JPH06105834A - Continuous rotation type x-ray ct apparatus - Google Patents

Abstract

PURPOSE:To achieve higher reliability in the transmission of signals in a continuous rotation type X-ray CT apparatus using a slip ring and a brush in the signal transmission. CONSTITUTION:This apparatus is provided with a transmitter to transmit signals to a slip ring 7 synchronizing an angle of a rotary plate 1 and a signal transmitter 6 having a transmission error generation detecting means which detects the generation of transmission errors during the transmission of signals through the slip ring 7 and a brush 8 to apply an angle of the rotary plate in the transmission of the signals being transmitted involved in the generation of the error to a memory 10 and a signal transmission control means which re-transmits the signal being transmitted involved in the generation of transmission errors at another angle when the same angle is stored in the memory at a specified frequency and thereafter. works to use the angle of the rotary plate in the retransmission for the transmission of signals replacing that when the transmission error occurs.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray CT for irradiating an X-ray from around a subject and obtaining a tomographic image of the subject cut into slices.
The present invention relates to an apparatus, and more particularly, to an improvement of a continuous rotation type X-ray CT apparatus capable of performing a plurality of continuous scans in the same direction.

[0002]

2. Description of the Related Art A conventional apparatus of this type has an opening for inserting an object to be examined in a central portion, and an X-ray tube and an X-ray detector are provided on a rotary plate opposed to each other across the opening. Of the rotating plate and the stationary side by a signal transmission device including a slip ring provided on the stationary side and a brush provided on the stationary side and slidingly contacting the slip ring, thereby continuing the rotating plate in a certain direction. It was possible to rotate, and multiple consecutive scans in the same direction were possible.

In order to obtain a tomographic image of an object to be inspected by using such a conventional apparatus, the object is inserted into the opening of the rotary plate and the rotary plate is rotated at least 360 ° around the circumference of the rotary plate. The X-ray is emitted from the X-ray tube while being allowed to do so. Then, the X-ray that has passed through the subject is received by the X-ray detector, and the output signal of this X-ray detector is sent by the transmitter to the signal transmission device equipped with the slip ring and the brush, and sent to the stationary image processing device. . The image processing device that receives the X-ray detection signal performs a calculation to obtain a tomographic image, and gives the calculation result to the image display device to display it as a tomographic image.

[0004]

However, in such a conventional continuous rotation type X-ray CT apparatus, the X-ray detection signal measured at each X-ray exposure is measured in synchronization with the measurement, in other words, It is transmitted to the stationary side through the slip ring and the brush in synchronization with the angle of the rotating plate at the time of being pressed.

Therefore, a signal transmission error such as a stain or a scratch on the position on the slip ring corresponding to the rotation plate angle at the time of signal transmission to the stationary side (rotation plate angle during signal transmission). If it occurs, there is a problem that a transmission error occurs every time the rotary plate angle during the signal transmission, and the reliability of the signal transmission decreases.

An object of the present invention is to provide a continuous rotation type X-ray CT apparatus with improved signal transmission reliability.

[0007]

The above object is to provide a rotating plate having an opening for inserting a subject in a central portion thereof, and an X-ray tube and an X-ray detector being opposed to each other across the opening. Of the rotating plate and the stationary side by a signal transmission device including a slip ring provided on the stationary side and a brush provided on the stationary side and slidingly contacting the slip ring, thereby continuing the rotating plate in a certain direction. Continuous rotation type X-ray CT that enables rotation and allows multiple continuous scans in the same direction
In the device, a rotary plate angle detector that detects the angle of the rotary plate, and the occurrence of a transmission error during signal transmission via the slip ring and brush A rotation plate angle storage device for storing the rotation plate angle of the rotation plate angle detector, and the signal transmission device detects the rotation plate angle detector in addition to the slip ring and the brush. A transmitter that sends a signal to the slip ring in synchronization with an angle, and the transmission error of the transmission target signal that is detected when the occurrence of a transmission error is detected during signal transmission through the slip ring and the brush. Transmission error occurrence detecting means for giving the rotation plate angle of the rotation plate angle detector to the rotation plate angle storage device when the transmission error occurs, and the rotation plate angle storage when the transmission error occurs When the same angle is stored a predetermined number of times in the apparatus, the transmission target signal in which the occurrence of the transmission error is detected is retransmitted at an angle other than the stored angle, and thereafter the rotary plate angle at the retransmission is set to the above-mentioned value. This is achieved by providing signal transmission control means used for signal transmission instead of the rotating plate angle when a transmission error occurs.

