JP2010233906A - X-ray diagnostic apparatus and long-sized image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form a long-sized image while suppressing a subject's exposure to radiation regarding an X-ray diagnostic apparatus and a long-sized image forming method for forming the long-sized image using a fluoroscopic image. <P>SOLUTION: This X-ray diagnostic apparatus includes an X-ray generating part 60 irradiating the subject 100 with X-rays; an X-ray detecting part 70 detecting X-ray signals based on X-rays transmitted through the subject 100; a driving part 130 moving an image system including the X-ray generating part 60 and the X-ray detecting part 70; a position sensor for detecting position information on the image system; an image processing part 112 adding a plurality of fluoroscopic image frames based on the X-ray signals obtained in the X-ray detecting part 70, based on the detected position information to form a long-sized image; and a display part 80 displaying the long-sized image. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an X-ray diagnostic apparatus and a long image creation method for creating a long image using a fluoroscopic image.

  The X-ray diagnostic device emits X-rays from the X-ray generator, detects transmitted X-rays transmitted through the subject with the X-ray detector, and detects X-ray signals based on the transmitted X-rays detected by the X-ray detector Is processed by the image processing unit, and a captured image or a fluoroscopic image is displayed on the display unit.

  The long image creation method used in the X-ray diagnostic apparatus is an image creation method performed when displaying an image related to a region of interest over a wide range of a subject. In the long image creation method, a plurality of captured images are connected based on position information of a video system including an X-ray generation unit and an X-ray detection unit at the time of X-ray imaging. One piece of connected image is referred to as a long image, and is used, for example, in the diagnosis of side bay disease. When a long image is created, captured images acquired in advance are sequentially displayed in an overlapping manner (for example, Patent Document 1).

JP 2008-17965 gazette

In Patent Document 1, when a long image is created, a part of each captured image must be captured in duplicate. For this reason, each of the overlapping portions of the photographed image is exposed. As described above, Patent Document 1 does not consider the suppression of the exposure of the subject.
An object of the present invention is to provide an X-ray diagnostic apparatus and a long image creation method capable of creating a long image while suppressing exposure of a subject.

  To achieve the above object, an X-ray generation unit that irradiates a subject with X-rays, an X-ray detection unit that detects an X-ray signal based on X-rays transmitted through the subject, the X-ray generation unit, and the X-ray generation unit A drive unit that moves an image system including an X-ray detection unit, a position sensor that detects position information of the image system, and a plurality of fluoroscopic image frames based on an X-ray signal obtained by the X-ray detection unit; An image processing unit that creates a long image by adding based on the detected position information, and a display unit that displays the long image.

  According to the present invention, it is possible to create a long image while suppressing exposure of a subject.

The figure which shows the mechanism system of the X-ray diagnostic apparatus of this invention. The figure which shows the whole structure of the X-ray diagnostic apparatus of this invention. The figure which shows the operation | movement flowchart of Example 1- Example 4 of this invention. 1 is a graph for explaining Example 1 of the present invention. 6 is a graph for explaining Example 2 of the present invention. The figure which shows the elongate image before correction | amendment of this invention, and after correction | amendment. 6 is a graph for explaining Example 3 of the present invention. 6 is a graph for explaining Example 4 of the present invention.

  The present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a mechanism system of the X-ray diagnostic apparatus 1 of the present invention. Details of the mechanical system are as shown in, for example, Japanese Patent Application Laid-Open No. 2008-136797. Here, the main part of the mechanical system related to the present invention will be described.

  The stand unit 10 is a housing that supports the entire photographing stand (the support arm unit 20, the support frame 30, the support column unit 50, and the like). Inside the stand unit 10, an elevating mechanism for moving the support arm unit 20 up and down relative to the stand unit 10 and a rotation mechanism for rotating the support arm unit 20 relative to the stand unit 10 are housed.

  The support arm unit 20 is provided with a slide mechanism that slides the support frame 30 with respect to the support arm unit 20 in the longitudinal direction of the support frame 30. Although not shown, the slide mechanism includes a motor, a main sprocket that rotates by driving the motor, two driven sprockets, and a chain meshed with each sprocket. Both end portions of the chain are fixed to fixing portions of the support frame 30. The chain can be sent out by the rotation of the main sprocket, and as a result, the support frame 30 can be slid in the longitudinal direction with respect to the support arm portion 20.

