Nuclear medicine scan
A scan that uses a small amount of a radioactive 'tracer', usually injected into a vein, to show how an organ or part of the body is working rather than just its shape.
✓ Medically reviewed by a GMC-registered consultant · last reviewed September 2026 · next review September 2027 · how we review
In short
- It uses a small amount of a radioactive tracer, usually injected, to show how an organ is working, not just its shape.
- It does use ionising radiation (the tracer, and sometimes a combined CT), kept low and only used when the benefit outweighs the small risk.
- Tell the team beforehand if you are or might be pregnant or are breastfeeding, so the scan can be adjusted.
- Afterwards you may be asked to limit close contact with young children and pregnant women for the rest of the day and to drink plenty of fluids.
A plain-English summary. The detail — including risks and recovery — is below.
At a glance
A general guide. Your radiologist will give you advice for your situation.
Shows how an organ is working, not just its shape, which other scans may not reveal.
It is usually avoided in pregnancy unless the benefit clearly outweighs the risk, because the tracer is radioactive.
You can usually go home and eat and drink as normal. There is no sedation, so you can drive.
Clear written advice on fluids and any contact precautions, with a time they end.
You can usually go home and eat and drink as normal. There is no sedation, so you can drive.
Drink plenty of fluids to help flush the tracer out, mainly in your urine. For some scans, keep your distance from...
The tracer largely clears from your body. Any short contact precautions end after the period your department...
A report goes to the clinician who referred you, who will discuss the findings and any next steps with you.
What is a nuclear medicine scan?
A nuclear medicine scan uses a very small amount of a radioactive substance, called a tracer or radiopharmaceutical, to show how part of the body is working. The tracer is usually injected into a vein in the arm or hand, though for some scans it is swallowed or breathed in. It travels to the organ being studied and gives off a tiny amount of radiation that a special camera (a gamma camera) detects to build a picture.
Unlike most scans, which mainly show shape and structure, a nuclear medicine scan shows function — for example how the kidneys, thyroid, heart or bones are working. Many different scans use this principle, such as kidney function scans, thyroid scans, heart (myocardial perfusion) scans, lung scans and others.
Because the tracer is radioactive, this scan does use ionising radiation, both from the tracer and, in some scans, from a combined CT. The amount is small and is kept as low as possible, comparable to other X-ray tests, and the scan is only done when the benefit clearly outweighs the small risk. Tell the team before the scan if you are, or might be, pregnant, or if you are breastfeeding, as the scan may be changed, delayed or done differently.
For a short time after some scans you may be asked to limit close contact with babies, young children and anyone who is pregnant, and to drink plenty of fluids to clear the tracer. This is a simple precaution, not a sign of danger.
Types, options & approaches
There may be different ways to do this. The right approach depends on the clinical question and your circumstances.
Nuclear medicine scan vs ordinary X-ray or CT
| Point | Nuclear medicine | X-ray / CT |
|---|---|---|
| Mainly shows | How an organ works (function) | Shape and structure |
| Uses radiation? | Yes, from a tracer | Yes, from X-rays |
| Tracer needed? | Yes (injected, swallowed or inhaled) | Usually not, sometimes contrast |
| Contact precautions after? | Sometimes, for a short time | No |
These tests answer different questions and are sometimes combined (for example SPECT-CT). Your clinician will explain why this scan was chosen.
Preparing for your scan
- Follow your appointment letter carefully, as preparation differs between scans (some need no preparation, others have specific instructions).
- Tell the department before the scan if you are, or might be, pregnant, or if you are breastfeeding.
- Ask whether any medicines need to be stopped or adjusted, as this depends on the scan.
- Plan for a longer visit than the scan time alone, as there is often a wait between the injection and the pictures.
- Drink and eat normally unless told otherwise; some heart scans ask you to avoid caffeine beforehand.
- Arrange your day so you can keep your distance from young children and anyone pregnant for the rest of the day if advised.
- Wear comfortable clothing and expect to remove jewellery or metal near the area being scanned.
What happens
Most nuclear medicine scans start with an injection of the tracer into a vein in your arm or hand, which feels like a routine blood test. For some scans the tracer is swallowed as a capsule or breathed in instead. You then usually wait, sometimes from a few minutes up to a few hours, while the tracer travels to the part of the body being studied; for some scans you can leave the department and come back.
