What is Off Focus Radiation.
The off Focus Radiation is produced by an x-ray tube when high speed electrons interact with metal surface of the anode. The main source of off Focus electrons is Backscatter from the anode. These scattered radiation second time strike the anode and produces x-ray from areas other than the anode focal track. The off Focus Radiation is control by the collimator and lead diaphragm placed close to the x-ray tube as possible. The metal enclosure decrease the off Focus Radiation by attracting off Focus electrons to the grounded metal wall of x-ray tube. The metal enclosure is at zero potential and the enclosure is relatively positive as compared to electrons which are at a negative potential.
Off Focus electrons may be attracted to the anode or to the grounded x-ray tube enclosure.where the electrons goes is in part a function of it’s distance from the anode or metal wall. So the off Focus electrons strick the metal wall and produce the off Focus Radiation.
