These data demonstrate that the effect of camera variations, as assessed by SEF, on the calibration factor CFrA was very low.
Fig. 3 Histogram match value variation graph related to camera variations, (a) distance variation effect, (b) rotation to left and right effect, (c) rotation to up and down effect [33].
Day-to-day variability's include gamma camera variations, stress (dogs should be acclimatized to the scintigraphic procedure), hydration status, water and food intake and composition, particularly protein content.
Phantom calibration provides a methodology for reducing inter-camera variations and recovering the true SBR value in human studies; however, its success is ultimately linked to the extent to which it is representative of the clinical context.
Camera sensitivity variation measured using a 57Co sheet source was small and had a weak relationship to calibration factor variations.
According to the results, camera sensitivity variations were small and had little effect on the variance of the calibration factor.
Since this was measured using a different radionuclide and collimator, it assesses only the radionuclide and collimator independent component of camera sensitivity variations.
For example, if SEF increased by one standard deviation, the calibration factor CFdA would have decreased by 0.0004 × 10−5 cps·Bq−1 (0.03%), meaning, there was a negligible effect of camera sensitivity variations (as measured by SEF) on the CFdA measurement.
A sensitivity factor calculated from a daily 57Co extrinsic flood acquisition, also acquired as part of routine quality control, was used to evaluate the impact of the camera sensitivity variations that are independent of radionuclide and collimator on the calibration factor measurement.
These roads were selected because of the availability of vantage points for mounting cameras and variations in flow among them.