  A top plate 40 on which the subject 100 is placed is provided on the upper portion of the support frame 30. In the imaging stand 1, the top plate 40 may be configured to be slidable in the longitudinal direction with respect to the support frame 30.

  Inside the support frame 30 is provided an X-ray generation unit drive mechanism that slides the support column 50 in the longitudinal direction (A direction) and the short direction (B direction) of the top plate 40 with respect to the support frame 30. . Although not shown, the X-ray generation unit drive mechanism includes a motor provided on one end side in the longitudinal direction of the support frame 30, a main sprocket that rotates by driving the motor, and a driven sprocket provided on the other end side of the support frame 30. And a chain connecting both sprockets. The base 51 of the support 50 is fixed to the chain, and the base 51, that is, the support 50 can be slid in the longitudinal direction (A direction) by rotating the chain with a sprocket. Note that the short direction (B direction) can also be slid by a mechanism similar to the X-ray generator drive mechanism in the long direction (A direction). The X-ray generator 60 is a device that is connected to the distal end side of the support column 50 and irradiates the subject 100 with X-rays. Therefore, the X-ray generation unit drive mechanism can move the X-ray generation unit 60 connected to the column unit 50 in the longitudinal direction (A direction) and the short direction (B direction).

  In addition, a rotation mechanism that rotates the X-ray generation unit 60 in the C direction with respect to the connection portion 53 is provided inside the connection portion 53 of the support column 50. The X-ray irradiation direction can be moved in the longitudinal direction of the top board 40. The support column 50 extends in the vertical direction from the base portion 51 and extends in both the longitudinal direction and the width direction of the support frame 30 toward the connecting portion 53. Therefore, the operator's standing position can be secured on both sides of the support frame 30 with the X-ray generation unit 60 interposed therebetween, and the subject 100 can be accessed from the head side and both sides of the subject 100. .

  The support column 50 is curved so as to protrude in a direction away from the support frame 30, that is, protrude to the stand unit 10 side. Therefore, the movement of the operator standing beside the support column 50 is not hindered. Further, a compression device 90 is provided on the side of the support 50 that faces the support frame 30. The compression device 90 is a device for performing imaging while compressing the region of interest of the subject 100.

  The X-ray detection unit 70 is installed inside the support frame 30. The X-ray detection unit 70 is configured by arranging a plurality of detection elements in a two-dimensional array. The X-ray detection unit 70 irradiates the X-ray according to the incident amount of X-rays irradiated from the X-ray generation unit 60 and transmitted through the subject 100. A device that detects a signal. The X-ray detection unit 70 may be configured as an image intensifier and a CCD (charge coupled device) camera or an imaging plate that stores an X-ray signal.

  An X-ray detection unit drive mechanism (not shown) for sliding the X-ray detection unit 70 is installed inside the support frame 30, and the X-ray detection unit 70 is moved in the longitudinal direction of the support frame 30 with respect to the support frame 30 ( And a slide mechanism that slides the X-ray detection unit 70 in the width direction (E direction) of the support frame 30 with respect to the support frame 30. The X-ray detection unit drive mechanism slides the X-ray detection unit 70 in the longitudinal direction (D direction) of the support frame 30 and the width direction (E direction) of the support frame 30 so as to face the X-ray generation unit 60. Specifically, the X-ray detector drive mechanism operates the X-ray detector 70 so that the optical axis of the X-ray of the X-ray generator 60 passes through the center of the X-ray detector 70. The control for operating the X-ray detection unit 70 to follow the X-ray generation unit 60 is based on positional information (sliding state) of the base portion 51 of the support column 50 and the X-ray detection unit 70 with respect to the support frame 30. This is performed based on a position sensor (not shown) to be detected. This position sensor is generally a linear encoder, a rotary encoder, or the like.

  The display unit 80 is supported on the stand unit 10 by an articulated arm 82. The display unit 80 can display a fluoroscopic image, a captured image, and the like of the subject 100.

