Algorithm for A/D window control for electronic Portal imaging in radiation therapy system adjusts pixel numbers and values in dark zones

摘要

The algorithm performs an initial estimation of the dark zones within a histogram relating to the adjustment of pixel numbers and values and determines the two dominant peaks within the dark zones. If these exceed twice the standard deviation relative to one another these limits are revised accordingly, otherwise the average value of the two peaks is used. It also determines the upper and lower cut off points at which a specific pixel value is reached outside the dark zone.