Showing papers in "Journal of Medical Systems in 1982"

A systems approach to the physiology of weightlessness

Abstract: This paper presents a systems approach to the unraveling of the complex response pattern of the human subjected to the challenge of weightlessness. The major goal of this research is to obtain an understanding of the role that each of the major components of the human system plays following the transition to and from space. The cornerstone of this approach is the utilization of a variety of mathematical models in order to pose and test alternative hypotheses concerned with the adaptation process. An integrated hypothesis for the human physiological response to weightlessness is developed.

Three-dimensional imaging in ultrasound

Abstract: Ultrasonic three-dimensional images are constructed by “stacking” B-scan tomograms or ultrasonic CAT scans with a computer algorithm for subsequent perspective or sectional display. Perspective images of surfaces representing Doppler measurements of fluid velocity are illustrated in combination with isovelocity contours for flows through a flexible tube in vitro. Isospeed contours calculated from a dynamically moving epicardial surface are mapped onto the heart surface illustrating the combination of quantitative parametric data with a qualitative surface display. The efficacy of three-dimensional displays for increasing the information density and comprehensibility of pictoral representations of ultrasonic data sets is discussed.

Statistical and dimensional analysis of the neural representation of the acoustic biotope of the frog.

Abstract: The field of investigation is the neural representation of acoustic stimuli occurring in the natural environment of the frog. The point of departure is the description of a stimulus ensemble consisting of natural sounds: the acoustic biotope. A relation of statistical and dimensional structure of the acoustic biotope is indicated. The animal used in the neurophysiological experiments is the grass frog,Rana temporaria L.; microelectrode recordings are made in the auditory midbrain. A method is described to determine the existence of a relation between acoustic stimulus and neural events. The form of this relation has been investigated by first- and second-order stimulus-event correlation. While the first one does not give significant results, the second one leads to the spectrotemporal receptive field of the neuron for natural stimuli. Questions are formulated to estimate the value of this receptive field as a functional descriptor of the neuron. Finally, an outline is sketched for a synthetic construction of the bioacoustic space from neuroacoustic subspaces.

Stereotactic neurosurgery using 3-D image data from computed tomography.

Abstract: During the last decade computer tomography (CT) scanners have provided images that show internal anatomy of unsurpassed resolution and that, since they are inherently digital, a format computer graphics software can easily process. By combining CT images, a specially designed head-mounted instrument, and the software to coordinate them, improved surgical accuracy can result for stereotactic surgery. Using the head-mounted frame and the interactive computer software described here, the entire stereotactic approach is transportable to computer systems of three major CT manufacturers. Neurosurgeons now have a tool that allows trajectory selection and probe placement entirely within the CT suite. Compared with conventional stereotaxis, the CT-aided approach offers increased accuracy, with a significant reduction in procedure time and patient risk due to both the elimination of cerebral spinal fluid contrast injection for finding reference points and the avoidance of important brain structures due to the direct visualization afforded with CT. Key interactive features are shown here that allow unrestricted views of anatomy in the area of surgical interest. For example, oblique views that are normal to the trajectory of neurosurgical instruments are extracted in real time during the surgical procedure. Standard sagittal (lateral) and coronal (frontal) image planes are also shown integrated with the interactive technique. The surgical procedure is outlined and details of the pattern recognition technique for image-to-frame registration are presented. Test, phantom, and patient results are given.

A county-wide obstetrical automated medical record system.

Abstract: Our strategy has been to achieve inexpensive and reliable data entry/data output while utilizing the functionality of a complex set of medical data previously developed by us. The front-end processor approach has achieved a 260-to-1 reduction in input/output channel calls on the IBM 370 for the OBAR system. The speed of data entry has doubled from the earlier mode of data entry through TSO during Phase I of the project. The Eclipse system has achieved a nearly consistent 24-hour availability independent of the state of the IBM 370/158. The system has excellent response time, and it is capable of growth in multiple physical locations. The system has met its functional goals at a reasonable cost.

An ultrasonic head position interface for wheelchair control.

