JP2001244814A - Data gathering system of multi-channel detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To structure a system which has superior data gathering capability at low cost. SOLUTION: This data gathering system is a semi-distributed system which is provided with one AD converter 4a for each of groups GR1 to GR15 of all channels sectioned so that nearby channels form groups and performs processes simultaneously in parallel; and AD converters which are needed are only as many as the channel groups, the process load on each AD converter 4a is lightened by sharing AD conversion processing, and the improvement of precision by processing of a digital adder 4b by the channels ch1 to ch64 can be expected, so system which can gather data fast with high precision by using inexpensive AD converters less number than all the channels can be actualized at low cost.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data acquisition system for converting an analog signal of each channel of a multi-channel type detector into a digital signal and collecting it as data (usually referred to as "DAS = Data Acquisition System"). In particular, the present invention relates to a technique for inexpensively constructing a system having excellent data collection capability.

[0002]

2. Description of the Related Art FIG. 7 is a block diagram showing the configuration of a conventional data acquisition system (abbreviated as "DAS") for a medical X-ray CT apparatus. The DAS shown in FIG. 7 includes channels CH1 to CH of a multi-channel X-ray detector 91 for detecting X-rays transmitted through a subject (not shown) to be subjected to X-ray CT.
The analog signal of M is converted into a voltage by a current / voltage converter 92, sequentially sent to an AGC amplifier (automatic gain amplifier) 94 by an analog switch 93, and is appropriately amplified. While the data is being converted, the digital signal is converted into a digital signal by an AD converter 96, and the digital signal is sent to a data pre-processing unit at a subsequent stage to collect data.

That is, the multi-channel X-ray detector 91 of the DAS shown in FIG. 7 has a scintillator 9 for converting X-rays into light.
Approximately 1000 X-ray detection channels CH1 to CHM each including a photodiode 1a and a photodiode 91b for converting converted light generated in the scintillator 91a into a current are provided, and the photodiodes 9 of the channels CH1 to CHM are provided.
The output current of 1b is sent to each current / voltage converter 92 as an analog signal. In addition, by performing switching control (on / off control) of each analog switch 93 in association with the channels CH1 to CHM, the analog signals of each channel CH1 to CHM are sequentially converted to digital signals.

On the other hand, in the DAS shown in FIG. 7, it is necessary to cope with a large dynamic range of about 10 ⁶ , and it is necessary to individually process signals of a large number of channels of about 1000 individually in a short time. Specifically, it must be able to cope with a precision of 20 bits and a conversion rate of 1 to 2 kHz per channel.
For this purpose, a converter with high accuracy and a high processing speed is used as the AD converter 96. Specifically, a hybrid (hybrid integration) type AD converter of a successive approximation type in a sub-ranging system is used.

FIG. 8 is a block diagram showing the configuration of another conventional DAS. The DAS of FIG.
An AD converter 97 is provided for each of the H1 to CHM, and a digital signal is sequentially sent to a subsequent data preprocessing unit via an interface circuit 98 for signal collection timing control. The other is a fully distributed system having substantially the same configuration as the above DAS. In the case of this DAS, an AGC amplifier is eliminated, and a delta-sigma A / D converter with a high precision and a high processing speed and a 20-bit precision is used.

[0006]

However, there is a problem that both of the above-mentioned conventional DASs are expensive systems. The former fully centralized DAS is AD
Even if only one converter is used, a sub-ranging type successive approximation type hybrid type A / D converter is very expensive, so the system is inevitably expensive.

[0007] The fully centralized DAS has some problems caused by one A / D converter handling the processing of an extremely large number of channels, and is not sufficiently practical. In other words, since analog signals of an extremely large number of channels are collected in one place, there is a problem that the wiring is long and noise is easy to be caused, and further, a problem that a gain linearity is reduced due to gain switching of the AGC amplifier. There is. In the case of the X-ray CT apparatus, there is a concern that the noise or the decrease in the gain linearity may cause a decrease in the image quality of the X-ray CT image. Further, in the case of the fully centralized DAS, the AD converter processes an extremely large number of channels and the margin is already exhausted, so that there is a problem that it is not possible to cope with an increase in channels and an increase in processing speed. .

On the other hand, the latter distributed type DAS eliminates the problem of centrally processing a large number of channels with a single AD converter, but also uses an expensive 20-bit delta-sigma AD converter with the total number of channels. Is used, the whole system becomes extremely expensive.

