THE MEDICAL IMAGING EXPERIENCE
INFORMATION FOR THE PATIENT
NUCLEAR MEDICINE THYROID UPTAKE & SCAN

WHAT IS IT?
The Nuclear Medicine Thyroid Uptake portion of the procedure is an exam to determine how much iodine the thyroid gland collects. The Thyroid Scan part of the exam also looks at the size and shape of the thyroid gland.

Nuclear Medicine scans are performed using very small amounts of radioactive material. The radioactive material is usually bound to other non-radioactive elements. These combined elements are called "radionuclide". The radionuclide emit energy called "photons". Radionuclide can be directed to many organs and systems in the body. Once a radionuclide is distributed in an organ or system, the photon energy is collected by a "Gamma Camera". The Gamma Camera detects the pattern of distribution of the radionuclide in the body and sends this information to a computer. The computer processes the information and displays the information in the form of a picture.

Nuclear Medicine exams differ from other x-ray procedures because the energy (x-rays and photons) come from different sources. X-ray energy is created by the x-ray tube and pass through the body. Another major difference is that Nuclear Medicine exams best demonstrate body physiology (system function), whereas x-rays show anatomical detail.

WHAT WILL HAPPEN TO ME?
The Nuclear Medicine Technologist will give you a special radioactive iodine pill to swallow which is then collected in the thyroid gland. The radioactive iodine in the pill slowly enters the blood stream after it is swallowed. To start the uptake part of the exam, the technologist will position you in front of a probe that will measure the amount of iodine from the pill that collected in your thyroid gland. After the uptake is complete, the technologist will assist you to lay on a flat table and position the Gamma Camera over your thyroid gland to take a picture. The Gamma Camera will be very close to you to obtain the best picture.

HOW LONG WILL THIS TEST TAKE?
It takes about 15 minutes to discuss the exam with you and to give you the radioactive pill. After taking the pill, you will need to wait four (4) hours before the uptake and scan can be performed. Once the actual uptake and scan are started it takes 30 - 60 minutes to complete. You will be required to return the next day for another thyroid uptake measurement. The second measurement takes about 15 minutes to complete.

WHAT WILL I FEEL -- WILL IT HURT?
You will need to stop taking thyroid medication for 4 - 6 week prior to the exam. Your doctor will give you instructions regarding your thyroid medication. You will not feel any effects from the radioactive pill. When your exam is begun, you will need to sit on a chair in front of a special probe for the uptake portion of the exam and then lay flat on a table for the scan with your head extended backwards and a sponge under your shoulders. You will need to lay very still while the uptake and scan is being performed so that the best picture can be made. You will not feel any effects from the probe or the Gamma Camera. It does not create radiation, it only detects the energy coming from the collection of radioactivity in your thyroid gland. The Gamma Camera is a large machine that collects the emitted photons from the radioactivity but produces very little sound. The Gamma Camera must be very close to you and will be moved over your body to obtain the pictures. The radiation will totally disappear from your body in about four (4) days. The radiation exposure you receive from this exam is no more than from a routine x-ray procedure.

WHAT WILL THE TEST SHOW?
The radioactivity in the pill is collected by your thyroid gland in different patterns depending on the function of the gland. If one area of the thyroid receives more of the radionuclide than other areas this can be seen on the scan. Very slight changes in the thyroid gland can be detected by the scan. Also the amount of radioactivity that is collected by the thyroid gland shows the level of gland function.

HOW DO I GET READY?
You should not eat or drink for six (6) hours before the exam. Some contrast x-ray procedures will interfere with this test. The Nuclear Medicine Technologist will ask you about these. The Nuclear Medicine Technologist will also question you about any medications you may be taking since some medications will interfere with the accuracy to this exam. After you have been given the radioactive pill, you should not eat for the following two (2) hours. You should remove any necklaces from around your neck since these will interfere with the pictures.

Reviewed: September 2005