Biomedical subjects

E Pietka

Publications and source records attributed to E Pietka.

3 recordsLinked to original sources

PubMed1992

Orientation correction for chest images.

This report presents an automatic procedure that determines the orientation of computed radiography (CR) chest images and rotates them to a standard position to be viewed by radiologists. As an input, CR images of a normalized size of 1,000 x 1,000 or 2,000 x 2,000 pixels are used. The analysis is performed in three steps. First, the orientation of the spine within the image is determined. Then, a function searches for upper extremities and the subdiaphragm. Finally, the lungs are extracted and their areas are compared. This indicates whether the image needs to be y-axis flipped. These three steps set the value of three parameters on the basis of which the final rotation angle is determined. The procedure has been implemented in the clinics at UCLA. The rate of correctly rotated images is 95.4%.

Algorithms↗

PubMed1992

Image preprocessing for a picture archiving and communication system.

OBJECTIVES AND RATIONALE: In a picture archiving and communication system (PACS), images are acquired from multiple modalities and displayed on an electronic workstation. Each modality has different image characteristics. This variability must be addressed before the image is displayed. METHODS: The authors developed methods to automatically process magnetic resonance (MR), computed tomographic (CT), and computed radiography (CR) images before display and subjectively evaluated their effectiveness. RESULTS: Unwanted background successfully was automatically removed from 89.5% of 615 CR images. Of 803 chest, abdomen, and hand images 93% were automatically rotated to the correct orientation. CONCLUSIONS: Automated preprocessing of PACS images can be performed successfully, improving speed and convenience for the radiologist interpreting images at an electronic workstation.

Image Processing, Computer-Assisted↗

PubMedDate not supplied

Correction of aberration in image-intensifier systems.

A mathematical model describing spatial distortions caused by an image intensifier has been developed. These distortions originate from projecting a flat plane onto a curved input phosphor surface. Considering the source of these distortions and their magnification along the radial distance, it is possible to describe them in terms of the geometrical relations between a point on a physical object and its projection onto an input phosphor screen's spherical surface. On the basis of these relations, the correction of pixel coordinates and pixel values has been performed. Parameters included in the derived formula consider the radius of curvature of the input screen, the view angle, the distance from the focal spot to the object, and the distance from the focal spot to the input phosphor screen. These parameters make the correction formula system independent and permit its application to any image projected under different view angle and/or acquired with different image-intensifier system. The correction leads to a nearly distortion-free image.

Angiography↗