Pshenichnov Igor, Mishustin Igor, Greiner Walter
Frankfurt Institute for Advanced Studies, Johann Wolfgang Goethe University, 60438 Frankfurt am Main, Germany.
Phys Med Biol. 2006 Dec 7;51(23):6099-112. doi: 10.1088/0031-9155/51/23/011. Epub 2006 Nov 8.
Depth distributions of positron-emitting nuclei in PMMA phantoms are calculated within a Monte Carlo model for heavy-ion therapy (MCHIT) based on the GEANT4 toolkit (version 8.0). The calculated total production rates of (11)C, (10)C and (15)O nuclei are compared with experimental data and with corresponding results of the FLUKA and POSGEN codes. The distributions of e(+) annihilation points are obtained by simulating radioactive decay of unstable nuclei and transporting positrons in the surrounding medium. A finite spatial resolution of the positron emission tomography (PET) is taken into account in a simplified way. Depth distributions of beta(+)-activity as seen by a PET scanner are calculated and compared to available data for PMMA phantoms. The obtained beta(+)-activity profiles are in good agreement with PET data for proton and (12)C beams at energies suitable for particle therapy. The MCHIT capability to predict the beta(+)-activity and dose distributions in tissue-like materials of different chemical composition is demonstrated.
基于GEANT4工具包（版本8.0）的重离子治疗蒙特卡罗模型（MCHIT）计算了聚甲基丙烯酸甲酯（PMMA）体模中发射正电子核的深度分布。将计算得到的碳-11（¹¹C）、碳-10（¹⁰C）和氧-15（¹⁵O）核的总产率与实验数据以及FLUKA和POSGEN代码的相应结果进行了比较。通过模拟不稳定核的放射性衰变并在周围介质中传输正电子，获得了正电子湮灭点的分布。以简化方式考虑了正电子发射断层扫描（PET）的有限空间分辨率。计算了PET扫描仪所看到的β⁺活度的深度分布，并与PMMA体模的现有数据进行了比较。在适合粒子治疗的能量下，所获得的β⁺活度剖面与质子束和碳-12（¹²C）束的PET数据吻合良好。展示了MCHIT预测不同化学成分的类组织材料中β⁺活度和剂量分布的能力。
