Cell Radiosensitivity Quiz

Cell Radiosensitivity

• Cells vary in their radiosensitivity. This means different cells respond differently to radiation exposure.
• Cell maturity and specialization influence radiosensitivity. Less mature, rapidly dividing cells tend to be more sensitive.

Examples of Radiosensitive and Radioinsensitive Cells

• Radiosensitive: Basal cells of the skin, blood cells (lymphocytes, erythrocytes), intestinal crypt cells, reproductive (germ) cells.
• Radioinsensitive: Brain cells, muscle cells, nerve cells.

Amount of Radiation Energy Transfer (LET)

• LET is the amount of radiation energy transferred to biological tissue.
• LET plays a crucial role in determining the biological response to radiation.
• As LET increases, the radiation's ability to cause biological effects also generally increases until it reaches a maximum value.
• LET influences cell radiosensitivity.

Law of Bergonie and Tribondeau

• Observed the effects of ionizing radiation on testicular germ cells in rabbits exposed to X-rays.
• Established that radiosensitivity is a function of the metabolic state of the cell receiving the exposure.
• States that radiosensitivity is directly proportional to reproductive activity and inversely proportional to the degree of differentiation. More active cells are more sensitive to radiation.
• This law initially applied only to germ cells, but is actually true for all cell types in the human body.
• The most pronounced effects from radiation occur in cells with low maturity, high reproductive activity, and long mitotic phases.

Effects of Ionizing Radiation on Human Cells

• Blood cells: Hematologic depression (depletion of immature blood cells), recovery period, effects on stem cells of the hematopoietic system, whole-body doses exceeding 5 Gy, effects on lymphocytes and neutrophils.
• Other effects: Effects on granulocytes, thrombocytes (platelets), radiation exposure during diagnostic imaging procedures, monitoring of patients undergoing radiation therapy treatment, and occupational radiation exposure monitoring
• Epithelial tissue, Muscle tissue, Nervous tissue: Effects of ionizing radiation on these tissues.
• Nerve tissue (adult & embryo/fetus): Effects of ionizing radiation differ by the stage of development.
• Reproductive cells: Effects on spermatogonia and ova.

Radiosensitivity of Organs and Tissues

• Highlights the radiosensitivity of organs and tissues, categorizing them as high or low sensitivity based on cell division activity.
• High sensitivity organs/tissues include the hematopoietic system (bone marrow, lymphatic tissues), reproductive system (testes, ovaries), gastrointestinal system (mucous membrane), epidermis/eyes (hair follicles, sweat glands, skin, lenses), and other organs / tissues (lungs, kidneys, liver, thyroid gland, etc.)
• Low sensitivity organs/tissues is the support system (blood vessels, muscles, bones) and the transmission system (nerves)