What is nuclear medicine?
Nuclear Medicine is a sub specialty within radiology. The images are developed based on the detection of energy emitted from a radioactive substance given to the patient, either intravenously or by mouth. This is called a radiopharmaceutical and comprises of two components. The radioactive substance and a pharmaceutical substance often referred to as the "carrier".
The radiopharmaceutical is usually administered intravenously, into the arm, but sometimes orally. This localises in specific body organs or systems, depending on the "carrier" used and gives of gamma rays. The gamma camera detects the rays and works with a computer to produce images and measurements of organs and tissues.
Generally, radiation to the patient is similar to that resulting from standard x-ray examinations.
What are the uses of the procedure?
Nuclear medicine images can assist the physician in diagnosing diseases. Tumours, infection and other disorders can be detected by evaluating organ function. Specifically, nuclear medicine can be used to analyse kidney function, image blood flow and function of the heart and scan the lungs for respiratory and blood flow problems. It can also identify blockage of the gall bladder, evaluate bones for fracture, infection, arthritis or tumour, determine the presence or spread of cancer, identify bleeding into the bowel, locate the presence of infection, and measure thyroid function to detect overactive or underactive thyroid.
What does the equipment look like?
During most nuclear medicine examinations the patient is asked to lie down on a scanning table. The gamma camera or detector used to detect the distribution of radioactivity within the patient consists of a large rectangular box containing sensitive electronic equipment. This is attached to a large gantry, which allows the camera to rotate through 360 degrees within the gantry and also enables the table to be moved over or under the face of the camera.
A computer system is connected to this equipment to acquire and process data from the procedure. Subsequently hard copy images of the scans are produced from a laser imager.
Preparation for a scan
Usually no preparation is needed for a nuclear medicine examination. However, if the procedure involves evaluation of the gastro intestinal system or urinary tract then specific instructions will be given. It is sometimes necessary to stop certain medications prior to the scan, but this would be evaluated at the time the appointment is given to the patient.
The nuclear medicine scan
A radiopharmaceutical is usually administered into a vein. Depending on which type of scan is being performed, the imaging will be done either immediately, a few hours later, or in some cases several days after the injection. Imaging time varies, generally ranging from 20 to 60 minutes.
The radiopharmaceutical that is used is determined by what part of the body is under study since some compounds collect in specific organs better than others. Depending on the type of scan, it may take several seconds to several days for the substance to travel through the body and accumulate in the organ under study, thus the wide range in scanning times. It is particularly important that the patient remains completely still whilst the images are acquired.
After the scan
After the procedure, a radiologist with specialised training in nuclear medicine will study the images and provide a report to the requesting consultant or physician.