Abstract：
:Because of the high energy of the treatment beam, contrast of portal verification films is very poor. A simple contrast enhancement technique is described which we have labeled selective histogram equalization (SHE), to improve visualization of double-exposure portal images and this facilitate the beam verification process. The technique performs separate histogram equalization on the treatment- and open-field sections of double-exposure portal images. Delineation of the treatment field edge and separation into two regions is performed automatically for off-line portal radiographs by a strategic combination of Sobel filtration and morphological processes. Analyses of images processed by SHE and other adaptive histogram equalization techniques indicate that SHE produces improved contrast enhancement with minimal addition of noise or artifacts, thus simplifying the beam verification procedure. The simple implementation of an automatic SHE process with on-line portal systems is also discussed.
journal_name
Med Physjournal_title
Medical physicsauthors
Crooks I,Fallone BGdoi
10.1118/1.597085subject
Has Abstractpub_date
1993-01-01 00:00:00pages
199-204issue
1eissn
0094-2405issn
2473-4209journal_volume
20pub_type
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