title: Area beam equalization: optimization and performance of an automated prototype system for chest radiography.
abstract: OBJECTIVE
  To evaluate the feasibility and performance of an x-ray beam equalization system for chest radiography using anthropomorphic phantoms.
  
  
  METHODS
  Area beam equalization involves the process of the initial unequalized image acquisition, attenuator thickness calculation, mask generation using a 16 x 16 piston array, and final equalized image acquisition. Chest radiographs of three different anthropomorphic phantoms were acquired with no beam equalization and equalization levels of 4.8, 11.3, and 21. Six radiologists evaluated the images by scoring them from 1-5 using 13 different criteria. The dose was calculated using the known attenuator material thickness and the mAs of the x-ray tube.
  
  
  RESULTS
  The visibility of anatomic structures in the under-penetrated regions of the chest radiographs was shown to be significantly (P < .01) improved after beam equalization. An equalization level of 4.8 provided most of the improvements with moderate increases in patient dose and tube loading. Higher levels of beam equalization did not show much improvement in the visibility of anatomic structures in the under-penetrated regions.
  
  
  CONCLUSIONS
  A moderate level of x-ray beam equalization in chest radiography is superior to both conventional radiographs and radiographs with high levels of beam equalization. X-ray beam equalization can significantly improve the visibility of anatomic structures in the under-penetrated regions while maintaining good image quality in the lung region.
authors.affiliation: Department of Radiological Sciences, University of California, Medical Sciences I, B-140, Irvine, CA 92697, USA.
authors.forename: Tong
authors.initials: T
authors.lastname: Xu
authors.forename: Polad M
authors.initials: PM
authors.lastname: Shikhaliev
authors.forename: Gholam R
authors.initials: GR
authors.lastname: Berenji
authors.forename: Jamshid
authors.initials: J
authors.lastname: Tehranzadeh
authors.forename: Farhood
authors.initials: F
authors.lastname: Saremi
authors.forename: Sabee
authors.initials: S
authors.lastname: Molloi
mesh_terms: D005240:Feasibility Studies; D006801:Humans; D019047:Phantoms, Imaging; D011856:Radiographic Image Enhancement / Q000295:instrumentation*; D013902:Radiography, Thoracic / Q000295:instrumentation*