1. A PET/CT procedure is started after 6-12 hours of fasting
2. The patient is allowed to rest for 15 min in lying position to reduce the muscular activity
3. An injection of 5-10 mCi of FDGis given in a vein on one arm of the patient
4. The patient may also be given a contrast agent for CT scan in some cases if required
5. Imaging is done after 40-60 minutes. The patient is allowed to lie on the imaging table of the PET/CT machine with hands kept resting on the sides or above the head
6. The table moves into the gantry and a whole body CT scan is done first, followed by a PET scan. The whole imaging process takes 15-20 minutes.

FDG is the most widely used PET radiopharmaceutical. FDG is glucose labelled with radioactive fluorine and hence has the same metabolism as that of glucose. Glucose the sourse of energy and therefore the fuel for cellular function. FDG is trapped and metabolised inside the cells similar to glucose. Cancer being an uncontrolled proliferation of cells; cancer tissues have intense uptake of FDG. Hence, a PET/CT scan after FDG injection highlights the cancerous tissues in the body. FDG is also used for studying the metabolism in the heart and brain.