A great many medical diagnostic tests have been developed to supplement the patient information obtained from history and physical examination. These tests vary greatly in amount of discomfort to the patient, complexity, and cost. It is obvious that diagnostic tests should be kept to a minimum. Logical consideration to help determine the minimum additional medical tests needed in a specific case will be discussed.
It is becoming increasingly recognized that electronic computers can aid certain aspects of medical diagnosis. But to use the computer for such purposes, the mathematical foundation of the medical diagnostic processes must first be well understood. Three mathematical disciplines are inherently involved in the diagnostic processes: logic, probability, and value theory.
Fluorescence emission spectra were obtained from single unfixed ascites tumor cells stained at 3.3 × 10 -7 M to 3.3 × 10 -4 M concentrations of the vital fluorochrome, acridine orange. The new RCA Intensifier Image Orthicon television camera tube was used as the light detector and afforded approximately a one-hundredfold increase in sensitivity over a standard image orthicon in this application. The light from the microscope was dispersed by a Leitz ``High Power'' Monochromator (exit slit removed) and the spectrum focused on the faceplate of the Intensifier Image Orthicon. Spectral curves were obtained by applying appropriate corrections to recordings of line selected oscilloscope traces. These curves show two emission peaks which indicate the presence of two molecular species in close agreement with in vitro data. Advantages of the technique and some implications of the results are discussed.
In connection with research on coronary heart diseases, the need arose to measure extremely low blood flows in uncannulated vessels in the immediate vicinity of the heart in a living animal. Measurement of flood flow in this instance is complicated by the typically small flow rates, the requirement to transmit faithfully the pulsating components of the flow, and the large interfering cardiac voltages in the vicinity of the implanted vessel. Nearly all of the development effort described in this paper was devoted to extending the range of the electromagnetic type of flowmeter. Critical system parameters in this particular application were found to be the input impedance level and coupling methods of the preamplifier, phase accuracy of the timing voltages, and common-mode rejection of the carrier amplifier. Significant but relatively less important factors are the coil-drive method, the waveshape of the coil-drive current, and the noise level of the gating system. The blood flowmeter described in this paper has been in daily use at the Buffalo Veterans' Administration Hospital since mid-June 1959. During most of this period, medical personnel have been operating the instrument and have performed the electrical adjustments which occasionally are needed to maintain the instrument at a suitable performance level.
This paper is to supplement last year's summary on swallowable radio transmitters. Included are general comments on procedure as well as specific items such as temperature sensitivity, the use of tunnel diodes in pH measurement, the use of multiple transmitters, and the design of a nondirectional receiving antenna system. The latter not only simplifies unattended recording in some cases but also helps in relaying the signal from a small booster transmitter carried by the subject. The frequency shift needed in relaying action is here a frequency doubling provided by suitable nonlinear receiver circuits.
A method is presented for simultaneous recording of the electrocardiogram on the cineangiocardigram. A system for direct visualization of the stylus recording has been designed. Simultaneous recording is helpful in determining the exact timing of the blood flow through intracardiac shunts.
Methods do not exist for the rapid, quantitative analysis of complex phasic patterns such as are seen on records of intraluminal gastrointestinal pressure or other parameters of motility. In an attempt to develop a more satisfactory method, these wave forms have been converted into digital form and then analyzed by the Whirlwind I digital computer at M.I.T. Generation of the autocorrelation function and the power density spectrum of these records has permitted a numerical, quantitative expression of certain information contained in these curves.
A description is given of the bio-instrumentation phase of two related Army Jupiter ballistic missile flights involving squirrel monkey passengers, one of which was recovered alive and in good physical condition. These flights marked the initial entry into space, and successful return, of a primate under ballistic flight conditions comparable to those to be encountered by man. The paper describes the relationship of the instrumentation program to the biocapsule design in terms of the telemetered measurements. An outline is presented of the signal conditioning circuitry and associated transducers used for the in-flight telemetry recording of the primate's electrocardiogram, respiration rate, chest sounds, and axilla body temperature. Instrumentation related to the recording of the ambient temperature and pressure of the biocapsule, flash temperatures, and cosmic ray particle tracks is also described.
Noting that the heterogeneous and complicated nature of medical data places severe restrictions on its analysis, a discussion of the feasibility of establishing standard procedures for this analysis follows. It is pointed out that computational difficulties can be overcome by the use of a high-speed, large-memory computer; principles of mathematical statistics and their application to investigation of medical data are outlined, and the extent of medical data needed to furnish various levels of clinical information is discussed.
The medical research groups have been somewhat at a disadvantage in securing certain instrumentation for their various projects because usually they must rely upon large established engineering organizations where close liaison is rather difficult. A group of volunteer engineers at the Illinois Bell Telephone Company, in their own spare time, have been able to produce instrumentation for a number of these projects in a unique manner. This paper describes the SAVE (Service Activities of Volunteer Engineers) operation and one of their projects, the portable (3-ounce) self-contained, cumulative heartbeat recorder.
