JPS58141137A - Data collecting apparatus for ct apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a tomography wave using a conbeater.
The present invention relates to an improvement of a data acquisition device for a CT device (hereinafter referred to as a CT device), particularly a data acquisition device using a plurality of analog-to-digital converters (hereinafter referred to as an AD converter).

A conventional whole-body OT rack data collection device converts a current signal from a detector into a voltage, performs AD conversion on the converted voltage signal, and then performs data processing using AI'
) Multiple AD converters are used when it is desired to increase the conversion speed. FIG. 1 shows the configuration of this example. In FIG. 1, D1 to D6 are detectors, PA+ to P
Aa is the preamplifier and integrator, SWl~SWs are analog switches, BA+, BAt are buffer amplifiers, ADI
, AI)t is an analog-to-digital converter, and the CPU is CT
This is the image processing section of the device.

In a conventional data acquisition device using such a plurality of AD converters (AD, AI), the buffer amplifier BA
8. Each gain of BAt and AD converter AD.

AD! Since there are variations in the conversion characteristics of each device and characteristics unique to each device such as gain, the output data of the AD converter A
Errors caused by the AD converter AD and ADt in data adjacent to the joint with the output data of the D converter AD,
That is, when the AD conversion systems are different, a difference in level occurs between adjacent data at the data joint. This data level difference causes ring-shaped arches and crests to appear on the reconstructed image.

An object of the present invention is to provide a means for removing ring-shaped artifacts on the image ψ caused by the AD converter. The present invention is provided with means for inputting data into an AD converter by overlapping data, and means for weighting and averaging the overlapped analog/digital converted data.

Hereinafter, the present invention will be described in detail along with examples.

FIG. 2 is a diagram showing the configuration of an embodiment of the present invention. Components having the same functions as those in FIG. 1 are given the same symbols, and the explanation thereof will be omitted.

In this embodiment, in order to overlap the output data of the detectors ~Ds shown in FIG.
, ~A plurality of analog switches SW above SW6, ~S
By increasing W1°, each analog switch SW1
~SW+o has a circuit configuration as shown in FIG. 2, and the output data of the detector and ~Ds are input to the buffer amplifiers BAl and BAt, respectively.

Next, the operation of this embodiment will be explained.

In Fig. 2, when X-ray pulses are simultaneously input to each detector ~D6, the preamplifier and integrator 1) A1~PA.
Each output current of the detectors D1 to D6 is inputted to.

It is integrated by an integrator and held. This held voltage is applied to the analog switches SWI to SW. are sequentially closed and input to buffer amplifiers BA+ and BAt, and AD
The signals are sent to converters ADI and AD for analog-to-digital conversion. This analog-to-digital converted digital data is sent to the image processing device CPU.

The digital data obtained from the AD converters ADI and ADt' adjust the output current of the detectors Dl to D to 111AD.
Assuming that the output data of converter AD is Xl and the output data of AD converter ADm is Yi, Table 1 is obtained.

As can be seen from Table 1, the outputs 1.
~■, Data is collected using Opara. That is, the output data X and Y of the AD converters AD+ and ADl
+, Xs and Yt, Xi and Ys, and Xs and Y4 are the output data, respectively, and these data are respectively averaged with predetermined weights in the image processing device CPU, and then sent to the AD converter A D +. AI), a gentle curve with no step is obtained in the adjacent data of the joint of the output data.

The weighted average is, for example, 0.75 Xt+0
．． 25 Y+, 0.5 Xs+ 0.5 Yt, 0.5
X4+ 0.5 Ys.

When 0.25

In this way, it is possible to eliminate the difference in level between adjacent data that occurs when data output from different AD converters is joined together.

Note that the number of overlaps is determined by the difference in level between adjacent data.

As explained above, according to the present invention, the level difference between adjacent data that occurs when the output data of different AD converters is spliced is removed. Ring-shaped artifacts caused by variations in conversion characteristics, gain, etc. can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of a data acquisition device of a conventional whole body CT apparatus, FIG. 2 is a diagram showing the configuration of an embodiment of the present invention, and FIG. 3 is a diagram showing the configuration of an AD converter of the present embodiment. FIG. 3 is a diagram illustrating a joint portion of output data with different values. D, ~D, Detector PA I~PAs Preamplifier and integrator SW, ~8
Wlo/analog switch B A r , B A t buffer 7 amplifier ADI,
ADt AD converter CPU Data processing device agent Patent attorney Autumn 1) Collection Figure 1 Figure 2

Claims (1)

[Claims] In a tomography system using a combination, a plurality of analog-to-digital converters and the adjacent data to which the analog-to-digital conversion of the analog-to-digital converters is switched are automatically wrapped and transferred to the analog-to-digital converter. A data acquisition device for a CT apparatus, comprising means for inputting the data and means for weighting and averaging the analog-to-digital converted data that has been automatically extracted.