Fig. 1

Examples of phantom images and ROIs. a Axial plane from the middle of the six hot spheres in the NEMA IQ phantom filled with ⁶⁸Ge as imaged with six different scanners using the local routine protocols. The signal void in the middle of the slice is from the cylindrical lung insert utilized in the AOC test. b Axial plane from the middle of the six hot spheres (left image) as well as one centimeter (middle image) and two centimeters (right image) from it. The locations of the NEMA specified background ROIs with a diameter of 37 mm are shown with the white circles. Besides the 36 out of 60 background ROIs shown here, the rest of the ROIs were situated in the planes of one and two centimeters before the middle plane. The background ROIs with smaller diameters (10, 13, 17, 22 and 28 mm) were centered inside the 37 mm ROIs. The ROI with a 30 mm diameter inside the lung insert is shown in black in these planes