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Baily, N. A.

Publications and source records attributed to Baily, N. A..

At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1977

Computerized tomography using video recorded fluoroscopic images

The use of video-recorded fluoroscopic images as input data for digital reconstruction of objects from their projections is examined. The fluoroscopic and the scanning apparatus used for the experiments are of a commercial type already in existence in most hospitals. It is shown that for beams with divergence up to about 15 deg, one can use a convolution algorithm designed for the parallel radiation case with negligible degradation both quantitatively and from a visual quality standpoint. This convolution algorithm is computationally more efficient than either the algebraic techniques or the convolution algorithms for radially diverging data. Results from studies on Lucite phantoms and a freshly sacrificed rat are included.

Kak, A. C.↗
NASA NTRS1976

The response of fluoroscopic image intensifier-TV systems

Three different types of X-ray fluoroscopic TV chains were investigated: two standard clinical units, one with a vidicon camera tube, the other with a plumbicon camera tube; and the third was a large flat-screen unit. In each an X-ray beam generated at 100 kVp was passed through 10 cm of H2O before aluminum absorbers of varying thickness were introduced. Five video recordings were made at each absorber thickness. The video image was digitized directly from the disk recording and quantized into 128 gray levels. The five recordings were averaged on a point-to-point basis, and the central 900 averaged points were again averaged to yield a value for the gray level assigned to each particular image. This 30 by 30 matrix of points corresponds to input screen areas of 29, 8.2, and 3.6 sq cm for the three units investigated.

Baily, N. A.↗
NASA NTRS1976

A computer program for the localization of small areas in roentgenological images

A method and associated algorithm are presented which allow a simple and accurate determination to be made of the location of small symmetric areas presented in roentgenological images. The method utilizes an operator to visually spot object positions but eliminates the need for critical positioning accuracy on the operator's part. The rapidity of measurement allows results to be evaluated on-line. Parameters associated with the algorithm have been analyzed, and methods to facilitate an optimum choice for any particular experimental setup are presented.

Keller, R. A.↗
NASA NTRS1976

Acquisition of quantitative physiological data and computerized image reconstruction using a single scan TV system

A single-scan radiography system has been interfaced to a minicomputer, and the combined system has been used with a variety of fluoroscopic systems and image intensifiers available in clinical facilities. The system's response range is analyzed, and several applications are described. These include determination of the gray scale for typical X-ray-fluoroscopic-television chains, measurement of gallstone volume in patients, localization of markers or other small anatomical features, determinations of organ areas and volumes, computer reconstruction of tomographic sections of organs in motion, and computer reconstruction of transverse axial body sections from fluoroscopic images. It is concluded that this type of system combined with a minimum of statistical processing shows excellent capabilities for delineating small changes in differential X-ray attenuation.

Baily, N. A.↗
NASA NTRS1976

Analog enhancement of radiographic images

The paper shows how analog methods for edge sharpening, contrast enhancement, and expansion of the range of gray levels of particular interest are effective for easy on-line application to video viewing of X-ray roentgenograms or to fluoroscopy. The technique for analog enhancement of radiographic images is a modified version of the system designed by Fuchs et al. (1972), whereby an all directional second derivative signal called detail signal is used to produce both vertical and horizontal enhancement of the image. Particular attention is given to noise filtration and contrast enhancement. Numerous radiographs supplement the text.

Baily, N. A.↗
NASA NTRS1976

A physical comparison of a fluoroscopic CAT system and the EMI head scanner

A quantitative comparison of the capabilities to produce computerized tomograms was made between the EMI head scanner and reconstructions from images provided by a large screen low light level-TV camera fluoroscopic system. A phantom made from lucite containing rods of various materials and sizes was used. The computer printout of each was analyzed and a correlation of 0.8 was noted between the results of both systems. The differential attenuation detectability of the fluoroscopic system was found to be comparable to or better than the EMI unit. As expected from a consideration of the quantum statistics for each system, the noise in the obtained reconstructions was also comparable. It is concluded that such a fluoroscopic system performs favorably when compared to the presently available commercial systems.

