In glaucoma the increased level of pressure within the eye results in atrophy of the optic nerve with loss in visual function. Impairment of the blood supply to the optic nerve by the increased pressure appears to be primarily responsible for the atrophy. Sequential photographs of the optic nerve head after an intravenous injection of fluorescein dye provide a detailed topography of its vascular system as a function of time. Densitometric techniques can be utilized as a means of objective analysis and measurement to separate normal vascular patterns from those of the glaucomatous patient. Techniques for the analysis of peak times, circulation times, intensity ratios and flow rates are described in normal and glaucomatous optic nerve heads.

High-fidelity digitization, communication, and display equipment and the development of computer programs to manipulate and analyze the high volumes of biomedical image data generated by video roentgenographic and closed-circuit television systems have become vitally necessary in order to fully exploit the potentialities of multiplanar roentgenographic and conventional video techniques. Although a great deal of information has been gained in the past by both simple and sophisticated analyses of these data(Ref. 1,2,3,4,5),additional objective and time economical measurements, determinations and estimates are required to extend understanding of the physiological and biological phenomena studied and to provide the insight necessary to properly resolve some of the problems concerned.

Medical radioisotope scintigrams are most commonly produced as photographic images in which count densities are displayed in various shades of grey. Such photographic grey scales are used both for recording the live images from a rectilinear scanner or scintillation camera and also for digitized images displayed with computer controlled data processing systems (Fig 1). Altho gh trade-offs are usually made between the conflicting demands for high photographic contrast and wide dynamic range or latitude), conventional photographic methods are often inadequate for the display of the entire range of count densities. Moreoever, these grey scale images lack quantitative information.

A system has been developed that automatically analyzes and displays the distribution of brightness (intensity) of individual picture elements in any scene or portion of a scene that can be observed with a television camera. Consisting of video camera (any line rate), mini-computer, system interface, video monitor, and operator keyboard, the system permits an operator to select one or more areas of the video image and schedule the analysis and display of brightness distributions for each area. Readily mated to most common digital input-output (I/O) devices, the system software includes a convenient Executive Language which facilitates control by a relatively untrained operator. Typical applications include quantitative measurement of ratios of light or dark picture elements in either a "live" (patient examination), or archival (X-ray, photograph, etc.) scene. Further potential applications may lie in the area of automatic exposure control during X-ray examination or treat-ment. Such digital analysis systems could also be coupled to ther-mal imaging cameras. The system can also be adapted to automatically digitize existing ECG or similar records.

Densitometry is a measurement of the absorption of light 1:), a material to give its optical density. Data can be used to plot the change in optical density across a region of a microscope specimen. In most practical applications microdensitometry provides an absolute or relative determination of some chemical component of the specimen by measurement of its total integrated density contribution. Integrated density determinations of this type have an increasingly wide range of applications in many biological fields and such measurements on DNA have been used in the study of various types of cancer. Microdensitometry can be used to study the biochemistry of individual cells and their alteration in disease states. Conventional microdensitometry is perfor ed by means of mechanical object plane scanning systems which are often modified microspectrophotometers. The systems are inherently accurate but are generally too slow to allow the accumulation of data from large populations frequently required for reasonable statistical accuracy. MAINCO has developed a faster television type microdensitometer system which offers great promise in biomedical research.

The artificial color definition of gray-scale levels has progressed through a number of evolutionary steps which started with early efforts to "color-label" the high-, medium- and low-intensity tone levels of infra red films. The three-layer color-composite, when registered and projected on a viewing screen, provided some coarse but readily recognizable bench marks for the gray-scale values of an image. While a three-point index spread over a wide range of image intensity was a rather crude and inflexible form of scaling indication, it was, neverthe-less, the first step in the right direction. Multispectral photographs provide distinctive information about ground terrain, from aerial views and when the individual spectral responses are encoded by projection through colored filters, the composite result may be registered and viewed on a common viewing screen.

