Computer simulation of the geometric unsharpness effect on radiologic images

Marcio A. Marques; Annie France Frere; Henrique J. Q. de Oliveira; Homero Schiabel; Paulo M. Azevedo Marques; Ricardo Jose Ferrari; Aledir S. Pereira

doi:10.1117/12.258274

14 November 1996 Computer simulation of the geometric unsharpness effect on radiologic images

Marcio A. Marques, Annie France Frere, Henrique J. Q. de Oliveira, Homero Schiabel, Paulo M. Azevedo Marques, Ricardo Jose Ferrari, Aledir S. Pereira

Author Affiliations +

Proceedings Volume 2847, Applications of Digital Image Processing XIX; (1996) https://doi.org/10.1117/12.258274
Event: SPIE's 1996 International Symposium on Optical Science, Engineering, and Instrumentation, 1996, Denver, CO, United States

Abstract

The magnitude of the image geometric unsharpness depends on the location in the field where the object is hit by the x- ray beam. This phenomenon is known as field characteristics and is caused by the target plane angulation. This yields different effective focal spot sizes and shapes when it is 'seen' from different directions and locations in the x-ray field . Due to the effect of the field characteristics, a more detailed evaluation of focal spot behavior in radiology systems is needed. Hence the focal spot should be evaluated in all field locations, which is very complex with experimental procedures, although feasible by computer simulation. This work describes an algorithm with the aim of determining the size and shape of effective focal spots in any location of the radiation field, on the basis of the focal spot size measurement in the filed center. The results obtained by the program have agreed with those obtained by pinholes matrix exposures in several radiology faculties. The program has proved efficient in computing the size of the focal spot projections for mammography systems, with a standard deviation around 0.03-0.04 mm.

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Marcio A. Marques, Annie France Frere, Henrique J. Q. de Oliveira, Homero Schiabel, Paulo M. Azevedo Marques, Ricardo Jose Ferrari, and Aledir S. Pereira "Computer simulation of the geometric unsharpness effect on radiologic images", Proc. SPIE 2847, Applications of Digital Image Processing XIX, (14 November 1996); https://doi.org/10.1117/12.258274

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