When it is time, you lie on a couch and a gamma camera, which has large flat detectors, moves slowly close to you to take the pictures. The camera does not give off radiation; it detects the tiny amount coming from you. You need to keep still, and the scan usually takes about 30 to 60 minutes depending on the type. Some scans are done in stages or combined with a low-dose CT.
Afterwards you can usually go home and eat and drink as normal. You may be advised to drink plenty of fluids to help clear the tracer, and for some scans to limit close contact with babies, young children and pregnant women for the rest of the day. The results are written into a report rather than given on the day.
Is this scan right for me?
A good consultation should explore whether it's the right choice for you now — including reasons to wait or consider something else.
May not be suitable if…
- It is usually avoided in pregnancy unless the benefit clearly outweighs the risk, because the tracer is radioactive.
- It mainly shows function rather than fine structure, so it is the wrong test when detailed anatomy is what is needed.
- An abnormal area is not a diagnosis on its own and often needs another test to explain it.
- It may need to be timed around breastfeeding, which sometimes has to be paused for a period.
Delay or rearrange if…
- You are, or might be, pregnant and the scan is not urgent.
- You are breastfeeding and have not had advice on whether to pause it.
- A medicine that affects the scan has not been reviewed.
- You have an active illness or cannot keep still enough for the pictures, which may affect quality.
Alternatives to discuss
- Ultrasound or MRI where appropriate, which use no ionising radiation.
- CT scan, where structure rather than function is the main question.
- Blood tests or other functional tests for some organs, such as the thyroid or kidneys.
- No scan, with a review of symptoms, if the result would not change management.
Before you decide
Use this as a shared-decision checklist. The aim is not just “can this be done?”, but whether it is right for you, now, with the risks and alternatives clearly understood.
What matters most to me?
Think about symptoms, daily life, work, caring responsibilities, sport, fertility, travel, appearance and anxiety — the right choice depends on your priorities, not just the medical facts.
What are all my options?
Ask about waiting, monitoring, medicines, rehabilitation, a smaller or larger procedure, a different test, NHS referral, or a second opinion where that would help.
What would make me pause?
Active infection, pregnancy, unstable medical problems, smoking, medicines that increase bleeding, poor support at home, or feeling pressured are all reasons to slow down and get tailored advice.
What happens if I do nothing today?
For some problems, waiting is safe; for others, delay can make treatment harder. A good consultation should explain the trade-off in plain English.
Benefits
- Shows how an organ is working, not just its shape, which other scans may not reveal.
- Can detect problems early, sometimes before they show on other imaging.
- Covers many different questions across bones, kidneys, thyroid, heart, lungs and more.
- Usually involves only a small injection, with no sedation and little discomfort.
- Can guide treatment, such as locating a gland before surgery or a lymph node.
- Provides functional information that helps plan further tests or treatment.
Risks & complications
- A brief pinprick and possible small bruise where the tracer is injected
- A long appointment with waiting time between the injection and the pictures
- Needing to limit close contact with young children and pregnant women for a short time afterwards (for some scans)
- Exposure to a small amount of radiation, balanced against the benefit of the scan
- An uncertain or 'incidental' finding that needs another test to explain
- Needing the scan repeated if you cannot keep still or the tracer does not behave as expected
- An allergic-type reaction to the tracer, which is rare
- A finding that turns out to be a false alarm (false positive) or a problem the scan does not show (false negative)
The radiation from the tracer is small and is kept as low as possible, but it is real, so the scan is only done when it will genuinely help. Over a lifetime, radiation carries a very small added risk, which is why pregnancy and breastfeeding need to be flagged in advance. The short contact precautions afterwards are a sensible safeguard for babies and pregnant women, not a sign you are unsafe to be around generally. Ask why this scan was chosen and what the result will change.
