X-ray or gamma ray systems or devices – Accessory – Testing or calibration
Patent
1994-11-28
1996-08-06
Wong, Don
X-ray or gamma ray systems or devices
Accessory
Testing or calibration
G01D 1800
Patent
active
055442382
ABSTRACT:
Methods and apparatus for correcting the effect on image quality of a film processor which develops a radiographic image of a structure of interest on a film having an emulsion is disclosed. Such methods and apparatus include shielding a first portion of the film along one edge from the x-ray energy used for imaging the structure of interest and impressing a first calibrated test pattern on the first portion of the film. The first pattern includes a first calibrated graded stepwise density pattern having density positions. The density pattern is produced by visible light. A first plurality of symbols is located adjacent the first pattern, wherein each symbol indicates the magnitude of one of the density positions. A control film of similar emulsion as the emulsion of the image film is provided and impressed with a second calibrated test pattern along one edge. The second pattern includes a second calibrated graded stepwise density pattern having density positions, which pattern was also produced by visible light. A second plurality of symbols is located adjacent the second pattern, wherein each symbol indicates the magnitude of one of the density positions. The intensity and spectrum of the visible light used for impressing the first and second patterns is adjustable. The film is processed in a film processor to develop the first pattern and the radiographic image of the structure of interest. The control film is processed to develop the second pattern. The performance of the film processor used to develop the film is measured by comparing and noting the symbols associated with those density positions between the first and second patterns which match. Physical parameters of selected portions of the developed image of the structure of interest are measured, such parameters define image quality. These parameters are corrected for the effect of film processor performance by adjusting the values of the measured physical parameters according to the optical density values at the match positions of the first and second patterns.
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Thomas Jefferson University
Wong Don
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