Nuclear Scan

Medically Reviewed By William C. Lloyd III, MD, FACS
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What is a nuclear scan?

A nuclear scan is an imaging test that uses imaging technology and trace amounts of radioactive materials, called radiotracers, to diagnose and monitor diseases and treatments. Nuclear scans can show the structure and function of most body organs and tissues. Doctors use nuclear scans to evaluate and treat a wide variety of conditions, including cancer, coronary artery disease, and seizure disorders.

In a nuclear scan, the radiotracer illuminates organs and tissues by releasing radiation inside the body, instead of targeting the radiation from outside the body, as with X-rays. Nuclear scans are based on your body’s ability to absorb, or take up, certain substances. Body tissue that is infected, inflamed, or growing abnormally (such as a cancer cell) absorbs the substance differently—usually more—than other tissues. Special cameras (nuclear scanners) detect the radiation once it is absorbed into your body.

Nuclear scans go beyond showing the structure of your body. They provide important information about how organs and tissues are functioning that generally cannot be learned using other imaging methods. Nuclear scans can also identify some diseases and conditions in their earliest, most treatable stage. 

A nuclear scan is only one method used to diagnose and treat various diseases and conditions. Discuss all of your testing options with your doctor to understand which options are right for you.  

Types of nuclear scans

General types of nuclear scans include:

  • Gallium scan looks for infection, inflammation or cancer in certain organs or in the whole body.

  • PET scan (positron emission tomography) evaluates such functions as blood flow, oxygen use, and glucose metabolism. Doctors often use PET scans to evaluate cancer, heart disease, and nervous system problems to see how they are responding to treatment.

  • PET/CT is a combination PET and CT scan to diagnose, stage or restage cancer and evaluate the treatment plan. PET/CT scans create three-dimensional (3-D) pictures to pinpoint the exact location of cancer and other diseased tissue.

  • SPECT scan (single photon emission computed tomography) creates 3-D images to show how blood flows to tissues and organs. SPECT scans are particularly useful in diagnosing heart and blood vessel conditions.

Specific types of nuclear scans include:

  • Bone scan checks for infection and bone cancer.

  • Gallbladder scan checks gallbladder function and helps find the cause of upper abdominal pain.

  • MUGA (multiple gated acquisition) scan and other nuclear heart scans evaluate the pumping of the heart, how blood is flowing to the heart muscle, and if heart muscle is damaged.

  • RBC scan (red blood cell) helps to identify bleeding along the gastrointestinal tract

  • Renal scan checks kidney function.

  • Thyroid scan checks for hyperthyroidism (overactive thyroid), thyroid cancer, and thyroid nodules.

Why is a nuclear scan performed? 

Your doctor may recommend a nuclear scan to screen, diagnose and monitor diseases, disorders and conditions in almost any part of the body. Examples include:

Who performs a nuclear scan?

A radiologic technologist may perform a nuclear scan under the supervision of a doctor. A radiologic technologist is a healthcare provider who performs imaging procedures and takes care of patients during procedures. 

The following types of doctors may supervise your nuclear scan and interpret the results: 

  • Radiologists specialize in using radiation and other imaging techniques to diagnose and treat a wide variety of conditions from broken bones and birth defects to cancer.

  • Nuclear radiologists specialize in using imaging technologies and radioactive materials to diagnose and treat disease.

  • Nuclear medicine doctors specialize in using radioactive materials to diagnose disease and guide treatment plans.

How is a nuclear scan performed?

Your nuclear scan will be performed in a hospital radiology or nuclear medicine department. The procedure takes 30 minutes to a few hours. 

There is a waiting period to have the scan after you receive the radiotracer. This varies from minutes to days, depending on the type of nuclear scan. Nuclear scanning procedures also vary but generally include these steps:

  1. You may or may not need to remove jewelry, undress, and put on a patient gown.

  2. You will receive a radiotracer through an IV or by drinking or inhaling it. Sometimes you may receive the radiotracer hours or days before pictures are taken. In this case, you may leave and come back later for the scan.

  3. You will lie on a padded table. Your radiologic technologist will position you in a way that makes the best images for a specific type of nuclear scan.

