JPH0268040A - Digital television tomographic photographing device - Google Patents

Abstract

PURPOSE:To obtain a tomographic picture of high picture quality having a little picture distortion or blurring by sending a detecting signal from a position information detector composed of a zebra scale and a photosensor to a controller and controlling the exposure of a radiant ray from a radiant ray source and the taking-in of projecting data to a recorder according position information. CONSTITUTION:The position information of relative movement for a radiant ray source 1 and a radiation detector 2 are detected by a position information detector 18 and the exposure of the radiant ray from the radiant ray source 1 and the taking-in of the projecting data to a recorder 6 is controlled. Then, the position information of the radiant ray source 1 is recorded to the recorder 6 in correspondence to the projecting data in respective projecting positions. Accordingly, concerning the respective projecting data, which projecting position of the radiant ray source 1 is photographed can be correctly made correspondent. Thus, in the correction of the picture distortion, a distortion vector in each projecting position can be exactly obtained and the correction of the picture distortion can be executed with high accuracy by using this distortion vector. In the shift addition of the respective projecting data, shift quantity can be exactly obtained at every projecting position and the shift addition can be executed with the high accuracy by using this shift quantity.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention involves relatively moving a radiation source and a radiation detector with a subject in between, and irradiating the subject with radiation. Capture tomographic images of arbitrary tomographic planes.

The present invention relates to a digital television tomography apparatus that displays images, and more particularly to a digital television tomography apparatus that detects positional information during relative movement between a radiation source and a radiation detector to control radiation exposure and capture of projection data.

[Conventional technology]

Conventional digital television tomography equipment includes a radiation source and
a radiation detector arranged to face the radiation source with the subject in between and convert the transmitted radiation image into visible light; a television camera that converts the output optical image into a video signal; and the radiation source and radiation detector. a fault machine part that relatively moves the
An A/D converter that converts the video signal from the television camera into a digital quantity, a recording device that stores this digital projection data, an arithmetic device that reads the projection data from this recording device and processes it, and this calculation device. It consisted of a display device that converted a processed digital signal into an analog video signal and displayed it, and a controller that controlled each of these elements.

Then, a plurality of images are taken while changing the relative positions of the radiation source and the radiation detector, and a tomographic image of an arbitrary tomographic plane within the subject is calculated and displayed.

[Problem to be solved by the invention]

However, in such a conventional digital television tomography apparatus, the radiation IA source is moved in a predetermined direction with the subject as the center of movement to emit radiation, and the radiation detector is relatively moved in the opposite direction to emit radiation. From the beginning of exposure, the subject was photographed and the projected images were independently captured using a radiation detector and a television camera. In this case, the synchronization signal of the television camera and the radiation exposure from the radiation source and the capture of the projected image are not synchronized at all, and the captured image of the projection image into the recording device is at most one frame (1 frame).
/30 seconds).

In such a situation, if you try to reconstruct a tomographic image of an arbitrary tomographic plane that is a certain distance away from a certain mounted plane using the projection images captured as described above, each projected image is Although the images are shifted and added as appropriate depending on which projection position the image was taken, it becomes uncertain to which projection position the projected image corresponds, and it may not be possible to shift with a highly accurate shift amount. Therefore, blurring occurs in the obtained tomographic image of an arbitrary tomographic plane. In addition, since the detection surface of the radiation detector is spherical and radiation is obliquely incident on the detection surface, large distortions occur in the obtained projection images, but in this case too, each projection image is If the correspondence between the projection position and the shooting position was not known, the angle of incidence could not be determined correctly, and distortion correction could not be performed with high precision. Therefore, the obtained tomographic image becomes difficult to detect, and good diagnostic information may not be obtained.

Therefore, an object of the present invention is to provide a digital television tomography apparatus that can solve these problems.

