Travelling Home After Your PET-CT: — Public Transport and Airports

Yes. The radiation you carry after a PET-CT scan does not pose a meaningful risk to people sitting near you on a bus, train or metro. The main precaution is to avoid prolonged close contact — more than a couple of hours side by side — with pregnant women, infants and young children on the day of the scan. Keep a little distance where practical. There is no reason to avoid public transport or to travel separately from your family.

Yes, you may. Airport radiation detectors are designed to be extremely sensitive, and the tracer from your PET-CT can register on them for days after the scan. This is a known situation and is not an emergency. Security officers at major airports are familiar with medical radioactivity alerts. Show your CION letter immediately when an alarm sounds. Without the letter, expect a longer delay while security verifies your situation through other means.

CION provides a patient letter at the time of your scan. It states your name, the date and type of scan, the tracer used, and the centre's contact details. Carry it whenever you pass through any radiation checkpoint — airports, some railway stations, and certain government buildings can all have detectors. Keep it for the number of days your scan team specifies, because the tracer takes time to leave your body fully.

The tracer used in a PET-CT breaks down naturally and leaves your body mainly through your urine. The amount falls significantly within hours of the scan. However, airport detectors are sensitive enough to register even small residual amounts for days afterwards. The exact period depends on which tracer was used. Your scan team will tell you how many days to carry your letter — follow their advice rather than assuming a fixed number.

Brief contact — a hug, sitting together for a meal — is not a concern. On the day of the scan, keep at least an arm's length of distance from pregnant women, infants and young children where practical, and avoid sitting pressed together for several hours at a stretch. Normal family life does not need to stop. By the following day, the tracer has fallen to a level where these precautions are no longer necessary for most tracers used in PET imaging.

Tell the imaging team before your scan starts so they can prepare your letter and advise you specifically. Flying the same day is not a medical safety concern, but the level of tracer in your body will be higher than it will be the next day, making an airport alert more likely. Arrive with your letter ready and consider informing a security supervisor before you approach the detector — doing it before the alarm rather than after is considerably calmer.

Stay calm and present your CION letter. Security officers are trained to handle medical radioactivity alerts and will ask to see documentation. In most cases the process takes only a few minutes once the letter is shown. If you are travelling internationally and the letter is in English, ask CION in advance whether a version in the destination country's language is possible. Carrying a photocopy alongside the original gives you a backup if the original is retained.

Yes. There is no medical reason to delay international travel after a PET-CT. The practical concern is airport security in other countries, which may have different protocols. Your CION letter follows guidance consistent with IAEA standards, which most countries recognise. Keep it with you for the period your scan team specifies. If you are crossing multiple borders or transiting through several airports, carry a photocopy as well as the original and be prepared to show it at each checkpoint.