Abstract

The multiple physical factors inherent to the acquisition process of positron emission tomography imply possible levels of imprecision in the image acquisition process, which can translate into an incorrect description of the patient’s pathology. It is necessary to know, analyze, and apply a quality assurance plan that includes the performance of the positron emission tomograph with respect to the initial acceptance and/or factory results to measure its level of reliability and ensure the quality of the medical diagnosis that is made to patients. The impact of the performance parameters of the tomograph was evaluated regarding its significance in the quality of the medical diagnosis. The PET sensitivity was determined using a linear source of 18F-FDG with 4.44 MBq (0.12 mCi); the sensitivity was obtained at 0 cm from the FOV axis: 6.28 cps/kBq, and at 10 cm from the FOV axis: 5.96 cps/kBq. The PET resolution was calculated by means of the sum of the FWHM of the PSF functions in each of the acquisition positions of a source of ~3.30 MBq (89.15 μCi) contained in a volume of ~1.9 mm3. The dispersion fraction, random-total radius and NECR were determined by means of a 71.0 ± 0.1 cm long linear source, with an activity of approximately 1070 MBq (28.92 mCi), obtaining 35.5% for the scatter fraction parameter and a NECR peak equal to 103.31 kcps. The evaluation of image quality was carried out using the usual acquisition protocol of the service. The percentage of contrast observed in the hot spheres was greater than 60%, and in the cold spheres, it was greater than 75%. The accuracy of attenuation correction and correction of scattered events was observed with percentages of 15.36% and 8.52% for the image plane closest to the scattering phantom. The performance evaluation of the PET component in the Biograph mCT tomograph, through the NEMA tests, allowed us to conclude an optimum operating condition.