[0008]

The transmission error occurrence detecting means detects the occurrence of a transmission error during the signal transmission through the slip ring and the brush, and detects the rotation plate angle of the rotary plate angle detector at the time of transmission of the transmission target signal whose occurrence is detected. When a transmission error occurs, it is given to the rotating plate angle storage device.

When the same angle is stored a predetermined number of times in the rotary plate angle storage device when the transmission error occurs, the signal transmission control means is a transmission object in which the occurrence of the transmission error is detected at an angle other than the stored angle. The signal is retransmitted, and thereafter, the rotation plate angle at the retransmission is replaced with the rotation plate angle when the transmission error occurs and used for signal transmission.

According to this, even if a signal transmission error occurs such as dirt or scratches on the slip ring, signal transmission is not performed at the rotating plate angle at the time of signal transmission, and Since the signal is transmitted at the normal angular position of, the transmission error does not occur thereafter, and the reliability of the signal transmission is improved.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration explanatory view showing an embodiment of a continuous rotation type X-ray CT apparatus according to the present invention. In this FIG.
Reference numeral 1 is a rotary plate having an opening 3 into which a subject 2 is inserted in a central portion thereof, and an X-ray tube 4 and an X-ray detector 5 facing each other across the opening 3.

Reference numeral 6 denotes a slip ring 7 provided on the rotary plate 1 and the slip ring 7 provided on the stationary side.
A signal transmission device comprising a brush 8 slidingly contacting with the rotating plate 1. By performing signal transmission between the rotating plate 1 side and the stationary side by the signal transmitting device 6, the rotating plate 1 can be continuously rotated in a fixed direction. , Multiple consecutive scans in the same direction are possible.

Reference numeral 9 is a rotary plate angle detector for detecting the angle of the rotary plate 1. Reference numeral 10 is a rotation plate angle storage device at the time of occurrence of a transmission error controlled by the controller 11, and when a transmission error occurs during signal transmission through the slip ring 7 and the brush 8, the transmission target whose occurrence is detected The rotating plate angle of the rotating plate angle detector 9 during transmission of the X-ray detection signal is stored.

Here, the signal transmission device 6 includes a transmitter 12 and a receiver 1 in addition to the slip ring 7 and the brush 8.
3 is provided. As shown in detail in FIG.
Sends an X-ray detection signal from the X-ray detector 5 or a transmission check pattern signal from a later-described transmission check pattern generator to the slip ring 7 in synchronization with the angle detected by the rotating plate angle detector 9. The transmitter 14, the transmission check pattern generator 15, the transmission controller 16, and the buffer 17.

When the same angle is stored a predetermined number of times in the rotating plate angle storage device 10 when the transmission error occurs, the transmission controller 16 stores an angle other than the stored angle, in this case, the storage device 10. The transmission target signal in which the occurrence of the transmission error is detected is retransmitted at an appropriate angle exceeding the angle. After that, the rotation plate angle in the re-transmission is replaced with the rotation plate angle when the transmission error occurs and used for signal transmission. The buffer 17 is a temporary storage device that stores the transmission target signal in which the occurrence of the transmission error has been detected, until the signal is retransmitted.

