Radiation Therapy

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Radiation Therapy

What is radiation therapy? According to wikipedia Radiation therapy discovered in 1889 also known as radiotherapy, radiation oncology, or XRT, is the medical use of ionizing radiation as a part of cancer treatment to control malignant cells. Radiotherapy may be used for curative or adjuvant cancer treatment, with curative being the cure and adjuvant being additional treatment. Radiation therapy can also be used as palliative treatment, which is where a cure is not possible and the aim is for disease control or relief of symptoms. It can also be used as therapeutic treatment, where the therapy can result in surviving the cancer and the cancer can be cured. A radiotherapy technique used to prepare the body to receive a bone marrow transplant is known as total body irradiation (TBI). There are several different types of radiation therapy including external beam radiotherapy, Brachytherapy, and systemic radioisotope therapy. From its discovery in the 19th century radiation therapy has come a long way through research and innovation.

Radiation therapy can be used in non-malignant cancer treatment or malignant cancer treatment. Radiation therapy has several applications in non-malignant conditions, such as the treatment of trigeminal neuralgia, severe thyroid eye disease, apterygial, pigmented villonodular synovitis, prevention of keloid scar growth, and prevention of heterotopy ossification. The use of radiation therapy in non-malignant conditions is limited due to the risk cancers that may be radiation-induced. Radiation therapy is also used for the treatment of malignant tumors, and is often used as the primary therapy. It is also common to combine radiotherapy with surgery, chemotherapy, hormone therapy or some mixture of the three. Almost all common types of cancer can be treated with radiation therapy in some way. The precise treatment intent (curative, adjuvant, neoadjuvant, therapeutic, or palliative) will depend on the tumor type, location, and stage, as well as the general health of the patient.

After reading “Radiation Treatment for Cancer” we collected the following information. Radiation therapy works by damaging the DNA of cells. The damage is caused by a photon, electron, proton, neutron, or ion beam directly or indirectly ionizing the atoms which make up the DNA chain. Indirect ionization happens as a result of the ionization of water, forming free radicals, notably hydroxyl radicals, which then damage the DNA. In the most common forms of radiation therapy, most of the radiation effect is through free radicals. Because cells have mechanisms for repairing DNA damage, breaking the DNA on both strands proves to be the most significant technique in modifying cell characteristics. Because cancer cells generally are undifferentiated and stem cell-like, they reproduce more, and have a diminished ability to repair sub-lethal damage compared to most healthy differentiated cells. The DNA damage is inherited through cell division, accumulating damage to the cancer cells, causing them to die or reproduce more slowly. According to wikipedia one of the major limitations of radiotherapy is that the cells of solid tumors become deficient in oxygen. Solid tumors can outgrow their blood supply, causing a low-oxygen state known as hypoxia.

Radiation comes in doses. The dose or amount or radiation used in radiation therapy is measured in gray (Gy), and may vary depending on the stage and type of cancer being treated. In curative cases, typically the dose for a solid epithelial tumor ranges from 60 to 80 Gy, while lymphoma tumors are treated with 20 to 40 Gy. Preventive or adjuvant doses are typically around 45-60 Gy in 1.8-2 Gy fractions respectively for breast, head, and neck cancers. Many other factors are considered by radiation oncologists when selecting a dose, including whether the patient is receiving chemotherapy, whether radiation therapy is being administered before or after surgery, and the...
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