Existing ultrasonography is limited by the slow velocity of sound in the body, namely the product of twice the scan depth, the number of scan lines and the frame rate could not exceed the speed of sound in the body, which is only about 1500 meters per second. If the scan depth is 20 centimeters and the frame rate is 30per second, the number of scan lines per frame is limited to about 120. In order to break through the barrier caused by the slowness of sound, we had devised a new technique, named simultaneous multifrequency ultrasonography in which we can treat two or more ultrasonic beams perfectly simultaneously. This is equivalent to making the sound velocity several times faster.
In simultaneous multifrequency ultrasonography, one of the most important things to solve is how to extract one signal from other signals by labels added at transmitting stage to avoid the crosstalk in the body. We examined three labeling methods, namely, pseudo random code modulation, chirp modulation and simple burst pulse, through computer simulation and an experimental circuit in simultaneous 2 beams model. To evaluate the three methods, we used both normalized signal to crosstalk ratio as a figure of merit and images which are obtained through the circuit. About 1MHz frequency separation was found to be almost enough to obtain usable normalized signal to crosstalk ratio—about -40--30dB in each method. After total evaluation, the simple burst pulse was judged to be the best method. At last, the outline of some applications of simultaneous multifrequency ultrasonography, realtime compounded dual B-mode images, realtime cross-sectional dual B-mode images and simultaneous B-mode and Doppler measurement, are introduced, which are obtained through a medical evaluating system in which the simple burst pulse method is adopted.

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For developing the total medical information system at the Hiroshima University Hospital, we designed a four-class model of medical information system. This model is made up of (1) operation system, (2) executive system, (3) expert support system and (4) full automation system.
In the total system, the component systems of each class must be synthesized. This paper shows our clinical laboratory system and medical records information system of first or second class in our model. Through these systems we have developed, it has been shown that Data Base Management System (DBMS) is one of the effective software for the systems of first and second classes of medical information system model.

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It is well known that the movements of parts of the body and facial expressions, particularly those of the head and hands, are synchronized with spoken language. This is observed not only in the speaker, but also in the listener during conversation. This synchronization phenomenon, which is called “entrainment” in communication, makes information exchange efficient in communication among people.
The object of this research is to develop a quantitative and objective analysis method for this entrainment by introducing an image analysis method using computers. Analysis of the entrainment of mother's talk and neonate's movement, which is one of the primitive forms of communication, and also the entrainment of speaker's talk and listener's nodding in adult conversation, by this method leads to the following two conclusions:
(1) Voice and movement synchronization in mother-neonate entrainment is similar to that of adult communication.
(2) The neonate discriminates the human voice, particularly that of the mother from the voice synthesized by computer, and moves the body in interactional synchronization with the human voice.
This analytical method of entrainment, which can be called “entrainography”, may be applied to detection of the basic process of language acquisition, and may also be applicable to early diagnosis of some neurological diseases.

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A method of applying Bayes' theorem to diagnosis of patients who may have more than one diseases in various combinations is described. The underlying model (multiple disease model) assumes that symptom S is a union of its subsets S_i—each caused solely by disease D_i—and that D₀ represents a base-line condition present in all people, healthy or ill, causing symptom S₀ which is unrelated to any disease. Further assumptions are that diseases, which are neither mutually exclusive nor inclusive, are independent, and that the conditional probability of S_i arising under D_i is independent of other coexisting diseases or symptoms. Thus, the likelihood ratios for any disease (whose posterior probability we would like to know), in the presence and absence of the symptoms, respectively, can be derived from the prior probabilities of all diseases, and relative frequencies of the symptom in healthy people as well as in patients each with single disease.
This method has been applied to detection of rectal cancer in an external sample of 59 patients with rectal cancer, 78 with hemorrhoid and 27 with both of these diseases, using 10 symptoms which are assumed to be independent. Of the 86 patients with rectal cancer, 74 have been correctly diagnosed as such by this method, as compared with 70 by the conventional method (single disease model). However, by the former and latter methods, 13 and 8 patients, respectively, with hemorrhoid alone have been incorrectly diagnosed as having rectal cancer. Of patients with rectal cancer, those with hemorrhoidal symptoms have shown lower probabilities of rectal cancer than those without the symptoms if the posterior probability is estimated by the conventional method.
Although this multiple disease model has been developed for automated interrogation and diagnosis system for coloproctological diseases, it may be applicable also to diagnosis of other diseases.

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This paper describes the possibility of analyzing gait pattern from the variation of the lower leg electrical impedance during walking. This impedance is measured by the four-electrode method. Two current electrodes are applied to the middle level of thigh and the ankle, and two potential electrodes are applied to the lateral aspect of the lower leg. The lower leg impedance Z_s in static condition is dominated by the magnitude of the ankle angle α and the magnitude of the moment M_α acting as the foot force. If α or M_α increases toward the plantarflexion, Z_s increases. The lower leg impedance Z_d during gait can be characterized by two phases, one being the pattern of its variation and the other, its mean impedance level. The pattern is dominated by the magnitudes of α and M_α in the same manner as in Z_s. The α causes variation of the muscular transverse sectional area and M_α causes variations of muscular conductivity and blood volume (vascular transverse sectional area) of the lower leg. The level is higher than that in static condition and responds to the change of M_α with a fairly long time constant, because the blood volume reserved in the lower leg gradually decreases by a muscular pump action. From such features of the lower leg impedance, it has been made clear that different gait patterns exhibit different impedance patterns and impedance levels.

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In intravenous infusion and feeding, it is necessary to select an appropriate combination of commercially available bottles which satisfy requirements of a patient with various disturbances of body fluid and nutritional state. However, the solution of the bottle selection problem cannot be achieved practically by the usual search technique because of the combinatorial nature of the problem. By applying the implicit enumeration method of integer programming we have been able to find an optimal solution in a huge number of possible combination of bottles in an acceptable short time. The program was written in standard Pascal for HP 1000 minicomputer system. The algorithm proposed in this study appears to have advantages over the previously published algorithms on the following points: (1) For any set of bottles, an optimal combination can be found on the basis of ‘optimality’ as defined by the user; (2) The computation time is acceptable even when the number of both constituents and types of bottles is as large as fifteen.
We tested the bottle selection system on 723 hypothetical cases of dehydration and on 21 representative cases of pathological nutrition. The validity and practicality of the algorithm have been confirmed.

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A new method for measuring red blood cell (RBC) velocity in capillary-sized vessels has been developed on the basis of the principle of multiple photographic frame method. Applicability of a solid-state image sensor was investigated using frog mesentery microcirculation. The image of moving RBCs was projected onto the face of a screen containing the image sensor which has 1024 discrete photodiodes with 28μm center-to-center element spacing. During a scanning time interval, the frozen image of moving RBCs on the sensor moves by a distance that can be estimated by the aid of cross-correlation. Dividing the distance by the scanning time interval gives RBC velocity. Preliminary results demonstrated the feasibility of using the image sensor to construct an on-line velocity measuring system by computer-television coupling.

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To identify a posture control system without external disturbance, the maximum likelihood method was applied to data of antero-posterior sway during quiet stance. Ankle joint moment was measured by means of a force plate. Sway angle of a body was measured by a position sensor camera which detects positions of a light emitting diode attached to the body.
Using data of 500 input-output pairs, which were sampled every 0.1s, parameters of a sensory feedback path were estimated and frequency response functions were calculated. These frequency response functions showed derivative characteristics that is necessary for the stabilization of a posture control system. The gain characteristics of a sensory feedback path under closed-eye condition tended to be greater than those under open-eye condition.

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