Nuclear medicine is a radiology sub-specialty encompassing a number of studies in which a small dose of radioactive material is administered to a patient, allowed to disperse through the body, and then imaged with a special camera that detects the radiation emitted from the body. These types of studies produce images of body anatomy and function that cannot be obtained by other methods.
How does the procedure work?
You are given a small dose of radioactive material, usually intravenously but sometimes orally, that localizes in specific parts of the body. This compound, called a radio-pharmaceutical or tracer, gives off energy as gamma rays. The radio-pharmaceutical that is used is determined by what part of the body is being studied since some compounds collect in specific organs better than others. Depending on the type of scan, it may take several seconds or several days for the substance to travel through the body and accumulate in the organ under study.
During the examination, you will lie down on a scanning table where a specialized nuclear imaging camera will be used to perform the procedure. Depending on what is being scanned, this camera may be a large, round, metallic apparatus suspended from a movable post or a metal arm that hanging over the table. The camera may also be within a large, doughnut-shaped structure similar to a CT scanner or beneath the table out of view.
The gamma camera detects and captures the energy emitted by the radio-pharmaceutical. Imaging time varies, generally ranging from 20 to 45 minutes. A nearby computer console processes the data from the procedure to produce images and measurements of organs and tissues. After the procedure, a Main Line Health Imaging radiologist with specialized training in nuclear medicine checks the quality of the images to ensure that an optimal diagnostic study has been performed.
Is nuclear medicine safe?
Nuclear medicine procedures result in exposure to very small doses of radiation.
Generally, radiation to the patient is similar to that resulting from standard X-ray examinations. Nuclear medicine has been used for more than five decades, and there are no known long-term adverse effects from such low-dose studies. However, pregnant women and breast-feeding mothers must be carefully screened to determine which studies are safe for them. In general, exposure to radiation during pregnancy should be kept to a minimum.
The radioactive agents used in these procedures are carefully handled and measured. The dosages involved are extremely low and are completely safe, though pregnant women and breast-feeding mothers must be carefully screened to determine which studies are safe for them. Most of the radioactivity passes out of your body in urine or stool. The rest simply disappears through natural loss of radioactivity over time.
Applications for nuclear medicine
Nuclear Medicine images can assist the physician in diagnosing many diseases and conditions:
- Analyze kidney and spleen function
- Image blood flow and function of the heart
- Scan lungs for respiratory and blood-flow problems
- Identify blockages of the gallbladder
- Evaluate bones for fracture, infection, arthritis or tumor
- Determine the presence or spread of cancer
- Identify bleeding into the bowel
- Locate the presence of infection
- Measure thyroid function to detect an overactive or under-active thyroid
- Detect tumors, infection and other disorders by evaluating organ function
How should I prepare for the procedure?
Usually, no special preparation is needed for a nuclear medicine examination. However, if the procedure involves evaluation of the stomach, you may have to skip the meal immediately before the test. If the procedure involves evaluation of the kidneys, you may need to drink plenty of water before the test.
Some minor discomfort during a nuclear medicine procedure may arise from the intravenous injection, usually done with a small needle. Allergic reaction to the radio-pharmaceutical material are extremely rare. With some special studies, a catheter may be placed into the bladder, which may cause temporary discomfort. As well, lying still on the examining table for long periods may be uncomfortable for some patients.
Benefits of nuclear medicine
- The information provided is unique and currently unattainable by using other imaging procedures
- For many diseases, nuclear medicine studies yield the most useful information needed to make a diagnosis and to determine appropriate treatment, if any
- Nuclear medicine is much less traumatic than exploratory surgery
Limitations of nuclear medicine
Nuclear medicine procedures can be time-consuming. Preparing and administering the radio-pharmaceutical requires time and it can take hours or days for the radio-pharmaceutical to accumulate in the part of the body under study. While the procedure is being performed, patients must remain as still as possible to ensure ideal image quality. This can be difficult because some imaging procedures can take up to three hours to perform—though new equipment is available that can substantially shorten the procedure time—and sometimes it may take awhile to thoroughly interpret the results.
