The Cell Dose Concept; a Potential Tool for Analyzing the Net Effect of Radiation in Multicellular Systems

Journal/Book: 2. Phys. Med. Baln. Med. Klim. (Sonderheft 2) 19 (1990) 8-11. 1990;

Abstract: Institute of Medicine Research Center Jülich and Department of Nuclear Medicine Düsseldorf West-Germany Anschr. d. Verf.: Prof. Dr. L. E. Feinendegen Institute of Medicine Research Center Jülich Postfach1913 D-5170 Jülich and Department of Nuclear Medicine Heinrich- Heine- University Düsseldorf Germany The action of ionizing radiation in the human body has to be considered in a holistic approach. Energy depositions to individual cells trigger effects within a hierarchical structure of interacting levels of biological systems consisting consecutively of atoms molecules cells and organ tissue. The cell elemental unit of live The perturbations introduced by ionizing radiation primarily at the atomic-molecular level of organization may be perpetuated to higher levels of organization. Yet this promotion of perturbation appears to be inhibited or blocked by mechanisms for protection. Cells have enzymes which defend against potentially toxic agents such as molecular radicals including oxygen containing free radicals that are produced in the course of normal metabolism; other enzymes take care of the repair of damaged molecules such as DNA and of there placement of lost structures as long as information for replacement through functional DNA remains available. At the organ tissue level mechanisms of defense repair and replacement operate through the immune system and the control of proliferation differentiation and maturation of cells. For all these responses the cell is the crucial element of tissue i. e. the elemental unit of life. The radiation dose to cells In correspondence with the practice in radiation protection the average mass either of the cell 1 ng or of the cell nucleus 270 pg is proposed to be taken as the gross sensitive volume GSV in assessing the evolution of radiation effects (BOND et al. 1966; CRONKITE et al. 1973; FEINENDEGEN et al. 1977; NCRP 1979). Even if the cell nucleus is known to be more radiosensitive than the cytoplasm regarding effects on DNA which is the most crucial molecule for cellular function the multitude of intracellular metabolic interactions make the cell a functional entity to be viewed as an individual whole. In the following the cell is taken to constitute a spherical volume having a mass of 1 ng. ... ___MH

Keyword(s): Net Effect - Multicellular Systems - Cell Dose Concept

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