[Means to solve the problem]

Means of the present invention for solving the above problems include a radiation source,
a radiation detector arranged to face the radiation source with the subject in between and convert the transmitted radiation image into visible light; a television camera that converts the output optical image into a video signal; and the radiation source and radiation detector. a fault machine part that relatively moves the
An A/D converter that converts the video signal from the television camera into a digital quantity, a recording device that stores this digital projection data, an arithmetic device that reads the projection data from this recording device and processes it, and this calculation device. It has a display device that converts the processed digital signal into an analog video signal and displays it, and a controller that controls each of these elements, and displays multiple images while changing the relative positions of the radiation source and the radiation detector. In the digital television tomography apparatus that takes images and calculates and displays tomographic images of arbitrary tomographic planes within the subject, the tomographic machine section includes a device for detecting positional information during relative movement of the radiation FA source and the radiation detector. To,
A position information detector consisting of a zebra scale and a photosensor is provided, and a detection signal from this position information detector is sent to the controller, and the position information is used to emit radiation from the radiation source and project data to the recording device. This is done by a digital television tomography device with controlled acquisition.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a block diagram showing an embodiment of a digital television tomography apparatus according to the present invention. This digital television tomography apparatus irradiates a subject with radiation to capture and display tomographic images of arbitrary tomographic planes within the subject, and includes a radiation source 1, a radiation detector 2, and a television camera 3. , a tomography machine section 4 , an A/D converter 5 , a recording device 6 , an arithmetic device 7 , a D/A converter 8 , a display device 9 , and a controller 10 .

The radiation source 1 irradiates the subject 11 with radiation, and is composed of, for example, an X-ray tube. The radiation detector 2 is
It converts the transmitted radiation image of the subject 11 into visible light, and is composed of, for example, an image intensifier, and is placed opposite the radiation source 1 with the subject 11 in between. The television camera 3 receives the optical image output from the radiation detector 2 and converts it into a video signal. The tomography machine section 4 moves the radiation source 1 and the radiation detector 2, which are attached to opposite ends of the connecting rod 12, relative to each other in the directions of arrows A and B, for example, about a point on the mounting surface 13. , has a drive unit 14 as a power source for the relative movement. The A/D converter 5 receives the video signal output from the television camera 3 and converts it into a digital quantity. The recording device 6 stores the digital projection data output from the A/D converter 5 for each projection position, and is composed of, for example, a frame memory. The arithmetic device 7 reads out the projection data stored in the recording device 6 and performs arithmetic processing, and performs image distortion correction and shift addition to reconstruct a tomographic image of an arbitrary tomographic plane. The D/A converter 8 converts the digital signal processed by the arithmetic unit 7 into an analog video signal. The display device 9 receives the analog video signal output from the D/A converter 8 and displays a tomographic image, and is composed of a television monitor. The controller 10 controls each of the above elements, and the radiation source 1
It is designed to control the radiation exposure, drive control of the tomography machine section 4, and capture of projection data into the recording device 6. In FIG. 1, the reference numeral 15 is a high voltage generator for applying a high voltage to the radiation source 1, the reference numeral 16 is a fault 1 regulator that controls the drive of the fault machine section 4, and the reference numeral 17 is a high voltage generator for applying a high voltage to the radiation source 1. is an operation console that performs operations for setting the tomography mode and displaying tomographic images of arbitrary tomographic planes.

Then, the two-dimensional radiation transmission or absorption distribution of the subject 11 is calculated using the radiation '/g1 and the radiation detector 2.
Capturing multiple images while changing the relative positional relationship of
Linear calculations are performed on a set of projection data passing through one point within the subject 11 from these multiple images, and
A tomographic image of an arbitrary tomographic plane within 1 is calculated and displayed.

Here, in the present invention, the tomographic machine section 4 is provided with a position information detector 18. This position information detector 1
Reference numeral 8 detects open side position information during relative movement of the radiation source 1 and radiation detector 2 in the directions of arrows A and B. The zebra scale 20 attached to the tomography machine section 4 and this It consists of a photosensor that reads relative position information between the radiation source 1 and the radiation detector 2 from the scale.

