Fig. 4
From: Calibration of PET/CT scanners for multicenter studies on differentiated thyroid cancer with 124I
Bland-Altman plots of measured activity A m,0 and calibrated activity A cal, versus reference activity A r for all scanners, shown per vendor (a vendor A and b vendor B). For presentation purposes, axes are on a log-log scale, and the relative errors are calculated as an absolute value: E r = │(A r − A m)/A r │and E r = │(A r − A cal)/A r │. To assess improvement of calibration, the average of reference activities A r and corresponding average relative errors are calculated for each reference activity decade. The blue and green solid lines indicate the average relative errors in measured and calibrated activities, respectively