Applications of Radioactivity in Medicine

Introduction

A radioactive element is an element with an unstable nucleus, which radiates alpha, beta or gamma radiation and gets converted to a stable element.

Both radioisotopes and enriched stable isotopes are essential to a wide variety of applications in medicine, where they are used in the diagnosis and treatment of illnesses. In addition, extensive applications of isotopes in biomedical research finds wide parallel uses in research chemistry, physics, biology and geosciences, with additional needs existing in the commercial sector.

HISTORY

Radioactivity arrived on the scene of the world in the 19th century, just when people thought they knew everything in science. With its discovery in 1896, radioactivity opened a box of many questions and revealed a new world, waiting to be explored in the microcosm of the atomic nucleus.

Radioactivity also helped in answering the questions which were not yet known. This helped science in many fields.

WHAT MAKES AN ELEMENT RADIOACTIVE?

There are three kinds of particles inside an atom: that is protons, neutrons and electrons. The nucleus contains the above mentioned two particles i.e. protons and neutrons. The region beyond the nucleus contains electrons that balance out the charge of the protons. The number of protons is equal to the number of neutrons that is why the atomic weight is twice the atomic number. Since like charges repel each other which results a force that tries to push the electrons and protons apart. If the ratio of protons to the neutrons is not within certain limits then the proton can not be held firmly together which leads to the formation of an unstable nucleus. Making the isotopes of some elements radioactive.

For example, carbon, the element found in all living things has a chemical symbol C. the normal form has an atomic weight of 12 and is written as carbon-12, but the radioactive version has two extra neutrons, so the symbol iscarbon-14.

As we shall see, the radioactive form behaves chemically just like the non-radioactive form, although one shall never change into the other. There are three kinds of radioactivity each with different radiation type.

RADIOACTIVITY

Radioactivity is a very interesting phenomenon in nature. Classical Electromagnetism cannot explain radioactivity. It’s a spontaneous and random phenomenon whereby nuclei of certain chemical elements like Uranium, radiate gamma rays, beta particles and alpha particles.

By the emission of these particles and radiation, the unstable nucleus gets converted into a stable nucleus. This is called RADIOACTIVE DECAY.

Radioactivity was accidentally discovered by HENRI BECQUEREL.

Scientists like Madam Curie and her husband Pierre also worked hard to isolate other radioactive elements such as Polonium and Radium. Knowledge of radioactivity helped scientists to work out the structures of atoms.

USES OF RADIOACTIVITY

We could not do without radioactive materials in today’s world, even if we wanted to. We rely on these radioactive elements every day to make us healthier, to help supply necessities like food and electricity, keep us safer, help us to protect our environment, add fun and convenience to our lives and help us learn more about our world.

Radioisotopes have found a large number of applications. Some of them are as follows:

• Medical Diagnosis
• Generate Electricity
• Synthesis of new elements
• Preservation of food
• Smoke detectors

and many more

RADIOACTIVITY IN MEDICINE

Ionizing radiations has many beneficial uses as they can be used for the diagnosis and for the curing of many diseases. Since infected cells can be killed by these radiations. Hence they are widely used in caner treatments.

Radioactive isotopes are commonly used in medicine, which help the physicians to know more about the body structures. For the treatment of cancers radioisotopes are commonly used which require destruction of harmful cells causing these type of diseases.

Although nuclear medicine started its clinical origin in the 1930 decade, the invention of gamma scintillation camera by an American engineer Hal Anger in the mid of 1950s, though, this invention brought an important turn back in medicine imaging Radioactive isotopes also allow excellent quality imaging of bones, heart, liver and many parts of our body. Gamma ray emitted tracers are used in large number of diagnostic procedures in nuclear medicine. These traces are formed due to the bonding of radioisotopes having short life period with chemical compounds that allow the targeting of a particular body regions or physiologic processes. Emitted gamma rays can be detected by gamma cameras and computer enhancement of the resulting images allows quick and relatively non-invasive assessments of trauma or physiological impairments.

CANCER which is a process of rapid growth of cells gets damaged by radio isotopic radiations. Somehow, some cancerous growth of cells can be eliminated or restricted by the use of radioisotope radiations. The most common forms of external radiations therapy is use of the gamma radiations and X-rays. During the last half of the twentieth century the radioisotope Cobalt-60 was most commonly used source of radiation used in such treatments.

Today thousands of hospitals all over the world use radioisotopes in medicine, and about 90% of the procedures are used for diagnosis. Technetium-99 is the most common isotope used in diagnosis, with some 30 million procedures in a year, accounting for 80% of all nuclear medicine procedures all over the world.

ISOTOPS COMMONLY USED IN MEDICINE:

There are about 20 radioactive isotopes used in medicine. Each isotope has its own use in this field.

Some of them are:

Chromium-51, cobalt 60, Erbium 169, Iodine-125, Iridium-192, Sodium-24, Xenon-133, Selenium-75, Strontium-89, Phosphorus-32 etc.