  FIG. 2 is a diagram showing the overall configuration of the X-ray diagnostic apparatus of the present invention. Power is supplied to the top plate 40 on which the subject 100 is placed, the X-ray generation unit 60 that irradiates the subject 100 with X-rays, the diaphragm device 62 that sets the X-ray irradiation area for the subject 100, and the X-ray generation unit 60 X-ray detection unit 70 for detecting X-rays transmitted through the subject 100 and the X-ray output from the X-ray detection unit 70. An image processing unit 112 that performs image processing on a line signal, an image storage unit 114 that stores an X-ray image output from the image processing unit 112, a display unit 80 that displays an X-ray image, and FIG. Driving unit 130 for driving each driving mechanism of the column unit 50, the X-ray generation unit 60, and the X-ray detection unit 70, a control unit 118 for controlling each component, and an operation unit for instructing the control unit 118 And 120. The X-ray detection unit 70 is disposed in the support frame 30. Each of the image processing unit 112, the image storage unit 114, and the drive unit 130 is indicated by a broken line, but is arranged in any one of the stand unit 10, the support arm unit 20, the support frame 30, the support column unit 50, and the base unit 51. Is done.

  The X-ray generator 60 has an X-ray tube that receives power supply from the high voltage generator 108 and generates X-rays. The high voltage generator 108 is a direct current that is applied between the anode and cathode of the X-ray tube by passing a current through the filament that is the cathode of the X-ray tube of the X-ray generator 60 to heat the filament to a predetermined temperature. This is a device for generating a tube voltage which is a high voltage. By applying this high voltage, X-rays are emitted from the X-ray tube. The X-ray dose is controlled by controlling the current flowing through the filament, which is the cathode of the X-ray tube, and controlling the tube current, tube voltage, and imaging time flowing through the anode and cathode of the X-ray tube.

  The diaphragm 62 has a plurality of X-ray shielding lead plates that shield the X-rays generated from the X-ray generation unit 60, and each of the plurality of X-ray shielding lead plates moves, so that Determine the irradiation area.

  The image processing unit 112 performs image processing on the X-ray signal output from the X-ray detection unit 70, and outputs an X-ray image subjected to image processing. Image processing includes gamma conversion, gradation conversion processing, image enlargement / reduction, and the like. The image storage unit 114 stores the X-ray image output from the image processing unit 112 together with the name, sex, age information, time information, and the like of the subject 100. The display unit 80 can display the X-ray image output from the image processing unit 112 as a fluoroscopic image, a captured image, or the like of the subject 100.

The drive unit 130 connects the X-ray generation unit 60 and the X-ray generation unit drive mechanism that slides the support column 50 in the longitudinal direction (A direction) and the short direction (B direction) of the top plate 40 with respect to the support frame 30. Rotation mechanism for rotating the part 53 in the C direction, X-ray detection unit 70 is slid in the longitudinal direction (D direction) and the width direction (E direction) of the support frame 30 relative to the support frame 30 It is connected to each drive mechanism of the detector drive mechanism.
The drive unit 130 controls the X-ray generation unit drive mechanism and the X-ray detection unit drive mechanism to slide the X-ray generation unit 60 in the longitudinal direction (A direction) and move the X-ray detection unit 70 in the longitudinal direction ( (D direction) can be slid. Further, based on a position sensor that detects the position (sliding state) of the base 51 of the support column 50 and the X-ray detector 70 with respect to the support frame 30, the drive unit 130 is driven by the X-ray generator 60. The detection unit 70 can be operated.

  When the operation signal operated by the operation unit 120 is input to the control unit 118, the control unit 118 sequentially calculates the distance between the floor, the ceiling, and the mechanism unit from the position information of each drive mechanism, An operation or stop signal is output to each drive mechanism so as to avoid contact with the drive mechanism.

  Here, Embodiment 1 in which a long image is created using a fluoroscopic image will be described. In the present invention, the fluoroscopic image is acquired while moving the X-ray generation unit 60 for irradiating X-rays and the X-ray detection unit 70 for detecting X-ray signals so as to follow each other. The fluoroscopy control method uses pulse fluoroscopy. Pulse fluoroscopy is an imaging technique in which imaging is performed by irradiating X-rays with pulses at preset time intervals. The image processing unit 112 adds the fluoroscopic image frame based on the X-ray signal obtained by the X-ray detection unit 70 according to the position information of the video system including the X-ray generation unit 60 and the X-ray detection unit 70, and adds a long Create a scale image.

