A time-delay approach for modeling chronic radiation injury dynamics

摘要

In the field of radiation related diseases a group of engineers at the Department of Measurement, Control, and Microtechnology has been working for many years in close cooperation with medical experts on the development of a system that supports medical doctors in the diagnosis of radiation injuries. The core of a recent development consists of a biomathematical time-delay model of the human granulopoiesis describing the dynamical maturation process of the granulocytes, a sub-class of white blood cells. From medical findings it is well known that granulocytes play the role of a key indicator for the severeness of radiation injuries.For both of the two possible irradiation cases—the acute and the chronic case—the implemented module performs an estimation of relevant model parameters by minimizing a quadratic objective function. The identification of these model parameters allows deep insight into the severeness of irradiation damages for an individual patient.In this paper, modeling of the granulopoietic cell system based on time-delay differential equations is presented. Starting from a basic model which has been evaluated for the acute radiation case special emphasis is placed on an extension of this model in order to describe the effects of chronic irradiation. For both of the previously mentioned cases the respective optimization problems are formulated and selected estimation results are presented.