The receiver 13 receives a signal transmitted through the slip ring 7 and the brush 8, a reception check pattern generator 19, and a receiver 1.
When the transmitter 8 receives the transmission check pattern signal from the transmission check pattern generator 15, the comparator 8 compares the reception check pattern signal from the reception check pattern generator 19 with the reception check pattern signal. The transmission check pattern generator 15 and the reception check pattern generator 19
And the comparator 20 includes the slip ring 7 and the brush 8.
It functions as a transmission error occurrence detecting means for detecting the occurrence of a transmission error during signal transmission via the.

In addition, in FIG. 1, reference numeral 21 is an image processing apparatus for reconstructing and calculating a tomographic image, and 22 is an image display apparatus for displaying a tomographic image.

In such an apparatus of the present invention, the subject 2 to be inspected is inserted into the opening 3 of the rotary plate 1, and the X-ray tube is rotated around the subject 2 by at least 360 °. X-ray is exposed from 4. And the subject 2
The X-ray detector 5 receives the X-rays that have passed through, and the X-ray detector output signal is sent to the slip ring by the transmitter 14 and sent to the stationary image processing device 21. The image processing device 21 which has received the X-ray detection signal performs a calculation for obtaining a tomographic image and gives the calculation result to the image display device 22 to display the tomographic image on the image display device 22.

Here, the X-ray detection signal (X-ray transmission data)
Will be described in more detail with reference to FIG. Figure 3
, The rotary plate 1 starts to rotate and its angle (X-ray tube 1
Is an angle from the position right above is θn
When the measurement is started at the time of, the X-ray transmission data at the time of θn is first transmitted through the signal transmission device 6 to the image processing device 21.
Send to. Next, when the angle when the rotary plate 1 is rotated by a slight angle is θn + 1, the X-ray transmission data at this angle θn + 1 is similarly sent to the image processing device 21 through the signal transmission device 6. This operation is performed for 360 ° to complete the acquisition of X-ray transmission data for reconstruction of one tomographic image. Hereinafter, the same operation as described above is repeated according to the required number of tomographic images.

In the above operation, when the signal passing through the slip ring 7 and the brush 8 has been normally transmitted, that is, when the transmission error occurs, the rotary plate angle storage device 1
When no rotation plate angle is recorded at 0 when a transmission error occurs, the collected X-ray transmission data is sent as it is to the image processing device 21 through the signal transmission device 6. When the transmission error occurrence rotary plate angle storage device 10 records the transmission error occurrence rotary plate angle, here, when the same angle is stored a predetermined number of times, the transmission controller 16
Is an angle other than the stored angle, for example, an angle greater than or equal to the angle stored in the rotating plate angle storage device 10 when the transmission error occurs and less than or equal to the angle during transmission of the X-ray transmission data measured at the next angle. Then, the signal to be transmitted in which the occurrence of the transmission error has been detected, here, the X-ray transmission data is retransmitted.
Then, after that, the rotary plate angle in the re-transmission is replaced with the rotary plate angle at the time of the occurrence of the transmission error and used for the transmission of the X-ray transmission data. The buffer 17 performs temporary storage for adjusting the transmission timing of the transmission target X-ray transmission data in which the occurrence of the transmission error is detected. Since the above series of operations are performed instantaneously, there is no obstacle to the transmission of the X-ray transmission data measured at the next angle.

Next, the determination of whether or not a transmission error occurs during signal transmission through the slip ring and the brush will be described. In order to make the above determination prior to the collection of X-ray transmission data, first, the transmission check pattern generator 15 is activated, the transmission check pattern signals from this are sequentially taken in by the transmission controller 16, and the slip ring 7 is transmitted by the transmitter 14. Send to. The transmission check pattern signal sent to the slip ring 7 is received by the receiver 18 via the brush 8 and sent to the comparator 20.

A reception check pattern signal having the same pattern as the transmission check pattern signal is output from the reception check pattern generator 19, and the comparator 20 compares and collates these two check pattern signals to confirm that a transmission error has occurred. The presence or absence is determined.