  Specifically, the control unit 118 calculates the moving amount of the video system for one X-ray irradiation from the positional information of the video system and the time interval of the X-ray irradiation. Then, the image processing unit 112 adds the shifted perspective image frames obtained sequentially by the calculated movement amount to create a long image. The display unit 80 displays the long image output from the image processing unit 112.

The first embodiment will be described in detail with reference to the operation flowchart of FIG.
(step 1)
The examiner uses the operation unit 120 to select a long image creation mode from various shooting modes. Then, the control unit 118 notifies each component that the long image creation mode has been selected.

(Step 2)
The examiner uses the operation unit 120 to determine the operation direction of the video system (X-ray generation unit 60 and X-ray detection unit 70) and the driving condition of the steady speed (operation speed) of the video system necessary for acquiring a long image. Set. Then, the control unit 118 outputs the driving direction of the video system and the driving conditions of the steady speed to the driving unit 130.

(Step 3)
The examiner sets with the operation unit 120 so that the video system moves to an image collection start point that is an end of the region of interest of the subject 100 for which a long image is to be acquired. The control unit 118 causes the drive unit 130 to move the video system to the image collection start point. For example, a light irradiation unit (not shown) that indicates the X-ray irradiation range of the subject 100 by irradiating light is used. The subject 100 is irradiated with light from the light irradiation unit, and the examiner moves the video system to the image collection start point while confirming the X-ray irradiation range.

(Step 4)
The control unit 118 detects the position information of the base 51 (that is, the X-ray generation unit 60) of the support column 50 and the position information of the position sensor of the X-ray detection unit 70, and recognizes the position information as the image collection start position. .

(Step 5)
When the examiner presses the image collection button of the operation unit 120, the X-ray generation unit 60, the X-ray detection unit 70, the image processing unit 112, and the like are in an image collection start preparation state. Then, the control unit 118 calculates a distance until the video system reaches a steady speed. FIG. 4 (a) is a graph showing the relationship between video system speed V (t) and time T. FIG. Here, it takes time (t1) to reach the steady speed (V1) from the initial speed (0), and the time to reach the stop speed (0) from the steady speed (V1) (t5)-(t4 ) The control unit 118 calculates the distance until the video system reaches the steady speed (V1) as (V1) × (t1).

(Step 6)
In response to an instruction from the control unit 118, the drive unit 130 outputs a video image on the outside by a distance (V1) × (t1) based on the image collection start position so that the image collection start position becomes the steady speed (V1) of the video system. Move the system. In FIG. 4A, the drive unit 130 moves the video system to the head side of the subject 100 by a distance of (V1) × (t1) with reference to the image collection start position. The control unit 118 recognizes the position moved as described above as the video system drive start position.

(Step 7)
In addition, the control unit 118, based on the steady-state speed (V1) of the video system, the X-ray conditions including the time interval of the X-rays that pulse the X-rays, the tube current flowing through the X-ray tube, the tube voltage, the imaging time, etc. Are set in the high voltage generator 108 and the X-ray generator 60.
Specifically, when the steady speed (V1) is equal to or higher than a predetermined value (for example, 100 mm / s or higher), the control unit 118 sets the time interval of the X-rays for pulsed X-ray irradiation to a predetermined value or less (for example, 10 ms or less). Or the X-ray dose per frame of the fluoroscopic image is set to a predetermined value or more (for example, 10 mAs or more). Conversely, when the steady speed (V1) is a predetermined value or less (e.g., 100 mm / s or less), the X-ray time interval for irradiating X-rays with pulses is greater than a predetermined value (e.g., 10 ms or more) The X-ray dose per unit is reduced to a predetermined value or less (for example, 10 mAs or less). In the present embodiment, the plurality of predetermined values may be set in the control unit 118 in advance.