Baily, N. A.↗
NASA NTRS1975

Development and investigation of single-scan TV radiography for the acquisition of dynamic physiologic data

A light amplifier for large flat screen fluoroscopy was investigated which will decrease both its size and weight. The work on organ contouring was extended to yield volumes. This is a simple extension since the fluoroscopic image contains density (gray scale) information which can be translated as tissue thickness, integrated, yielding accurate volume data in an on-line situation. A number of devices were developed for analog image processing of video signals, operating on-line in real time, and with simple selection mechanisms. The results show that this approach is feasible and produces are improvement in image quality which should make diagnostic error significantly lower. These are all low cost devices, small and light in weight, thereby making them usable in a space environment, on the Ames centrifuge, and in a typical clinical situation.

Baily, N. A.↗
NASA NTRS1975

Simple computer method provides contours for radiological images

Computer is provided with information concerning boundaries in total image. Gradient of each point in digitized image is calculated with aid of threshold technique; then there is invoked set of algorithms designed to reduce number of gradient elements and to retain only major ones for definition of contour.

Newell, J. D.↗
NASA NTRS1975

Computerized tomography using video recorded fluoroscopic images

A computerized tomographic imaging system is examined which employs video-recorded fluoroscopic images as input data. By hooking the video recorder to a digital computer through a suitable interface, such a system permits very rapid construction of tomograms.

Kak, A. C.↗
NASA NTRS1975

The capability of fluoroscopic systems to determine differential Roentgen-ray absorption

A clinical fluoroscopic unit used in conjunction with a TV image digitization system was investigated to determine its capability to evaluate differential absorption between two areas in the same field. Fractional contrasts and minimum detectability for air, several concentrations of Renografin-60, and aluminum were studied using phantoms of various thicknesses. Results showed that the videometric response, when treated as contrast, shows a linear response with absorber thickness up to considerable thicknesses.

Baily, N. A.↗
NASA NTRS1975

The radiobiological implications of statistical variations in energy deposition by ionizing radiations

Traditional approaches to microdosimetry, the fundamental physics of energy deposition, the importance of statistical processes, an illustration of possible radiobiological interpretation, and modeling based on microdosimetric concepts are discussed. Emphasis is on the inadequacies in linear energy transfer (LET) theory. For many reasons, concepts based on averaging may not be applicable to ionizing radiation absorption by and damage to small biological targets.

Baily, N. A.↗
NASA NTRS1975

Acquisition of quantitative physiological data and computerized image reconstruction using a single scan TV system

Single scan operation of television X-ray fluoroscopic systems allow both analog and digital reconstruction of tomographic sections from single plan images. This type of system combined with a minimum of statistical processing showed excellent capabilities for delineating small changes in differential X-ray attenuation. Patient dose reduction is significant when compared to normal operation or film recording. Flat screen, low light level systems were both rugged and light in weight, making them applicable for a variety of special purposes. Three dimensional information was available from the tomographic methods and the recorded data was sufficient when used with appropriate computer display devices to give representative 3D images.

Baily, N. A.↗
NASA NTRS1974

Development and investigation of single-scan TV radiography for the acquisition of dynamic physiologic data

Research data obtained by the low dose electronic radiography system are reported. Data cover: (1) localization and tracking of Ta screws implanted in the inner wall of the right ventrical of the heart, (2) use of cross hairs to outline inner or outer heart wall contours, (3) quantitative measure of anatomical components which are stationary in size or change size dynamically, and (4) study of dynamic quantitative data from roentenologic or fluoroscopic procedures.

Baily, N. A.↗
NASA NTRS1974

Fluoroscopic tomography

A fluoroscopic tomography system capable of synthesizing body sections at a number of levels within the body has been developed. The synthesized body sections may lie either in a range of planes parallel to, tilted with respect to, skewed with respect to, or both tilted and skewed with respect to the plane of motion of the X-ray tube target. In addition, body sections can be presented which are contoured to the patient's anatomy. That is to say, they may even encompass such complex surfaces as a quadratic hyperplane. In addition, tomograms of organs in motion can be imaged.

Baily, N. A.↗
NASA NTRS1974

A simple method for the generation of organ and vessel contours from roentgenographic or fluoroscopic images

A simple method for outlining or contouring any area defined by a change in film density or fluoroscopic screen intensity is described. The entire process, except for the positioning of an electronic window, is accomplished using a small computer having appropriate softwave. The electronic window is operator positioned over the area to be processed. The only requirement is that the window be large enough to encompass the total area to be considered.

Newell, J. D.↗