title: Portal radiographs: digital enhancement of contrast.
abstract: The quality of low-contrast portal radiographs for radiation therapy can be improved with electronic contrast enhancement. After the image is copied digitally with a laser scanner microdensitometer into 4,096 gray-scale levels (12 bits) and 1,686 X 2,048 pixels, a special software package permits linear, logarithmic, exponential, or sigmoid transformations of the optical density. The precise representation of the portal image can then be interactively adjusted to emphasize the desired anatomy. Clinical examples demonstrate the value of the digital enhancement approach.
authors.affiliation: Department of Radiation Oncology, Hospital of the University of Pennsylvania, Philadelphia 19104.
authors.forename: W D
authors.initials: WD
authors.lastname: Powlis
authors.forename: I
authors.initials: I
authors.lastname: Brikman
authors.forename: S B
authors.initials: SB
authors.lastname: Seshadri
authors.forename: P
authors.initials: P
authors.lastname: Bloch
mesh_terms: D011856:Radiographic Image Enhancement; D014057:Tomography, X-Ray Computed / Q000379:methods*