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Hardcopy quality parameters to ensure structures detection at digital mammography* * Study developed at Coordination of Physics and Radiations Hygiene, Department of Diagnostic Imaging, Escola Paulista de Medicina – Universidade Federal de São Paulo (EPM-Unifesp), São Paulo, SP, Brazil. Financial support: Fundação de Amparo à Pesquisa do Estado de São Paulo (Fapesp).

Objective

To develop procedures to ensure consistency of printing quality of digital images, by means of hardcopy quantitative analysis based on a standard image.

Materials and Methods

Characteristics of mammography DI-ML and general purpose DI-HL films were studied through the QC-Test utilizing different processing techniques in a FujiFilm®-DryPix4000 printer. A software was developed for sensitometric evaluation, generating a digital image including a gray scale and a bar pattern to evaluate contrast and spatial resolution.

Results

Mammography films showed maximum optical density of 4.11 and general purpose films, 3.22. The digital image was developed with a 33-step wedge scale and a high-contrast bar pattern (1 to 30 lp/cm) for spatial resolution evaluation.

Conclusion

Mammographic films presented higher values for maximum optical density and contrast resolution as compared with general purpose films. The utilized digital processing technique could only change the image pixels matrix values and did not affect the printing standard. The proposed digital image standard allows greater control of the relationship between pixels values and optical density obtained in the analysis of films quality and printing systems.

Hardcopy; Quality control; Contrast sensitivity; Mammography


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