Details Patients receiving PET diagnosis are given a short half-life, low dose radiopharmaceutical which discharges positrons. The amount of exposure the patient receives is only about as much as from two chest X-rays.
Radiopharmaceuticals can target particular organs.
By placing the patient between the two detectors, the gamma rays' origin can be deduced and the organ of interest studied. These positron camera images show the metabolism of secondary liver tumours, illustrating how drug therapy reduces the tumours' metabolism over 4 weeks, indicating early response to the drug. CLRC has developed a novel gamma ray detection technique, giving higher efficiency and count rates. Annihilation photons incident on BaF2 scintillators produce UV light which interacts with the detector's TMAE gas filling, producing photoelectrons. These cause an electron avalanche which in turn induces an electrical pulse, forming half of a coincidence circuit.