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Radiation therapy or radiotherapy is a treatment using ionizing radiation, generally provided as part of cancer therapy to either kill or control the growth of malignant cells. It is normally delivered by a linear particle accelerator. Radiation therapy may be curative in a number of types of cancer if they are localized to one area of the body, and have not spread to other parts. It may also be used as part of adjuvant therapy, to prevent tumor recurrence after surgery to remove a primary malignant tumor. Radiation therapy is synergistic with chemotherapy, and has been used before, during, and after chemotherapy in susceptible cancers. The subspecialty of oncology concerned with radiotherapy is called radiation oncology. A physician who practices in this subspecialty is a radiation oncologist.
Acute radiation syndrome (ARS), also known as radiation sickness or radiation poisoning, is a collection of health effects that are caused by being exposed to high amounts of ionizing radiation in a short period of time. Symptoms can start within an hour of exposure, and can last for several months. Early symptoms are usually nausea, vomiting and loss of appetite. In the following hours or weeks, initial symptoms may appear to improve, before the development of additional symptoms, after which either recovery or death follow.
Brachytherapy is a form of radiation therapy where a sealed radiation source is placed inside or next to the area requiring treatment. The word "brachytherapy" comes from the Greek word βραχύς, brachys, meaning "short-distance" or "short". Brachytherapy is commonly used as an effective treatment for cervical, prostate, breast, esophageal and skin cancer and can also be used to treat tumours in many other body sites. Treatment results have demonstrated that the cancer-cure rates of brachytherapy are either comparable to surgery and external beam radiotherapy (EBRT) or are improved when used in combination with these techniques. Brachytherapy can be used alone or in combination with other therapies such as surgery, EBRT and chemotherapy.
The gray is the unit of ionizing radiation dose in the International System of Units (SI), defined as the absorption of one joule of radiation energy per kilogram of matter.
Radiation dosimetry in the fields of health physics and radiation protection is the measurement, calculation and assessment of the ionizing radiation dose absorbed by an object, usually the human body. This applies both internally, due to ingested or inhaled radioactive substances, or externally due to irradiation by sources of radiation.
A radiation burn is a damage to the skin or other biological tissue and organs as an effect of radiation. The radiation types of greatest concern are thermal radiation, radio frequency energy, ultraviolet light and ionizing radiation.
Total body irradiation (TBI) is a form of radiotherapy used primarily as part of the preparative regimen for haematopoietic stem cell transplantation. As the name implies, TBI involves irradiation of the entire body, though in modern practice the lungs are often partially shielded to lower the risk of radiation-induced lung injury. Total body irradiation in the setting of bone marrow transplantation serves to destroy or suppress the recipient's immune system, preventing immunologic rejection of transplanted donor bone marrow or blood stem cells. Additionally, high doses of total body irradiation can eradicate residual cancer cells in the transplant recipient, increasing the likelihood that the transplant will be successful.
The National Oncologic Institute or ION is a specialized hospital for cancer treatment, located in Panama City, Panama. Between August 2000 and March 2001, patients receiving radiation treatment for prostate cancer and cancer of the cervix received lethal doses of radiation, resulting in eight fatalities.
Dose fractionation effects are utilised in the treatment of cancer with radiation therapy. When the total dose of radiation is divided into several, smaller doses over a period of several days, there are fewer toxic effects on healthy cells. This maximizes the effect of radiation on cancer and minimizes the negative side effects. A typical fractionation scheme divides the dose into 30 units delivered every weekday over six weeks.
Image-guided radiation therapy (IGRT) is the process of frequent imaging, during a course of radiation treatment, used to direct the treatment, position the patient, and compare to the pre-therapy imaging from the treatment plan. Immediately prior to, or during, a treatment fraction, the patient is localized in the treatment room in the same position as planned from the reference imaging dataset. An example of IGRT would include comparison of a cone beam computed tomography (CBCT) dataset, acquired on the treatment machine, with the computed tomography (CT) dataset from planning. IGRT would also include matching planar kilovoltage (kV) radiographs or megavoltage (MV) images with digital reconstructed radiographs (DRRs) from the planning CT.
Particle therapy is a form of external beam radiotherapy using beams of energetic neutrons, protons, or other heavier positive ions for cancer treatment. The most common type of particle therapy as of August 2021 is proton therapy.
Radiobiology is a field of clinical and basic medical sciences that involves the study of the effects of ionizing radiation on living things, in particular health effects of radiation. Ionizing radiation is generally harmful and potentially lethal to living things but can have health benefits in radiation therapy for the treatment of cancer and thyrotoxicosis. Its most common impact is the induction of cancer with a latent period of years or decades after exposure. High doses can cause visually dramatic radiation burns, and/or rapid fatality through acute radiation syndrome. Controlled doses are used for medical imaging and radiotherapy.
