ELECTRONIC PORTAL IMAGING

In our institute, we have developed an electronic portal imaging syste m based on a matrix of 256 x 256 ionisation chambers. By improvements to the electronics, the system produces images with the same quality a s the original system but 3-10 times faster. Software for automatic im age analysis has been applied to more than 10 000 images over the last two years. Using an off-line correction strategy, the systematic pati ent set-up error has been limited to 5 mm or less for 98% of the patie nts treated for prostate cancer.