Published figures to discuss
Radiation dose, diagnostic value and the chance of false alarms vary widely between the many different nuclear medicine scans. Doses are small, kept as low as possible and justified individually, but they are not zero. Reliable single percentages do not apply across such different scans, so the note below gives the broad radiation picture rather than a precise figure, which your department can provide for your specific scan.
| Figure | Reported range | How to interpret it | Source / confidence |
|---|---|---|---|
| Radiation dose from the tracer | Small and varies by scan; broadly comparable to other X-ray tests, often a few mSv | Kept as low as reasonably possible; your department can give the dose for your specific scan and what it compares to. | Guide sourcesClinical context |
| Radiation-safety restrictions after some scans | Usually brief and scan-specific | You may be advised about close contact with pregnant people or small children for a short time. | Guide sourcesClinical context |
| False-positive tracer uptake | Common enough to require correlation | Inflammation, infection, arthritis, healing injury and normal variants can mimic disease depending on tracer. | NHS — Nuclear medicine scan information (Gloucestershire Hospitals)gloshospitals.nhs.ukSource-linked context |
These are literature figures, not a personalised prediction. Your own risks and likely benefits depend on your circumstances, your health, and how your care is carried out and followed up.
What happens afterwards
There is no physical recovery from the scan itself. 'Afterwards' is mainly about clearing the tracer by drinking fluids, following any short contact precautions, and then waiting for the report.
- No physical after-effects beyond a possible small bruise at the injection site
- Passing slightly radioactive urine for around a day, which is expected
- Following short contact precautions for some scans
- No immediate result, with a report following afterwards
Aftercare
- Drink plenty of fluids for the rest of the day to help clear the tracer.
- Flush the toilet as normal and wash your hands well after using it.
- Follow any advice to limit close contact with babies, young children and pregnant women for the period given.
- There is no need to stop giving essential care to your own children — ask the team how to balance this.
- Resume your usual medicines and diet unless told otherwise.
- Carry any card or letter the department gives you, as the tracer can occasionally trigger sensitive radiation detectors for a short time.
- Make sure you know who will give you the result and when.
- Appointment letter read for preparation and timing
- Pregnancy or breastfeeding flagged to the department in advance
- Medicines checked in case any need adjusting
- Day planned around possible contact precautions
- Plenty of fluids planned for afterwards
- A note of how and when results will be given
⚠ Get urgent help if…
- Difficulty breathing, swelling of the face or throat, or a widespread rash after the injection (possible reaction)
- Increasing redness, swelling, pain or warmth at the injection site
- Feeling faint, unwell or developing a fever after the scan
- Symptoms returning to what you were being investigated for, which should be reported to your clinician
- Any new severe symptom while waiting for the result
- Concerns about contact precautions if you care for a baby or live with someone pregnant — ask the department
Who to contact: your clinician, clinic or test provider first (keep their number to hand). For urgent advice when you can't reach them, call NHS 111. In an emergency, call 999.
General guidance — it doesn't replace the specific advice your radiologist gives you.
Results & realistic expectations
A useful nuclear medicine scan shows how the organ being studied is working — for example whether one kidney is doing more of the work, whether the thyroid is overactive, or whether an area of bone or heart muscle behaves abnormally. The pattern of tracer uptake is what the specialist interprets.
It is important to know the limits. A scan shows function and 'activity', not a precise diagnosis, so an abnormal area can have several causes and often needs another test to explain it. A normal scan is reassuring but does not rule out every problem. Your clinician will put the result together with your symptoms and other tests before deciding what it means and what to do next.
The scan reflects how the organ is working on the day. Because conditions and treatments change, a result may need repeating later to track progress or response to treatment. Your clinician will advise whether and when a repeat scan is useful.
Related tests, treatments or support
Nuclear medicine scans are often combined with other tests. Some are done with a low-dose CT at the same time (SPECT-CT) to add anatomical detail, and results are interpreted alongside blood tests, other imaging and your symptoms. For some conditions a scan is one step before treatment, such as locating a gland or lymph node before surgery.
Follow-up & long-term care
Results are not given on the day. A report is written and sent to the clinician who referred you, usually within days to a couple of weeks, and they will then discuss it with you and arrange any further test or treatment. Make sure you know who is responsible for giving you the result and how to get in touch if you do not hear.
Repeat, follow-on and what comes next
- An uncertain or abnormal finding often needs another test, such as MRI, CT or a biopsy, to explain it.
- A scan may be repeated later to track a condition or response to treatment.
- A scan of poor quality, for example from movement, may need repeating.
Ask what happens if the result is unclear or needs repeating, and what is included if further tests or follow-up are needed.
What good aftercare looks like
- Clear written advice on fluids and any contact precautions, with a time they end.
- A named contact and a defined route and time for getting the report.
- A plan for any further test needed to explain a finding.
