The blood-forming cells of the bone marrow are among the most radiosensitive cells in the body. If a large percentage of such cells are killed, as can happen when intensive irradiation of the whole body occurs, the normal replacement of circulating blood cells is impaired.
The most radiation-sensitive organs include the hematopoietic system [4], the gastrointestinal (GI) system [5], skin [6, 7], vascular system [8, 9], reproductive system, and brain [10–12].
Radiation can damage the DNA in our cells. High doses of radiation can cause Acute Radiation Syndrome (ARS) or Cutaneous Radiation Injuries (CRI). High doses of radiation could also lead to cancer later in life.
The most important factors relating to the development of radiation late effects in the lung are dose and volume. With respect to dose, it is the total dose affecting the lung normal tissue that dictates the level of late reaction, as well as the size of the daily fraction.
Skin changes. The most common long term side effect is a change to the skin where you have had radiotherapy treatment. The skin may look permanently sunburnt or develop a network of tiny blood vessels near the surface.
Some types of late effects of radiotherapy may include fatigue, changes in the skin and breast size and contour, and less commonly lymphedema, cardiac and lung toxicity, alterations in bone health and arm and shoulder mobility.
The organs at risk (OAR) of radiotherapy-associated toxicity, including optic nerves, optic chiasm, retinae, lenses, brainstem, pituitary, cochlea and hippocampus, should be (properly) delineated.
In rare cases, radiation can cause more severe and permanent side effects such as damage to the lungs, heart, bowel, bladder or other organs. There is also a small risk that the radiation treatment may actually cause, years later, a new cancer.
More or less every organ is affected by radiation exposure. Some require a higher dose to be affected while others may be affected at a lower dose. All the endocrine glands are susceptible to damage by radiation exposure; however, pituitary, thyroid and gonads are most likely to be affected.
The mature brain and nervous system are relatively resistant to radiation injury, but the developing brain is radiosensitive to damage (see below).
The gastrointestinal (GI) tract is among the most radiosensitive organ systems in the body.
From these discussions we can conclude that Bone marrow is the most radiosensitive tissue of the body.
Solution: Bone marrow is the part of body first affected with nuclear radiation.
Ionizing radiation is a known reproductive hazard. It has been linked to birth defects and other reproductive problems.
Radiation-induced reduction in ATP levels are known to disintegrate the cell structure and function, leading to necrosis, apoptosis, autophagy [102,103,104,105,106,107].
Many people who get radiation have some fatigue and skin reactions. Based on the area of your body being treated, you may also have some: Hair loss. Appetite changes.
Radiation nephropathy is kidney injury and impairment of function caused by ionizing radiation. It may occur after irradiation of one or both kidneys, and it may result in kidney failure. Exposure to ionizing radiation can cause tissue reactions depending on the absorbed dose.
Radiation treatment uses beams of energy to destroy cancer cells. If you receive radiation therapy to your chest, it can damage your heart. Radiation heart disease describes a range of heart problems that occur due to radiation therapy. These problems can develop weeks or years after receiving radiation therapy.
Treatments for cancer, including some types of chemotherapy, radiation therapy and stem cell transplants, can cause kidney problems.
Irradiation often causes acute unwanted reactions, such as nausea, diarrhoea or redness of the skin, which, although troublesome, normally resolve within a few weeks. 1 Acute bone marrow depression can also occur, particularly following irradiation of the whole body, but this too may be transient.
Impact on the Brain
The side effects you have depend on the area of the brain that received radiation. In some cases, the whole brain is treated. The most common side effects are short-term memory loss, feeling tired, trouble concentrating or learning, and problems with walking and balance.
Late radiation toxicity has been observed when the radiation absorbed doses from radiopharmaceuticals were based on external beam organ tolerance dose limits. This is because the determinants for estimating the tolerance doses for the two radiation therapies are different.