Abstract: To give quadriplegics independent mobility, a “smart” microprocessor-based electric wheelchair has been developed by the Palo Alto Veterans Administration Medical Center and Stanford University. Ultrasound distance-ranging technology is employed to track the user's head position in two-dimensional space. These data are then used to determine the chair's direction and speed. A working prototype vehicle using this type of motion control has been successfully demonstrated. Obstacle detection, wall-following, and cruise control modes are other implemented features of the current design.

Use of computer-based medicaid drug data to analyze and correct inappropriate medication use

Abstract: In an experimental controlled trial, prescribing records were obtained from the Medicaid Management Information Systems (MMIS) of four states for all physicians participating in the Medicaid programs of those states. Three categories of drugs that are commonly misprescribed were identified, and moderate to high prescribers of these drugs were identified from the MMIS data set. These physicians were then randomly divided into three groups. One group received no intervention, the second group received an innovative series of print materials urging appropriate drug use, and a third group received the print materials and was visited by consultant pharmacists to discuss the drugs in question. Our experience suggests that use of Medicaid prescribing data can be an efficient and accurate way of conducting large-scale surveillance of misprescribing, and of targeting interventions that can improve such suboptimal drug utilization. Use of the same data set in a follow-up period can monitor the effectiveness of each mode of intervention and will measure the degree of behavior change for each physician.

Dynamic volume imaging of moving organs.

Abstract: The Dynamic Spatial Reconstructor system has been developed to dynamically (up to 60/sec) image the entire 3-D volume (up to 240 adjacent 1-mm-thick transverse sections) encompassing moving organs of the body, particularly the heart and lungs, or the circulation in any organ. This capability permits accurate regional and global measurements to be made of the important relationships between structure and function within and among these organs, which in turn facilitates achievement of new insights into the basic physiological processes of these organs, and promises increased sensitivity and specificity in the diagnosis of pathology that affects normal organ function. This article explains the biomedical and technological rationale for development of the DSR, describes the design concepts and practical operation of the system, and presents preliminary results obtained with the system, including initial data from one of the first patient studies.

Knowledge-based acquisition of rules for medical diagnosis

Abstract: Medical consultation systems in the EXPERT framework contain rules written under the guidance of expert physicians. We present a methodology and preliminary implementation of a system that learns compiled rule chains from positive case examples of a diagnostic class and negative examples of alternative diagnostic classes. Rule acquisition is guided by the constraints of physiological process models represented in the system. Evaluation of the system is proceeding in the area of glaucoma diagnosis, and an example of an experiment in this domain is included.

Removal of streaking artifact in computed tomography.

Abstract: In transmission computed tomography, relative X-ray attenuation measurements are made at various angles around a patient's body. These input projection data are reconstructed to yield a cross-sectional view of internal structure. If the body section contains material that severely attenuates the X-ray beam (e.g., surgical clips, lead fragments), high-density streaks that obliterate internal structure will be produced in the process of image reconstruction. This loss of diagnostic information renders the scan useless. A technique has been developed that removes this imaging artifact. The approach views the affected projection data as misinformation. These data are assigned new values, and image reconstruction is performed without changing existing computer hardware or software. Projection data for a head section containing a lead fragment were obtained by Monte Carlo simulation. Three methods of obtaining replacement data were examined. A nearest-neighbor pattern recognition technique yielded excellent results.

A prototype generalized network technology for hospitals: initial implementation.

Abstract: A demonstration implementation of a distributed data-processing hospital information system using an intelligent local area communications network (LACN) technology is described. This system is operational at the UCSF Medical Center and integrates four heterogeneous, stand-alone minicomputers. The applications systems are PID/Registration, Outpatient Pharmacy, Clinical Laboratory, and Radiology/Medical Records. Functional autonomy of these systems has been maintained, and no operating system changes have been required. The LACN uses a fiber-optic communications medium and provides extensive communications protocol support within the network, based on the ISO/OSI Model. The archtecture is reconfigurable and expandable. This paper decribes system architectural issues, the applications environment, and the local area network.

