Definitions

Nuclear Medicine

Over the last century, medical technology has exploded in an unprecedented wave. The average human life span has increased due to this technological explosion and medical conditions that had previously been considered untreatable are now easily remedied. Due to these medical innovations, early diagnosis of diseases have increased exponentially and the appropriate treatments to these diseases are becoming easier and easier.

One of the most important medical innovations of recent years is Nuclear Medicine. Although the word nuclear has a number of negative connotations, nuclear medicine simply utilizes radioactive substances as an instrument that images the body and treats disease. Whereas in the past, exploratory surgery was the most common method for doctors to look inside the body, nuclear medical techniques allow doctors to examine the insides of the human body in a non-invasive manner. Nuclear medical techniques derive information from both the physiology (function) of the body as well as the body’s anatomy to establish both a diagnosis and the appropriate treatment.

Although the medical use of nuclear technology can be traced back to as early as 1895 when Wilhelm Roentgen discovered x-rays, nuclear medicine has only gained prominence in the mid-20th century. In the 1930s, the use of nuclear technology in medicine increased with the development of the Cyclotron and Fission Reaction, a device capable of splitting atoms into radioactive materials. Despite these innovations, nuclear medical materials only became widespread during the 1950s as the development of scanners that traced the distribution of radioactive materials in the body soon paved the way for the development of radiopharmaceuticals (radioactive tracers). Within nuclear medicine, radiopharmaceuticals are given to a patient and will travel to the target organs and tissues. The radiopharmaceuticals give off gamma rays that are detected through the use of special cameras. These images of the targeted organs and tissues form the basis of the nuclear medical physician’s diagnosis and recommended treatment.

As nuclear medicine has evolved, the number of radiopharmaceuticals has increased, thus allowing this technology to be used on a variety of body functions. Consequently, nuclear medicine has moved from in its initial use of solely treating to thyroid disease to incorporate such useful medical applications as:

• Analyzing kidney function
• Imaging blood flow and heart function
• Scanning for respiratory and blood-flow problems in the lungs
• Identifying gallbladder blockage
• Evaluating bones for arthritis, fracture, infection or tumor
• Determining the presence or spread of cancer
• Identifying bowel bleeding
• Locating infection presence
• Measuring thyroid function to detect irregularities such as an overactive or underactive thyroid.

Positron Emission Tomography

As nuclear medical technology has advanced in the last half-century, it has paved the way for a number of new medical technological procedures that are rooted in nuclear medical practices. One such medical technique is positron emission tomography (PET). Positron Emission Tomography, or PET imaging or PET scan as it is also referred to, a non-invasive diagnostic imaging procedure that allows physicians to examine organs such as the heart and brain.

Originally used solely as a research tool, it was not until 1975 that the first primarily used commercial PET scanner was introduced. With technological advances made in the nuclear medicine field, the PET scan procedure moved from producing digital coincidence to producing 3-D images in the 1980s. Despite these innovations, Positron Emission Tomography was predominantly used in research. However, in the early 1990s, the use of PET expanded into clinical use. Hospitals, diagnostic clinics, mobile systems and physician practices began to understand the promise of PET and began to master its use.

With cutting edge medical technological research, the use of PET does not seem to be on the wane. A recent medical advance is the development of the PET/CT to diagnose cancer. This device combines the unique ability of Positron Emission Tomography technology to detect the metabolic signal of actively growing cancer cells in the body with the ability of computed tomography (CT) to produce detailed images of the internal anatomy, thus revealing the size, location, and shape of abnormal cancerous growth. With this medical device, the images that are produced provide a physician complete information of cancer location and metabolism.

The PET scan procedure differentiates itself as an imaging procedure from other procedures like x-rays, computed tomography (CT), and magnetic resonance imaging (MRI) as it produces images that are able to detail the chemical function of the targeted organ or tissue. The aforementioned procedures are only able to detail body structure. This pronounced difference is important, as PET imaging are able to make the distinction between benign (alive tissue) and malignant (dead tissue) disorders. The aforementioned imaging procedures are only able to confirm the presence of a mass. Consequently PET is a valuable tool for physicians who require information about the chemical function of such vital organs as the heart and brain in recommending a medical course of action.

How Positron Emission Tomography is able to produce these images are rooted in the basis of nuclear medicine. In the PET scan procedure, a patient is given a substance that is usually tagged with a radiopharmaceutical that has a short decay time. Although many individuals are concerned about the presence of radiopharmaceuticals within their body, the PET procedure is actually safe. The radiation content of radiopharmaceuticals are minute and the patient is exposed to the radiation equivalent of two chest x-rays. Radiopharmaceuticals are given to a patient predominantly through injection, but can also be given through an existing intravenous line or inhaled as a gas. Once the radiopharmaceutical is inside the body, it travels to its targeted source.