The present invention has been made in view of the above circumstances,
It is an object of the present invention to provide an inexpensive multi-channel detector data collection system which can perform high-speed processing and is practical.

[0010]

In order to solve the above-mentioned problems, a data acquisition system for a multi-channel detector according to the present invention has a multi-channel detection system in which a large number of detection channels are provided. In a data collection system configured to convert an analog signal for each channel of the device into a digital signal and collect it as data, a plurality of adjacent channels form one channel group so that all channels are a plurality of channels. An A / D converter that sequentially performs analog-to-digital conversion of analog signals of each channel for each channel group that is set in advance by being divided into groups, and performs addition processing of the digitally converted digital signals a plurality of times for each channel. A signal adder is provided, and AD conversion processing is performed by each channel group. Adding processing of the fine digital signal is configured to proceed concurrently.

According to a second aspect of the present invention, in the data acquisition system for a multi-channel detector according to the first aspect, the multi-channel detector has channels arranged in a one-dimensional array. Each channel group is assigned N channels 1 to N arranged in numerical order along the one-dimensional array line from the channels of the one-dimensional array array, and the AD conversion processing for each channel group is performed. , N is an odd number, channel 1, channel N, channel 2, channel (N-1),..., Channel (N / 2−2)
0.5), channel (N / 2 + 0.5), and if N is an even number, channel 1, channel N, channel 2, channel (N-1),.
..., channel (N / 2), channel (N / 2 +
The configuration is executed in the order of 1).

[Operation] Next, the operation when data is collected by the data collection system according to the present invention will be described. In the data collection system according to the first aspect, all channels of the multi-channel detector are preset by being divided into a plurality of groups such that a plurality of adjacent channels form one channel group. For each channel group, the analog signal of each channel is sequentially converted to a digital signal by an AD converter, and the digital signal that has been AD converted by a signal adder is added a plurality of times for each channel, and then the data to be collected is post-processed. The process of outputting data to the computer is performed simultaneously and concurrently, and data is collected.

Therefore, in the case of the data collection system according to the first aspect of the present invention, a semi-dispersion method is used in which one AD converter is provided for each of a plurality of channels and processing is performed in parallel. May be the same as the preset number of the plurality of channel groups. Also, the AD sharing process is performed by a plurality of AD converters at the same time.
In addition to reducing the processing load per converter,
Since the accuracy can be expected to be improved by the addition process for each channel by the signal adder, each AD converter is a low-cost converter (for example, a monolithic AD) whose accuracy and processing speed are not exceptional.
Converter) can perform sufficiently high-precision and high-speed processing. That is, according to the data collection system of the first aspect of the present invention, it is possible to inexpensively construct a system capable of collecting data with high accuracy and high speed by using inexpensive AD converters whose number is far less than the total number of channels.

Further, in the case of the data collection system according to the first aspect of the present invention, since a plurality of channels are close to each other in each channel group, it is possible to avoid a situation in which the wiring for collecting analog signals of the channels becomes long, thereby reducing noise. In addition, the problem of easy riding is eliminated, and the problem of deterioration in gain linearity caused by gain switching is eliminated because there is no need for an AGC amplifier. In addition, the number of assigned channels per AD converter is small, the processing load is reduced, and there is room for processing capacity. Therefore, it is possible to sufficiently cope with an increase in the number of channels and an increase in processing speed.

In the data collection system according to the second aspect, in each channel group, ADs for N channels 1 to N which are arranged in numerical order along a one-dimensional array line.
If N is an odd number in the conversion process, channel 1, channel N, channel 2, channel (N−1),.
..., Channel (N / 2−0.5), channel (N / 2 + 0.5), and when N is an even number, channel 1, channel N, channel 2, channel (N -1),..., Channel (N
/ 2) and channel (N / 2 + 1).
In other words, in each channel group, the channel to be subjected to the AD conversion process alternates between one end and the other end of the one-dimensional array line in order from the end to the inside as the time elapses. As a result, in the data acquisition system according to the second aspect, a large time lag does not occur between two digital signals of adjacent channels.

If the AD conversion processing for N channels 1 to N arranged in numerical order along the one-dimensional array line is performed, channel 1, channel 2, channel 3,.
..., channel (N-2), channel (N
-1), when performed in the order of channel N, a period during which the AD conversion process of N channels 1 to N makes a cycle between both digital signals of two adjacent channels in an adjacent channel group ( A large time shift substantially equal to one AD conversion processing cycle period occurs. This is because A of one of two adjacent channels in an adjacent channel group
The D conversion processing is performed at the beginning of each AD conversion processing cycle, but the other AD conversion processing of the two channels is performed at the end of each AD conversion processing cycle.
This is because there is a time difference corresponding to almost one AD conversion processing cycle period between the AD conversion processing timings of both channels. The large time lag between the two digital signals causes an inconvenience that, for example, in the case of an X-ray CT apparatus, the final tomographic image (CT image) appears as an artifact (false image).