The field of Bio-Imagery - and, indeed, any high technology discipline - often produces voluminous data which must be carefully analyzed before meaningful results can be obtained. This task can be admirably handled by the modern digital computer once the data have been presented in compatible form. While there are many devices available to translate various physical measurements into computer format, technical developments have only recently made high-speed "eyes" for the computer feasible. Because of this tremendous potential for optical data acquisition, EMR -Photoelectric has undertaken the development of a series of versatile electro-optical computer peripheral equipment known as the Optical Data Digitizer (ODD) . The primary function of the ODD is to present, at high speed and in digital computer input/output format, the spatial intensity data contained in a two-dimensional scene; i.e., the ODD provides to the computer the intensity information of a given X, Y location selected by the computer program. Both storing and nonstoring sensors are used.

Clinical radiology has until recent years been confined to morphologic examinations. Questions relating to a patient's health have been answered by visual examinations of the patient's x-ray films. A priori knowledge of altered physiology, injury, etc., combined with the radiologist's skills has usually been sufficient to enable the physician to make an intelligent diagnosis. However, within the past few years new and innovative techniques of diagnosis involving the electronic analysis of video recorded fluoroscopy have evolved. These techniques have been grouped under the general heading of videodensitometry. (Ref. 1-9) They allow the radiologist to directly assess and measure physiologic parameters from the televised roentgen image. By utilizing information that is normally available during routine roentgenographic examinations, the patient is not exposed to any additional radiation hazard.

Many areas of research have a real need for motion stopping x-ray cinematography. Most have in common the problem of recording high speed transient events through opaque bodies; as: fluid flow , fragmentations , interior motion analysis, ballistic transitions, and impact trau-ma. Research into the latter area is especially important to the medical community, because impact trauma is the most common cause of death in the United States between the ages of one and thirty-five (Ref. 13) . In the impact trauma field, there presently exists little quantitative information on the precise anatomic movements occurring during injury. The chief reason for this has been the lack of suitable radiographic instrumentation with high speed stop-motion capability . However, the design of the necessary apparatus is now technically feasible, and a phototype flash x-ray cinefluorographic system capable of one thousand frames per second operation has been developed. The use of repetitive flash x-ray exposures of 30 nanoseconds per frame provides essentially absolute motion stopping effect for biomedical research. Additionally the x-ray penetration is adequate for human and primate radiography and the resolution is sufficient to visualize 250 micron contrast media filled blood vessels.

When a radiologist examines an organ angiographically, he injects a radiopaque contrast material into selected vessels and takes a series of radiographs of the opacified vascular network. Then he searches the vessel images for abnormalities that indicate either pathology or pathophysiology within the organ. Some of his diagnostic criteria for an abnormality are (1) displacement and deformity of vessel complexes or individual vessels, (2) intrinsic changes within the vessels such as variations in caliber and contour, and (3) alteration of the circulation time or the direction of the flow of contrast material within arteries and veins. In cases of tumors he also searches for clues as to the nature of the growth, i.e., whether benign or malignant. Obviously his ability to record small vessels clearly has a decided effect upon the accuracy of his diagnosis.

With the low priority for R and D, research and development, for laser applications in medicine, it is surprising that any current report of progress could be developed. However, still in an all too limited phase, laser medicine continues in this country both for diagnosis and treatment other than for diseases of the eye. (Ref. 1, 2). Fortunately,there is increased activity both in laser biology and medicine in Europe and Russia at the present time. A laser cancer treatment institute has been established in Kiev, Russia. West Germany has plans to develop a laser institute of biology and medicine through the Gesllschaft fur Strahlen und Umweltforschung. So progress in this important field of laser applications will be continued at least, if not here. It is not recognized by those who have withdrawn funding for basic research that research in biology and medicine helps to develop programs for laser safety. With effective programs of laser safety, the field of applications of the laser has expanded and will continue to expand. Work in laser biology is necessary for progress in laser medicine.

In 1965 the first model of a laser cane for the blind was produced for the Veterans Administration (VA)* by Bionic Instruments, Inc. Since then, development has prcceeded through three more models (Ref. 1) to the present C-5 cane (Ref. 2)-- the final "prcduction" model to be described here.

