Orton B R, Vorsatz D, Macovei D
Physics Department, Brunel University, Uxbridge, UK.
Acta Oncol. 1996;35(7):895-9. doi: 10.3109/02841869609104043.
Dosimetry from 125I emitting Auger electrons in the follicles of the thyroid will improve when their complete interaction with the molecular structure about the Auger emitting atoms is known to Angstrom distances. Extended x-ray absorption fine structure (EXAFS) can provide this information. EXAFS experiments gave intermolecular and intramolecular distance for pure solid L-thyroxine (T4) (C15H11I4NO4) using a model based on crystalline T4 hydrochloride monohydrate (C15H11I4NO4HCl.H2O). For a solution of L-thyroxine the structure consists of the intramolecular distances found for T4 and an additional shell of four carbon atoms distances of 2.01 A. Atomic density functions from Fourier transformed EXAFS measurements are suitable for estimating very short range interactions of Auger electrons in thyroid thyroglobulin over a radial distance of 7.71 A. Examination of density functions provided a plausible argument for the difference in biological effect between 131I and 125I in the thyroid.
当甲状腺滤泡中发射俄歇电子的¹²⁵I与俄歇发射原子周围分子结构的完全相互作用已知到埃级距离时，¹²⁵I在甲状腺滤泡中的剂量学将得到改善。扩展X射线吸收精细结构（EXAFS）可以提供此信息。EXAFS实验使用基于一水合盐酸结晶L-甲状腺素（C₁₅H₁₁I₄NO₄HCl·H₂O）的模型，给出了纯固体L-甲状腺素（T4）（C₁₅H₁₁I₄NO₄）的分子间和分子内距离。对于L-甲状腺素溶液，其结构由T4的分子内距离和一个额外的四个碳原子壳层（距离为2.01 Å）组成。傅里叶变换EXAFS测量得到的原子密度函数适用于估计甲状腺甲状腺球蛋白中半径为7.71 Å的俄歇电子的极短程相互作用。对密度函数的研究为¹³¹I和¹²⁵I在甲状腺中的生物学效应差异提供了一个合理的论据。