Remote Medical Diagnosis System (RMDS) concept.

Abstract: The goal of the Remote Medical Diagnosis System (RMDS) is to provide assistance to medical personnel on navy ships and at remote locations by providing an adequate consulting link with a physician at some other site. The RMDS utilizes navy communication links and commercial telephone lines for the exchange of patient physiological information and diagnostic/treatment advice. Narrow band-width (3 kHz) hf and uhf radio and satellite communication channels are utilized. The RMDS terminals perform the function of processing analogue physiological information (images, electrocardiograms, (ECG), auscultation, and voice) into a digital format suitable for transmission over the communication links. These terminals also perform the inverse operation of processing the received digital bit streams into analogue information for visual display. The digital data are transmitted at a rate of 2,400 bps.

Computer representation of molecular surfaces

Abstract: This review article surveys recent work on computer representation of molecular surfaces. Several different algorithms are discussed for producing vector or raster drawings of space-filling models formed as the union of spheres. Other smoother surfaces are also considered.

An experimental transformation of a large expert knowledge base.

Abstract: An experiment is described in which a significant part of the INTERNIST knowledge base for diagnosis in internal medicine is translated into an EXPERT model. INTERNIST employs the largest and broadest knowledge base of all the medical consultation systems that have been developed in recent years. EXPERT is a general system for designing consultation models. The translated model shows reasonable competence in the final diagnostic classification of 431 test cases. There are differences in the internal representation and reasoning strategies of the two systems. However, when a knowledge base has been encoded in a relatively uniform manner, this experiment demonstrates the feasibility of transfer of knowledge between large-scale expert systems.

Data base design for natural language medical data

Abstract: The natural language of clinical reporting exhibits the properties of a sublanguage, having a grammar and vocabulary greatly restricted in comparison to the language as a whole. This paper presents a CODASYL-type (network) data base schema for natural language medical records based on the structures and relationships identified in such material through computerized language processing. While the schema described is special to the medical sublanguage, the methods of analysis and of schema design are applicable to natural language material in other subject areas.

Positron Emission Tomography (PET)

Abstract: Among emerging medical diagnostic imaging modalities, positron emission tomography, often abbreviated to its acronym “PET”, belongs in the category of nuclear medicine. Indeed, the image forming variable in PET is the distribution in the structure under study of a radionuclide administered systemically in the form of a selected radiopharmaceutical prior to the imaging procedure. Yet a number of specific features endow PET with a distinct identity within the broader category of nuclear medicine imaging.

NMR zeugmatographic imaging in medicine.

Abstract: The history of the application of nuclear magnetic resonance techniques to biology and medicine is outlined, and the fundamental principles and certain techniques of nuclear magnetic resonance zeugmatographic imaging are described, with emphasis on true three-dimensional reconstruction methods.

The human element in computer-generated patient management plans.

Abstract: The Johns Hopkins Oncology Center is one of 21 Comprehensive Cancer Centers designated by the National Cancer Institute. As part of its clinical activities, the center provides specialized care to patients with cancer using advanced techniques for chemotherapy, radiation therapy, and combined modality treatment plans. The medical treatment of adult patients is centered in a 56-bed facility that also has the capacity for serving 500 outpatients per week. Treatment of these patients follows well-defined therapy plans, which require precisely timed administration of drugs and the timely collection of clinical and laboratory data that quantitate tumor response, drug toxicity, biochemical markers, and other parameters of therapeutic evaluation. A clinical information system has been developed by the center that assists in the care of the 2,000 patients currently under treatment there. The Oncology Clinical Information System (OCIS) ~-~ maintains an extensive clinical data base for each patient treated at the center as either an inpatient or an outpatient. The data include descriptive text abstracts of diagnosis, treatment, and follow-up; and objective data such as laboratory results, medications, vital signs, graded status of symptoms, measurement of tumOrs, and bacteriology reports. Data are available on line and, where possible, are automatically transferred in computer-readable form from other Johns Hopkins Hospital automated systems. Printed plots and flow sheets are prepared for morning rounds and all outpatient visits. The format of the output is determined by the physician as a function of the patient's diagnosis, therapy, and current clinical status. For the past year the center has been working with an extension to the data system producing management plans (daily care plans) for each inpatient and outpatient

Considering human factors in the initial analysis and design of a medical computer system.

