Paper Info
Title
Automated detection of small spherical pellets with gradient filtering on digitized XRII images
Abstract
Small pellets are often used as fiducial markers in a calibration phantom to estimate the geometrical parameters in 3D (three-dimensional) reconstruction. But calibration accuracy depends on the accuracy of locating the pellet centers. Here we describe an technique for fast and accurate detection of these centers. The phantom consists of tungsten carbide pellets arranged in a helical trajectory. The plastic holder mounting the pellets may cause unequal distribution of attenuation around edge pellets compared to the center ones. After log subtraction with flood frames the grayscale gradient in the background is derived within the mask for every point for a reliable background correction. The pellets are identified from the amplitude projections of each frame and a mask is used to refine its position. The grayscale gradient of the background is suitably estimated at each point by the equation of a plane. The center obtained after gradient filter correction is compared with manual measurement, and to measurement using a single background value for each mask. Gradient correction gives centers within 0.3 +/- 0.1 pixel of the manual measurements for the edge pellets, while a single value for background correction yields results within 0.6 +/- 0.3 pixel.
Year
DOI
Venue
2000
10.1117/12.387657
Proceedings of SPIE
Keywords
Field
DocType
calibration,center-detection,phantom,C-arm gantry,reconstruction,gradient filter
Iterative reconstruction,Fiducial marker,Pellets,Imaging phantom,Filter (signal processing),Optics,Pixel,Mathematics,Calibration,Grayscale
Conference
Volume
ISSN
Citations 
3979
0277-786X
0
PageRank 
References 
Authors
0.34
0
3
Name
Order
Citations
PageRank
Anindya Sen132.50
michael d silver231.77
satoru oishi310.75