Silvio Ricardo Pires

Hardcopy quality parameters to ensure structures detection at digital mammography

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.

QualIM®: software para treinamento na interpretação de imagens médicas digitais

OBJECTIVE: A software called QualIM® – Qualificacao de Imagens Medicas was developed for training of practitioners in the interpretation of digital mammograms classified according to BI-RADS® categories, utilizing images manipulation tools on state-of-the-art displays. MATERIALS AND METHODS: A Delphi 7-based system stores data resulting from mammographic findings interpretation during the training, comparing them with a golden-standard data set. The database includes computed radiography, direct radiography and digitized images. The software converts computed radiography and direct radiography images into TIFF format, preserving their original spatial and contrast resolution. During the training, the images are manipulated with the aid of the software tools (zoom, inversion, digital rulers and others). Depending on the image complexity, up to eight mammographic views, six ultrasonography images and two anatomopathological images can be displayed. RESULTS: The training was initiated in 2007 and is currently included in the radiology residency program. Based on data entered by the practitioner, the software automatically generates a BI-RADS compliant text that is compared with a database. CONCLUSION: The QualIM software is a digital educational tool aimed at assisting practitioners in the recognition of visual patterns on mammographic images as well as in the interpretation of mammograms based on the BI-RADS classification.

Pedagogic Tool for Learn-Teaching on Digital Mammography Using Dedicated Software

The purpose of this work is to evaluate the effectiveness of a training methodology developed in the Medical Image Qualification Laboratory - QualIM to assist in the complex learning process of reading mammography images. A dedicated software was used by residents and specialists for image manipulation (contrast, brightness, zoom, inversion) and also to analyze the readings performance. Sixty images of statistical phantom (Alvim®) were acquired with mammographic equipment using different techniques and presented in monitors and a specific view box (screen film). The readings’ performance was evaluated by statistical parameters: probability of detectability (Pdet), kappa (K), true positive results (TP), false positive results (FP) and the area under the ROC curve, considering different objects (fibers and microcalcifications) and their different dimensions. The residents’ detection performance was superior in monitors (softcopy) for both objects (fibers and microcalcifications) suggesting that digital tools were useful since they promoted higher contrast resolution. The ROC analysis show a higher performance in the digital system (Az=0.808) than in the screen film system (Az= 0.707). Also the experts got better results in the digital system (Az=0.841) than with another reading system (Az=0.803). The methodology allowed to quantify and compare the readings performance among different groups based on Signal Detection Theory.