Abstract
Biological dosimetry based on chromosome aberration scoring in peripheral blood lymphocytes enables timely assessment of the ionizing radiation dose absorbed by an individual. Here, new Bayesian-type count data inverse regression methods are introduced for situations where responses are Poisson or two-parameter compound Poisson distributed. Our Poisson models are calculated in a closed form, by means of Hermite and negative binomial (NB) distributions. For compound Poisson responses, complete and simplified models are provided. The simplified models are also expressible in a closed form and involve the use of compound Hermite and compound NB distributions. Three examples of applications are given that demonstrate the usefulness of these methodologies in cytogenetic radiation biodosimetry and in radiotherapy. We provide R and SAS codes which reproduce these examples.
Highlights
In spite of strict safety measures and regulations, radiation accidents or unplanned exposures occur, for instance in radiology services and radiotherapy departments at hospitals, or using radiography cameras in industry
In the event of a radiation accident, biological dosimetry is essential for the timely determination of the radiation dose to which an individual has rspa.royalsocietypublishing.org Proc
We have presented several Bayesian-type methods for count data inverse regression, showing its application in the field of cytogenetic dosimetry
Summary
In spite of strict safety measures and regulations, radiation accidents or unplanned exposures occur, for instance in radiology services and radiotherapy departments at hospitals, or using radiography cameras in industry. From the point of view of IAEA [3], β are the calibration coefficients and f(xi, β) is the mean of aberrations per cell (called yield or frequency of aberrations per cell, in the cytogenetics field) The parameters of this regression model are usually estimated by maximum likelihood [6], and the MLE and its estimated variance–. We present a new Bayesian-type method to use cytogenetic data to estimate the dose to which a patient has been exposed. This method uses dose–effect calibration curves estimated by the classical (frequentist) approach suggested in the IAEA manual. A new R package called ‘radir’, which implements the Poisson response models presented here, is available under request to the corresponding author
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