TECHNICAL FIELD

This invention relates to the improvements in image forming apparatus applied to computer tomography and NMR imaging. More particularly, this invention relates to the image forming apparatus in which the time from when data acquisition is started until the first image is obtained is reduced in case of conducting acquisition of image forming data and image formation in parallel by pipe-line system.

BACKGROUND ART

In computer tomography and NMR imaging, first data for image formation on a detected body is acquired by scan using X-ray or nuclear magnetic resonance, and subsequently an image is reconstructed by a designated algorithm using these data. In case of continuously scanning the detected body plural times to acquire a plurality of scan data and reconstructing an image one by one according to the respective scan data, data acquisition and image reconstruction are conducted in parallel by a pipe-line system to achieve speeding up of the operation. At that time, as shown in FIG. 4, a large-capacity buffer memory 2 (intermediate buffer) comprising a magnetic disc device or the like is interposed between a data acquisition device 1 and an image reconstruction device 3 to absorb a difference in speed between the data acquisition operation and the image reconstruction operation. The reconstructed image is displayed on a display device 4. In the thus constructed apparatus, reconstruction of an image can not be started by the image reconstruction device until data for one scan at least is collected in the intermediate buffer, so that the time spent until the first reconstructed image is made longer for that. On the contrary, according to Scan & Recon system, image reconstruction is started simultaneously with the start of scan, so that the time spent until the first reconstructed image is obtained is made shorter. In this system, however, the next scan can not be started before image reconstruction is completed. Accordingly, this system is not suitable for use in continuously scanning plural times at high speed.

DISCLOSURE OF INVENTION

It is an object of the present invention to provide an image forming apparatus which is an image forming apparatus adopting a pipe-line system having an intermediate buffer between a data acquisition device and an image reconstruction device, in which image reconstruction can be started simultaneously with the start of scan.

The image forming apparatus of the present invention is characterized in that there is provided a path for supplying data from a data acquisition device directly to an image reconstruction device to send the first scan data also to the image reconstruction device simultaneously with sending data to an intermediate buffer, so that image reconstruction according to the scan data can be immediately started.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a conceptual block diagram of one embodiment of the present invention;

FIGS. 2 and 3 are conceptual block diagrams of the other embodiments of the present invention; and

FIG. 4 is a conceptual block diagram of the conventional image forming apparatus.

BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 1 shows the conceptual constitution of one embodiment of the present invention. In FIG. 1, a data acquisition device 11 is generally provided in computed tomography and NMR imaging apparatus and adapted to acquire scan data by continuously scanning a detected body plural times using X-ray or nuclear magnetic resonance. The device incorporates a buffer memory 11a having a capacity enough to store data for one scan. The scan data in the buffer memory 11a is transferred to a large-capacity intermediate buffer 12 formed by a magnetic disc or the like to be stored. The data transfer rate of the intermediate buffer 12 is far higher than the data acquisition rate of the data acquisition device 11. A change-over switch 13 is provided to supply the scan data transferred from the data acquisition device 11 to the intermediate buffer 12 or scan data stored in the intermediate buffer 12 to the image reconstruction device 14. The change-over switch 13 has three switching positions (a), (b), (c), whereby when the switch is placed at the position (a), the scan data transferred from the data acquisition device 11 to the intermediate buffer 12 can be supplied to the image reconstruction device 14, and when it is placed at the position (c), the scan data stored in the intermediate buffer 12 can be supplied to the image reconstruction device 14. The position (b) is the neutral position which is in the state of cutting off the supply of scan data. The image reconstruction device 14 is generally provided in computed tomography and NMR imaging apparatus, for example, and implemented by a special-purpose computer operated by a designated alogorithm. The image reconstruction device 14 incorporates a buffer memory 14a having a capacity enough to store data for one scan. The scan data supplied through the change-over switch 13 is stored in the buffer memory 14a and provided for image reconstruction. The speed of reconstructing one sheet of image by the image reconstruction device 14 is slower than the speed of acquiring data for one scan by the data acquisition device 11. The operation of the data acquisition devicell, the intermediate buffer 12, the change-over switch 13 and the image reconstruction device 14 is controlled by a control device 15. A transmission path for a control signal is shown by a broken line. The control device 15 is implemented by a computer or the like.

The thus constructed image forming apparatus operates as follows. The data acquisition device 11 is adapted to acquire scan data by continuously scanning a detected body plural times and transfer the scan data to the intermediate buffer 12 through the buffer memory 11a. At this time, the first scan data is supplied also to the image reconstruction device 1e through the change-over switch 13 put in the state of being placed at the position (a) to be written in the buffer memory 14a. The image reconstruction device 14 starts image reconstruction simultaneously with writing data in the buffer memory 14a. Thus, the first sheet of image is reconstructed simultaneously with sending the first scan data to the intermediate buffer, so that the time from when scan is started until the first image is obtained can be reduced to that in case of Scan & Recon system. The change-over switch 13 is switched to the position (b) after the first scan data is supplied to the buffer memory 14a of the image reconstruction device 14 to separate the image reconstruction device 14 from the data acquisition device 11. As the operating speed of the image reconstruction device 14 is slower than that of the data acquisition device 11, at a point of this time, the image reconstruction device 14 is in the process of reconstructing the first sheet of image using the first scan data written in the buffer memory 14a. During this time, the scan data acquired successively by the data acquisition device 11 is transferred to the intermediate buffer 12 to be stored. The change-over switch 13 is switched to the position (c) every time the image reconstruction device 14 reconstructs one sheet of image, whereby the data for the next one scan is transferred from the intermediate buffer 12 to the image reconstruction device 14 to be provided for the next image reconstruction. Thus, acquisition of scan data and image reconstruction are carried out by pipe-line system.

Though the above embodiment deals with the case in which both the data acquisition device 11 and the image reconstruction device 14 respectively incorporate a buffer memory for one scan, if the data acquisition device does not incorporate a buffer memory, as shown in FIG. 2, a buffer memory 17 is interposed between the data acquisition device 16 and the intermediate buffer 12. If neither the data acquisition device nor the image reconstruction device incorporates a buffer memory, as shown in FIG. 3, the second buffer memory 19 is further provided to be used as a buffer device for data transferred between an image reconstruction device 18 and the data acquisition device 16 or the intermediate buffer 12. In that case, a change-over switch 20 comprising two interlocking devices is provided in an input circuit on the data acquisition device side of the buffer memory 19 and in an input circuit on the intermediate buffer side thereof, respectively, thereby alternatively switching input data of the buffer memory 19. Further, it goes without saying that a control device similar to that in the case of FIG. 1, not shown, exists in apparatus of FIGS. 2 and 3.

Though the above description deals with the best mode for carrying out the present invention, it is easy for persons having general knowledge of technical field to which the present invention belongs to make various modifications without departing from the scope of the appended claims.