Here is a list of isotopes with there half life period and uses:

• Chromium-51: Half life period 28 days Purpose: Used to label red blood cells and quantify gastro- intestinal protein loss.
• Cobalt-60: Half life period is 10.5 months Purpose: Formerly used for external beam radiotherapy.
• Erbium-169 Half life period is 9.4 days Purpose: Use for relieving arthritis pain in synovial joints.
• Iodine-125 Half life period is 60 days Purpose: Used in cancer Brach therapy (prostate and brain), also diagnostically to evaluate the filtration rate of kidneys and to diagnose deep vein thrombosis in the leg. It is also widely used in radioimmunology- assays to show the presence of hormones in tiny quantities.
• Iodine-131 Half life period is 8 days Purpose: Widely used in treating thyroid cancer and in imaging the thyroid; also in diagnosis of abnormal liver function, renal (kidney) blood flow and urinary tract obstruction. A strong gamma emitter, but used for beta therapy. Iodine used for curing thyroid cancer
• Iridium-192 half life period is 74 days Purpose: Supplied in wire form for use as an internal radiotherapy source for cancer treatment (used then removed).
• Sodium-24 Half life period is 15 hours Purpose: For studies of electrolytes within the body.
• Xenon-133 Half life period is 5 days Purpose: Used for pulmonary (lung) ventilation studies.
• Phosphorus-32 Half life period is14 days Purpose: Used in the treatment of polycythemia Vera (excess red blood cells). Beta emitter.
• X-Rays are used to examine the internal parts of the body that is bones to see the fractures.

Applications of X-Rays:

• Radiography: Radiography is used to diagnose the ailment and diseases of the internal and hidden parts of the body using x-rays.
• Fluoroscopy: Fluoroscopy is a type of medical imaging that shows a continuous x-ray image on a monitor.
• Digital Subtraction Angiography: Digital Subtraction Angiography (DSA) is used to image blood vessels.
• Computerized Axial Tomography: A computerized axial tomography scan is an x-ray procedure that combines many x-ray images with the aid of a computer to generate cross-sectional views and, if needed, three-dimensional images of the internal organs and structures of the body.
• Mammography: Mammography is a special type of x-ray that is used for the detailed images of breast.
• Radiation Therapy: Radiation therapy (also called radiotherapy), high-energy rays are used to damage cancer cells and stop them from growing and dividing. A specialist in radiation therapy is called a radiation oncologist.

Uses of Radioactive Materials in Medical Research

Used in Biomedical researches: – The Radioactive isotopic materials are very essential in curing many dreadful diseases like AIDS, cancer and Alzheimer’s disease.

In Pharmaceutical drug testing: – The U.N. Food and Drug Administration require all new pharmaceutical drugs to be tested for safety and effectiveness. More than about 80 percent of those drugs are tested with radioactive materials. One of the most important tests is to determine if the pharmaceutical is going to the other parts of the body than the desired or intended target and what effect it can cause to the parts where it is not needed. By adding a radioactive tag to the pharmaceutical, researchers can pinpoint all the parts of the body and the concentration that accumulates non-targeted areas. From this they can determine if there is likelihood of adverse reactions in other parts of the body.

Metabolic Research: – Radionuclide is used extensively in metabolic studies and genetic engineering.

Chemical Reaction Imaging: – the latest single photon emission typography (SPET) on positron emission tomography (PET) enable scientists to watch colour images of chemical reactions in living tissue and, in particular, to trace opioid molecules- naturally occurring morphine-type drugs – which eliminate pain within the brain.

Side Effects of Radiation

The form of the energies that are released from these elements in radiation therapy is often administered by machine. The machine aims those radiations at the cancer. Radioactive substances can also be kept inside the body of a person. These types of treatments can cause many side effects.

These side effects may include:

• hair loss
• nausea
• vomiting
• swelling
• difficulty swallowing
• urinary and bladder changes

The side effects caused due to the treatment of the patient can last long for a certain period of time. It may be a period of two months, six months or even a year. So the patient has to bear some pains after or during the curing of fatal diseases like cancer using radiation therapy.

Radioactive Waste Disposal: An Environmental Perspective

Any activities that produce or use radioactive materials generate radioactive wastes. Various processes in medicine, scientific result and in all other fields produce bi products that include radioactive wastes. Radioactive waste can be in gas, liquid or solid form, and its level of radioactivity can vary. The waste can remain radioactive for a few hours or several months or even hundred or thousands of years. Because it can be hazardous and can remain radioactive for so long, finding suitable disposal facilities for radioactive wastes is very difficult. Depending on the type of waste disposed, the disposal facility may need to contain radiations for a very long time. Proper disposal is essential to ensure protection of the health and safety of the public and quality of the air, soil and water supplies.

Radioactivity waste disposal practices have changed substantially over the last twenty years. Evolving environmental protection considerations have provided the impetus to improve disposal technologies, and, in some cases, clean up facilities that are no longer in use. Designs for new disposal facilities and disposal methods must meet environmental protection and pollution prevention standards that are stricter than were foreseen at the beginning of the atomic age.

CONCLUSION

One hundred years ago, a group of scientists unknowingly ushered in the atomic age. Driven by curiosity, these men and women explored the nature and also the functioning of atom. Their work initiated the paths of research which changed our understanding of the building blocks of matter. There discoveries prepared the way for development of new methods and tools used to explore our origins, the functioning of our bodies both in sickness and health, and much more. How did our conceptions of atomic properties change? How has that change affected our lives and our knowledge of world?

Radiation is a two edged sword: its usefulness in both medicine and anthropological and archaeological studies is undisputed, yet the same materials can be used for destruction. Human curiosity drove inquiring scientists to harness the power of an atom. Now humankind must accept the responsibility for the appropriate and beneficial uses of this very powerful tool.