Which organ is most radiosensitive?
digestive tract
The digestive tract is among the most radiosensitive organs in the body and its function, which is partly regulated by gastrointestinal (GI) peptides, can be affected by radiation exposure.
What is the most radioresistant?
The differentiated fixed postmitotic cells are the most radioresistant. This class includes the long-lived neurons, skeletal muscle cells and erythrocytes.
What is radiosensitive tumor?
Radiosensitive tumours are tumours which respond well to radiotherapy. Radiotherapy may be effective alone, or may require the addition of cytotoxic chemotherapy as in the more advanced stages of a Wilm’s tumour and Hodgkin’s disease.
What tissues are radioresistant?
The radioresistant tissues, heart, liver, lung and kidney, contain 2 to 15 times more protein per cell, nucleus and chromatin compared with the radiosensitive tissues, spleen and thymus.
Is the liver radiosensitive?
In clinical radiation oncology, however, the liver is known to be a radiosensitive organ (,2). Fractionated doses greater than 20 Gy can result in life-threatening radiation-induced liver disease, a fact that limits treatment for patients requiring hepatic irradiation.
Is the brain radiosensitive?
The inherent radiosensitivity of normal brain tissue manifests as late toxicity in the form of radionecrosis and is evident in some patients after completing CNS-directed radiotherapy.
What two cells are the most radiosensitive in the human body?
Amongst the body cells, the most sensitive are spermatogonia and erythroblasts, epidermal stem cells, gastrointestinal stem cells. The least sensitive are nerve cells and muscle fibers. Very sensitive cells are also oocytes and lymphocytes, although they are resting cells and do not meet the criteria described above.
Which is most radiosensitive tumor?
Among these tumors, undifferen- tiated carcinoma and small cell carcinoma have relatively high radiosensitivity, followed by squa- mous cell carcinoma.
Which is the most radiosensitive ovarian tumor?
The TOV21G and CAOV4 lines showed the highest levels of radiation sensitivity, while HEY, and OVCA420 were the most radioresistant from the panel tested. Curiously, the control cell line IOSE29, derived from normal ovarian tissue, is intermediate in the range of radiosensitivities measured (Fig. 1).
Is nerve tissue radiosensitive?
The least sensitive are nerve cells and muscle fibers. Very sensitive cells are also oocytes and lymphocytes, although they are resting cells and do not meet the criteria described above.
What makes a tissue system more radiosensitive?
Stem cells are radiosensitive. The more mature the cell the more sensitive. The older the tissue or organ, the more radiation resistant it is. The lower the metabolic activity, the higher the resistance.
What are radiosensitive organs?
Hematopoietic system: Bone marrow and lymphatic tissues. (spleen, thymus gland, lymph node) Reproductive system: Testis and ovary. Gastrointestinal system: Mucous membrane and small‐intestinal.
Which is the best definition of radiosensitivity?
Radiosensitivity is the relative susceptibility of cells, tissues, organs or organisms to the harmful effect of ionizing radiation .
Is the radiocurability of a tumor the same as radiosensitivity?
Understanding that radiosensitivity and radiocurability are not identical in meaning is essential. Relatively radioresistant tumors accessible to high-dose local radiation therapy can be cured, but radiosensitive tumors that are widely metastatic can only be controlled locally.
How is radiosensitivity measured in a survival curve?
Cellular radiosensitivity is generally quantified by measuring the loss of reproductive capacity, which can be plotted in a survival curve. Survival curves are characterized by an initial slope, α, and the terminal slope, β. α represents irreparable damage to the cell, and β represents the repairable damage ( Fig. 23.6).
What are the factors that influence the radiosensitivity of a tumor?
These factors include the ability to repair damage, hypoxia, cell cycle position, and growth fraction. In addition, the volume of the initial tumor has been demonstrated to influence the ability to eradicate tumors. Understanding that radiosensitivity and radiocurability are not identical in meaning is essential.