Gamma Camera Scans: What They Are and What to Expect
A plain-language guide to nuclear medicine scans — how they work, how long they take, how to prepare and what a gamma scan can tell your doctor.
Painless
No discomfort during imaging
1–4 hours
Typical total visit
24–48 hours
For your report
Low dose
Comparable to routine CT
What is a gamma camera scan?
A gamma camera scan — also called a nuclear medicine scan, scintigraphy or simply a “gamma scan” — is an imaging test that shows how an organ is working rather than only what it looks like. A very small amount of a radioactive substance, called a radiotracer, is given by injection, orally or by inhalation. The tracer travels through the body and collects in the organ being studied, where it gives off tiny amounts of gamma rays.
The gamma camera detects those rays and builds an image of the organ. Because the tracer is taken up differently by healthy and abnormal tissue, the scan can reveal problems that may not be visible on an X-ray, CT or MRI. This is why nuclear medicine is often described as functional imaging.
At Uchit Diagnostic we use a Siemens dual-head gamma camera that supports planar imaging, whole-body scanning, gated cardiac studies and SPECT (three-dimensional) imaging. Where needed, SPECT images can be combined with CT for precise localisation.
Planar imaging
A single two-dimensional picture of an organ or the whole body.
SPECT imaging
A rotating camera creates detailed three-dimensional images.
SPECT-CT
Functional images fused with CT for exact anatomical localisation.
How the scan works
Four simple ideas explain almost everything that happens during a gamma scan.
1. A tracer is given
A tiny amount of radioactive tracer is injected, swallowed or inhaled.
2. It targets the organ
The tracer travels in the blood and is taken up by the organ being studied.
3. Gamma rays are detected
The gamma camera records the rays emitted by the tracer inside your body.
4. Images are reviewed
A specialist interprets the images and prepares a report for your doctor.
Types of gamma scans we offer
Each scan uses a different tracer and timing. Select a scan to read its detailed page, or call us if you are unsure which test your doctor has advised.
Bone scan
3–4 hours (imaging 30–45 min)
Detects cancer that has spread to the bones, hidden fractures, bone infection and joint inflammation.
View detailsThyroid scan
30–60 minutes
Assesses thyroid nodules, an overactive thyroid (Graves’ disease) and the size of a goitre.
View detailsRenal (kidney) scan
45–60 minutes
Measures how well each kidney filters and drains urine, and checks for obstruction or transplant function.
View detailsParathyroid scan
2–3 hours
Locates an overactive parathyroid gland before surgery in patients with high calcium levels.
View detailsCardiac MUGA scan
45–60 minutes
Measures the heart’s pumping efficiency, often before or during chemotherapy that can affect the heart.
View detailsHepatobiliary (HIDA) scan
1–2 hours
Examines the liver, gallbladder and bile ducts, especially when gallstones or duct blockage is suspected.
View detailsLung perfusion scan
30–45 minutes
Maps blood flow through the lungs and helps detect pulmonary embolism (blood clots in the lungs).
View detailsSPECT & SPECT-CT
45–90 minutes
Creates three-dimensional images of an organ and can be fused with a CT scan for precise localisation.
View detailsPaediatric nuclear medicine
Varies with the scan
Child-friendly protocols with weight-adjusted tracer doses and a calm, parent-friendly environment.
View detailsWhat happens during the procedure?
Every scan follows the same general path. Exact timings depend on the type of scan and the tracer used.
- 1
Before your appointment
We explain any preparation over the phone when you book. Bring your doctor’s prescription, previous scans and reports, and a list of the medicines you take.
- 2
Check-in and consent
On arrival our staff confirms your details, reviews your medicines, allergies and pregnancy status, and answers any questions before the scan.
- 3
The radiotracer is given
A tiny amount of a radioactive tracer is injected into a vein (or sometimes swallowed or inhaled). You may feel a cool sensation or a mild taste — both are normal.
- 4
Waiting for the tracer to reach the organ
Depending on the scan, you may wait between 20 minutes and 4 hours while the tracer travels to the organ being studied. You can usually relax in our waiting area.
- 5
Imaging
You lie on a comfortable table while the gamma camera moves close to your body. You simply need to stay still. The camera does not touch you and makes no noise.
