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Abstract：
OBJECTIVE: Gallium-68 DOTA-DPhe1-Tyr3-Octreotide (68Ga-DOTATOC) has been applied by several European centers for the treatment of a variety of human malignancies. Nevertheless, definitive dosimetric data are yet unavailable. According to the Society of Nuclear Medicine and Molecular Imaging, researchers are investigating the safety and efficacy of this radiotracer to meet Food and Drug Administration requirements. The aim of this study was to introduce the optimized procedure for 68Ga-DOTATOC preparation, using a novel germanium-68 (68Ge)/68Ga generator in Iran and evaluate the absorbed doses in numerous organs with high accuracy.
METHODS: The optimized conditions for preparing the radiolabeled complex were determined via several experiments by changing the ligand concentration, pH, temperature and incubation time. Radiochemical purity of the complex was assessed, using high-performance liquid chromatography and instant thin-layer chromatography. The absorbed dose of human organs was evaluated, based on biodistribution studies on Syrian rats via Radiation Absorbed Dose Assessment Resource Method.
RESULTS: 68Ga-DOTATOC was prepared with radiochemical purity of >98% and specific activity of 39.6 MBq/nmol. The complex demonstrated great stability at room temperature and in human serum at 37°C at least two hours after preparation. Significant uptake was observed in somatostatin receptor-positive tissues such as pancreatic and adrenal tissues (12.83 %ID/g and 0.91 %ID/g, respectively). Dose estimations in human organs showed that the pancreas, kidneys and adrenal glands received the maximum absorbed doses (0.105, 0.074 and 0.010 mGy/MBq, respectively). Also, the effective absorbed dose was estimated at 0.026 mSv/MBq for 68Ga-DOTATOC.
CONCLUSIONS: The obtained results showed that 68Ga-DOTATOC can be considered as an effective agent for clinical PET imaging in Iran.
METHODS: The optimized conditions for preparing the radiolabeled complex were determined via several experiments by changing the ligand concentration, pH, temperature and incubation time. Radiochemical purity of the complex was assessed, using high-performance liquid chromatography and instant thin-layer chromatography. The absorbed dose of human organs was evaluated, based on biodistribution studies on Syrian rats via Radiation Absorbed Dose Assessment Resource Method.
RESULTS: 68Ga-DOTATOC was prepared with radiochemical purity of >98% and specific activity of 39.6 MBq/nmol. The complex demonstrated great stability at room temperature and in human serum at 37°C at least two hours after preparation. Significant uptake was observed in somatostatin receptor-positive tissues such as pancreatic and adrenal tissues (12.83 %ID/g and 0.91 %ID/g, respectively). Dose estimations in human organs showed that the pancreas, kidneys and adrenal glands received the maximum absorbed doses (0.105, 0.074 and 0.010 mGy/MBq, respectively). Also, the effective absorbed dose was estimated at 0.026 mSv/MBq for 68Ga-DOTATOC.
CONCLUSIONS: The obtained results showed that 68Ga-DOTATOC can be considered as an effective agent for clinical PET imaging in Iran.
摘要：
目的：镓-68DOTA-DPhe1-Tyr3-奥曲肽（68Ga-DOTATOC）已被多个欧洲中心用于治疗多种人类恶性肿瘤。然而，目前还没有确定的剂量测定数据。根据核医学和分子影像学会，研究人员正在研究这种放射性示踪剂的安全性和有效性,以满足食品和药物管理局的要求.本研究的目的是介绍68Ga-DOTATOC制备的优化程序，在伊朗使用新型锗-68（68Ge）/68Ga发生器，并以高精度评估许多器官中的吸收剂量。
方法：通过改变配体浓度，通过多次实验确定了制备放射性标记配合物的最佳条件，pH值,温度和孵育时间。评估了复合物的放射化学纯度，采用高效液相色谱法和即时薄层色谱法。评估人体器官的吸收剂量，基于通过辐射吸收剂量评估资源法对叙利亚大鼠进行的生物分布研究。
结果：68Ga-DOTATOC的放射化学纯度>98％，比活性为39.6MBq/nmol。在制备后至少两小时,复合物在室温下和在37°C下在人血清中表现出极大的稳定性。在胰腺和肾上腺组织等生长抑素受体阳性组织中观察到明显的摄取(12.83%ID/g和0.91%ID/g,分别)。人体器官的剂量估计显示胰腺，肾脏和肾上腺接受最大吸收剂量（0.105、0.074和0.010mGy/MBq，分别)。此外，68Ga-DOTATOC的有效吸收剂量估计为0.026mSv/MBq。
结论：获得的结果表明，68Ga-DOTATOC可被认为是伊朗临床PET成像的有效药物。
方法：通过改变配体浓度，通过多次实验确定了制备放射性标记配合物的最佳条件，pH值,温度和孵育时间。评估了复合物的放射化学纯度，采用高效液相色谱法和即时薄层色谱法。评估人体器官的吸收剂量，基于通过辐射吸收剂量评估资源法对叙利亚大鼠进行的生物分布研究。
结果：68Ga-DOTATOC的放射化学纯度>98％，比活性为39.6MBq/nmol。在制备后至少两小时,复合物在室温下和在37°C下在人血清中表现出极大的稳定性。在胰腺和肾上腺组织等生长抑素受体阳性组织中观察到明显的摄取(12.83%ID/g和0.91%ID/g,分别)。人体器官的剂量估计显示胰腺，肾脏和肾上腺接受最大吸收剂量（0.105、0.074和0.010mGy/MBq，分别)。此外，68Ga-DOTATOC的有效吸收剂量估计为0.026mSv/MBq。
结论：获得的结果表明，68Ga-DOTATOC可被认为是伊朗临床PET成像的有效药物。
