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SPECT performance evaluation on image of Yttrium 90 - Bremsstrahlung using Monte Carlo simulation
Applied Radiation and Isotopes ( IF 1.6 ) Pub Date : 2020-12-10 , DOI: 10.1016/j.apradiso.2020.109456
Carlos O Pastrana Orejuela 1 , Francisco de Assis Coelho 2 , Susie Medeiros Oliveira 2 , Sergio A L Souza 2 , Lidia Vasconcellos de Sá 3 , Ademir Xavier da Silva 1 , Mirta B Torres Berdeguez 1
Affiliation  

Yttrium-90 (90Y) is one of the most widely used radionuclides in Nuclear Medicine practice. However, characteristic energy of this beta emitter constitutes a difficulty for dose planning using SPECT imaging. This work aimed to study bremsstrahlung X-rays effects produced by 90Y beta particles during SPECT image acquisition using Monte Carlo code MCNPX. Several simulations were carried out to evaluate different aspects that could affect SPECT image quality, such as: collimator type, source-collimator distance and composition of each interacting material. Two configurations of 90Y sources were simulated: a point source in several spheres of different materials (soft tissue, water, articular cartilage, and bone) and dimensions with radius ranging from 1 to 20 mm; and a uniformly distributed source in a Lucite cylindrical phantom filled with water. It was evaluated the bremsstrahlung photon emission generated inside different materials; for this was considered the number photons that passing through every different sphere's surface for each radii and material. In case of cylindrical phantom filled with water, in order to obtain the energy deposited over NaI (Tl) crystal detector; there was considered Median Energy General Purpose (MEGP) and Low Energy High Resolution (LEHR) collimators. Moreover, using TMESH routine available in the MCNPX Monte Carlo code, energy distribution images according to the collimator type and the source-collimator distance were obtained. The simulation was validated by comparing with the spectral distribution of the 90Y bremsstrahlung X-rays obtained experimentally from an acrylic cylindrical phantom. Results corroborated the importance of Monte Carlo simulation method to evaluate a performance of SPECT image acquisition with 90Y. The best resolution was obtained with MEGP collimator independent of source-collimator distance.



中文翻译:

使用蒙特卡罗模拟对 Yttrium 90 - Bremsstrahlung 图像进行 SPECT 性能评估

Yttrium-90 ( 90 Y) 是核医学实践中使用最广泛的放射性核素之一。然而,这种 β 发射器的特征能量构成了使用 SPECT 成像进行剂量规划的困难。这项工作旨在使用蒙特卡罗代码 MCNPX 研究 SPECT 图像采集过程中90 Y β 粒子产生的轫致辐射 X 射线效应。进行了多次模拟以评估可能影响 SPECT 图像质量的不同方面,例如:准直器类型、源-准直器距离和每种相互作用材料的成分。90的两种配置Y 源被模拟:在不同材料(软组织、水、关节软骨和骨骼)和半径范围从 1 到 20 毫米的尺寸的几个球体中的点源;和一个均匀分布的源在一个充满水的 Lucite 圆柱形幻影中。评估了不同材料内部产生的轫致辐射光子发射;因为这被认为是通过每个不同半径和材料的每个不同球体表面的光子数。在装满水的圆柱形体模的情况下,为了获得沉积在 NaI (Tl) 晶体探测器上的能量;考虑了中值能量通用 (MEGP) 和低能量高分辨率 (LEHR) 准直器。此外,使用 MCNPX Monte Carlo 代码中可用的 TMESH 例程,根据准直器类型和源准直器距离获得能量分布图像。通过与光谱分布的比较来验证模拟90 Y 轫致辐射 X 射线通过实验从丙烯酸圆柱体模获得。结果证实了蒙特卡罗模拟方法对评估 SPECT 图像采集性能的重要性,90 Y。使用 MEGP 准直器获得最佳分辨率,与源准直器距离无关。

更新日期:2020-12-14
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