An Austrian framework for PET quality control

Full text: The European patient protection directive (97/43 EURATOM) requires regular routine quality control (QC) of PET imaging devices. Since no standards were available covering this area and in order to comply with the directive a joint working party of the Austrian societies of nuclear medicine and of medical physics have developed a set of procedures suitable for both dedicated PET scanners and gamma cameras operating in coincidence mode (GCPET). The routine procedures proposed include both manufacturer recommended procedures and tests for specific parameters and calibration procedures. Wherever possible, procedures adapted or derived from NEMA standards publication NU 2-2001 were used to permit direct comparison with specified parameters of image quality. For dedicated PET scanners the most important procedures are the checking of detector sensitivities and the attenuation calibration scan. With full ring scanners the attenuation calibration scan is a blank scan, with partial ring devices a special attenuation calibration phantom has to be used. Test protocols are specific to manufacturer and scanner type. They are usually performed automatically overnight. In addition, some instruments require special calibrations, e.g. gain adjustments or coincidence timing calibration. GCPET procedures include the frequent assessment in coincidence mode of detector uniformity, energy resolution and system sensitivity. Common to both dedicated PET and GCPET are the regular quarterly assessment of tomographic spatial resolution and the calibration of the system for quantitative measurements. As a total performance test for both systems assessment of image quality following NU 2-2001 was included, to be carried out after major system changes or repairs. The suite of QC procedures was tested on several dedicated PET and GCPET systems including all major manufacturers' systems. Due to missing hardware or software not all tests could be performed on all systems. Some of the tests could not be performed on all systems due to lack of suitable acquisition modes. Special acquisition and analysis software will be required on those systems. Manufacturers may have to develop software tools dedicated to routine QC to comply with the requirements of the EU directive and its national implementations. (author)