[0017]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram illustrating a configuration of a main part of a medical X-ray CT apparatus that performs data collection by the data collection system according to the embodiment. FIG. 2 is a block diagram illustrating a configuration around the data collection system according to the embodiment.

The X-ray CT apparatus shown in FIG. 1 includes an X-ray tube 1 for irradiating a subject M with a fan-shaped X-ray beam FB, and a large number of X-ray detection channels CH1 to CHM for the fan-shaped X-ray beam FB. A multi-channel X-ray detector (arbitrarily abbreviated as “X-ray detector”) 2 arranged in a one-dimensional array along the spread of the fan, and a body axis Z of the subject M with the subject M mounted thereon And a top plate 3 capable of reciprocating in the direction of. The X-ray tube 1 and the X-ray detector 2 face each other with the X-ray tube 1 and the X-ray detector 2 interposed therebetween during X-ray CT imaging. The subject M is configured to rotate around the M and move straight in the direction of the body axis Z together with the top 3.

The X-ray CT apparatus converts analog (current) signals output from each of the channels CH1 to CHM of the X-ray detector 2 with the irradiation of the fan-shaped X-ray beam FB by the X-ray tube 1 into digital signals. Data acquisition system (DAS) 4 for converting the data into original data for creating an X-ray CT image (X-ray computed tomographic image), and sensitivity correction for eliminating variations in sensitivity between channels with respect to the original data And a computer (CPU) 6 that performs image reconstruction based on the preprocessed data sent from the data preprocessing unit 5 and creates an X-ray CT image. X-ray C finally obtained
A display monitor 7 for displaying a T image and a console 8 for performing input operations necessary for operating the apparatus are also provided.

The X-ray CT by the X-ray CT apparatus shown in FIG.
In the case of imaging, the X-ray tube 1 and the X-ray detector 2 emit a fan-shaped X-ray beam while moving the subject M at a speed of, for example, one rotation per second, and the X-ray detector 2 emits X-rays. Will be detected. On the other hand, the DAS 4 repeatedly performs a process of collecting data of all channels while the X-ray tube 1 and the X-ray detector 2 make one rotation, for example, at 1 ° intervals. usually,
One data collection process is also called one view. Hereinafter, the configuration of the X-ray detector 2 and the DAS 4 will be specifically described mainly.

The X-ray detector 2 includes, for example, 960 X-rays provided with a scintillator 2a for converting X-rays shown in FIG. 2 into light and a photodiode 2b for converting the converted light generated in the scintillator 2a into a current. Channel CH for line detection
1 to CHM, each channel CH1 to C
The output current of the photodiode 2b of the HM is sent to the DAS 4 as an analog signal. In the case of this X-ray detector 2, 15 channels are arranged by dividing all channels into groups by forming one channel group by 64 channels that are continuously arranged along the one-dimensional array line and are in close proximity. Channel groups GR1 to GR15 are set in advance. That is,
In the case of the embodiment, 960 channels CH1 to CHM
Are channels CH1 to CH64 and channel CH65
To CH128,..., Channel CH (M-6
3) It is preliminarily divided so as to form one group by 64 pieces each including -CHM. For convenience of explanation, the numbers of ch1 to ch64 are assigned to the 64 channels of the channel groups GR1 to GR15 in an ascending order.

On the other hand, in the case of the DAS 4, each of the channels ch1 to c is assigned to each of the channel groups GR1 to GR15.
A for sequentially converting h64 analog signals into digital signals
A set of an AD converter 4a for performing D conversion processing and a digital adder (signal adder) 4b with a built-in RAM for performing addition processing of the AD converted digital signal a plurality of times for each of the channels ch1 to ch64 are provided for each channel group. And each of the channel groups GR1 to GR
The AD conversion process and the digital addition process in R15 are configured to proceed simultaneously and in parallel. That is, as shown in FIG. 2, 15 DAS units U1 to U15 for simultaneously performing the AD conversion process and the digital addition process for each of the channel groups GR1 to GR15 are provided one by one.