The position information detector 18 is connected to the controller 1o via a signal line 19, and a detection signal S1 of, for example, a shooting position detected by the position information detector 18 is sent to the controller 10 via the signal line 19. It is now possible to do so.

Next, the operation of the digital television tomography apparatus configured as described above will be explained with reference to the timing diagram shown in FIG. First, a drive signal S2 is sent from the controller 10 to the tomography controller 16 in synchronization with the vertical synchronization signal (2) of the television camera 3 shown in FIG. 1, for example (see FIG. 2(a)). Then, under the control of the tomography controller 16, the tomography machine section 4 starts scanning in synchronization with the vertical synchronization signal v2, as shown in FIG. 2(b).

At this time, the drive section 14 of the tomography machine section 4 operates,
Rotate the connecting rod 12 in a predetermined direction, thereby connecting the radiation source 1
and the radiation detector 2 start relative movement as shown by arrows A and B. At the same time, the position information detector 18 provided on the connecting rod 12 also starts operating, and outputs, for example, a detection signal S1 of the photographing position and sends it to the controller 10, as shown in FIG. 2(c). The controller 1o converts the detection signal S1 into a vertical synchronization signal V1°V shown in FIG. 2(a).
21 V31 ... Monitors every ■o, and when the value exceeds a preset constant value (threshold), it is judged, and in synchronization with the vertical synchronization signal immediately after, for example, ■4, the high voltage generator 15 The exposure signal S3 is sent to the target. Then, this high voltage generator 15 applies a high voltage of a predetermined value to the radiation source 1, whereby the radiation g1 is
As shown in Figure (d), radiation exposure is started in synchronization with the vertical synchronization signal V4.

This radiation passes through the subject 11 and faces the opposite F5! , the radiation image is converted into visible light, and this output optical image is further incident on the television camera 3 and converted into a video signal.

The video signal output from this television camera 3 is
This A is input to the D converter 5 and converted into a digital quantity.
Digital projection data output from the /D converter 5 is sent to a recording device 6. At this time, immediately after the image pickup tube of the television camera 3 starts up, the recording device 6 does not capture projection data while the video signal is not yet stable. Then, as shown in FIG. 2(e), after a while after the radiation exposure has started, the video signal is stabilized, for example, from the point of vertical synchronization signal ■6, continuously for each projection position. Each frame F 11
F 21 F 3r... Import projection data into F, . At this time, at the same time, momentary position information regarding the relative movement of the radiation rA1 detected by the position information detector 18,
For example, the data of the detection signal Sl of the photographing position is input from the controller 10, and is recorded in an area that does not affect the image display in correspondence with the projection data of each frame F1 to Fn. Then, as shown in Fig. 2(e), when n frames of projection data have been captured, radiation exposure is stopped as shown in Fig. 2(d), and further as shown in Fig. 2(b). For example, the tomography machine section 4 is synchronized with the vertical synchronization signal vn.
Stop scanning.

After N images of the subject 11 are photographed in this way, the projection data and position information are read out from the recording device 6 for each frame F1 to F, and the arithmetic device 7 corrects image distortion and A tomographic image of an arbitrary tomographic plane is reconstructed by performing shift addition.

The data of the tomographic image reconstructed by this arithmetic unit 7 is converted into an analog video (i.
This analog video signal is input to the display device 9, and a tomographic image of a desired arbitrary tomographic plane of the subject 11 is displayed on the screen.

Here, the positional information recorded in the recording device 6 along with each projection data as described above, for example, the detection signal S1 of the photographing position, is used for image distortion correction and shift addition calculation processing as described below. First, regarding correction of image distortion, since image distortion is complicated by the use of an image intensifier as the radiation detector 2 and oblique incidence on the detection surface, the distortion vector of the representative point of the image is calculated for each imaging position. , it is usual to find the distortion vector for each pixel from this representative distortion vector. The representative distortion vector table used for this purpose is shown in Table 1.

