Measurement of the increase in light pohotns due to converssion efficiency of output screen
What is conversion efficiency? How does it affect patient dose?
Ability of the phosphor to emit as much light per x-ray photon interaction aspossible.
As conversion efficient increases, patient exposure dose decrease
How do you calculate total brightness gain?
Total brightness gain = minification gain x flux gain
What is brightness control used for?
To automttically maintain satisfactory fluro image density and contrast.Known as ABC ( automatic brightness control )
What is lag?
persistence of luminescence after x-ray stimulation has been terminated.
What causes size distortion in fluoro?
What causes shape distortion in flouro?
Caused by geometric problem in the shape of the image intesification tube.Peripheral electrons do not strike output screen where they are focused resulting in unequal magnification producing peripheral distortion.