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Australian Nuclear Science and Technology Organisation
Nuclear medicines and radioisotopes What is a radioisotope? Radioisotopes are atoms that contain an unstable combination of neutrons and protons. The combination can occur naturally as in radium-226, or can be produced artificially by altering the atoms. This can be done in either a nuclear reactor or a cyclotron. Atoms containing this unstable combination emit radiation in the form of alpha, beta and gamma rays. For more information, also see: Nuclear Medicine - Your questions answered What are they used for? The main uses for radioisotopes are in medicine, industry and research. On average, every Australian can expect at some stage in their life to have a nuclear medicine procedure that uses a radioisotope for diagnostic or therapeutic purposes. Nuclear medicine uses small amounts of radiation to provide information about a person's body and the functioning of specific organs. In most cases, the information is used by physicians to make an accurate diagnosis of the patient's illness via nuclear imaging. In certain cases radiation can be used to treat diseased organs or tumours. Radioisotopes are also commonly used for analysis, quality control and safety checking in a wide range of industries from mining and manufacturing to food production and packaging. Radioisotopes are also used as tracers in many research areas. Naturally occurring radioisotopes are used particularly in dating, such as estimating the age of water from underground bores from the ratio of naturally occurring radioisotopes in the water. What is a radiopharmaceutical? A radiopharmaceutical is a radioactive pharmaceutical. They are used for the treatment and diagnosis of many cancers and diseases. What is nuclear medicine and is it safe? 1
Nuclear medicine uses radiopharmaceuticals for diagnosis and treatment. Radiopharmaceuticals can be injected, inhaled or ingested in order for the physician to diagnose disease using imaging techniques, or to directly treat or relieve pain. More than 90 per cent of radioisotopes used in nuclear medicine are reactor-produced. Doctors would not recommend the use of nuclear medicine if they did not consider that it was safe. Can you provide a list of radioisotopes made at ANSTO and their uses? Some of the isotopes produced include: •
Technetium-99m - images the brain, heart, bones, thyroid, salivary glands and blood pool - also for bone disease in diabetic patients.
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Thallium-201 - useful in imaging and localisation of heart blood vessel blockage, which is a primary cause of heart attacks. Used during stress testing to diagnose bloodstarved heart tissue.
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Gallium-67 Citrate - Hodgkin's disease, cancer of lymphatic system, cancer of the lungs, aids in detecting infections and acute inflammatory lesions. Iodine-123 - whole body scans and specific brain functions.
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Leukoscan - diagnostic imaging of bones in diabetic patients.
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Fluorodeoxyglucose - diagnosis of abnormal glucose metabolism, heart disease, brain foci of epileptic seizures.
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Iodine-131 - (therapy) hyperthyroidism and Non-Hodgkin's lymphoma.
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Yttrium - (therapy) liver cancer.
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Samarium - (palliative - pain suppression) relief of bone pain and bone scans. What is a cyclotron? A cyclotron is a type of particle accelerator that is used for medical, industrial and research processes. It accelerates charged particles around a circle and aims them at a target that breaks the particles open. This method can be used to produce radioisotopes for medical purposes. The radiopharmaceuticals that are produced in a cyclotron have shorter half lives than those produced in the OPAL reactor. If we only used a cyclotron to produce radiopharmaceuticals for Australian patients, then people living in other states would not receive radiopharmaceuticals as they would have decayed by the time that they reached the patients.
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See: PETNET Solutions for more information. Why do we need both cyclotrons and reactors? The radioisotopes made in cyclotrons complement those made in a reactor. Atoms with extra neutrons in the nucleus are called neutron-rich and are produced in a nuclear reactor. Atoms with extra protons in the nucleus are called neutron-deficient and are produced in a particle accelerator such as a cyclotron. Neutron-rich and neutron-deficient radioisotopes decay by different means and hence have different properties and different uses. It depends on the radioactive properties required whether a nuclear reactor or a cyclotron is used to produce the radioisotope. Both types of radio-isotopes are needed to service all of Australia's nuclear medical needs. Over 80% of the radioisotopes actually used in medical procedures worldwide come from reactors. The most commonly used radioisotope, molybdenum-99 (which decays into technetium-99m) can only be produced in a nuclear research reactor. Also, the emerging generation of therapeutic isotopes can only be produced in a reactor such as OPAL. Why can't we import our radioisotope needs from overseas? Reliability of supply is the greatest concern in importing radioisotopes rather than producing them in Australia. A delay in shipment can results in radioactive decay which reduces the amount of active usable radioisotope that arrives in Australia. Supplies can be delayed because of head winds, weather conditions, airline policies or because of restrictions preventing radioactive freight being carried with animals or food. - See more at: http://www.ansto.gov.au/AboutANSTO/WhatANSTOdoes/FAQ/Nuclearmedicinesandr adioisotopes/index.htm#sthash.OGnlXBwx.dpuf
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