Asmi Hicham, Bentayeb Farida, Bouzekraoui Youssef, Bonutti Faustino
Department of Physics, LPHE, Modeling and Simulations, Faculty of Science, Mohammed V University, Rabat, Morocco.
Department of Medical Physics, Academic Hospital of Udine, Udine, Italy.
Indian J Nucl Med. 2019 Jan-Mar;34(1):24-26. doi: 10.4103/ijnm.IJNM_109_18.
In iodine-131 (I-131) imaging, the image quality is degraded by scatter and penetration in a collimator. In this work, we assessed the penetrated and the scattered photon fractions in the photopeak energy window using Monte Carlo Simulation code.
The Siemens Medical System equipped with high-energy collimator was simulated. We evaluated the acceptance angle values on geometric, penetration, and scatter components in a separate file. Binary images in a data file are obtained and each one of them was imported in software ImageJ. Full-width at half-maximum (FWHM) and sensitivity were calculated and compared.
The simulation data show that for the acceptance angle value equal to 4.845°, the geometric, scatter, and penetration components were 93.20%, 4.13%, and 2.67%, respectively. Moreover, the resolution is improved (FWHM = 7.21 mm, full width at tenth maximum = 12.36 mm) for a point source at 12 cm from the detector.
The small acceptance angle has a major impact on the image quality in I-131 single photon emission computed tomography.
在碘 - 131（I - 131）成像中，准直器中的散射和穿透会降低图像质量。在本研究中，我们使用蒙特卡罗模拟代码评估了光电峰能量窗口中的穿透光子分数和散射光子分数。
对配备高能准直器的西门子医疗系统进行了模拟。我们在一个单独的文件中评估了几何、穿透和散射分量的接受角值。获取数据文件中的二进制图像，并将它们逐一导入ImageJ软件。计算并比较了半高宽（FWHM）和灵敏度。
模拟数据表明，对于等于4.845°的接受角值，几何、散射和穿透分量分别为93.20%、4.13%和2.67%。此外，对于距探测器12 cm处的点源，分辨率得到了提高（半高宽 = 7.21 mm，十分之一最大宽度处全宽 = 12.36 mm）。
小接受角对I - 131单光子发射计算机断层扫描的图像质量有重大影响。
