In nuclear medicine, nuclear radiation is greatly used in medical diagnosis. For instances, Technitium-99 is extensively used for bone cancer and prostate cancer diagnosis; the radioimmunoassay is used to determine the levels of hormones, vitamins, enzymes, drugs; the myocardial perfusion imaging maps the blood flow to the heart enabling doctors to see whether a patient has heart diseases. X-ray, Computer Aided Tomography (CAT), Nuclear Magnetic Resonance (NMR), and Positron Emission Tomography (PET) are the examples of medical imaging instruments.
CAT is a medical imaging instrument with the combination of "ordinary" X-ray technology and sophisticated computer signal processing. It is possible to generate an 3-D images of body tissues which is not obscured by other organs. It is more advanced that X-ray imaging. CAT scan is used to scan for head tumours, bone fractures as well as emboli found inside the blood vessels.
NMR is a new technique for obtaining the cross-sectional pictures through the human body without exposing the patient to ionizing radiation. Through this scanning, the functional and physiological state of an organ under examined is revealed. Biochemists often use NMR to monitor metabolite reactions in human beings and animals.
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PET takes images of internal body tissues. It is useful in diagnosing brain tumours and the effect of strokes on the brain, along with other mental illness.
Besides that, nuclear radiation also contributes so much in medical scientific research and development. The US Food and Drug Administration(FDA) required all new drugs to be tested with radioactive tagging before approval. Furthermore, radioisotopes are also used in the research that seeks for the causes and cures for diseases such as Alzheimer's disease, AIDS and cancers.
Radioisotopes also help to treat diseases. For example, radioactive iodine is now widely used in the therapy for thyroid cancer due to the lower recurrence rate as compared to the drug therapy.
Hospitals also use radioisotope radiation to sterilize surgical dressing, syringes, and sutures in order to prevent the spread of diseases.
2) Industrial Application
The industries which use radioactive materials in their processes and products are mining and oil companies, construction companies and automobile and aircraft manufactures.
Radioisotopes are always used as tracers in manufacturing industries. Tracers are essential in ensuring the high efficiency of the product-producing systems. For instances, the tracers can track leakage from piping systems and the rate of engine wear and corrosion of processing equipment also can be monitored. Hence, immediate repairing actions can be taken to maintain the yield of production.
Radiation loses energy as it passes through substances. Highly sensitive gauges are developed by using radioisotopes from industries to measure and detect the thickness and density of materials. For examples, the thickness of metal sheets, photographic film, paper, napkins, textiles and plastics are often controlled, monitored and measured using thickness gauges. Thickness gauges are also used inspect the finished products for weaknesses and flaws.
Density gauges are used by many mining and petroleum companies to locate and identify the reservoir of natural resources such as oil, natural gas and minerals that are embedded deep inside the earth.
Radioactive materials are also used by many industries to inspect the defects of metal parts and welds; to manufacture ceramics and glassware; calibrate instruments; and involved in generation of heat or power for remote, space satellites, weather stations and other special applications.
3) Food Irradiation
The process of exposing food to ionizing radiation is known as food irradiation. It is mainly to kill the microorganisms, pest, viruses and bacteria that may be found in a food and hence prolonging the shelf-life of it. The types of radiation sources include Gamma-ray, X-ray generator, and accelerated electrons. The approved sources of Gamma-ray are cobalt-60 and caesium-137.
Besides killing pathogenic organisms in the food, there are also some other further applications of food irradiation. This depends on the dosage of radiation subjected to or absorbed by the food.
Low dose irradiation is used mainly to inhibit sprouting, disinfest insects as well as delay the ripening of fruits. For examples, potatoes, onions, garlics and gingers are irradiated with low dose of radiation to prevent sprouting. Citrus fruits such as bananas, mangos, guavas and avocados can only be exposed to low level of radiation in order to reduce the loss of vitamins. Food irradiation is an important process for companies that stress on food exportation activities.
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Medium dose irradiation is responsible for controlling food-borne illness and food preservation. This kind of irradiation can be used to effectively eliminate the pathogens that cause illness such as salmonella. Besides, it also destroys or inactivates the microorganisms that cause spoilage and decomposition, thereby extending the shelf-life of food. This ensures a safer food supplies to the society.
High dose irradiation is meant for food sterilization purpose. The irradiated food can be stored in room temperature for several years. Sterilized foods are useful in hospitals for patients with severely impaired immune system. These foods are also used by military as well as for space flight.
The food that has undergone irradiation does not become radioactive. This is because the irradiation process involves only passing the food through the radiation field and the food itself does not come into contact with the radiation source.
Besides that, the nutritional value of the irradiated food is not distorted. Macro-nutrient such as proteins, carbohydrates and fats are relatively stable to radiation dose up 10 kGy.
Nuclear radiation also plays an important role in agricultural sector. Tracers are used in agriculture by scientists to study the physiology of plants and their intake of fertilizers. It is to optimize the usage of fertilizer and weed killing chemicals in order to save money and reduce chemical pollution. This is because the excessive fertilizers will run off and pollute the nearby rivers. The sipping of the excessive chemical through the soil to the underground water directly contaminates the clean water supply. Hence, tracers are often used to overcome these problems. The fertilizers and weed-killers are usually tagged with phosphorus-32 and nitrogen-15 radioisotopes before being used. With this the amount of chemicals consumed by the plants compared to the original amount used is determined.
The yield of crops production is always influenced by the pest infestation. About 10 % of the world's agricultural products are destroyed by insects. In order to control the phenomena, the sterile insect technique (SIT) is introduced. It is a technique of sterilizing insects with ionizing radiation before hatching and releasing the sterile-laboratory raised insect to the wild. The sterile insects do not reproduce after mating with the wild type insects. This reduces the population of insects drastically. This technique is considered to be safer and more effective than insecticides. This is due to the fact that insects can easily develop resistance against insecticides. This means that more powerful or stronger chemicals have to be used. However, the consumption of intensive chemical-treated crops can cause health problems. This technique was conducted in Mexico against Mediterranean screwworm and fruit-fly s in 1981 as the largest application.