FDG dose for a PET scan: what to know

The FDG dose for a PET scan is tailored to your body, scan purpose, and imaging protocol by the nuclear medicine team. The tracer contains a small amount of radioactive material that is measured carefully before it is given.

The team considers your weight, the area being examined, the scanner, the timing of imaging, and local safety procedures. FDG behaves like glucose, so active tissues take it up and can appear on the scan. The dose is not a fixed amount for every patient, and a planned adjustment does not mean that anything is wrong.

Tell the department if you have diabetes, are pregnant or may be pregnant, are breastfeeding, or have difficulty lying still. These details can change preparation or scheduling.

Follow the appointment instructions about fasting, medicines, and fluids. Avoid strenuous activity beforehand if the imaging team advises this, because muscle activity can affect the pictures. After injection, rest quietly while the tracer distributes. Drink fluids afterward if permitted and use the bathroom regularly; the body clears much of the tracer through urine.

Tell staff immediately about symptoms during or after the appointment, such as trouble breathing, facial swelling, faintness, or severe discomfort. Contact your care team promptly if you cannot follow the preparation instructions, your blood glucose is difficult to control, or you think you may be pregnant.

Ask which preparation rules apply to you, whether your diabetes medicines need special timing, how long the visit may take, and when you can resume normal activity.