Q95396460 Dotaz Zobrazit nápovědu
Creation of a real picture of the observed object on the retina by optical system of the eye is the primary physical condition of the visual perception. Absorption of the light energy initiates the sequence of further physicochemical, biochemical and psychophysiological events partially taking place already in the retina but mostly in the higher cerebral and spinal centres. So the visual perception and its final evaluation is the result of a complicated complex of processes where the optical imaging itself plays the role of the starting factor. In the publication particularly the physical substance of the optical imaging on refraction surfaces between media with different refraction index has been accentuated. The laws of reflection and refraction and their origin are derived in the terms of the physical (Maxwell equations) and geometrical (Fermat principle, principle of the mutual independence of light beams) optics. In the adequate extent the development and structure of the eye and the whole visual complex, the bases of the quantification of the visual perception and contemporary opinions on mechanisms of the colour vision (trichromatic theory) have been described. The publication is completed by a mathematical appendix explaining some relations usually absent in the biomedical literature.
- MeSH
- elektromagnetické jevy MeSH
- lidé MeSH
- oči - fyziologické jevy * MeSH
- optika a fotonika * MeSH
- zrak fyziologie MeSH
- zraková percepce fyziologie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- anglický abstrakt MeSH
- časopisecké články MeSH
The successfulness of tumour radiotherapy depends before all on achieving the maximal effect of radiation on the tumour with contemporary minimalization of the injury of normal tissues in its vicinity. Such selectivity of radiation action may be realized by utilization of physical (kind and energy of radiation, irradiation conditions) as well as biological (modification of radiation effects) factors. The aim of this publication is to give a survey of fundamental biophysical and radiobiological principles conditioning the differential action of ionizing radiation on tumorous and normal cell populations from the standpoint of the relevancy of experimental radiobiology (radiation effect on the proliferative capacity of the tumorous and normal tissue) to radiotherapy. More accent than customary in medical literature is put on the physical interactions of radiations in matter and dosimetry as well as microdosimetry of radiation. The importance of microdosimetry will perhaps increase in future in connection with the therapeutic usage of non-conventional kinds of radiation (neutrons, heavy charged particles, pi-mezons). Basic biophysical machanisms of radiation action on cells and cell populations are described and explained in terms of quantum radiobiology (single- and multihit theory, target theory, stochastics of radiation injury development, etc.) as well as the main principles of modification of radiation effects (oxygen effect, radiosensitizers, fractionation of the dose). A brief interpretation of the Strandquist model of isoeffect curves for the fractionated irradiation is presented enabling to relate mutually the total absorbed dose to the total irradiation time and the number of fractions.
- MeSH
- lidé MeSH
- nádory radioterapie MeSH
- radiobiologie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- anglický abstrakt MeSH
- časopisecké články MeSH
- přehledy MeSH
- MeSH
- cystamin MeSH
- DNA biosyntéza účinky záření MeSH
- experimentální radiační poranění farmakoterapie MeSH
- hepatektomie MeSH
- krysa rodu rattus MeSH
- radioprotektivní látky MeSH
- regenerace jater účinky léků účinky záření MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- ženské pohlaví MeSH
- zvířata MeSH