  4. The nuclear scanner will take a series of images. You will need to lie still while the scanner takes the pictures. Some types of nuclear scanners move around you, while others have a table that moves you through a doughnut shaped scanner. Some scans involve taking series of images over time. You may need to change positions between pictures during certain types of scans.

  5. You will wait briefly while the doctor or radiologic technologist checks the images to make sure they are clear.

  6. You will go home right away after an outpatient nuclear scan.

Will I feel pain?

Your comfort and relaxation is important to both you and your care team. The nuclear scanning machine never touches you and taking the images is not painful. Your positioning on the table should be comfortable. Tell your care team if you are uncomfortable or have problems breathing. 

If you need an IV to receive the radiotracer, you may feel a brief stick or pinch during IV insertion. You may also feel a fleeting warm sensation when the radiotracer is injected. Take a few long, deep breaths to help yourself relax. Tell you care team if any discomfort does not pass not pass quickly.

What are the risks and potential complications of a nuclear scan? 

Nuclear scans are generally safe. There is a very small increased risk of cancer due to the radiation exposure involved with nuclear scan. Nuclear scans expose you to about as much radiation as a standard X-ray. Your care team follows strict standards for nuclear medicine techniques. Your team will use the smallest amount of radiation possible to produce the best images.

Your doctor will generally not order a nuclear scan if you are pregnant due to the danger of radiation to an unborn child. If you are breastfeeding, you may need to pump breast milk and dispose of it until the radiotracer is gone from your system. It is very important to tell your doctor if there is any chance that you are pregnant or if you are breastfeeding.

Allergic reactions to radiotracers are rare, and nuclear scan teams are well prepared to handle allergic reactions. 

How do I prepare for my nuclear scan?

You are an important member of your own healthcare team. The steps you take before your test can improve your safety and comfort and help obtain the most accurate results. 

Your care team will give you instructions to prepare for your nuclear scan. This may include not taking certain medications or not eating or drinking before the test. In general, you can prepare yourself for a nuclear scan by:

  • Answering all questions about your medical history, allergies, and medications. This includes prescriptions, over-the-counter drugs, herbal treatments, and vitamins. It is a good idea to carry a current list of your medical conditions, medications, and allergies at all times.

  • Leaving all jewelry and metal objects at home

  • Telling your doctor and your radiologic technologist if you feel nervous or anxious about lying still or having the nuclear scan

  • Telling your doctor if there is any possibility of pregnancy or if you are breastfeeding

Questions to ask your doctor

Preparing for any medical testing can be stressful. It is common for patients to forget some of their questions during a doctor’s office visit. You may also think of other questions after your appointment. Contact your doctor with concerns and questions before your procedure and between appointments.

It is also a good idea to bring a list of questions to your appointments. Questions can include:

  • Why do I need a nuclear scan? Are there any other options for diagnosing or screening my condition?

  • How will I receive the radiotracer for the nuclear scan?

  • How long will the procedure take? When can I go home?

  • When and how will I receive the results of my nuclear test?

  • What other tests or treatments might I need?

  • When should I follow up with you?

  • How should I contact you? Ask for numbers to call during and after regular hours.

What can I expect after my nuclear scan?

Knowing what to expect after a nuclear scan can help you get back to your everyday life as soon as possible.

The radiotracer will gradually disappear from your body over several hours to days. Your care team may recommend that you drink extra fluids to help flush out the radiotracer. You should wash your hands frequently and flush the toilet immediately for several days after urinating to avoid exposing others to radiation as the radiotracer is washed out of your system.   

The radiation in the radiotracer may set off certain security systems, such as at the airport, until it is completely gone from your body. Your care team will give you a card that explains this. Carry the card with you for several days. 

How will I feel after the nuclear scan?

You should be able to return to all your normal activities right away after an outpatient nuclear scan or as advised by your doctor. 

When can I go home?

Most people go home immediately after an outpatient procedure. If you are hospitalized, you will stay in the hospital for further evaluation and treatment.

When should I call my doctor?

It’s important to keep your follow-up appointments after a nuclear scan. Contact your doctor if you have questions or concerns between appointments.

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Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2020 Nov 10
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THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.
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  3. What is a Nuclear Heart Scan? National Heart Lung and Blood Institute.
  4. Nuclear Medicine Imaging. American Society of Radiologic Technologists.