Some areas of application of the infrared image converter to diagnostic procedures in cases of corneal opacification are presented. Further extension of areas of usefulness will be paced by technical advances in infrared optics, quality of screen image, and simplification of design to facilitate the adaptation of the tube as an auxiliary for direct ophthalmic examination.
1) Absorption of sound in solutions of macromolecules has been found to be comparable in magnitude and similar in frequency dependence to that of tissues and blood. The absorption has been shown to arise through a relaxation process. Several experimental observations suggest that the relaxation may be related to the protein-water interactions. 2) The absorption of sound in normal blood, although predominately a molecular process, has in addition a component arising from the relative motion between the cells and the plasma. 3) In certain tissues, the experimental evidence points out again the importance of direct molecular absorption. This may be modified to some extent in inhomogeneous tissues where there is the possibility of selective absorption arising at macroscopic discontinuities.
A miniature glass dosimetry system, is described that, when employed with a gold shield of suitable wall thickness and ``softer energy'' portals, is energy independent over a specified photon energy spectrum. A brief review of the characteristics that this dosimeter must meet before its use as a clinical in vivo doosimeter is included. Various physical characteristics relating to range, integration of daily dose, and orientation with respect to the source of radiation, etc., are also considered. Its clinical applications are reviewed as well as its use with radium and other discrete sources as implants. A brief review is made of its possible use in the detection of gamma radiation in the presence of neutrons. The applications of this dosimeter, as the authors indicate, are not limited to any specific field; rather, its use is determined if one wants the daily and/or total dosage of radiation delivered to a specific point. A separate electronic reader is required to read the dosimeter.
The major activity of this laboratory is to establish mathematical models that approximately describe the various parts of the cardiovascular and pulmonary systems. With this knowledge descriptive equations can be derived that are suitable for solution by computer techniques. These solutions are of potential diagnostic value. Two examples will be cited in which 1) blood velocity is computed from a measured pressure gradient and 2) the physical properties of certain intrathoracic pulmonary structures may be deduced from air flow measurement.
In the course of a study on the relationship between tissue damage and pain sensation due to thermal stimulation,1 a computer method was developed for the analysis of the experimental data. Considerable interest in the details of this method has been expressed by various investigators who encounter similar data analysis problems. This report is written, therefore, to state the problem and its solution as an indication of some of the possibilities computer methods offer the biological investigator having little or no previous experience in the use of computers. The rationale, physiological observations, and results of the study itself have been reported elsewhere1 so that only those facts necessary to an understanding of the computer solution are noted here.
A phonocardiographic system has been designed and built using standard units of known frequency characteristics. The system is calibrated, as the relative and absolute intensity of the signal can be computed from the records' amplitude, given the conversion factor of the transducer and the degree of amplification in decibels. The system is standardized. It allows the spectrum to be scanned in bands of 1 octave of 3-db attenuation (therefore ideally flat) with the low-cut-off frequency coinciding with the nominal frequency. A 36 db per octave attenuation for the high-pass section is suggested for the selective recording of the high-frequency vibration of low intensity. Representative phonocardiographic tracings are presented.
Lens opacities result from exposure of the rabbit eye to 2450-mc continuous wave radiation. Threshold for a single damaging exposure is determined by power density and duration. Opacities may also result as a cumulative effect of repeated subthreshold exposures. Intraocular temperature increases during irradiation, the extent and rate of increase being related to power density. Inasmuch as a particular temperature critical for opacity induction cannot be identified, it is suggested that the intraocular thermal response may be coincident with, rather than the cause of, induction of opacities. Lens damage may result from irradiation at power levels not sufficient to cause discomfort to nonanesthetized animals. Pulsed radiation with high peak intensities appears to be more potent in inducing lens opacities than continuous wave radiation of equal average power. Since ocular temperature is related to average rather than to peak power, these findings further suggest the possibility of a nonthermal biological effect of microwave radiation.
Many problems in medical research concerning the transmembrane diffusion, transport, and metabolism of oxygen require its detection with microliter accuracy. The paper describes the construction and operating characteristics of an electronic polarograph sensing system with a membrane-covered gold electrode having a sensing error of less than 0.5 microliter of oxygen at atmospheric pressure.
Some of the potential advantages of computer aids to medical data processing are: making available to the physician quantitative methods in areas relating to data analysis and differential diagnosis; assisting in the evaluation of the best alternative courses of action during stages of the diagnostic testing processes; making easily available to the physician reference to the most current information about new preventive measures, and diagnostic and therapeutic techniques; and periodic recording and evaluating of individual physiologic norms for the more sensitive determination of an individual's health trend relative to disease prevention.