The selective damage of cell structures by partial irradiation is a technique employed by biologists since the early 1900's.(See reviews: Refs. 1, 2, 3, 4) The approach is simple: expose a specific cellular region or structure to a non-lethal dose of radiation, and then examine the cell with respect to altered structure and function. In this way, much can be learned about various subcellular structures (organelles) and general cell function. In theory, this approach to the study of organelle function could be most productive. Indeed, several hundred studies have been published. However, of these only a few have resulted in substan-tial progress in understanding the cell. The types of radiation have included particulate (protons, electrons, alpha particles, etc.) and electromagnetic (ultra-violet, X-ray, gamma ray). It is probable that the general damaging properties of these types of radiation have resulted in much secondary cell damage, thus making strict interpretation of the results difficult. It was not until the early 1960's that successful partial cell irradiation was performed with visible wavelengths. The intensity attainable at a single or few wavelengths with laser light has permitted the selective damage of numerous cell organelles. Surprisingly, secondary effects to non-target structures appear to be minimal , if not non-existent. Though a coherent explanation of this capability cannot be given at this time, the fact remains that numerous cell structures can be affected selectively without apparent damage to nearby organelles. These results have been confirmed by assaying subsequent cell function as well as cell ultrastructure. In fact, it has been possible to demonstrate that the unirradiated regions of an otherwise irradiated organelle are structurally (and apparently functionally) unaffected.

The laser is unique in its capacity to deliver very high heat energy in a short time. This paper will describe the aleration of the carious process in vitro and in vivo by laser induced physical changes of the surface enamel. It will also broadly consider future laser application in dentistry.

A holographic image projection and tracking system has been developed which can automatically map a surface with high precision. To illustrate the potential usefulness of this technique to bio-medical applications, point coordinate data for preselected points and automatically scanned surface profile data has been taken of a skull geometry model. The model is representative of the average American male. System design studies on this holographic technique show that 1) dimensions of objects of the order of 1 meter in size can be produced from their image to an accuracy of 1 part in 10 and 2) the precise location of the image surface can unambiguously be determined for even matte, feature-less surfaces without the need for surface preparation. The skull model data and suggestions for other bio-medical applications are presented.

Holographic interferometry is firmly established as a versatile tool for the research scientist and the practical engineer. The principal applications of the method up to now have been in the general area of non-destructive testing of various mechanical structures. The purpose of this paper is to review the recent advances in the state-of-the-art of holographic interferometry and to discuss the potential of the technique for biomedical applications.

This paper reexamines laser-excited pulsed dye lasers since they may be advantageous over other types of pulsed lasers in some holographic applications. Of particular interest is the capability of dye lasers to generate sufficient energy per pulse and with sufficient coherence to record holograms. This capability was demonstrated just recently (Ref. 1) and will be discussed in more detail in this paper. The additional capabilities of the dye laser to be frequency tuned throughout the entire visible spectrum and to operate at two or more frequencies have potential importance in holographic contouring and underwater holography. (Dyes can be selected and tuned to match the optimum transmissivity of the working medium.) The selective interaction of dye laser light with living organisms may permit minute dimensional changes to be observed and measured. The low intrinsic cost of the active materials and operational reliability of dye lasers are other desirable features.

Radiographic diagnostic evaluation of numerous specific pathogenic entities in medicine and dentistry can be significantly enhanced through the use of recently developed mathematical data processing techniques. A method is described to non-destructively section a human organ, at any desired angle of orientation, using computer processed data derived from a series of ordinary radiographs.

Optic-disc topography respresents a major parameter for assessing optic-nervehead damage in patients with glaucoma. For example, Kirsch and AndersonI have found that glaucoma patients generally evidence a totally cupped optic disc, a cup that extends upward or downward to touch the margin of the disc, or a cup that is vertically oval. By contrast, they note that normal discs have cups that are round or horizontally oval, with a rim of tissue along the entire disc circumference. Similarly, Kolker and Obstbaum have found an asymmetry in the cup/disc ratio in patients with asymmetric intraocular pressure. According to Kolker and Obstbaum, these findings suggest that progressive cupping may precede the development of field lo3ss in openangle glaucoma. Finally, Armaly has studied the correlation between opticcup appearance and visual function, and concluded the importance of using quantitative parameters to analyze opticcup configuration.

