When we think radioactivity, our minds naturally go to nuclear weapons or power plants. We all know radiation is DANGEROUS. But we rarely think about its beneficial uses, especially when it comes to medicine.
But radioactivity is the energy behind one of the most useful diagnostic imaging modalities in use today: nuclear medicine. The modality is unlike any other medical imaging technique because it allows the physician to see how organs, tissues and bones function at the cellular level. Even the most powerful MRI cannot do that.
How does it work?
Radioactive isotopes (called tracers) are introduced into the body either through an IV injection or orally. These tracers make their way to the part of the body being studied. Interestingly, there are about 20 different radioactive isotopes that can be used and each of these tends to be attracted to certain body systems. For example, iodine-123 goes to the thyroid gland, making it very helpful in diagnosing hyper- and hypothyroidism.
As the tracer makes its way to the system being studied, a special camera that measures gamma radiation, records how the system processes (uptakes) the tracer. Based on these studies, the radiologist can determine whether the organ or system is functioning normally on a cellular level.
Nuclear medicine is useful in diagnosing a wide array of conditions affecting the bones, gallbladder and thyroid.
Is it safe?
The amount of radiation the patient receives during a nuclear medicine study is typically quite low: usually less than that received during a routine x-ray and significantly less than that received during a CT scan.
There are three primary reasons for this. First, only a minute amount of tracer is required to capture nuclear medicine images. Tracers degrade quickly. And the body excretes them naturally, usually within 24 hours. Patients are able to resume their normal daily activities immediately following a nuclear medicine study with few restrictions. Drinking plenty of fluids will help to flush the tracer from the body.
Because nuclear medicine scans show function, they are very good at finding problems early in the course of a disease. Other modalities can determine the extent of the problem after physical change has occurred, but they cannot capture the damage in process.
Some things nuclear medicine does that makes it different than other scans:
