Radiosensitivity

Radiosensitivity refers to the relative susceptibility of cells, tissues, organs or organisms to the harmful effect of radiation. It is a significant concept in radiobiology and radiation therapy.

Overview

Radiosensitivity is determined by a number of factors, including the rate of cell division, the type of tissue, and the stage of cell cycle. Cells that are rapidly dividing, such as cancer cells, are generally more radiosensitive than cells that are not. Similarly, tissues that have a high rate of cell turnover, such as the skin and the lining of the gastrointestinal tract, are more radiosensitive than tissues with a low rate of cell turnover, such as muscle and nerve tissue.

Factors affecting radiosensitivity

Several factors can affect the radiosensitivity of a cell or tissue. These include:

• Cell cycle: Cells are most radiosensitive in the late G2 and M phases of the cell cycle, and least radiosensitive in the late S phase.
• Oxygen effect: The presence of oxygen in a cell can increase its radiosensitivity, a phenomenon known as the oxygen effect.
• Repair capacity: Cells with a high capacity for DNA repair are less radiosensitive than cells with a low repair capacity.
• Genetic factors: Certain genetic conditions, such as Ataxia telangiectasia and Nijmegen breakage syndrome, are associated with increased radiosensitivity.

Radiosensitivity and cancer treatment

In the context of cancer treatment, radiosensitivity is a critical factor in the success of radiation therapy. Tumors that are highly radiosensitive, such as lymphomas and seminomas, can often be effectively treated with radiation. Conversely, tumors that are radioresistant, such as melanomas and sarcomas, are less likely to respond to radiation therapy.

See also

• Radioresistance
• Radiobiology
• Radiation therapy
• DNA repair