MRD441: Cells Radiosensitivity - PDF

# MRD441: Cells Radiosensitivity ## Law of Bergonie and Tribondeau * Jean Alban Bergonie (1857-1925) * Louis Tribondeau (1872-1918) * Claudius Regaud (1870-1940) ## Cell Radiosensitivity * **Cell maturity and specialization** The human body is composed of different types of cells and tissues, w...

# MRD441: Cells Radiosensitivity ## Law of Bergonie and Tribondeau * Jean Alban Bergonie (1857-1925) * Louis Tribondeau (1872-1918) * Claudius Regaud (1870-1940) ## Cell Radiosensitivity * **Cell maturity and specialization** The human body is composed of different types of cells and tissues, which vary in their degree of radiosensitivity. | Radiosensitive Cells | Radioinsensitive Cells | |---|---| | Basal cells of the skin | Brain cells | | Blood cells such as lymphocytes and erythrocytes | Muscle cells | | Intestinal crypt cells | Nerve cells | | Reproductive (germ) cells | | * **Amount of radiation energy transferred to biologic tissue** Plays a major role in determining the amount of biologic response. * **As LET increases, the ability of the radiation to cause biologic effects also generally increases until it reaches a maximal value.** LET can influence cell radiosensitivity. ## Law of Bergonie and Tribondeau (cont.) * Observed the effects of ionizing radiation on testicular germ cells of rabbits they had exposed to x-rays. * Established that radiosensitivity was a function of the metabolic state of the cell receiving the exposure. * States that the radiosensitivity of cells is directly proportional to their reproductive activity and inversely proportional to their degree of differentiation. * **Law was originally applied only to germ cells; it is actually true for all types of cells in the human body** * **The most pronounced radiation effects occur in cells having the least maturity and specialization or differentiation, the greatest reproductive activity, and the longest mitotic phases** ## Effects of ionizing radiation on human cells (cont.) * **Blood cells** * Hematologic depression * Depletion of immature blood cells * Repopulation after a period of recovery * Effects on stem cells of the hematopoietic system * Whole-body doses in excess of 5 gyt * Effects of ionizing radiation on lymphocytes * Effects of ionizing radiation on neutrophils * Effects of ionizing radiation on granulocytes * Effects of ionizing radiation on thrombocytes (platelets) * Radiation exposure during diagnostic imaging procedures * Monitoring of patients undergoing radiation therapy treatment * Occupational radiation exposure monitoring * **Epithelial tissue** * **Muscle tissue** * **Nervous tissue** * Nerve tissue in the human adult * Nerve tissue in the embryo-fetus * **Reproductive cells:** * Spermatogonia * Ova ## Radiosensitivity of Organs and Tissues | | | |---|---| | Active cell division | High sensitivity | | Hematopoietic system: Bone marrow and lymphatic tissues (spleen, thymus gland, lymph node) | | | Reproductive system: Testis and ovary | | | Gastrointestinal system: Mucous membrane and small-intestinal villus | | | Epidermis and eyes: Hair follicle, sweat gland, skin and lens | | | Other: Lung, kidney, liver and thyroid gland | | | Support system: Blood vessel, muscle and bone | | | Transmission system: Nerve | | | No cell division | Low sensitivity |