An Appraisal of the Value of the Contaminated Poisson Method to Estimate the Dose Inhomogeneity in Simulated Partial-Body Exposure

Abstract

The situation in which inhomogeneous radiation exposure is likely to occur with accidental overexposure was simulated by studying chromosome aberrations in mixtures of male irradiated and female nonirradiated lymphocytes. The data were evaluated by means of the contaminated Poisson method. For X-ray doses from 1 to 10 Gy and ratios of irradiated to nonirradiated blood from 1:1 to 1:19, a good agreement was found between calculated and applied radiation doses and fractions exposed.

A statistical framework for radiation dose estimation with uncertainty quantification from the γ-H2AX assay

“…The dicentric assay enjoys “gold–standard” status due to its good adherence of the aberration counts to the Poisson model, with a stable quadratic dose–response curve which takes very similar shapes for both X– and γ –rays [4], and which is robust to inter–individual [1] and inter–laboratory variation [5]. Overdispersion can still arise, for instance from partial body exposure, which can be dealt with through Dolphin’s contaminated Poisson method [6]. Deviation from the Poisson property may also occur under densely ionising radiation or when using automatic scoring procedures, among other causes [7, 8].…”

“…The computation of these uncertainties is, however, challenging, which has its reasons in (i) the difficulty of the required mathematical and statistical concepts as such (ii) the need to incorporate several different types of uncertainty (iii) the fact that, partly as a consequence of (ii), focus counts are usually strongly overdispersed relative to the mean–variance equality inherent to the Poisson model, and hence standard techniques available for the dicentric assay no longer apply. While it is the case that some methods have been developed to deal with overdispersion in the context of the dicentric assay, such as the consideration of zero–inflated models, [6, 8], it should be stated that the mechanisms which generate overdispersion for the γ -H2AX assay are of quite different nature, and also require adjusted methodology to deal with.…”

Calibration Curve for Dicentric Chromosomes Induced in Human Blood Lymphocytes Exposed to Gamma Rays at a Dose Rate of 12.5 mGy/s

“…Poisson distribution (U-test) of dicentric chromosomes among metaphases was a parameter that used to check the uniformity of the radiation field. [ 2 6 7 9 ] Consulting Chi-square table with k = 5, α = 0.05 had χ 2 k−1 (α) = 9.19. The data presented (α), it means that induced dicentric distribution in the irradiation cells fitted well with Poisson distribution.…”

“…[ 2 7 8 ] The correlation coefficient r (y, d) was used to find model equation, and recurrent equation was solved to find recurrent coefficients for independent curves, statistical and presenting general calibration dose–effect curve. [ 6 7 8 9 10 ]…”

Short Communications: Chromosome Aberrations in Circulating Lymphocytes after Brachytherapy for Uterus Carcinoma

“…colchicine was added after a culture period of 45 h, and the culture was continued for a total of 48 h. Metaphase slides were prepared and stained in the usual way as described previously (6). In general, 200.-300 metaphases were examined for different types of chromosome aberrations (Table).…”