When it is determined that a transmission error has occurred, the controller 11 is notified of the error occurrence. As a result, the controller 11 reads the angle of the rotary plate 1 at this time by the rotary plate angle detector 9 and records it in the rotary plate angle storage device 10 when a transmission error occurs.

The determination of the occurrence of such a transmission error is performed, for example, three times, and it is assumed that a signal transmission error occurs in a specific position on the slip ring such as dirt or scratches. A transmission error occurs every time the rotating plate angle is transmitted during the signal transmission, and the same angle is recorded three times in the rotating plate angle storage device 10 when the transmission error occurs.

Rotating plate angle storage device 10 when a transmission error occurs
When the same angle is stored in, for example, three times, the transmission target signal is retransmitted at an angle other than the stored angle is determined to be a transmission error due to disturbance (noise). This is to invalidate the determination result in the case of the error.

The determination of the occurrence of such a transmission error may be made by using the check pattern signal without X-ray exposure as in the above-mentioned embodiment, but at the time of starting preparation before using the apparatus, For example, an X-ray detection signal obtained by actual X-ray exposure may be used during calibration or aging operation. In this case, the transmission check pattern generator 15,
Instead of the reception check pattern generator 19 and the comparator 20, a known error control method or the like is used as the transmission error occurrence detecting means.

[0027]

As described above, according to the present invention, in a continuous rotation type X-ray CT apparatus using a slip ring and a brush for signal transmission, a signal such as a stain is attached to a specific position on the slip ring. Even if an error occurs in the transmission, the signal can be transmitted, and the reliability of the signal transmission can be improved.

[Brief description of drawings]

FIG. 1 is a structural explanatory view showing an embodiment of a device of the present invention.

2 is a block diagram showing details of a signal transmission device in FIG. 1. FIG.

FIG. 3 is an explanatory diagram of a rotation angle of a rotating plate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 rotating plate 2 subject 3 opening 4 X-ray tube 5 X-ray detector 6 signal transmission device 7 slip ring 8 brush 9 rotating plate angle detector 10 rotating plate angle storage device at the time of transmission error 11 controller 12 transmitter 13 Receiver 14 Transmitter 15 Transmission check pattern generator 16 Transmission controller 17 Buffer 18 Receiver 19 Reception check pattern generator 20 Comparator 21 Image processing device 22 Image display device

Claims (1)

[Claims] 1. A slip ring provided on a rotating plate having an opening for inserting a subject in the center thereof, and an X-ray tube and an X-ray detector facing each other across the opening, and a stationary side. By performing signal transmission between the rotary plate side and the stationary side by a signal transmission device provided with a brush that is in sliding contact with the slip ring, continuous rotation of the rotary plate in a fixed direction is possible, and in the same direction. In a continuous rotation type X-ray CT apparatus capable of performing a plurality of continuous scans, a transmission error occurs during signal transmission through a rotation plate angle detector that detects the angle of the rotation plate and the slip ring and brush. A transmission error occurrence rotary plate angle storage device that stores the rotary plate angle of the rotary plate angle detector at the time of transmission of the transmission target signal whose occurrence is detected. In addition to the ring and the brush, a transmitter that sends a signal to the slip ring in synchronization with the angle detected by the rotary plate angle detector, and a transmission error occurring during the signal transmission through the slip ring and the brush. Transmission error occurrence detecting means for giving the rotation plate angle of the rotation plate angle detector to the rotation plate angle storage device at the time of occurrence of the transmission error at the time of transmission of the transmission target signal whose occurrence is detected. When the same angle is stored a predetermined number of times in the rotary disk angle storage device, the transmission target signal in which the occurrence of the transmission error is detected is retransmitted at an angle other than the stored angle, and the subsequent transmission Continuous rotation type X, wherein the rotation plate angle is replaced with the rotation plate angle when the transmission error occurs and is used for signal transmission. C
T device.