Table 1 where PL, P2. ...pn is the representative point of the image "2," Xi,
In Ql~, the projection data of each image is the above lit
Since positional information regarding X 1 +X2+ . . . Therefore, using this distortion vector, image distortion can be corrected with high precision.

Next, regarding shift addition, a shift amount table as shown in Table 2 is prepared for each mounting surface.

Table 2 Here, xt, XI, ... IXn are representative positions of photographing positions, and numerical values p1~Pn+ ql~'Tn+...
, z1 to Zn are the respective devices xt, X2. ...
In the present invention, the above-mentioned [X
l+X2. ..., since the position information regarding Xn is recorded, by performing interpolation calculation in the direction of the position,
It is possible to accurately determine the shift amount for each photographing position. Therefore, using this shift amount, shift addition can be performed with high precision. Note that the shift amount is not limited to the one using the shift amount table shown in Table 2, but the shift amount can be expressed analytically once the geometric system of the tomography apparatus is determined, and it can be expressed directly from the position information regarding the position. It can also be calculated and found.

〔Effect of the invention〕

Since the present invention is configured as described above, the position information detector 18 detects the position information during the relative movement of the radiation source 1 and the radiation detector 2, and the radiation emitting and recording device from the radiation source 1 can be performed. In addition to controlling the acquisition of projection data to the recording device 6, the recording device 6 can record positional information of the radiation source 1 in association with projection data at each projection position.

Therefore, it is possible to correctly associate each projection data with which projection position of the radiation source 1 the image was taken.

Therefore, in correcting image distortion, it is possible to accurately obtain a distortion vector for each projection position, and using this distortion vector, it is possible to perform correction of image distortion with high precision. Further, in the shift addition of each projection data, the shift amount for each projection position can be accurately determined, and the shift addition can be performed with high precision using this shift amount.

Therefore, it is possible to obtain a high-quality tomographic image with little distortion or blurring of one image, and it is easy to perform AM, and it is possible to obtain good diagnostic information. Furthermore, since each projection data can be correctly associated with the projection position of the radiation source 1 at which the image was taken as described above, various changes can be made by changing the scanning speed or changing the projection data capture position. The shooting mode can be easily realized.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the digital television tomography apparatus according to the present invention, and FIG. 2 is a timing diagram showing the imaging operation. DESCRIPTION OF SYMBOLS 1... Radiation source, 2... Radiation detector, 3... Television camera, 4... Tomography machine section, 5... A/D converter, 6... Recording device, 7... Arithmetic device, 8...D/
A converter, 9... Display device, 10... Controller, 11... Subject, 12... Connecting rod, 14... Drive unit, 18... Position information detector, 19... ·Signal line,
20...Zebra scale.

Claims (1)

[Claims] 1. A radiation source, a radiation detector placed opposite the radiation source with a subject in between and converting a transmitted radiation image into visible light, and converting the output optical image into a video signal. A television camera, a tomographic machine section that relatively moves the radiation source and the radiation detector, an A/D converter that converts the video signal from the television camera into a digital quantity, and a record that stores this digital projection data. an arithmetic device that reads projection data from this recording device and processes it, a display device that converts the processed digital signal into an analog video signal and displays it, and a controller that controls each of these elements. In the digital television tomography apparatus, which captures a plurality of images while changing the relative positions of the radiation source and the radiation detector, and calculates and displays a tomographic image of an arbitrary tomographic plane within the subject, the tomographic machine A position information detector consisting of a zebra scale and a photosensor is installed in the unit to detect position information during the relative movement of the radiation source and radiation detector, and a detection signal from this position information detector is sent to the controller. A digital television tomography apparatus characterized in that the radiation exposure from the radiation source and the capture of projection data to the recording device are controlled based on the position information. 2. The digital television tomography apparatus according to claim 1, wherein the detection signal from the position information detector is captured and recorded at the same time as the projection data is captured. 3. The digital television tomography apparatus according to claim 1, wherein the tomographic machine section is driven in synchronization with a vertical synchronization signal of a television camera.