Although we used a PET scanner that was equipped with an external transmission source, PET/CT scanners with CT-based transmission scans are mainstream among PET devices.
It was suggested to solve the scaling problem in TOF MLAA by incorporating prior knowledge of the attenuation values by using for instance an external transmission source.
It consists in a cylindrical sample confined in a steel tube, the cylindrical sample being inserted between the incident bar and the internal transmission bar, and the confinement tube being leant against the external transmission bar.
The high impedance of the external transmission bar keeps the confinement tube quasi-motionless whereas the impedance of the internal transmission bar is calculated to reach the desired pressure and the desired velocity at the tube sample interface.
Unsurprisingly, the probability of FIV extinction decreases with increasing external transmission rate (εM).
The rates εM and εF are termed the external transmission rates.
Finally we look at the impact of the external transmission rate εM on FIV spread in already infected populations.
Since we do not model spatial structure explicitly, we assume that connectivity between populations affects external transmission rate.
In Fig. 3b we analyze the effect of the external transmission rate on the mean and standard deviation of FIV prevalence in males.
In contrast, for the highest values of external transmission rate in the confidence region, we can expect a correlation in FIV prevalence between connected populations.
