Bone Scintigraphy (Bone Scan)

A bone scintigraphy (bone scan) is a nuclear medicine imaging test that uses a small amount of radioactive tracer to produce detailed pictures of bone activity throughout the entire skeleton.

A substance called a radiotracer (a mildly radioactive material that the body processes like a natural chemical) is injected into a vein. Bones that are unusually active — because of injury, infection, tumour, or other disease — absorb more of this tracer than healthy bone. A special camera called a gamma camera then detects the radiation given off and converts it into an image. Areas of high tracer uptake appear as bright "hot spots", while areas of very low uptake appear as dark "cold spots". This pattern helps doctors see changes in bone activity long before they would show up on a regular X-ray.

Doctors order a bone scan when they need to find, monitor, or assess the extent of a condition affecting bone tissue. Because it shows the whole skeleton in a single exam, it is especially useful for detecting problems that could be spread across multiple bones.

• Cancer that has spread (metastasised) to the bones from another part of the body, such as the breast, prostate, or lung
• Primary bone tumours (cancers that start in the bone itself)
• Osteomyelitis (bone infection), which can be difficult to see on a plain X-ray in its early stages
• Stress fractures (hairline cracks caused by repeated strain) that are too small to appear on X-ray
• Paget's disease of bone (a condition where bone breaks down and rebuilds abnormally, becoming enlarged and misshapen)
• Avascular necrosis (death of bone tissue due to lost blood supply)
• Unexplained bone pain when other tests have not given a clear answer
• Monitoring the response of bone disease to treatment over time
• Assessment before and after joint replacement or bone surgery

A bone scan may not be the right choice in certain situations. Your doctor will weigh the benefits against other available imaging options.

• Pregnant women: the radiotracer can reach the developing baby, so the scan is generally avoided unless there is no safe alternative
• Women who are breastfeeding may need to temporarily stop breastfeeding for a period after the injection — the doctor will give specific guidance
• People with severe kidney impairment, since the tracer is cleared from the body by the kidneys
• Patients who are unable to lie still for the duration of the scan (the camera pass can take thirty minutes or more)

A bone scan is a diagnostic test and carries a very low risk profile; it does not involve surgery or anaesthesia. The recognised risks are worth knowing about, but for most patients the procedure is straightforward.

• Radiation exposure: the dose of radiation is small and comparable to that of several standard X-rays; it leaves the body through urine within a day or two
• Allergic reaction to the radiotracer: true allergic reactions are rare, but mild redness, swelling, or itching at the injection site can occur
• Discomfort at the injection site: a brief sting when the tracer is injected into the vein, similar to any routine blood test
• False results: some bone conditions (such as very early or very aggressive cancer) may not always show a clear abnormality, and other conditions (such as arthritis) can produce "hot spots" that are not cancer — the scan result is always interpreted alongside other tests and clinical findings
• Pregnancy risk: if there is any chance of pregnancy that was not disclosed before the scan, the radiotracer may pose a risk to the developing baby

Bone scans usually do not require fasting, but you will be asked to drink plenty of water in the hours before and after the tracer injection. This helps flush the radiotracer out of soft tissues and through the kidneys more quickly, which improves image quality. Your medical team will give you personalised instructions, since some hospitals or specific scan types may have different requirements.

Tell your doctor or the nuclear medicine team about all medications you currently take, including supplements and herbal remedies. Certain medicines — particularly those containing bismuth (found in some stomach remedies) or barium (used in some bowel tests) — can interfere with the images. Blood thinners, anti-inflammatory medicines, and others are usually continued unless the doctor decides otherwise. Also inform the team if you are pregnant, breastfeeding, or have kidney problems.

Before the scan, the team may review recent blood tests (especially kidney function tests, since the kidneys clear the tracer), previous imaging such as X-rays, CT, or MRI, and your medical history. No special skin preparation or shaving is needed.

Here is what typically happens on the day of the scan:

• 1. Arrival and check-in: you register at the nuclear medicine department and the team reviews your history and consent form.
• 2. Tracer injection: a small needle is placed into a vein in your arm, and the radiotracer is injected. This takes only a few seconds.
• 3. Waiting period: you will be asked to wait, usually for two to four hours, while the tracer travels through the bloodstream and is absorbed by bone tissue. Most patients can sit comfortably, walk around, and eat and drink normally during this time (unless instructed otherwise).
• 4. Pre-scan urination: just before imaging begins, you will be asked to empty your bladder. This removes tracer that has collected in the bladder and keeps it out of the images.
• 5. Positioning on the scanning table: you lie flat and still on a padded table. You do not need to remove clothing beyond what is necessary for the camera to work clearly, but you will be asked to remove metal objects such as jewellery.
• 6. Imaging: the gamma camera moves slowly over your body, sometimes taking images from the front and back, and occasionally from the sides. This pass may take thirty minutes or longer depending on what the doctor needs to see.
• 7. Possible additional views: the team may take close-up images of specific areas (called SPECT — single photon emission computed tomography — a three-dimensional technique) if more detail is needed. Your doctor will explain this in advance if it is planned.

Recovery after a bone scan is minimal because the procedure does not involve surgery or sedation. Most people feel completely normal immediately after the scan and can drive, eat, and return to their usual routine the same day. The main focus of aftercare is helping the body clear the radiotracer quickly and safely.

• Drink plenty of water for the rest of the day after the scan to flush the remaining radiotracer out through the kidneys and urine — this is the single most important aftercare step
• Wash your hands thoroughly after using the toilet for the first day or two, as small amounts of radiotracer are present in the urine
• If you are breastfeeding, follow the doctor's specific guidance on when it is safe to resume breastfeeding — this varies depending on the tracer used
• Pregnant women and young children should avoid prolonged close physical contact with you for the remainder of the scan day as a precaution, though the radiation level is very low
• The injection site in the arm requires no special wound care and should heal on its own like any routine blood test puncture
• A nuclear medicine specialist (a doctor trained in interpreting these images) will analyse the scan, usually within a few days, and send a report to your referring doctor
• Your referring doctor will discuss the results with you at a follow-up appointment; the bone scan result is always considered alongside your symptoms, blood tests, and other imaging before any decisions about treatment are made
• If you feel any unusual symptoms such as a rash, swelling, or difficulty breathing after leaving the department, contact the hospital promptly