This paper discusses the photogrammetric aspects of a current multidisciplinary cooperative effort between Washington University, St. Louis, and the University of Illinois at Urbana-Champaign on the development of a trileaflet prosthetic heart valve. Photogrammetric measurements are undertaken on silicon rubber molds of human aortic heart valves. A Hasselblad 500C camera equipped with a 50 mm Planar f/4 lens is used for data acquisition. A semianalytical solution is used for data reduction. The final outputs include: sketch plans, digital models, profiles, contour maps and dimensions of the coaption areas of the leaflets. The items to be highlighted in this presentation include: data acquisition, data reduction, data processing, accuracy aspects, and a review of the various outputs.

Quantitative morphological analysis of the structure of biological materials or systems is generally carried out from observations made upon thin histological sections. The stereological problem involved in this type of analysis is the statistical relationship between measurements made on transmitted images and the morphology of the structure. The section is thus a statistical sample of the structure from which transmitted images are formed using optical or electron micros-copy, radiography, autoradiography, or other techniques. These images contain projections of the structural features cut by or contained within the thin sample, and thus are significantly different from reflected light images which can usually be assumed to approximate true two-dimensional samples of the structure. The stereological problems associated with the quantitative analysis of morphology from transmitted images will be considered in this paper.

Dermatoglyphic patterns refer to the configurations formed by dermal ridges on the fingers, palms, toes, and soles. There is a recognized relationship between the dermato-glyphic patterns and certain developmental defects in individuals. Previous methods of dermal pattern analysis are rather subjective and tedious to perform. This paper proposes a hybrid optical-digital system for the quantitative analysis of the dermal patterns. The proposed system extracts dermatoglyphic features through the medium of an optical Fourier transform and a solid-state photodiode array. Preliminary classification results for a group of 11 individuals exhibiting Trisomy-21 (Down's Syndrome) and 10 individuals selected from a normal control group are given.

The classification of burns is an area of considerable confusion (Ref. 1,2). The popu-lar description of first, second, and third degree was originated over 150 years ago by Boyer. This classification was based on superficial appearance and was used almost exclusively with minor modifications until about 30 years ago. Burn physicians then began to realize that the depth of injury was of prime importance, and not this superficial appearance. Thus, there evolved a two-category description which is defined as follows: The partial-thickness burn is a wound in which sufficient epithelial elements remain to allow spontaneous skin repair, and the full-thickness burn is a wound in which the epithelial elements necessary for spontaneous skin repair have been destroyed. In the latter case, skin repair can occur by contraction of the wound and cell migration from the edge. When this peripheral regrowth is not possible or adequate, grafting is necessary.

Implementation of a computer image processing system is costly in terms of equipment outlay, software development and the sporadic utilization of such equipment.

The statistical quality of a fluoroscopic examination can be improved without an increase in the dose of radiation delivered to the patient by using an image intensifier to raise the light flux reaching the retina and by further increasing the luminance of the image to the level of photopic vision. All currently used x-ray image intensifiers attempt to accomplish both of these purposes, but, in addition, these devices form the basis of modern television transmission of fluoro-scopic images, cineradiography, and small format ( 70-105 mm ) photography of the image intensifier output image.

The homosapien, when placed in perspective with other mammals is a diurnal creature; that is, his primary activities are carried out during daylight hours. (Ref. 1) The fact that man is diurnal rather than nocturnal will not rattle the cages of our civilization, but when we look at ourselves relative to other mammals we find the homo sapien making up part of a 15% minority (Ref. 2) of animals. One need not refer to his slide rule to calculate the fact that 85% of all mammals are eithe r nocturnal or functional at night. (Ref. 3)

The existing 16 mm movie cameras are too heavy and clumsy to be coupled with lightweight delicate examining (endoscopic) instruments, which are introduced into the patient. It can carry the risk of interference with the tactile sensation in the finger-tips of the examiner, resulting in dangerous pressure or even perforation.

A new light source for endoscopic examinations has been developed. This device is safe, while at the same time yielding high illumination levels, at an excellent color temperature and without inordinate heat production.

The paper concerns the perceptual movement image produced without actual target displacement. The perceptual movement image is variously named the beta movement, phiphenomena, or apparent movement. The production of the movement images depends upon such physical factors as the proper distance between targets, the proper time interval between presentation of the targets, and the target intensities. The influence of these physical conditions on the perceptual movement images and their application are discussed in the paper; specifically, the emphasis is placed on the measurement methods. Psychological research in this area may provide some clues for designing optical instruments.