Phys Med Biol. 2013 Nov 21;58(22):8099-120. doi: 10.1088/0031-9155/58/22/8099.
Patient-specific absorbed dose calculation for nuclear medicine therapy is a topic of increasing interest. 3D dosimetry at the voxel level is one of the major improvements for the development of more accurate calculation techniques, as compared to the standard dosimetry at the organ level. This study aims to use the FLUKA Monte Carlo code to perform patient-specific 3D dosimetry through direct Monte Carlo simulation on PET-CT and SPECT-CT images. To this aim, dedicated routines were developed in the FLUKA environment. Two sets of simulations were performed on model and phantom images. Firstly, the correct handling of PET and SPECT images was tested under the assumption of homogeneous water medium by comparing FLUKA results with those obtained with the voxel kernel convolution method and with other Monte Carlo-based tools developed to the same purpose (the EGS-based 3D-RD software and the MCNP5-based MCID). Afterwards, the correct integration of the PET/SPECT and CT information was tested, performing direct simulations on PET/CT images for both homogeneous (water) and non-homogeneous (water with air, lung and bone inserts) phantoms. Comparison was performed with the other Monte Carlo tools performing direct simulation as well. The absorbed dose maps were compared at the voxel level. In the case of homogeneous water, by simulating 10(8) primary particles a 2% average difference with respect to the kernel convolution method was achieved; such difference was lower than the statistical uncertainty affecting the FLUKA results. The agreement with the other tools was within 3–4%, partially ascribable to the differences among the simulation algorithms. Including the CT-based density map, the average difference was always within 4% irrespective of the medium (water, air, bone), except for a maximum 6% value when comparing FLUKA and 3D-RD in air. The results confirmed that the routines were properly developed, opening the way for the use of FLUKA for patient-specific, image-based dosimetry in nuclear medicine.
用于核医学治疗的患者特异性吸收剂量计算是一个日益受到关注的话题。与器官水平的标准剂量相比，体素水平的 3D 剂量学是开发更准确计算技术的主要改进之一。本研究旨在使用 FLUKA 蒙特卡罗代码通过对 PET-CT 和 SPECT-CT 图像进行直接蒙特卡罗模拟来进行患者特异性 3D 剂量学。为此，在 FLUKA 环境中开发了专用例程。在假设均匀水介质的情况下，对模型和体模图像进行了两组模拟。首先，通过将 FLUKA 结果与基于体素内核卷积方法以及为同一目的开发的其他基于蒙特卡罗的工具（基于 EGS 的 3D-RD 软件和基于 MCNP5 的 MCID）获得的结果进行比较，测试了 PET 和 SPECT 图像的正确处理。然后，通过对同质（水）和非同质（带空气、肺和骨插件的水）体模进行直接模拟，测试了 PET/SPECT 和 CT 信息的正确集成。与其他直接进行模拟的蒙特卡罗工具进行了比较。在体素水平上比较了吸收剂量图。在同质水的情况下，通过模拟 10(8)个初级粒子，与内核卷积方法相比，平均差异为 2%；这种差异低于影响 FLUKA 结果的统计不确定性。与其他工具的一致性在 3-4%以内，部分归因于模拟算法之间的差异。包括基于 CT 的密度图，无论介质（水、空气、骨）如何，平均差异始终在 4%以内，除了在比较空气时 FLUKA 和 3D-RD 最大差异为 6%。结果证实例程已正确开发，为在核医学中使用 FLUKA 进行基于患者的基于图像的剂量学开辟了道路。
