Quality control for whole body scan: An open discussion

Quality assurance program in Nuclear Medicine (NM) is responsible for equipment tests application and analysis to ensure better functional images to patients. Due to the wide variety of exams that employ scan protocols for patient's diagnostic and therapeutic assessment, quality control tests for scan speed verification are indicated by International Atomic Energy Agency (IAEA) and National Nuclear Energy Commission. Therefore, the aim of this study was to evaluate variations in scan speed, equipment adequations necessity and corrective actions based on IAEA criteria with three different experiments throughout the use of a ⁵⁷Co flood. First consisted of 07 scan acquisitions in continuum mode employing different scan speed and fixed length of 100 cm.In second experiment, scan speed of 12 cm/min remained fixed for continuum mode, whereas length of 07 acquisitions varied. For third trial, spot scan mode and 140 cm length were selected. Under these images, for first and second experiments it was possible to identify a pitfall, which reflects low count density, located always at the same distance of image's beginning, an indicative of scan speed non-uniformities. We have confirmed this problem by longitudinal profiles, which did not show a flat form. In third trial, strip pitfall was not observed. Thus, this study allowed the application of a scan quality test that is little performed in NM to verify a gamma camera performance in this type of exams. It demonstrated itself adequate and efficient for image regional non-uniformities identification due to scan speed variations. (author)