On the other hand, in the case of the DAS 4, the addition result for each channel by the digital adder 4b is sent to an interface circuit 4d for controlling signal collection timing, and then the data preprocessing section 5 The original data for generating an X-ray CT image is collected by being transmitted to the computer in a timely manner. In the DAS 4 of the embodiment, the digital adder 4b performs digital addition 64 times for one channel to collect data of one view.

In each of the DAS units U1 to U15, a current / voltage converter 4c and an analog switch SW1 to SW64 are interposed between each channel ch1 to ch64 and the AD converter 4a, respectively. Is converted into a voltage by the current / voltage converter 4c, and then the analog switch SW1
Through the SW 64 to be sent to the AD converter 4a. Note that the analog switches SW1 to SW
The reference numeral 64 is opened and closed so that it is closed (turned ON) for a predetermined short period only during the AD conversion processing of the corresponding channel.

Further, in the case of the DAS 4 of the embodiment, the order of the AD conversion processing for the channels ch1 to ch64 is as follows: channel 1, channel 64, channel 2, channel 63,.
The process is performed in the order of channel 32 and channel 33. That is, as shown in FIG. 3, in each channel group, the channels ch1 to ch.
The channel 64 is configured to change in order from one end to the other while alternately moving between one end and the other end of the one-dimensional array line. Therefore, the analog switches SW1 to SW64 of the DAS units U1 to U15
, SW1, SW64, SW2, SW63,...
The switches are closed (ON) in the order of SW31, SW34, SW32, and SW33.

That is, in the case of DAS4, channel c
The order of the AD conversion processing for h1 to ch64 is as shown in FIG.
.., Channel 61, channel 62, channel 63, and channel 64 are not simply arranged in order. In FIGS. 3 and 4, ○ indicates each of the channels ch1 to ch6.
4 shows the respective AD conversion processing timings. As a result, when the AD conversion processing is performed in the order shown in FIG. 3, the time lag between the digital signals of the channels ch1 to ch64 in the channel group is as small as T / 32 when T is the AD conversion cycle period. Channel group (k +
The time lag of the digital signal of channel ch1 in 1) is also T
/ 64 is also slight.

On the other hand, when the AD conversion process is performed in the order shown in FIG.
The time lag between the digital signals h1 to ch64 is T / 64.
However, the time lag between the digital signal of ch64 of the channel group k and the digital signal of the channel ch1 of the adjacent channel group (k + 1) is a very large lag of substantially the AD conversion processing cycle period T, and this is a singular point. There is a concern that it will appear as an artifact (false image) in the final X-ray CT image. However, in the case of the DAS 4 of the embodiment, since the time lag of the digital signal of the adjacent channel is very small within T / 32, the time lag becomes an artifact (false image) in the final X-ray CT image. Don't worry.

On the other hand, the digital adders 4b of each of the DAS units U1 to U15 add the digital signal sent from the AD converter 4a 64 times for each channel. As shown in FIG. 5, looking for a certain arbitrary one channel k in the channel Ch1～ch64, digital signal Sk ₁ ~Sk ₆₄ is placed AD conversion cycle T with the progress of AD conversion process since sequentially obtained, so that the original data Vk (= ΣSk _n, where where n = 1 to 64) of the collection target by integrating the digital signal Sk ₁ ~Sk ₆₄ as feeds to the interface circuit 4d process is repeated. The integration of the digital signals can be said to be an averaging process of the digital signals Sk _{1 to} Sk ₆₄ . The same applies to all channels other than the channel k.

The A / D converter 4a used in the DAS 4 of the embodiment is a successive approximation type 16-bit monolithic IC type A / D converter of a charge redistribution method having good accuracy and processing speed.
Although a converter is used, the AD converter is not limited to the successive approximation type but may be another AD converter such as an integral type or a flash type. On the other hand, X
Looking at the required accuracy of the DAS4 of the X-ray CT system, 1
A signal-to-noise ratio (S / N) of about 10 dB is necessary, but the 16-bit AD converter used here has a 9/9 ratio.
There is only 0dB S / N and the accuracy should be insufficient.
As described below, in the case of the DAS 4, the S / N is improved by the addition processing by the digital adder 4b.
The required high precision has been secured.

