Instituto de Radioproteção e Dosimetria, Avenida Salvador Allende, 9, 22780-160, Rio de Janeiro, RJ, Brazil.
Dep. de Anatomia e Imagem/Faculdade de Medicina, Universidade Federal de Minas Gerais, 30130-100, Belo Horizonte, MG, Brazil.
Med Phys. 2018 Nov;45(11):5283-5292. doi: 10.1002/mp.13181. Epub 2018 Oct 23.
The main goal of this study was to determine the dose rate constant of radionuclides used in Nuclear Medicine when they are biodistributed in humans. The secondary goal was to calculate the effective half-life for the same radionuclides in order to determine the realistic dose due to the incorporation of these nuclides for a variety of reasons.
Anthropomorphic voxel phantoms, with characteristics based on ICRP-110 were considered and the biodistributions of radionuclides were simulated using the Monte Carlo code MCNPX. In addition, the effective half-lives for all simulated radionuclides were calculated.
The results for the dose rate constant, taking into account the patient body attenuation, showed no correlation between the biodistribution of the radionuclide and the energy of the radiation emitted. Body attenuation ranged between 6.7% and 94.1%. Also, the priority angle of radiation emission was determined. The values found for the body attenuation agree with the literature, corroborating the calculation of the body dose rate constant.
The results for the body dose rate constant calculated in this work, for 30 radionuclides and 57 radiopharmaceuticals, and their effective half-lives, may be used to estimate the dose emitted by a person who has incorporated a radionuclide in the Nuclear Medicine activity range. This dose will be optimized when the body dose rate constant and the effective half-life determined in this study are used together with dose reduction factors.
本研究的主要目的是确定在核医学中当放射性核素在人体中进行生物分布时的剂量率常数。次要目标是计算相同放射性核素的有效半衰期，以确定由于各种原因掺入这些核素的实际剂量。
采用基于 ICRP-110 的人体模型体素模型，使用蒙特卡罗代码 MCNPX 模拟放射性核素的生物分布。此外，还计算了所有模拟放射性核素的有效半衰期。
考虑到患者身体衰减的剂量率常数结果表明，放射性核素的生物分布与辐射发射的能量之间没有相关性。身体衰减范围在 6.7%至 94.1%之间。此外，还确定了辐射发射的优先角。发现的身体衰减值与文献相符，证实了体剂量率常数的计算。
本工作为 30 种放射性核素和 57 种放射性药物计算的体剂量率常数及其有效半衰期的结果，可用于估计在核医学活动范围内摄入放射性核素的人的剂量。当使用本研究中确定的体剂量率常数和有效半衰期以及剂量减少因子时，该剂量将得到优化。