The medical effects of the atomic bomb upon humans can be put into the four categories below, with the effects of larger thermonuclear weapons producing blast and thermal effects so large that there would be a negligible number of survivors close enough to the center of the blast who would experience prompt/acute radiation effects, which were observed after the 16 kiloton yield Hiroshima bomb, due to its relatively low yield:
Osteoradionecrosis (ORN) is a serious complication of radiation therapy in cancer treatment where radiated bone becomes necrotic and exposed. ORN occurs most commonly in the mouth during the treatment of head and neck cancer, and can arise over 5 years after radiation. Common signs and symptoms include pain, difficulty chewing, trismus, mouth-to-skin fistulas and non-healing ulcers.
Prophylactic cranial irradiation (PCI) is a technique used to combat the occurrence of metastasis to the brain in highly aggressive cancers that commonly metastasize to brain, most notably small-cell lung cancer. Radiation therapy is commonly used to treat known tumor occurrence in the brain, either with highly precise stereotactic radiation or therapeutic cranial irradiation. By contrast, PCI is intended as preemptive treatment in patients with no known current intracranial tumor, but with high likelihood for harboring occult microscopic disease and eventual occurrence. For small-cell lung cancer with limited and select cases of extensive disease, PCI has shown to reduce recurrence of brain metastases and improve overall survival in complete remission.
Radiation exposure is a measure of the ionization of air due to ionizing radiation from photons. It is defined as the electric charge freed by such radiation in a specified volume of air divided by the mass of that air. As of 2007, "medical radiation exposure" was defined by the International Commission on Radiological Protection as exposure incurred by people as part of their own medical or dental diagnosis or treatment; by persons, other than those occupationally exposed, knowingly, while voluntarily helping in the support and comfort of patients; and by volunteers in a programme of biomedical research involving their exposure. Common medical tests and treatments involving radiation include X-rays, CT scans, mammography, lung ventilation and perfusion scans, bone scans, cardiac perfusion scan, angiography, radiation therapy, and more. Each type of test carries its own amount of radiation exposure. There are two general categories of adverse health effects caused by radiation exposure: deterministic effects and stochastic effects. Deterministic effects are due to the killing/malfunction of cells following high doses; and stochastic effects involve either cancer development in exposed individuals caused by mutation of somatic cells, or heritable disease in their offspring from mutation of reproductive (germ) cells.
Radiation-induced lumbar plexopathy (RILP) or radiation-induced lumbosacral plexopathy (RILSP) is nerve damage in the pelvis and lower spine area caused by therapeutic radiation treatments. RILP is a rare side effect of external beam radiation therapy and both interstitial and intracavity brachytherapy radiation implants. RILP is a Pelvic Radiation Disease symptom.
A radiotherapy accident in Columbus, Ohio, also known as the Riverside radiation case, occurred as the result of an incorrectly calibrated cobalt teletherapy unit, occurred between 1974 and 1976, leading to 10 deaths.
The Lia radiological accident began on December 2, 2001, with the discovery of two orphan radiation sources near the Enguri Dam in Tsalenjikha District in the country of Georgia. Three villagers from Lia were unknowingly exposed. All three men were injured, one of whom eventually died. The accident was a result of unlabeled radioisotope thermoelectric generator (RTG) cores which had been improperly dismantled and left behind from the Soviet era. The International Atomic Energy Agency (IAEA) led recovery operations and organized medical care.
References
- ↑ Fluoroscopically Guided Interventional Procedures: A Review of Radiation Effects on Patients’ Skin and Hair Stephen Balter, John W. Hopewell, Donald L. Miller, Louis K. Wagner, and Michael J. Zelefsky Radiology 2010 254:2, 326-341
- ↑ van den Aardweg GJ, Hopewell JW, Simmonds RH . Repair and recovery in the epithelial and vascular connective tissues of pig skin after irradiation . Radiother Oncol 1988; 11 : 73 – 82 .
- ↑ Suresh R., Yuen F., Murase J.E. Methods for decreasing the incidence of moist desquamation in patients undergoing radiotherapy. J Am Acad Dermatol. 2018 S0190–9622(18)32317
- ↑ Mukherji, A. (2018). Management of Skin Reactions. In: Basics of Planning and Management of Patients during Radiation Therapy. Springer, Singapore. https://doi.org/10.1007/978-981-10-6659-7_23
- ↑ Huda, W. Review of Radiologic Physics. 3rd edition. Lippincott, Williams & Wilkins, 2009.
- ↑ Zenda S, Ota Y, Tachibana H, et al. A prospective picture collection study for a grading atlas of radiation dermatitis for clinical trials in head-and-neck cancer patients. J Radiat Res. 2016;57:301-6.
- ↑ Junker JP, Kamel RA, Caterson EJ, Eriksson E. Clinical Impact Upon Wound Healing and Inflammation in Moist, Wet, and Dry Environments. Adv Wound Care (New Rochelle). 2013 Sep;2(7):348-356. doi: 10.1089/wound.2012.0412. PMID 24587972; PMCID: PMC3842869.
- ↑ Michael J. Veness, Julie Howle, in Clinical Radiation Oncology (Fourth Edition), 2016