 2012 Aug;39(8):5238-47. doi: 10.1118/1.4737096.
GATE is a Monte Carlo simulation toolkit based on the Geant4 package, widely used for many medical physics applications, including SPECT and PET image simulation and more recently CT image simulation and patient dosimetry. The purpose of the current study was to calculate dose point kernels (DPKs) using GATE, compare them against reference data, and finally produce a complete dataset of the total DPKs for the most commonly used radionuclides in nuclear medicine.
Patient-specific absorbed dose calculations can be carried out using Monte Carlo simulations. The latest version of GATE extends its applications to Radiotherapy and Dosimetry. Comparison of the proposed method for the generation of DPKs was performed for (a) monoenergetic electron sources, with energies ranging from 10 keV to 10 MeV, (b) beta emitting isotopes, e.g., (177)Lu, (90)Y, and (32)P, and (c) gamma emitting isotopes, e.g., (111)In, (131)I, (125)I, and (99m)Tc. Point isotropic sources were simulated at the center of a sphere phantom, and the absorbed dose was stored in concentric spherical shells around the source. Evaluation was performed with already published studies for different Monte Carlo codes namely MCNP, EGS, FLUKA, ETRAN, GEPTS, and PENELOPE. A complete dataset of total DPKs was generated for water (equivalent to soft tissue), bone, and lung. This dataset takes into account all the major components of radiation interactions for the selected isotopes, including the absorbed dose from emitted electrons, photons, and all secondary particles generated from the electromagnetic interactions.
GATE comparison provided reliable results in all cases (monoenergetic electrons, beta emitting isotopes, and photon emitting isotopes). The observed differences between GATE and other codes are less than 10% and comparable to the discrepancies observed among other packages. The produced DPKs are in very good agreement with the already published data, which allowed us to produce a unique DPKs dataset using GATE. The dataset contains the total DPKs for (67)Ga, (68)Ga, (90)Y, (99m)Tc, (111)In, (123)I, (124)I, (125)I, (131)I, (153)Sm, (177)Lu (186)Re, and (188)Re generated in water, bone, and lung.
In this study, the authors have checked GATE's reliability for absorbed dose calculation when transporting different kind of particles, which indicates its robustness for dosimetry applications. A novel dataset of DPKs is provided, which can be applied in patient-specific dosimetry using analytical point kernel convolution algorithms.
GATE是一个基于Geant4软件包的蒙特卡罗模拟工具包，广泛应用于许多医学物理领域，包括单光子发射计算机断层扫描（SPECT）和正电子发射断层扫描（PET）图像模拟，以及最近的计算机断层扫描（CT）图像模拟和患者剂量测定。本研究的目的是使用GATE计算剂量点核（DPK），将其与参考数据进行比较，并最终生成核医学中最常用放射性核素的总DPK完整数据集。
可以使用蒙特卡罗模拟进行患者特异性吸收剂量计算。GATE的最新版本将其应用扩展到放射治疗和剂量测定。对生成DPK的提议方法进行了比较，对象包括：（a）能量范围为10千电子伏至10兆电子伏的单能电子源；（b）发射β粒子的同位素，例如镥-177（¹⁷⁷Lu）、钇-90（⁹⁰Y）和磷-32（³²P）；（c）发射γ光子的同位素，例如铟-111（¹¹¹In）、碘-131（¹³¹I）、碘-125（¹²⁵I）和锝-99m（⁹⁹ᵐTc）。在球形体模中心模拟各向同性点源，并将吸收剂量存储在源周围的同心球壳中。使用已发表的针对不同蒙特卡罗代码（即MCNP、EGS、FLUKA、ETRAN、GEPTS和PENELOPE）的研究进行评估。生成了水（相当于软组织）、骨骼和肺部的总DPK完整数据集。该数据集考虑了所选同位素辐射相互作用的所有主要成分，包括发射电子、光子以及电磁相互作用产生的所有次级粒子的吸收剂量。
在所有情况下（单能电子、发射β粒子的同位素和发射光子的同位素），GATE比较都提供了可靠的结果。GATE与其他代码之间观察到的差异小于10%，与其他软件包之间观察到的差异相当。生成的DPK与已发表的数据非常吻合，这使我们能够使用GATE生成独特的DPK数据集。该数据集包含镓-67（⁶⁷Ga）、镓-68（⁶⁸Ga）、钇-90（⁹⁰Y）、锝-99m（⁹⁹ᵐTc）、铟-111（¹¹¹In）、碘-123（¹²³I）、碘-124（¹²⁴I）、碘-125（¹²⁵I）、碘-131（¹³¹I）、钐-153（¹⁵³Sm）、镥-177（¹⁷⁷Lu）、铼-186（¹⁸⁶Re）和铼-188（¹⁸⁸Re）在水、骨骼和肺部生成的总DPK。
在本研究中，作者检查了GATE在传输不同类型粒子时进行吸收剂量计算的可靠性，这表明其在剂量测定应用中的稳健性。提供了一个新颖的DPK数据集，可使用解析点核卷积算法应用于患者特异性剂量测定。
