Hal C. Becker

AUTOMATED COMPUTER ANALYSIS OF RADIOGRAPHIC IMAGES.

Lee B. Lusted in his Memorial Fund Lecture (1) anticipated the device: “an electronic ‘scanner-computer’ to look at chest photofluorograms and to separate the clearly normal chest films from the abnormal chest films. The abnormal chest films would be marked for later study by the radiologist.” This automated computer analysis concept was based on some preliminary studies by Pendergrass and Tolles who showed that automatic scanning of photofluorograms could produce satisfactory density tracings. We are now reporting a method of automated computer analysis of radiographic images utilizing algorithms (a rule of procedure for solving a recurrent mathematical or logical problem) for recognizing parts of the radiographic image. Method and Results Thirty-seven 70 mm. photofluorograms were digitized and put on magnetic tape, using an improved image-scanning system similar to one previously reported (2). The radiographic image of the chest on magnetic tape contains 502 digit samples per line times 320 horizontal s...

Digital Computer Determination of a Medical Diagnostic Index Directly from Chest X-Ray Images

Image matrices of chest X-ray films were recorded in digital form on magnetic tape using a flying spot scanner, an analog-to-digital converter, and a digital computer system. These taped images were used as input to the computer which, by means of its stored program, automatically measured the maximum transverse diameter of the heart shadow, maximum transverse diameter of the rib cage shadow, then calculated and printed out the ratio of these two measured values. This is the cardiothoracic ratio, which is a standard diagnostic index employed by physicians for detection of cardiac pathology, e.g., heart enlargement. To our knowledge, this is the first practicable and useful diagnostic index successfully determined directly from an unaltered X-ray film through the use of a digital computer.

A roentgenographic stereotaxic technique for implanting and maintaining electrodes in the brain of man

Abstract A single stage roentgenographic stereotaxic technique has been presented which permits accurate placement of stimulating and recording electrodes having flexible leads into subcortical structures of the human brain (visualized by air ventriculography). A simple and rapid system for correcting the roentgenographic mapping errors which result from a noncollimated X-ray beam has been developed. Design information has been given on electrodes and lucite skull buttons which are easily fabricated. The buttons prevent displacement of electrodes from their target positions. Leadwires are flexible, inexpensive, and readily available. These electrodes are comfortably tolerated for periods of time ranging up to two years and are easily connected to equipment for electrical stimulation and recording.

A variable frequency, variable selectivity filter for electroencephalography

Abstract An instrument is described which consists of simple revision of an inexpensive commercially available oscillator kit to allow its use both as an oscillator and a tunable frequency analyzer. These minor revisions, indicated in the electrical diagram, allow it to be coupled in the circuit of the EEG machine to accept single ended inputs of 1.5 V. or higher and deliver an output as high as 35 V. peak to peak, push-pull. Range of selectivity extends to a Q of about 35. Write-out is direct on the EEG channel, where it provides an indication of the amount or amplitude of the chosen frequency.

Cardiac Measurements in Systole and Diastole

Two postero-anterior chest roentgenograms were exposed, one during diastole and one during systole, on each of 359 patients, 35 sets of films being later discarded because of technical errors. Fifty-two per cent of the patients showed changes of 0.3 cm or less, 41 per cent showed alterations of 0.4 to 0.9 cm, and 7 per cent a variation of 1.0 to 1.7 cm in transverse cardiac diameter. It is concluded that the set of films is more useful in evaluating heart size than one film exposed at a random point along the cardiac cycle.

An application of autosyns to multi-channel physiological recording.

Summary An apparatus has been described which employs autosyns for the recording of displacements produced by physiological activity. The apparatus appears to have certain advantages over the kymographs customarily used for such recordings.

LASER LIGHT DIFFRACTION, SPATIAL FILTERING, AND RECONSTRUCTION OF MEDICAL RADIOGRAPHIC IMAGES: PRELIMINARY RESULTS

Using a laser light source, an optical bench, transform lenses, and spatial filters in a system called Laserscan,’ we are studying laser light diffraction, spatial filtering, and reconstruction of medical radiographic images with the help of GTS Corporation whose laboratories house the laser computer. Medical radiographs are minified to a 35 mm second-generation transparency, then transilluminated by monochromatic, coherent, collimated light from a helium-neon gas laser. A first transform lens produces a Fourier Transform (FT) of the minified image in the form of a diffraction pattern that is photographed on Polaroid film, and/or viewed with a CCTV system. Spatial filtering is accomplished in the plane of the diffraction pattern by using various opaque elements of appropriate geometric form to filter undesired spatial frequencies. Spatial filters take the form of “wires,” “sector-wedges,’’ and circular apertures, as well as other empirically determined shapes. A second lens performs an inverse FT on the diffraction pattern producing a reconstructed, filtered, real image of the minified film. This reconstructed image is also photographed on Polaroid film or viewed on the CCTV screen. One of our goals is to remove certain ,unnecessary pattern detail from particular radiographic images so that characteristic patterns of diagnostic picture detail might be more readily identified and diagnosed. Experimental results including photographs of diffraction patterns and some filtered reconstructed images are presented. We first considered image conditioning by means of spatial filtering during 1963 and 1964 as a data reduction technique that might be used to preprocess medical radiographic images as a first phase in pattern recognition and analysis. Coherent optics was attractive because of the many possibilities offered by use of the two-dimensional FT, empirically determined variable density spatial filters in the frequency plane (plane of the diffraction pattern), and the inverse FT, to produce a reconstructed filtered image of the original picture. Conceivably, one could experimentally determine the particular diffraction patterns characteristic of specific diseases, then prepare spatial filters in the form of variable density masks that would remove (filter out )all image information not part of the pathological pattern structure. One might then, after this first preprocessing (data reduction) phase, take either the resultant diffraction patterns, or the filtered reconstructed images, or both, to the next phase, e.g., some type of pattern recognition and/or analysis, either analog or digitaL2 machine or human. Many excellent papers on coherent optics are now available. A superb collection, rich in references, is contained in the volume that comprises the Proceedings of the 1964 Symposium on Optical and Electro-Optical Information Processing Te~hnology.~ Additional pertinent papers not specifically referred to in the text are those of References 19 through 24.