Stereoscopy, stereoscopic imaging or 3-D (three-dimensional) imaging is any technique capable of recording three-dimensional visual information or creating the illusion of depth in an image. The illusion of depth in a photograph, movie, or other two-dimensional image is created by presenting a slightly different image to each eye. Many 3D displays use this method to convey images. It was first invented by Sir Charles Wheatstone in 1840.
Stereoscopy is used in photogrammetry (Photogrammetry is the first remote sensing technology ever developed, in which geometric properties about objects are determined from photographic images) and also for entertainment through the production of stereograms. Stereoscopy is useful in viewing images rendered from large multi-dimensional data sets such as are produced by experimental data. Modern industrial three dimensional photography may use 3D scanners to detect and record 3 dimensional information. The three-dimensional depth information can be reconstructed from two images using a computer by corresponding the pixels in the left and right images. Solving the correspondence problem in the field of computer vision aims to create meaningful depth information from two images.
Traditional stereoscopic photography consists of creating a 3-D illusion starting from a pair of 2-D images. The easiest way to create depth perception in the brain is to provide the eyes of the viewer with two different images, representing two perspectives of the same object, with a minor deviation similar to the perspectives that both eyes naturally receive in binocular vision. If eyestrain and distortion are to be avoided, each of the two 2-D images preferably should be presented to each eye of the viewer so that any object at infinite distance seen by the viewer should be perceived by that eye while it is oriented straight ahead, the viewer's eyes being neither crossed nor diverging. When the picture contains no object at infinite distance, such as a horizon or a cloud, the pictures should be spaced correspondingly closer together.
Stereoscopic digital mammography technology allows radiologists to detect more cancers with fewer false positives. In a clinical trial of 1,093 women, stereoscopic digital mammography detected more true lesions than standard digital mammography and reduced false-positive findings by nearly half.
Stereoscopic digital mammography is a diagnostic technique capable of producing three-dimensional, in-depth views of breast tissue that could significantly reduce the number of women who are recalled for additional tests following routine screening mammography.
Standard mammography is one of the most difficult radiographic exams to interpret, in a two-dimensional image of the breast, subtle lesions may be masked by underlying or overlying normal tissue and thus be missed, and normal tissue scattered at different depths can align to mimic a lesion, leading to false-positive detections.
Stereoscopic digital mammography consists of two digital x-ray images of the breast acquired from two different points of view separated by about eight degrees. When the images are viewed on a stereo display workstation, the radiologist is able to see the internal structure of the breast in three dimensions. The workstation enables the mammographer to fuse the stereo image pair and to view the breast in true depth.
Results from clinical trials suggest that stereo digital mammography could contribute to the earlier detection of cancer. A small percentage of the additional lesions missed by standard mammography but detected by stereoscopic mammography may turn out to be cancerous.
In studies, stereo digital mammography reduced false positives by 49 percent. This could have a significant impact by cutting in half the number of women who are needlessly recalled for additional diagnostic work-ups, resulting in a large savings in cost and patient anxiety.
Summary: A new mammography technology that allows radiologists to detect more cancers with fewer false positives.
Stereoscopic digital mammography produces three-dimensional, in-depth views of breast tissue.
In a clinical trial of 1,093 women, stereoscopic digital mammography detected more true lesions than standard digital mammography and reduced false-positive findings by nearly half.
Sources:
http://www.medicalnewstoday.com/articles/90102.php
http://www.medicexchange.com/mall/------/departments-contentview
http://www.sunnybrook.ca/research/groups/dm/projects/stereo_mg
Compiled and Edited by John Sandham IEng MIET MIHEEM
November '07
