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Medical Applications

Nuclear medicine and radiology are the whole of medical techniques that involve radiation or radioactivity to diagnose, treat and prevent disease.  While radiology has been used for close to a century, “nuclear medicine” began approximately 50 years ago.  Today, about one-third of all procedures used in modern hospitals involve radiation or radioactivity.  These procedures are among the best and most effective life-saving tools available, they are safe and painless and don’t require anesthesia, and they are helpful to a broad span of medical specialties, from pediatrics to cardiology to psychiatry.

While both nuclear medicine and radiology are used in diagnostic procedures (to determine a patient’s health, monitor the course of an illness or follow the progress of treatment) and therapeutic procedures (to treat illnesses), they are implemented differently. In nuclear medicine, radioisotopes are introduced into the body internally, whereas in radiology X-rays penetrate the body from outside the body.


Personal health improves with radiation.

  • It allows for quick, safe, early, and more accurate medical diagnoses.
  • It can be harnessed as a treatment for certain diseases.
  • Tens of millions of patients are treated with nuclear medicine each year and more than 10,000 hospitals worldwide use radioisotopes in medicine.
  • Employment of nuclear medicine technologists is projected to grow 10 percent from 2016 to 2026, faster than the average for all occupations.

Major Advances in Nuclear Medicine Diagnosis and Treatment

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Exploratory surgery used to be the way doctors investigated health problems. Doctors would cut, poke, and prod. But since the 1940’s, nuclear technologies have offered an increasing array of diagnostic techniques that help patients avoid the pain of surgery while their physicians gain knowledge of the body’s inner workings.

X-rays, MRI scanners, CAT scans, and ultrasound each use nuclear science and technology to troubleshoot different parts of the body and diagnose conditions. Each of these are non-invasive procedures, meaning patients do not need to undergo surgery. More advanced nuclear medicine uses computers, detectors, and radioisotopes to give doctors even more information about a patient’s internal workings. Known as nuclear imaging, these procedures include bone scanning, Positron Emission Tomography (PET), Single Photon Emission Computed Tomography (SPECT) and Cardiovascular Imaging. The use of these procedures depends on the patient’s symptoms.

Radioisotopes are useful because the radiation they emit can be located in the body. The isotopes can be administered by injection, inhalation, or orally. A gamma camera captures images from isotopes in the body that emit radiation. Then, computers enhance the image, allowing physicians to detect tumors and fractures, measure blood flow, or determine thyroid and pulmonary functions.

The first radiopharmaceutical to be widely used was the fission product, iodine-131, in the form of the simple salt, sodium iodide. Its use was established in the late forties as a diagnostic test for certain thyroid disorders. Since the drug could be administered orally, in solution, it was referred to in the press as the “Atomic Cocktail”.

Since those pioneering days, the practice of nuclear medicine has soared in most developed countries. Approximately 16 million people in the United States are tested diagnostically each year with a radioactive drug, either in vivo or in vitro.

In vivo

There are fewer than 50 radiopharmaceuticals for in vivo administration that are in common use. Many of them are used for identical diagnostic tests; the choice of a particular one frequently depends on the personal preferences of the practitioner. The development of more effective radiopharmaceuticals is being intensively investigated in several laboratories all over the world and it is likely that the drugs used in nuclear medicine will be altered considerably during the next 10 to 20 years.

Radiopharmaceutical Application
1311 (also 12SI)- Sodium iodide Thyroid uptake
1311 – Rose Bengal Liver scan
1311 – Hippuran Kidney scan
1311 – Human serum albumin Blood volume, circulatory studies
1311 – lodinated oils Fat absorption studies
51 Cr – Sodium chromate Spleen scanning (by tagging red blood cells)
57Co – Vitamin B-12 Pernicious anemia diagnosis
198Au – Gold colloid (less than 1 micron diameter particle) Liver scan
197Hg – Chlormerodrin Brain and kidney scans
75Se – Selenomethionine Pancreas scan
1311 or 99mTc – Macroaggregated serum albumin (30- 50 micron diameter particles) Lung scan
18F – Sodium fluoride Bone scan

In vitro

There are a number of in vitro clinical tests which employ radioactive reagents, but the most important one in present use is the radioimmunoassay (RIA) for body hormones.Radioimmunoassay is an exceedingly sensitive technique that is capable of measuring most hormones at the nanogram to picogram level. It is also very specific since the antibody binds its specific hormone very selectively. A surprisingly wide range of hormones and other antigens can be assayed by this method. A few examples are assays for insulin, thyroxine, prostaglandins, digitoxin, human growth hormone, and the “hepatitis associated” antigen, the test for which can minimize hepatitis injection through blood transfusions by pre-testing donors.


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