Use of storage phosphors for portal imaging in radiation therapy

A major drawback in the interpretation of portal images in radiation therapy is their low contrast. This is due to the low differential absorption of body tissues at therapeutic energies and the relatively large focal spot. The authors have used an experimental storage phosphor imaging system to produce portal images. The system consists of a storage phosphor detector, a laser scanner (12 bit), an image processing module, and a laser printer (12 bit). Both a conventional portal image and a storage phosphor were obtained in patients undergoing radiation therapy. The storage phosphor image was scanned, processed, and displayed side-by-side with the conventional image; both were evaluated by several radiation therapists for information content. Storage phosphor images were found to be superior to conventional images, particularly with respect to visibility of bony landmarks