PET-CT Scans for — Children with Cancer

The total time at the imaging centre is longer than the scan itself, because there is a waiting period after the FDG injection before scanning can begin. If sedation is needed, the whole appointment takes longer still. The team will give you a time estimate before the day so you can plan — ask for it when the appointment is booked.

Not always. Children old enough to understand simple instructions and lie still usually do not need sedation. Younger children, and some older children who are very anxious, may need a light sedative or general anaesthetic. The team will assess this before the scan day and discuss it with you. If sedation is planned, you will receive separate fasting and preparation instructions.

The FDG tracer activity is calculated per kilogram of body weight, following EANM paediatric dosimetry guidelines. A young child receives a fraction of the activity given to an adult. The CT component can also be adjusted to lower the X-ray dose. If you want to know the estimated effective dose for your child's specific scan, ask the team — that is a reasonable question and they can give you a figure to put in context.

FDG PET-CT is accurate for the cancers it is indicated for, but not all childhood cancers take up FDG equally. Wilms tumour is harder to assess on PET because FDG is excreted through the kidneys, limiting what shows clearly in that area. Neuroblastoma is often better evaluated with MIBG scanning alongside or instead of PET. Your oncologist selects the imaging that suits your child's specific diagnosis, which is why the same scan is not used for every cancer.

During the waiting period after the injection, one parent or carer can usually remain with the child. Whether a parent can be present in the scanning room itself depends on the centre's radiation safety protocols. Many centres allow a parent nearby for a young or anxious child, though you would wear a protective apron. The team will tell you exactly what is possible at your appointment.

Very young children almost always need sedation or a general anaesthetic for PET-CT, because lying still in a scanner is not realistic at that age. A paediatric anaesthetist will be involved in planning the sedation, and the preparation instructions will differ from those for an older child. Ask specifically about the sedation plan and who will be present so you know what to expect on the day.