Daisaki Hiromitsu, Kubota Chihiro, Ishikawa Kazuma, Sato Mitsuru, Yasumoto Yoshiaki, Fukai Shohei, Sakashita Tetsuya
Department of Radiological Technology, Gunma Prefectural College of Health Sciences.
Department of Radiology, Saitama City Hospital.
Nihon Hoshasen Gijutsu Gakkai Zasshi. 2024 Jun 20;80(6):593-604. doi: 10.6009/jjrt.2024-1451. Epub 2024 Apr 4.
To predict side effects and optimize injection doses in the dosimetry of Lu imaging, highly accurate quantitative SPECT images are required. Monte Carlo simulations were performed to verify the accuracy and variability of quantitative values for Lu imaging under various imaging conditions.
SPECT data of NEMA body phantom were assumed to simulate intrahepatic tumors 6 h after administration of 7.4 GBq of Lu-Dotatate. SPECT data were acquired using the SIMIND program with different combinations of collimators and energy windows. For variability evaluation, 30 SPECT images with Poisson noise were generated for each acquisition time. The relative error was evaluated for accuracy evaluation, and the coefficient of variation was estimated for variability evaluation.
The accuracy of BG quantification was less than 10% relative error. The accuracy of hot sphere quantification was highest with the combination of MEGP and an energy window of 208 keV±10%. However, the accuracy of hot sphere quantification decreased significantly with decreasing hot sphere diameter. Variability varied with imaging conditions and improved with longer acquisition time.
Monte Carlo simulations revealed the accuracy and variability of quantitative values for each SPECT imaging condition for Lu imaging.
在镥成像剂量测定中预测副作用并优化注射剂量，需要高精度的定量单光子发射计算机断层扫描（SPECT）图像。进行了蒙特卡罗模拟，以验证在各种成像条件下镥成像定量值的准确性和变异性。
假定使用NEMA体模的SPECT数据来模拟在注射7.4GBq的镥-奥曲肽6小时后的肝内肿瘤。使用SIMIND程序，通过准直器和能量窗的不同组合采集SPECT数据。为了评估变异性，在每个采集时间生成30幅带有泊松噪声的SPECT图像。为进行准确性评估，评估相对误差；为进行变异性评估，估计变异系数。
本底（BG）定量的准确性相对误差小于10%。使用中能通用准直器（MEGP）和208keV±10%的能量窗组合时，热球定量的准确性最高。然而，随着热球直径减小，热球定量的准确性显著降低。变异性随成像条件而变化，且采集时间越长变异性改善。
蒙特卡罗模拟揭示了镥成像每种SPECT成像条件下定量值的准确性和变异性。
