Gardin I, Linhart N C, Petiet A, Bok B
Department of Biophysics, University X. Bichat, Paris, France.
J Nucl Med. 1992 Mar;33(3):380-4.
The radiation dose to Kupffer cells was estimated at the cellular level after intravenous injection of 99mTc labeled sulphur colloids in rats. The results were then compared with those obtained using macroscopic dosimetry. From the microscopy appearance observed using a "track" microautoradiographic method (MAR), it was shown that only 0.2% of the Kupffer cells were actually involved in the pinocytosis of radioactive colloids. For each electronic emission from 99mTc (Auger and internal conversion), the fraction of the emitted energy actually absorbed within the Kupffer cell was calculated using the values provided by Berger. About 15% of the total energy emitted by electrons was absorbed in 0.2% of the Kupffer cells. If these results are extrapolated to humans, the dose absorbed by the labeled cells can be estimated to be between 0.5 and 0.9 Gy/MBq. This represents about 15,000 times the average electron dose to the liver as estimated from macrodosimetric methods. In cases such as this one where an important distribution heterogeneity is expected, dosimetric estimations at a cellular level may be particularly useful.
在大鼠静脉注射99mTc标记的硫胶体后，在细胞水平上估算了肝巨噬细胞的辐射剂量。然后将结果与使用宏观剂量测定法获得的结果进行比较。通过“轨迹”显微放射自显影法（MAR）观察到的显微镜图像显示，实际上只有0.2%的肝巨噬细胞参与了放射性胶体的胞饮作用。对于99mTc发出的每一次电子发射（俄歇电子和内转换），利用伯杰提供的值计算了在肝巨噬细胞内实际吸收的发射能量的分数。电子发射的总能量中约15%被0.2%的肝巨噬细胞吸收。如果将这些结果外推至人类，标记细胞吸收的剂量估计在0.5至0.9 Gy/MBq之间。这大约是根据宏观剂量测定法估算的肝脏平均电子剂量的15000倍。在预期存在重要分布异质性的此类情况下，细胞水平的剂量测定估计可能特别有用。
