Abstract

Purpose

Inhomogeneous exposures to ionizing radiation can be detected and quantified with the dicentric chromosome assay (DCA) of metaphase cells. Complete automation of interpretation of the DCA for whole-body irradiation has significantly improved throughput without compromising accuracy, however, low levels of residual false positive dicentric chromosomes (DCs) have confounded its application for partial-body exposure determination.

Materials and methods

We describe a method of estimating and correcting for false positive DCs in digitally processed images of metaphase cells. Nearly all DCs detected in unirradiated calibration samples are introduced by digital image processing. DC frequencies of irradiated calibration samples and those exposed to unknown radiation levels are corrected subtracting this false positive fraction from each. In partial-body exposures, the fraction of cells exposed, and radiation dose can be quantified after applying this modification of the contaminated Poisson method.

Results

Dose estimates of three partially irradiated samples diverged 0.2–2.5 Gy from physical doses and irradiated cell fractions deviated by 2.3%–15.8% from the known levels. Synthetic partial-body samples comprised of unirradiated and 3 Gy samples from 4 laboratories were correctly discriminated as inhomogeneous by multiple criteria. Root mean squared errors of these dose estimates ranged from 0.52 to 1.14 Gy² and from 8.1 to 33.3%² for the fraction of cells irradiated.

Conclusions

Automated DCA can differentiate whole- from partial-body radiation exposures and provides timely quantification of estimated whole-body equivalent dose.

中文翻译：

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通过自动细胞遗传生物剂量学估算身体局部电离辐射暴露。

摘要

目的

可以通过中期细胞的双着丝粒染色体检测（DCA）检测和量化电离辐射的不均匀暴露。完全自动化的DCA全身照射解释功能，在不影响准确性的情况下，显着提高了通量，但是，残留假阳性双中心染色体（DC）的含量低，混淆了其在部分身体暴露测定中的应用。

材料和方法

我们描述了一种估计和校正中期细胞的数字处理图像中的假阳性DC的方法。通过数字图像处理几乎可以将未辐照校准样品中检测到的所有DC引入。校正了辐射校准样品的DC频率和暴露于未知辐射水平的DC频率，从每个样品中减去此假阳性分数。在部分身体暴露中，在对污染的泊松方法进行这种修改后，可以量化暴露的细胞比例和辐射剂量。

结果

三个部分辐照样品的剂量估计值与物理剂量相差0.2–2.5 Gy，辐照细胞分数与已知水平相差2.3％–15.8％。通过多个标准正确区分了来自4个实验室的未辐照和3个Gy样品组成的合成部分样品。这些剂量估计的均方根误差在被照射细胞的分数范围为0.52至1.14 Gy ²和8.1至33.3％²。

结论

自动化的DCA可以区分全身和局部辐射，并及时量化估计的全身等效剂量。