Understanding Nuclear Medicine

What is 'nuclear medicine'?

Nuclear medicine is a branch of medicine and medical imaging that uses a small amount of what we call radiotracers, or radiopharmaceuticals, to diagnose disease and to treat disease.

How does nuclear medicine differ from other types of radiology?

Nuclear medicine differs from other modalities that you may know about, like CT or MRI, in that those studies are anatomically based. They look at anatomy structure. Nuclear medicine looks at physiology of the body and of all the organ systems. We can follow the physiological processes as they occur in a living human using these radiopharmaceuticals and through use of appropriate imaging systems.

Why is it called nuclear medicine?

It is called nuclear medicine because we use a small amount of radioactive material, which are based on the nuclear properties of a substance.

How long has nuclear medicine been around?

Nuclear medicine has been around basically since the end of the second World War, so I would say five decades, or a little bit over five decades. In that sense, it's actually a brand new area of medicine.

How does nuclear medicine work?

The way that nuclear medicine works is that we have a patient, of course, with a specific need that requires a nuclear medicine technique. Then we have the radiopharmaceutical that is administered to that patient based upon what the problem is and we can go into detail later on about that. And then of course, we have the imaging system that is required to basically take an image of the distribution, of the bio-distribution, of this radioactive material. So, for example, suppose a patient has metastatic prostate cancer with lesions in the bone. We want to know how extensive the metastatic prostate cancer is in the bone. And, we have a radio tracer which is specifically designed for going to sites of bone metastases where the bone is being repaired or is reactive to the cancer. So the patient is administered with this radiopharmaceutical intravenously, and then after an appropriate amount of wait of the radiotracer to be distributed to the body. Then they position the patient in the chamber system, and as I mentioned, we have these gamma rays coming off from that radioactive activity that is within the patient. And that gamma ray is detected by these imaging systems. Then we have computer systems which gather up these gamma rays and form an image of the distribution of that tracer, radiotracer, in the body. That image is presented on a computer monitor, which we can manipulate, in fact these are not always static images, and we have a lot of dynamic images that we deal with in nuclear medicine. So we can manipulate them, we can look at them with different projections, different contrasts, colours, and basically in combination with the clinical data that we have on that patient, plus other imaging that we have available; for example, anatomical imaging, such as CT or MRI or other imaging mentalities, to interpret what you are looking at. And we put it all together to generate a report that basically discusses what we see and what does it mean from what we see.

What are the benefits and risks of nuclear medicine?

Well, the benefits of nuclear medicine is quite a lot, and it has contributed to the well being of humans for long time through helping with diagnosis and especially more recently helping with therapy in many of the conditions that humans suffer. For example, thyroid cancer and more recently lymphoma. The risks are actually compared to the benefits that we gain from nuclear medicine, and it's actually quite minimal. There is a radiation risk but that's also very small, and it's approximately the same level you receive from natural sources. And there's very little side effects associated with the administration of radio pharmaceuticals if any, and therefore the benefit to risk ratio for nuclear medicine is tremendous.

Who performs procedures in nuclear medicine?

Nuclear medicine is performed by a team of professionals. As a patient comes into the clinic, they are usually greeted by the nuclear medicine technician. These are certified technicians who administer the radio tracer and position the patient appropriately for taking the images. When the images are ready, they are presented to the nuclear medicine physician who may ask for additional images or different manoeuvres. And then finally, it is the nuclear medicine physician who interprets the images in association with all the other clinical data and quality of images to form a report which is given back to the referring physician.

What are examples of the uses of nuclear medicine?

Nuclear medicine is more than just diagnostic imaging. Most of it is diagnostic imaging, but we do actually do a lot of therapy with radioactive sources. One of the major areas is treatment of thyroid cancer, where we use radio iodine for treatment of the thyroid cancer. There are also radio traces available for bone palliation - in patients, for example, that have metastatic prostate cancer, which have bone pain in connection with metastatic disease. These radioactive materials or pharmaceuticals are used to alleviate some of their pain. Also, we can use nuclear medicine, radiopharmaceuticals for treatment of low-grade lymphoma, and its role has been expanding especially recently.

What are some nuclear medicine exams?

Myocardial profusion imaging, which looks at the profusion of the heart in coronary artery disease, is a nuclear medical exam. There is bone scanning that is usually used for looking at the distributional extent of metastatic disease of some sort of cancer to the bone.

Which areas of the body does nuclear medicine help treat?

Nuclear medicine is used for all organ systems in the body - the central nervous system, the heart and major vessels, for gastrointestinal tract, for the urinary system including the kidneys, for soft tissues, for bones and skeleton, and for the lungs. Basically, every organ system is touched upon by nuclear medicine.

How is nuclear medicine used in relation to treating illnesses?

Nuclear medicine is used for a number of very important illnesses, including cancer, cardiac disorders such as coronary artery disease, inflammatory disorders, infections of any organ systems including soft-tissue and bone infections and brain disorders, for example, and gastrointestinal and urinary disorders.

Are there any new up and coming applications for nuclear medicine?

There are always up and coming new applications for nuclear medicine. More recently, there has been a lot of expansion in the role of pository emission tomography, or PET, in a variety of different cancers and also other disorders, for example in neurology and Alzheimer's disease, which is one of the most important ones in which PET is rapidly taking its strides. From the therapy point of view, nuclear medicine is expanding its role in treatment of lymphoma, for example, and through radio labelled antibodies. That's going to expand even more, perhaps into other types of cancer.

What advancements will nuclear medicine see moving forward?

There's always a stride for new tracers and new radio tracers, and that's why radiochemistry is very important in nuclear medicine. As we develop new tracers we are able to look at other physiological processes that we haven't been able to look at very carefully or accurately in the past. There's also strides in imaging systems, especially in what we call hybrid imaging systems which combine anatomy or a structure with physiological information through nuclear medicine. So both from the point of view of what is administered, radiochemistry, and from how we form the image through instrumentation of both, there are great advancements that are going on today.