Abstract: The primary objective of a medical computer system is (should be?) to support patients and the people who care for them. Successful human factors design in these systems depends primarily on successful identification and resolution of management-level issues during the systems' concept development stage. Traditional human factors issues (user, dialogue, terminal characteristics) that affect the man-machine interface are resolved based upon decisions made during concept development phase; inappropriate decisions “early on” result in poor human factors designs.

Structuring information systems for more effective disease control programs.

Abstract: The design of effective health programs involves a complex set of information flows needed to support the planning, implementation, and evaluation of alternative intervention strategies. While several information system models are available, few have actually been applied to specific disease cycles. The objective of this paper is to consider the design of information systems in terms of organizational contextual factors and user/decision-maker preferences relevant to the structure and operation of such information systems. A heuristic procedure is developed and applied to the design of information systems responsible for supporting effective parasitic disease control efforts. Recent research based on this application indicates substantial technical advantages to an intersectoral, multidimensional approach to parasitic disease control. In particular, analysis reveals that information system designs can significantly enhance the effectiveness of disease intervention through a higher level of sensitivity to such factors as disease etiology, socioeconomic conditions, and population health beliefs and perceptions.

A flexible system for closed-loop ventilator development.

Abstract: The feasibility of using a microcomputer to regulate the delivery of artificial ventilation was investigated experimentally. To carry out this study, a sampled-data proportional, integral, derivative feedback controller was implemented on a commercial microcomputer and interfaced with a digital/analogue model of a prototype ventilator and two-compartment patient. The microcomputer sampled end-tidal CO2 and calculated a new frequency of ventilation from the difference of end-tidal CO2 and a desired set point value. Use of a microcomputer programmable in BASIC allowed easy manipulation of feedback structure. With the proper choice of feedback constants, the microcomputer was able to maintain end-tidal CO2 at a desired set point.

Reconstruction algorithms for nonstandard CT scanner designs

Abstract: Data collected by a CT scanner provide estimates of line integrals of the X-ray attenuation distribution in a cross section of the human body. The lines along which integrals are collected are determined by the positions of the source-detector pairs during the data collection. Since only the lines are important (and not the positions of the source and the detector on the line), essentially the same data may be collected by scanners of very different design. In this article we illustrate that in certain situations the problem of reconstruction from data collected by a CT scanner of a new (and nonstandard) design can be “reduced” to the problem of reconstruction from data collected by a CT scanner for which the problem has already been solved. The “reduction” involves identifying values of free parameters in the old design (such as the radius of the circle in which the source rotates), which would make the geometry of data collection essentially identical to that of the proposed new design. Since reconstruction algorithms for the old design already exist, they can be applied without any change to the data collected by the new scanner. In other words, the problem of finding a reconstruction algorithm for a nonstandard mode of data collection can sometimes be solved by describing a (virtual) machine of standard design whose reconstruction algorithms are immediately applicable to the data collected by the nonstandard machine. The method is demonstrated on a recently proposed concept for transforming a radiotherapy simulator into a CT scanner.

C2: a data base management system developed for the Coronary Artery Surgery Study (CASS) and other clinical studies.

Abstract: For the Coronary Artery Surgery Study (CASS), large variable amounts of data on different form-types are collected on many different patients. In this paper, we describe C2, a "state-of-the-art" command-oriented data base system developed in response to the needs of maintaining a large complex data base and performing subsequent analyses on a large number of studies. C2 provides a friendly, interactive interface with the researcher as well as a powerful method for data extraction, data transformation, and the merging of files from the CASS data base.

Diffusion of medical information systems technology in the United States.

