**3. Depth dose distribution in biological objects irradiated with accelerated electrons**

Irradiation of biological objects is particularly sensitive to depth dose distribution due to the nature of such objects, different physical and chemical composition as well as a lack of homogeneity and complex geometry. All these factors have an impact on the irradiation uniformity and the efficiency of irradiation processing.

In treatment with accelerated electrons, non-uniformity of irradiation is inevitable due to the nature of the depth dose distribution throughout the irradiated object. The ratio of the minimum value of absorbed dose *Dmin* to the maximum value of absorbed dose *Dmax* in the object volume is commonly used as a criterion of irradiation dose uniformity [1]. Different categories of biological objects, such as transplantology objects, pharmaceuticals, and food products, require uniformity of at least 80% [1, 38]. Considering that achieving an irradiation uniformity of more than 80% for the objects with a mass thickness of more than 2 g/cm<sup>2</sup> is a challenging task, it is necessary to take into account such factors as packaging filling irregularity, as well as geometry, structure, chemical composition, and density of irradiated objects [15, 43].

This part will discuss the factors, which affect the depth dose distribution in the biological object irradiated with accelerated electrons.
