Among the medical disciplines, the field of nuclear medicine has made one of the most remarkable progress in the past decade. This progress is based on the rapid development of relating fields especially those of nuclear instrumentation and of radioisotope production. In this report survey on the instrumentation in nuclear medicine was attempted.
Instrumentation is devided into two categories, one for the in vitro measurement and the other for the in vivo measurement. For the in vitro measurement of medical samples the simplified well counter and the programmed well counter were recently introduced. These are to meet the requisit of the expanding diagnostic use of thyroid function test (T-3) in many hospitals and quick handling of medical samples to assess the circulating blood volume in emergency cases. Advantage and importance of large volume detector in nuclear medicine were emphasized. Instrumentation for the radioisotope chromatography, liquid scintillation spectrometry and neutron activation analysis in the in vitro measurement of nuclear medicine was also discussed.
The in vivo measurement, which provids us with unique information of the disease, has showed remarkable progress by the introduction of unique medical instrumentations. Among them the scintillation scanner, now one of the most important instrumentation in nuclear medicine as a routine diagnostic means, and the γ camera showed sophistication in their design. Varieties of external γ counter, whole body counter are discussed in this chapter, included here also the most recent device of author's catheter type semiconductor radiation detector for the in vivo measurement of cardiac output and upper GI tract malignancy.
Because of the world famous electronics industry in Japan, most nuclear instrumentation is now supplied through domestic industries. Fourteen figures are selected which indicates the tendency of the Japanese products.
In summary, instrumentation in nuclear medicine becomes the one for single purpose rather than multiple-purpose machine used at the cradle stage of this field. Rapid and remarkable progress having been achived in the last decade is almost sure to come in the following years, because, for example, the short life nuclide is only recently applied to the still limited field of nuclear medicine.

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In computer diagnosis, correct decision depends not only on the adequecy of the decision logic or the categorizer, but also on the selection of characteristics or symptoms which effectively contribute to diagnosis among a large number of data.
From this point of view, P. M. Lewis presented a goodness measure useful in data.
reduction.
The goodness measure is the same meaning as relative information in information theory. In general its value is not so easily caluculated except when the measurements are subject to a normal distribution.
In this paper we propose an approximate calculation method of the goodness measure and showed experimentally that the goodness measure is proportional to the percentage of correct diagnosis with a Bayesian approach.

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A program to accomplish simulation of the propagation process of the ventricular excitation in a digital computer was devised and succesfully executed. The comparison of the simulated propagation process by this program with that observed in animal experiments may give a newer knowledge in regard to the spread of excitation in the ventricles. Combination of this simulation scheme and the reconstruction method of the electrocardiographic QRS patterns to be reported elsewhere will give a newer clue to interpretation of genesis of QRS pattern. Further, there is a good possibility that the present study will be utilized as a new scheme for computer diagnosis of electrocardiogram in the near future.
On the basis of the horizontal cross-sections of the human heart, a model for the ventricles of the heart was assumed as a cluster of 3 mm cubic blocks. The specialized conduction system was also set in this model. The model was fed into the computer in such a way that each of the blocks provided a memory address in the computer.
Referring to the physiological evidence in regard to conduction of the excitation in cardiac muscle, three principles were postulated : 1) the excitation being to spread radially with a uniform velocity, 2) no repeated firing of a block in virtue of refractoriness mechanism and 3) higher conduction velocity in the specialized conduction system than in the proper cardiac muscle. In order to simulate the propagation of excitation so as to fulfill the above principles, a program was written and executed. The excitation was let to spread imaginarily in the model stored in the computer memory.
The simulated propagation process thus obtained of the ventricles in a normal mode was found consistent in principle with that observed in animal experiments. This meant that the simulation program was largely justifiable and applicable to the intended purpose mentioned above.
Modification of the program in the aspects found to be inadequate is under way. The next step will naturally be application of this simulation program to the abnormal conductions such as ventricular extrasystole, bundle branch block and myocardial infarction. An example in case of ventricular extrasystole was demonstrated.

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Two types of fluid amplifier with a moving part were devised. One of them is a T-shaped pipe into which an elastic sack is inserted. The flow through the pipe is controlled by the pressure within the elastic sack. This element has a close resemblance in its character to an electronic triode or a transistor; so that the element is used as a general circuit element in fluid system. Another amplifier has a diaphragm and -a tube through which controlled fluid flows. The tube contacts with or is closely adjacent to the diaphragm. The diaphragm is moved by controlling pressure and thus the flow is controlled. This element has an avalanche characteristic like a thyratron or an SCR. Both elements described above may be constructed in a miniature size. They have a very high input impedance (to the direct current, this is infinitive), and work under a low supply pressure.
The present fluid elements are convenient for biomedical purpose because the elements may be directly connected with biological system and controlled fluid does not escape out of the elements. The blood pressure was artificially controlled by means of the fluid element used as an amplifying element. These elements may be applied widely to biomedical uses such as in artificial heart and artificial respirator.

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There are so many kinds of vectorcardiographic lead systems that a great deal of inconvenience arises in the clinical use of vector cardiography.
We have already reported a mutual transformation theory in vectorcardiogram (VCG) by which a VCG of any lead system could be transformed into a VCG of any other lead system without moving the electrodes among VCG lead systems of McFee, Schmitt, Frank, Grishman, Kimura and Wenger-Hupka.
According to the theory, the authors devised a VCG coordinate changer, which can perferm automatically the above mentioned mutual transformation of VCG_s with the aid of the coefficients of our transformation equations.
Moreover, with the use of the coordinate changer, the loops of VCG, as a whole, can rotated to various directions. Therefore, VCG can freely observed from optional directions of a human body.

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