- Sensible advice for parents and carers on balancing precautions with caring for children.
What affects the cost
Costs vary a great deal between people and providers, and we don't publish prices. What matters is understanding what drives the cost and making sure your quote is complete. The main things that affect it:
- The type of scan and the tracer used
- Whether a combined low-dose CT (SPECT-CT) is part of the scan
- The seniority of the specialist reporting the scan
- The length of the appointment and number of imaging stages
- Whether a same-day report is included
- Any follow-up consultation or further test needed
- The scan fee, including the tracer and any combined CT
- Who performs and reports the scan and their qualifications
- Whether a written report goes to your GP or referring clinician
- A follow-up appointment to discuss results
- What happens, and what it costs, if another test is needed afterwards
- How and when results are provided
On the NHS? Nuclear medicine scans are widely available on the NHS when clinically needed; some people choose private imaging for speed or convenience.
You're entitled to your total cost in writing — including reports, follow-up and what happens if the result is inconclusive — before you decide.
Consent traps and marketing red flags
These are not small details. They are often where patients lose choice, time to reflect, or realistic expectations.
Consent traps
- Not being told the scan involves a radioactive tracer and a small radiation dose.
- Not being asked about, or not disclosing, pregnancy or breastfeeding beforehand.
- Not being given clear contact precautions for after the scan where they apply.
- Believing the scan gives a precise diagnosis on its own rather than showing function.
Marketing red flags
- Promoting a scan as a complete or definitive answer to a problem.
- Not mentioning radiation, the tracer, or pregnancy and breastfeeding precautions.
- Offering scans without considering whether a radiation-free test would do.
- Implying a normal scan rules out all disease.
Choosing a specialist safely
- Check the radiologist is on the GMC Specialist Register for this area.
- Make sure they work at a CQC-registered service, and look for membership of the relevant Royal College or professional body.
- You're entitled to time to consider and to have your questions answered before you agree — the radiologist who looks after you should explain it, not a salesperson.
- Be wary of pressure: time-limited offers or deposits taken before you've had time to think are red flags, not bargains.
- You're entitled to your total cost in writing — including any follow-up — before you decide.
Questions to ask your medical professional
Take this to your consultation. A good radiologist will welcome every one of these.
- Why is this scan the right test for my problem?
- How much radiation is involved, and is it justified for me?
- What contact precautions will I need afterwards, and for how long?
- What will the result change about my care?
- What happens if the scan is normal or the finding is uncertain?
- Who will give me my result, and when?
- Are you on the GMC Specialist Register for this area, and which Royal College or professional body are you a member of?
- Will you be the radiologist who carries out my scan, and who looks after me afterwards?
- What are the risks for someone like me, and how often do your own patients have a problem or need it repeated or redone?
- What does a realistic result look like — and what can this scan not achieve?
- What are my options, including waiting, doing nothing for now, or choosing a different approach?
- Can I have written information, results and aftercare instructions in a format I can use, including any accessibility or communication support I need?
- What is the total cost in writing, including any follow-ups, and how much time do I have to decide?
Frequently asked questions
Is the radioactive tracer dangerous?
Does a nuclear medicine scan use radiation?
Why do I need to avoid children and pregnant women afterwards?
Is it safe if I am pregnant or breastfeeding?
Why does the appointment take so long?
Will it hurt?
When will I get my results?
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How we made this page
Medically reviewed by a GMC-registered consultant. Written in plain English, checked against NHS, NICE, GMC and relevant Royal College / specialist-society guidance, and kept under review. No clinic paid to appear on this page, and we publish no pricing. This is general information to help you prepare — it is not a substitute for advice from your own clinician. How we review our guides →
Source hierarchy: UK regulator and NHS/NICE guidance first, then relevant Royal College or specialist-society guidance, then peer-reviewed evidence for procedure-specific figures where available.
Sources & standards: NHS — Nuclear medicine scan information (Gloucestershire Hospitals) GOV.UK (UKHSA) — Ionising radiation: dose comparisons RCR — Clinical radiology standards and guidance NHS — Radiotherapy and imaging using radiation (about radiation safety)
Reviews reflect patients' experience of care, not clinical outcomes. For procedure volumes and outcome data see PHIN.
Last medically reviewed 2026-09-21. Spotted something wrong or out of date? Report an error in this guide.
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