Abstract

Purpose

Dosimetry of Auger electron-emitting nuclear medicine radioisotopes on cellular and DNA scales is essential in order to assess the biological effects and damage of these radioisotopes to the DNA molecule. This study examined the effects of widely used radioisotopes in nuclear medicine and also two therapeutic radioisotopes in the scale of micrometer and nanometer.

Methods

In this paper, on cell scale (micrometer scale), the S-values for widely used Auger electron-emitting diagnostic radioisotopes ¹²³I, ¹²⁵I, ^99mTc, ⁶⁷Ga, ²⁰¹Tl and ¹¹¹In and two therapeutic radioisotopes of ¹³¹I and ²¹¹At in three different geometrical cell models (spherical, elliptical and cubic) were calculated using Geant4-DNA and the results were compared with the results of other simulation codes as well as the MIRD technique. On DNA scale (nanometer scale), the average number of DNA strand breaks (SSB and DSB) resulting from the direct and indirect effects was calculated for the specified radioisotope.

Results

The results showed that in the cell scale, S-values of the diagnostic radioisotopes were mostly greater than the S-values of the therapeutic radioisotope ¹³¹I, but they were less those of ²¹¹At. On DNA scale, two different geometric models of DNA molecule were simulated and the results of these two models were compared with each other, as well as with the literature. The results showed that the geometric shape of sugar-phosphate groups has a significant effect on the break rates of DNA molecules.

Conclusions

Among the widely used diagnostic radioisotopes, ²⁰¹Tl and ¹²⁵I had the greatest effect on the rate of SSBs and DSBs, respectively, while the ¹³¹I therapeutic radioisotope almost had no effect and therapeutic radioisotope of ²¹¹At had a moderate effect on the number of breaks.

中文翻译：

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使用Geant4-DNA模拟进行微米和纳米级俄歇电子发射核医学放射性同位素剂量学研究。

摘要

目的

为了评估这些放射性同位素的生物学效应和对DNA分子的破坏，在细胞和DNA尺度上进行俄歇电子发射核医学放射性同位素的剂量测定至关重要。这项研究检查了核医学中广泛使用的放射性同位素以及微米级和纳米级两种治疗性放射性同位素的作用。

方法

在本文中，在细胞尺度（微米尺度）上，广泛使用的俄歇电子发射诊断放射性同位素¹²³ I，¹²⁵ I，^99m Tc，⁶⁷ Ga，²⁰¹ Tl和¹¹¹ In以及两个治疗放射性同位素¹³¹ I和¹¹¹ S的S值。²¹¹在三个不同的几何单元模型（球形，椭圆形和立方）中，使用Geant4-DNA进行了计算，并将结果与​​其他仿真代码以及MIRD技术的结果进行了比较。在DNA尺度（纳米尺度）上，针对指定的放射性同位素计算了由直接和间接作用导致的DNA链断裂（SSB和DSB）的平均数。

结果

结果表明，在细胞规模，š诊断放射性同位素-值大多比越大小号治疗放射性同位素-值¹³¹ I，但它们不太那些²¹¹在。在DNA尺度上，模拟了两种不同的DNA分子几何模型，并将这两种模型的结果相互比较，并与文献进行了比较。结果表明糖-磷酸基团的几何形状对DNA分子的断裂速率具有显着影响。

结论

在广泛使用的诊断放射性同位素中，²⁰¹ T1和¹²⁵ I对SSB和DSB的发生率影响最大，而¹³¹ I治疗性放射性同位素几乎无作用，而²¹¹ At的治疗放射性同位素对SSB和DSB的影响中等。休息。