A nuclear bone scan is an imaging technique that uses radioactive substances to create three-dimensional (3D) images of the bones.

Doctors use bone scans to diagnose and monitor bone diseases, such as cancers, infections, and fractures.

Keep reading to learn more about bone scans, including the uses, risks, and what to expect from the procedure, including the before and after.

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A nuclear bone scan is a type of nuclear medicine tool that uses trace amounts of radioactive substances, called radiotracers, to evaluate physical and chemical bone changes.

A special camera, called a gamma camera, detects radiation emitted from the radiotracers. A computer creates 3D images from the gamma camera data.

A bone scan uses an imaging technique called single-photon emission computed tomography (SPECT). SPECT involves a radioactive substance and a special camera. Together, these tools produce 3D images of the organs and other internal structures.

Unlike an X-ray, which shows what internal structures look like, SPECT shows how these structures work. For instance, a bone scan shows areas of increased bone activity, such as bone metabolism, a continuous process that forms new bone and breaks down existing bone.

Areas that exhibit higher-than-normal bone formation may indicate a bone fracture. Regions of bone that show bone loss can suggest a bone infection or disease, such as osteoporosis. But it is important to note that it is difficult to differentiate bone loss with a nuclear bone scan. Diagnosis requires a medical history as well.

Doctors can also use bone scans to determine whether cancer has metastasized, or spread, from another area of the body, such as the lung or prostate gland.

A nuclear bone scan is an extremely sensitive diagnostic test that can detect minor bone irregularities. Doctors can use this test to diagnose suspected bone diseases, identify the cause of unexplained bone pain, and monitor a person’s response to treatment.

A doctor may order a bone scan to:

  • identify bone cancer
  • determine whether cancer from another part of the body has spread to the bones
  • locate hidden bone fractures that do not appear on X-rays
  • diagnose bone damage due to an infection
  • monitor a person’s response to treatment for a bone disease

A bone scan can help detect the following conditions:

  • benign or cancerous bone tumors
  • secondary (metastatic) cancer to the bone
  • non-Hodgkin lymphoma
  • tumors in the soft tissue
  • arthritis or joint inflammation
  • osteomalacia, or bone softening, due to vitamin D deficiency
  • osteomyelitis, or bone infection
  • Paget’s disease, a rare disorder that disrupts bone metabolism
  • avascular necrosis, or loss of bone tissue due to restricted blood flow (although an MRI usually detects this)

Many people may feel concerned or hesitant at the thought of having radioactive material inside their bodies. But a bone scan requires minimal amounts of radioactive material.

On average, a bone scan exposes a person to 4.44–8.88 millisieverts (mSv) of radiation. CT and PET-CT scans expose a person to 10 mSv and 25 mSv of radiation, respectively.

The most commonly used radiotracer is Technetium-99m methylene (Tc99m), and it has a short half-life of about 6 hours. The body quickly removes excess Tc99m through urine and feces.

This imaging procedure is noninvasive. But it does involve intravenous (IV) injections of radioactive materials. IV injections are usually painless, but they can cause some bruising or redness near the injection site.

There is a low risk of having an allergic reaction to radiotracers.

A bone scan may be unsafe for people who are currently pregnant or breastfeeding. A doctor may recommend using baby formula and disposing of any breast milk until all radiotracers leave the body.

A doctor will provide detailed instructions for how to prepare for a bone scan. They will also explain what to expect during and after the test.

People should share the following information with their doctor:

  • all current medications, including vitamins and supplements
  • whether they have recently taken bismuth-containing medicine, such as Pepto-Bismol
  • if they recently underwent a radiological procedure, such as an X-ray
  • whether they are currently pregnant or breastfeeding
  • any recent illnesses, existing medical conditions, or allergies

Unless a doctor instructs otherwise, people can eat and drink normally before the test. This test involves a long waiting period, so people are encouraged to bring reading materials, work, or something to pass the time.

At the appointment, a doctor, nurse, or technologist will explain why they are performing the test and what to expect during and after the test.

The procedure begins with an IV injection of the radiotracer. Once inside the bloodstream, the radiotracer will circulate throughout the body and adhere to the bones, which can take 2–4 hours.

During this time, a person must drink at least a liter of water to help remove excess radiotracer from the body. They will need to empty their bladder before the scan. Any radiotracer in the urine can block or distort the pelvic bones.

In some cases, imaging occurs immediately after the injection and again a few hours later. This is known as a triple-phase bone scan.

When it is time for the scan, a person will change into a hospital gown. There will be a space to store their clothing, wallets, and electronic devices during the test. They should leave all jewelry and other valuable items at home.

A technologist will lead a person to the scanning room, where they will position the person on the scanning table. The gamma camera will take a series of images of the body. The camera may rotate around the table, or a person may need to change positions on the table.

The person must remain still while the camera is capturing images. Staying still may present a challenge. Claustrophobia could also be a concern for some people, though not to the extent of the tunnel-like MRI scans. A doctor or nurse may administer a sedative to help a person relax during the scan, especially if they experience joint or bone pain.

Parents are encouraged to accompany their child into the scanning room to provide support and comfort during the test.

The technologist will review the images. If the images are unclear or the technologist wants more information on a particular area, they may ask the person to come back for additional scans.

Unless a doctor instructs otherwise, most people can immediately return to their normal activities after a bone scan.

Some radiotracer may remain in the body after the test. It will naturally decay and lose its radioactivity over time. Drinking plenty of water can help flush excess radiotracer from the body.

It can take up to 3 days for the radiotracer to leave the body.

A nuclear bone scan is a nuclear imaging tool that doctors use to diagnose bone diseases, such as cancer, infections, and fractures. This test uses trace amounts of radioactive substances, called radiotracers, and a specialized camera to create 3D images of the bones.

Nuclear bone scans are generally very safe and carry no greater risk than conventional X-rays or other radiology procedures.

This procedure may be unsafe for people who are pregnant or breastfeeding. A person should tell their doctor if they are pregnant or think they might be pregnant. People who are breastfeeding are encouraged to use formula and discard any breast milk until the radiotracer has left the body.

The radiotracer used for bone scans has a short half-life of about 6 hours. Small amounts of the radiotracer can stay in the body for up to 3 days.