Nuclear Medicine & Positron Emission Tomography (PET)

Nuclear Medicine is a medical specialty that uses tiny quantities of radioactive material or radiopharmaceuticals (tracers) to diagnose or treat diseases. For imaging different organs and diseases, different radiopharmaceuticals are used.

Radiopharmaceuticals in Action

Tracers (radiopharmaceuticals) are introduced into the patient’s body by injection, swallowing, or inhalation. The amount given is very small. The medicine part of the tracer goes to a specific organ in the body where a disease or abnormality is expected. The radioactive part of the tracer emits radiation, which is detected using a special camera called a gamma camera.

Are radiopharmaceuticals safe?

Absolutely. The quantity of pharmaceutical part of the tracer is very small, generally 1/10th of a millionth of an ounce. As a rough estimate, one tea-spoon of sugar is sufficient to perform approximately 5 million scans. The risk of a reaction is 2-3 incidents per 100,000 injections, over 50% of which are rashes.

Is the radioactivity harmful?

A larger exposure to radioactivity is always harmful. However, the amount of radioactivity in tracer is carefully selected and appears to be safe. No reports have yet been made available, regarding any harmful human effects in diagnostic Nuclear Medicine procedures.


Generally, no special preparation is required for most of the tests. In a heart scan, you may be required to discontinue certain medications for a limited time prior to the test.

In a case of renal (kidney) scan, you must drink more water before the test. Generally, drinking more fluids after the procedures will help to eliminate the radiopharmaceutical quickly from the body.

At the clinic, you may be asked to change into an x-ray gown and remove jewellery or ornaments which may obscure the region of interest.

For female patients, they will be asked to certify that they are not pregnant. If there is any possibility of pregnancy, this should be brought to the attention of the physician or radiographer or nurse attending to you.


Administering the tracer

  • A small amount of the tracer may be injected, inhaled or swallowed. Once administered, depending upon the nature of scan, you may be asked to wait for about 15 minutes to two hours. The staff will brief you about waiting time for the procedure.
  • The wait time is to allow the tracer to reach the area of interest.


  • When it is time for the scan, you will be asked to lie on the bed with the camera placed close to the part of the body being images. It is important to remain still as any movement would result in blurred images that are difficult to interpret.
  • A delayed image may be necessary in selective cases. The radiographer will inform you should such a need arise.
Benefits and risks
Nuclear Medicine & Positron Emission Tomography is available at:

Nuclear Medicine & PET Centre
Mount Elizabeth Hospital

3 Mount Elizabeth, Level 1
Singapore 228510
(65) 6731 2928
Fax: (65) 6734 2928

Radiology Department,
Mount Elizabeth Novena Hospital

38 Irrawady Road, Level 2
Singapore 329563
(65) 6933 1188
Fax: (65) 6933 0526


Visit this FAQs page for more information.



For any enquiries, feel free to contact us.

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