That is, the original data Vk for an arbitrary channel k is obtained by accumulating ₆₄ digital signals Sk _{1 to} Sk ₆₄ by the digital adder 4b.
This is an average of four samples, and the number of samples is ²⁶ times. On the other hand, it is known from the sampling theorem that the S / N is improved by 3 dB when the number of samples is doubled. Therefore, when the number of samples is ²⁶ times, 3d
Since the S / N is improved by B × 6 = 18 dB, in the case of the DAS 4 of the embodiment, the S / N of the entire system is [90
[dB + 18 dB] = 108 dB and required 110 dB
S / N of about B is secured. Conversely, DAS
In the case of 4, oversampling by 2 ^{(110−90) / 3} ≒ 2 ⁶ may be used to compensate for the required S / N of about 110 dB and the S / N difference of 90 dB of the 16-bit AD converter of 20 dB. is there.

As described above, in the case of the DAS 4 of the embodiment, the AD converter 4a is connected to each of the channel groups GR1 to GR1.
Since there is one for each GR 15, the AD converter 4
The number of a may be 15 which is the same as the number of channel groups. Further, the processing load per AD converter is reduced by simultaneous sharing of the AD conversion processing by the 15 AD converters 4a, and the accuracy can be expected to be improved by the addition processing for each channel by the digital adder 4b. , Each AD
The converter 4a is a low-cost converter whose accuracy and processing speed are not exceptional, and can collect data with high accuracy and high speed. As a result, it can be said that the DAS 4 that can perform high-accuracy and high-speed processing is a system that can be realized inexpensively with 15 low-cost AD converters, which is far less than the total number of channels 960.

Further, in the case of the DAS 4 of the embodiment, 64 channels are close to each other in each of the channel groups GR1 to GR15, and the situation that the wiring becomes long to collect analog signals of the channels can be avoided. In addition to eliminating the problem of easy riding, there is no AGC amplifier for higher accuracy, so that the problem of reduced gain linearity caused by gain switching is also eliminated. Furthermore, since the processing load per AD converter is reduced and the processing capacity is marginal, and the system can sufficiently cope with the increase in the number of channels and the increase in the processing speed, it is said that the system is highly practical. it can.

Subsequently, the X-ray C having the above-described configuration
The data acquisition process of the DAS 4 when performing X-ray CT imaging by the T device will be specifically described with reference to the drawings. FIG. 6 is a flowchart showing the progress of the data collection process by the DAS 4 of the embodiment. [Step S1] After the subject M is placed on the top 3 and set at the imaging position, imaging is started by an input operation from the console 8.

[Step S2] X-ray tube 1 and X-ray detector 2
While the X-ray tube 1 irradiates the fan-shaped X-ray beam FB while integrally rotating around the subject M, the X-ray detector 2 starts detecting X-rays, and the DAS units U1 to
U15 starts collecting data all at once.

[Step S3] Each DAS unit U1
In U15, each AD converter 4a is connected to channels ch1 to ch.
AD that sequentially converts 64 analog signals into digital signals
Execute the conversion process.

[Step S4] Each DAS unit U1
The digital adder 4b of U15 converts the digital signals sent from the AD converter 4a one after another into channels ch1 to ch6.
A process of adding four is performed.

[Step S5] Return to step S3 until the number of additions by each digital adder 4b reaches 64. When the number of additions by each digital adder 4b reaches 64, the result of addition is sent to the interface circuit 4d as original data for creating an X-ray CT image, and data collection for one view is completed, and the process proceeds to the next step S6.

[Step S6] If data collection for all views is completed, the process proceeds to the next step S7. If data collection is not completed, the process returns to step S3 to collect data for the next view.

[Step S 7] The subject M is lowered from the top 3. This completes the data collection operation. X-ray C
In T imaging, the computer 6 subsequent to the DAS 4 continuously performs image reconstruction processing and processing for creating an X-ray CT image, and the obtained X-ray CT image is displayed on the screen of the display monitor 7 as necessary. And so on.

The present invention is not limited to the above embodiment, but can be modified as follows. (1) In the case of the embodiment, each channel group GL1 to GL
Although the number of channels of L15 were all the same even value,
The number of channels in each of the channel groups GL1 to GL15 does not need to be the same, and may be the number of channels in which even values and odd values are mixed.

(2) In the embodiment, the order of the AD conversion processing is channel 1, channel 2, channel 3, channel 4, ..., channel 61, channel 6.
A DAS having exactly the same configuration except that the order of the channels 2, 63 and 64 is the modified example. When the time lag between the two digital signals of the two adjacent channels does not matter, the DAS of the modified example can sufficiently collect data.

