Often, the patient is imaged shortly after the administration of the radionuclide, but occasionally the patient may be asked to return 30 minutes to four hours after administration of the radionuclide, to begin the imaging process. For some exams, the radionuclide will be administered the day before the exam. This allows time for the radionuclide to be "taken up" by the specific organ(s) being imaged. Different organs take up or absorb the radionuclide at different rates.
The patient is positioned by the technologist on an examination table. Some nuclear medicine studies allow the patient to be seated. The nuclear medicine camera is then positioned over the area of interest, for example, the heart. Some nuclear medicine cameras have a patient aperture ("doughnut hole") like a CT scanner and the patient is positioned inside of this aperture for the study. The patient is simply required to relax and stay calm during the examination. During the nuclear medicine examination, the technologist and patient can communicate at any time.
After the examination, which can last from 15 to 60 minutes, the technologist will ask the patient to get dressed and wait while the nuclear medicine images are reviewed (either on film or a computer monitor).
Nuclear medicine "stress tests" involve exercise on a treadmill or stationary bicycle, followed by a nuclear medicine acquisition. After a sufficient period of rest, a second acquisition is made to acquire images of the heart at rest. Occasionally when exercise is contraindicated or not recommended for a patient, "stress" to the heart may be accomplished by the administration of medication. Patients who will undergo a stress test should wear low healed, rubber-soled shoes or tennis shoes and comfortable clothing that will allow them to walk on the treadmill as required. This will make the exam easier for most patients.
After the nuclear medicine images are reviewed, the patient will be released from the imaging department or center. In some cases, more images will need to be taken. For more information see "what happens during a diagnostic imaging examination?"
Patients retain the low level radioactivity administered during a radionuclide study for relatively short periods. The radiation doses involved are so low that a person accompanying a patient can stay with them throughout the day. For example, with bone scans studies, patients can leave while the radionuclide distributes in their body and come back several hours later for the procedure.
The radioactive energy dissipates on its own, and some of the radiation is eliminated through urine or bowel movement. The result is that the radioactive material is only in the patient for a short time. Once the energy is eliminated, patients no longer carry the radioactivity. The levels of radiation involved in most nuclear medicine studies are usually considerably lower than a patient would receive in a conventional x-ray study or CT scan. Approximately 12 million nuclear medicine exams are performed in the U.S. each year.