- 6
After the scan
You can eat, drink and go home. Drinking water helps clear the tracer from your body. A nuclear medicine specialist reviews the images and reports are usually ready in 24–48 hours.
Preparation at a glance
These are general guidelines. Always follow the specific instructions given when your appointment is booked, and check with your treating doctor before stopping any medicine.
| Scan | Fasting | What to do |
|---|---|---|
| Bone scan | Not required | Drink plenty of water. Empty your bladder just before imaging. Tell us about recent contrast studies or a recent bone scan. |
| Thyroid scan | Not required | Avoid iodine-rich food, iodised salt supplements and iodine contrast for the period advised by your doctor. Thyroid medicines may need to be paused only if your doctor instructs it. |
| Renal scan | Not required | Stay well hydrated. Some blood-pressure medicines may need adjustment — check with your doctor. Empty your bladder before the scan if asked. |
| Parathyroid scan | Not required | Continue your medicines unless told otherwise. Calcium and vitamin D supplements may be stopped for a short period only on your doctor’s advice. |
| Cardiac MUGA | Not required | Avoid caffeine on the day if advised. Wear comfortable clothing and avoid strenuous exercise immediately before the test. |
| HIDA scan | 4–6 hours | Do not eat for 4–6 hours before the scan. Small sips of water are fine. Some pain medicines may affect the result, so tell us what you take. |
| Lung perfusion scan | Not required | No special preparation. Tell us if you have had recent lung imaging or are unable to lie flat comfortably. |
| Paediatric scans | As advised | Bring a comfort item, a favourite toy or a feed for infants. A parent or guardian stays with the child throughout. Sedation is rarely needed. |
For full instructions, see our preparation guidelines.
Is the radiation safe?
Nuclear medicine has been used safely for decades. The radiation dose from a diagnostic gamma scan is small, and the tracer loses its activity quickly.
Good to know
- The dose is comparable to many routine CT examinations.
- The tracer decays on its own and leaves the body mainly in urine.
- Drinking water after the scan helps clear it faster.
- For routine diagnostic scans you can usually return to normal activities immediately.
Please tell us if you are
- Pregnant, or think you might be pregnant.
- Breastfeeding — we will advise on timing and precautions.
- Allergic to any medicine or contrast dye.
- Taking thyroid medicine, calcium, vitamin D or blood-pressure medicines.
Your results
A qualified nuclear medicine specialist reviews every image. Reports are usually ready within 24–48 hours and are shared with you and your referring doctor. Please bring any earlier scans and reports so that the new study can be compared.
A scan is only one part of your assessment. Your doctor will interpret the report together with your symptoms, examination findings and other tests.
Frequently asked questions
Is a gamma camera scan painful?
No. Apart from the small needle prick when the tracer is injected, the scan is painless. The gamma camera never touches you and does not produce heat, noise or vibration.
How long does a gamma scan take?
The whole visit usually takes between 1 and 4 hours, depending on the type of scan. Most of that time is spent waiting for the tracer to reach the organ; the actual imaging is typically 20–45 minutes.
Do I need to fast before a nuclear medicine scan?
Only some scans require fasting. A HIDA scan usually needs 4–6 hours of fasting, while bone, thyroid, renal and lung scans do not. We give you exact instructions when your appointment is booked.
Is the radiation from a gamma scan safe?
The amount of radiation is small and comparable to many routine CT examinations. The tracer loses its radioactivity quickly and leaves the body mainly through urine. Drinking water afterwards helps clear it faster.
What should I tell the team before my scan?
Tell us if you are pregnant, breastfeeding, allergic to anything, taking any medicines or supplements, or if you have had recent imaging with contrast. This helps us choose the safest protocol for you.
Can I drive myself home after the scan?
Yes, for routine diagnostic scans you can drive and return to normal activities. If you received sedation or a high-dose therapy, we will give you specific instructions.
How is a gamma scan different from a CT or MRI?
CT and MRI mainly show anatomy — the structure of organs. A gamma scan shows function — how an organ is working at a cellular level. That is why it can detect problems before structural changes appear.
When will I get my report?
Reports are usually ready within 24–48 hours. A nuclear medicine specialist reviews every study, and you should discuss the report with your referring doctor.
Ready to book your scan?
Our team will confirm the preparation for your specific scan and answer any questions before your visit.
Monday – Saturday, 9:00 AM – 6:00 PM