(3) In the DAS of the embodiment, the number of additions by the digital adder is 64, but the number of additions by the digital adder is not limited to 64, and the accuracy of the AD converter and the DAS are required. An appropriate number of additions is selected according to the accuracy.

(4) The number of DAS channel groups and the number of channels in each channel group are not limited to the values shown in the embodiment.

(5) X to which the DAS of the embodiment is applied
The X-ray detector is a solid-state detector using a scintillator and a photodiode.
The line detector may be a gas detector using an ionization chamber.

(6) The DAS of the embodiment is a medical X-ray C
Although the DAS of the present invention has been used in a T apparatus, it is not limited to a medical X-ray CT apparatus. For example, it collects data of an X-ray detector of an industrial X-ray CT apparatus, For example, it can be used to collect magnetic data of a multi-channel SQID sensor of a bioelectric current source measuring device.

[0046]

As described above in detail, according to the data acquisition system for a multi-channel detector of the first aspect of the present invention, one AD converter is provided for each of a plurality of channels, so In this system, the number of AD converters may be the same as the number of a plurality of channel groups set in advance. Also multiple AD
The processing load per AD converter can be reduced by simultaneously sharing the AD conversion processing by the converters. Furthermore, since the accuracy can be improved by the addition process for each channel by the signal adder, each AD converter collects data with high accuracy and high speed using a low-cost converter whose accuracy and processing speed are not exceptional. can do.

Further, according to the data collection system of the multi-channel detector of the first aspect of the present invention, in each channel group, a plurality of channels are close to each other, and the wiring becomes long to collect analog signals of the channels. Since the situation is avoided, the problem of noise being easily ridden is eliminated. Further, since there is no need to provide an AGC amplifier for high accuracy, the problem of a decrease in gain linearity caused by gain switching is also solved. Furthermore, since the processing load per AD converter is small and the processing capacity is sufficient, it is possible to sufficiently cope with an increase in the number of channels and an increase in the processing speed, and a system with high practicality is obtained.

According to the data acquisition system for a multi-channel detector of the second aspect of the present invention, in each channel group, the channels to be subjected to the AD conversion processing are arranged at one end and the other end of the one-dimensional array line as time passes. , And sequentially changes inward from the end while going back and forth, so that a large time lag does not occur between both digital signals of two adjacent channels.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a main configuration of an X-ray CT apparatus using a DAS according to an embodiment.

FIG. 2 is a block diagram illustrating a configuration around a DAS according to the embodiment.

FIG. 3 is a schematic diagram illustrating AD conversion processing timing of each channel of a DAS channel group according to the embodiment.

FIG. 4 is a schematic diagram showing AD conversion processing timing for each channel of a DAS channel group of a reference example.

FIG. 5 is a graph showing a generation state of a digital signal per view of an arbitrary channel of a DAS channel group of the embodiment.

FIG. 6 is a flowchart illustrating the progress of a data collection process by the DAS according to the embodiment.

FIG. 7 is a block diagram showing a main configuration of a conventional fully centralized DAS.

FIG. 8 is a block diagram illustrating a main configuration of a conventional fully distributed DAS.

[Explanation of symbols]

 2 Multi-channel X-ray detector 4 Data acquisition system 4a AD converter 4b Digital adder GR1 to GR15 Channel group CH1 to CHM Channel Ch1 to CH64 Channel

Claims (2)

[Claims] In a data collection system configured to convert an analog signal for each channel into a digital signal and collect it as data in a multi-channel detector in which a large number of detection channels are provided. All channels are divided into a plurality of groups such that a plurality of channels form a single channel group, so that analog signals of the respective channels are sequentially AD-converted for each preset channel group. An A / D converter and a signal adder for adding the A / D converted digital signal a plurality of times for each channel are provided.
A data acquisition system for a multi-channel detector, wherein the D conversion processing and the digital signal addition processing are configured to proceed simultaneously and in parallel. 2. The data acquisition system of a multi-channel detector according to claim 1, wherein the multi-channel detector has channels arranged in a one-dimensional array, and each channel group has a one-dimensional array. N channels 1 to N arranged in numerical order along the one-dimensional array line from the channels of the array array are sequentially assigned, and the AD conversion processing for each channel group is performed in the case where N is an odd number. , Channel 1, channel N, channel 2, channel (N-1),.
Channel (N / 2-0.5), channel (N / 2 +
0.5), and if N is an even number, channel 1, channel N, channel 2, channel (N-1),.
A data acquisition system for a multi-channel detector configured to be executed in the order of channel (N / 2), channel (N / 2 + 1).