Abstract: The development of computer-based medical information systems (MIS's) has been a central concern of American medical informatics workers for over 20 years. Despite many apparent successes, the technology is not now even close to universally used, even in our larger hospitals. The present report will define MIS, present an analytic framework with which to describe the current state of the art of MIS's, and will discuss the obstacles to diffusion of this technology. Definition. An MIS is a set of formal arrangements by which facts concerning the health or health care of individual patients are stored and processed in computers.

Distributed processor for noninvasive blood flow analysis

Abstract: High-resolution ultrasound imaging of peripheral arteries offers a powerful technique for screening of potential stroke victims. However, the technique becomes inaccurate in cases of low-grade stenosis and the presence of noncalcified plaque. In these cases Doppler flow measurement can be used to augment the imaging system to arrive at a more accurate diagnosis. This paper describes a duplex system that combines high-resolution imaging with Doppler measurements. The various real-time processing and control tasks are implemented in a distributed processing system using three different processors. A high-speed digital signal processor (DSP) performs Fourier transforms on the Doppler-shifted signals and also performs some of the premultiplications required for Doppler parameter computations. A dedicated Doppler CPU receives the spectral coefficients from the DSP and computes several parameters such as gray-scale spectrogram coefficients, frequency centroids, spectral broadening coefficients, and velocity profiles. A third CPU is used to control the imaging system and to perform the housekeeping tasks such as control of the video display and the interface with the control panel.

Cost-effectiveness analysis of computerized ECG interpretation system in an ambulatory health care organization.

Abstract: The cost-effectiveness of a computerized ECG interpretation system in an ambulatory health care organization has been evaluated in comparison with a conventional (manual) system. The automated system was shown to be more cost-effective at a minimum load of 2,500 patients/month. At larger monthly loads an even greater cost-effectiveness was found, the average cost/ECG being about $2. In the manual system the cost/unit is practically independent of patient load. This is primarily due to the fact that 87% of the cost/ECG is attributable to wages and fees of highly trained personnel. In the automated system, on the other hand, the cost/ECG is heavily dependent on examinee load. This is due to the relatively large impact of equipment depreciation on fixed (and total) cost. Utilization of a computer-assisted system leads to marked reduction in cardiologists' interpretation time, substantially shorter turnaround time (of unconfirmed reports), and potential provision of simultaneous service at several remotely located "heart stations."

Budgeting and controllable cost variances. The case of multiple diagnoses, multiple services, and multiple resources.

Abstract: This paper examines an unfavorable cost variance in an institution which employs multiple resources to provide stay specific and ancillary services to patients presenting multiple diagnoses. It partitions the difference between actual and expected costs into components that are the responsibility of an identifiable individual or group of individuals. The analysis demonstrates that the components comprising an unfavorable cost variance are attributable to factor prices, the use of real resources, the mix of patients, and the composition of care provided by the institution. In addition, the interactive effects of these factors are also identified.

Computer-based three-dimensional medical imaging.

Abstract: To be able to \"see\" into the body has always been and remains a primary capability desired and necessary to study and elucidate the basic processes of life, and to diagnose and treat the disease conditions that perturb and endanger the normal function of these biological processes. This capability can be achieved by surgically cutting into the body to look directly at the structures and functions of interest. However, because of the life-threatening risk and pain involved, this approach should be restricted to treatment of disease, rather than diagnosis. The discovery of X rays in 1895 heralded a new era in the practice of medicine-visualization into the body without painful and often life-threatening surgery. Not until the 1970s, however, did any new advances in medical imaging have major impact on the practice of medicine. During the last decade computers have made possible the development of several new imaging modalities, such as X-ray computed tomography, radionuclide emission tomography, ultrasound tomography, and nuclear magnetic resonance (NMR), which now permit or demonstrate significant potential for providing greater specificity and sensitivity in medical diagnostic procedures than ever before possible. Although these modalities may differ somewhat in the details of the physics, mathematics, and equipment used in the image formation process, they all have in common a unique capability--to produce noninvasively true three-dimensional images of the distributions of various structures and/or functional processes within the body. The best known of these new 3-D imaging modalities is X-ray computed