Abstract: The present invention aims to optimize image quality for a conventional scan (axial scan) or a cine scan or a helical scan of an X-ray CT apparatus by a data acquisition system having a limited number of channels. The optimum view numbers determined or defined by image quality to be determined depending upon the positions of the respective channels at image reconstruction are determined by a sampling theorem. Thus, the optimum view numbers, which depend upon the respective channel positions, are allocated. The data acquisition system performs data acquisition in accordance with the views to make it possible to obtain a tomographic image having the optimum image quality. Thus, the number of A/D converters of the data acquisition system and its performance can also be optimized.

Abstract: Enhancement of the resolution of tomograms obtained by conventional scanning (axial scanning), cine-scanning, helical scanning or variable-pitch helical scanning by the X-ray CT apparatus using a multi-row X-ray detector or a two-dimensional X-ray area detector of a matrix structure is to be realized by a simple method. An X-ray CT apparatus is realized in which a multi-row X-ray detector or a two-dimensional X-ray area detector of a matrix structure with a small amount of processing work, and image reconstructing device capable of providing high-resolution tomograms by image reconstruction is provided.

Abstract: To make it possible to decrease an X-ray exposure on an operator and to obtain an image of high quality upon fluoroscopy operation an X-ray tube is rotated to acquire data, an X-ray radiation dose is set to "0" in a predetermined angular range including an angle at which the alignment of the X-ray tube with the operator's hand is brought about, and the X-ray radiation dose is set to an ordinary one at an angle in a range other than that angular range. The predetermined angular range is established using a light beam which enables to see what part of the field has no X-ray radiation exposure, thereby increasing his safety.

Abstract: An image forming apparatus is capable of starting image reconstruction simultaneously with the start of scan. A pipe-line system image forming apparatus having an intermediate buffer between a date acquition device and an image reconstruction device, and the apparatus is characterized in that there is provided a path for supplying data from the data acquisition device directly to the image reconstruction device, whereby the first scan data is sent also to the image reconstruction device simultaneously with sending data to the intermediate buffer so as to immediately start image reconstruction according to the scan data.

Abstract: A received ultrasonic phase matching circuit of the present invention, which utilizes variable delay lines having short delay times as the structural element of variable focus means having a larger aperture and realizes focusing to the regions from the region near the surface of object and to the deeper region thereof, comprises variable attenuators to be controlled individually and variable delay lines having the equal maximum delay times also to be controlled individually to the respective receiving channels forming the maximum aperture for reception of the ultrasonic echoes to form variable aperture by controlling variable attenuators and distribution of delay times for focusing in the aperture using only the variable delay times belonging to such aperture and add and combine the receiving signals delayed by the variable delay lines in the beam steering means.

Abstract: An image reconstruction data processing unit of a simple structure which is capable of fast data processing by parallel operations of a plurality of fast processing units (FPU) is provided.The image reconstruction data processing unit according to the present invention comprises a plurality of FPUs and a single back projection unit (BPU) connected to the formers and is characterized in that the BPU includes a plurality of back projection execution parts corresponding to the FPUs, respectively, and a single pixel memory in which a total sum of output data from the back projection execution parts are stored in a back-projected state.

Abstract: A radiation CT system packs projection data and reads the data in a DMA mode, and separates the packed data into individual data items through format conversion when the data are to be processed. The system has a memory for storing raw projection data and processed image data for one full image. With this arrangement, a high speed processing program for image reconstruction can be executed exclusively for image reconstruction immediately after scanning operation has started. During image reconstruction processing, no data transfer to and from an external memory is performed, thereby to reduce the period of time required for image reconstruction after data have been collected.

Abstract: A signal transmission system of the type used in process control systems for conveying a signal between a field telemetering instrument and a central controller, or between a central controller and a process control device. The signal transmission system is arranged with a transmitter accepting an input signal, a transmission line for carrying a transmission signal, and a receiver receiving the transmission signal and developing an output signal.In accordance with the invention, converter means in the transmitter develop a pulse width signal with a duration corresponding in a predetermined manner to the value of the input signal, and means in the transmitter provide the transmission signal (e.g., a current signal) with two states (e.g., opposite polarities), one of which has a duration corresponding to the duration of the pulse width signal.