DETERMINATION OF RADIATION DOSIMETRY FOR PET RADIOPHARMACEUTICALS

介绍新的正电子发射断层扫描（PET） 人类使用的放射性药物需要适当的辐射 剂量估计值。我们已经开发出一种方便的剂量测定方法 在恒河猴身上进行PET成像。动物（5-6 kg） 定位在全身PET扫描仪的机架中， 平行于成像平面的动物轴，以获得矢状面 切开身体因此，大部分或所有的动物都在 扫描仪的视野，提供同步可视化 所有的器官和组织都没有重新定位。大型动物可以 使用标准的轴向切片成像。感兴趣区域（RO 1） 在发射图像中的放置由来自 用于衰减校正的透射扫描， 氧-15水扫描描绘高流量器官。既然是 不可能准确识别器官的边界， 发射图像，以获得其总活性，RO用于 样本组织活性。在非连续的序列上对ROI数据求和 衰减校正的发射图像提供以下时间积分： 每cc组织的放射性。为了计算停留时间， 关于器官密度的信息（以获得每克组织的数据），以及 来自标准兽医表的猴器官重量（以获得 整个器官数据）。测定的器官停留时间 然后使用一种方法将猴子外推到人类身上， 根据体重调整器官重量。剂量估计值 然后可以使用标准MIRDOSE软件获得。 这种方法被用来获得C-11的辐射剂量估计 研究脑磷脂的放射性示踪剂花生四烯酸 新陈代谢.发现肝脏接受最大剂量（0.11 rad/mCi），其次为肺和肾，有效剂量为0.021 雷姆/毫居里该方法已应用于辐射剂量的测定 其他C-11和F-18标记的PET放射性药物的估计值。

The introduction of new positron emission tomography (PET) radiopharmaceuticals for human use requires appropriate radiation dose estimates. We have developed a convenient approach to dosimetry using PET imaging in the rhesus monkey. Animals (5-6 kg) are positioned in the gantry of a whole-body PET scanner with the long axis of the animal parallel to the imaging planes to obtain sagittal slices through the body. Thus most or all of the animal is within field of view of the scanner, providing simultaneous visualization of all organs and tissues without repositioning. Larger animals can be imaged using standard transaxial slices. Region-of-interest (RO1) placement in the emission images is aided by information from the transmission scan used for attenuation correction and from an oxygen-15 water scan that delineates high-flow organs. Since it is not possible to identify accurately the border of organs in the emission images to obtain their total activity, ROls are used to sample tissue activity. Summing ROI data over the sequence of non- decay corrected emission images provides the time-integral of radioactivity per cc of tissue. To calculate residence times, information on organ density (to obtain data per gram of tissue) and monkey organ weights from standard veterinary tables (to obtain whole organ data) are used. The organ residence times determined in the monkey are then extrapolated to humans using a method that adjusts for organ weight in relation to body weight. Dose estimates can then be obtained with standard MIRDOSE software. This approach was used to obtain radiation dose estimates for C-11 arachidonic acid, a radiotracer to study brain phospholipid metabolism. The liver was found to receive the largest dose (0.11 rad/mCi), followed by lung and kidney; the effective dose was 0.021 rem/mCi. This method is being applied to determine radiation dose estimates for other C-11 and F-18 labeled PET radiopharmaceuticals.