(Step 8)
The drive unit 118 drives the video system from the drive start position of the video system, and the control unit 118 detects position information of the video system with a position sensor and determines whether the video system has reached the image collection start position. . When the video system reaches the image acquisition start position, the control unit 118 outputs a start signal to the high voltage generation unit 108, the X-ray generation unit 60, the X-ray detection unit 70, the image processing unit 112, and the like. The high voltage generation unit 108 and the X-ray generation unit 60 are determined based on the steady-state speed (V1), the time interval of the X-rays that pulse the X-rays, the tube current flowing through the X-ray tube, the tube voltage, and the imaging time X-rays are generated under X-ray conditions including the above, and the X-ray detection unit 70 detects an X-ray signal transmitted through the subject 100.

(Step 9)
The image processing unit 112 captures the fluoroscopic image frame based on the X-ray signal output from the X-ray detection unit 70 in real time together with the position information of the video system. Then, the image processing unit 112 adds a plurality of fluoroscopic image frames based on the position information and connects them to create a long image. Here, the addition is to sequentially superimpose the luminance values of a plurality of fluoroscopic image frames in accordance with the position of the video system from which the fluoroscopic image frames are acquired.

  Specifically, when a 5 mm video system moves per fluoroscopic image frame, the image processing unit 112 joins the fluoroscopic image frames by adding 5 mm sequentially in the moving direction to add a long image. Create an image. When a 10 mm video system moves per fluoroscopic image frame, the image processing unit 112 adds the fluoroscopic image frames by sequentially shifting the fluoroscopic image frame by 10 mm in the moving direction of the video system, thereby joining the fluoroscopic image frames and adding a long image. create. As described above, the image processing unit 112 manages the position information for each fluoroscopic image frame, thereby creating a long image by connecting the fluoroscopic image frames.

  FIG. 4 (b) is a graph showing the relationship between the added number F (t) and the time T at a point where fluoroscopy is performed at an arbitrary elapsed time from the image collection start position. As shown in FIG. 4 (b), the fluoroscopic image frames are joined from time (t1) to time (t4) which is the image collection start position. The number of fluoroscopic image frames to be added increases from time (t1) to time (t2). When the time (t2) is reached, the added number is (F1). The number of fluoroscopic image frames added from time (t2) to time (t3) is constant at (F1). The number of fluoroscopic image frames to be added decreases from time (t3) to time (t4).

(Step 10)
The examiner continues to press the image collection button of the operation unit 120 to the region of interest of the subject 100 for which the long image is desired to be acquired while confirming the connected long image on the display unit 80. Then, the examiner releases the image collection button when the operation of the video system passes the region of interest. When the image acquisition button is released, the control unit 118 recognizes that the image acquisition has ended, and the high voltage generation unit 108, the X-ray generation unit 60, the X-ray detection unit 70, the image processing unit 112, and the like enter an image acquisition end state. .

  The examiner may set an image collection end point at which the collection of the fluoroscopic image frames is stopped in advance. Specifically, the video system is moved by the drive unit 130 to the image collection end point that is the other end of the image collection start point, and the position information of the X-ray generation unit 60 and the position information of the X-ray detection unit 70 are detected. The position sensor that reads the position information reads. The control unit 118 recognizes the position information of the video system read by the position sensor as the image collection end position. The control unit 118 detects position information of the video system in the position sensor, and determines whether or not the video system has reached the image collection end position. When the video system reaches the image collection end position, the control unit 118 outputs an image collection end signal to the high voltage generation unit 108, the X-ray generation unit 60, the X-ray detection unit 70, the image processing unit 112, and the like. The high voltage generation unit 108, the X-ray generation unit 60, the X-ray detection unit 70, the image processing unit 112, and the like enter an image acquisition end state.

(Step 11)
Based on the press information of the image acquisition button of the operation unit 120 (image acquisition button OFF) or the position information of the position sensor (the video system moves to the image acquisition end position), the control unit 118 generates the high voltage generation unit 108 and the X-ray generation End signals are output to the unit 60, the X-ray detection unit 70, the image processing unit 112, and the like. The high voltage generator 108 and the X-ray generator 60 stop the generation of X-rays, and the drive unit 130 stops the movement of the video system.

  As shown in FIG. 4 (a), the moving speed of the video system is decelerated from time (t4), and the moving of the video system is stopped at time (t5). As shown in FIG. 4 (b), the image processing unit 112 ends joining of the fluoroscopic image frames at time (t4). Therefore, the added number of sheets F (t) also gradually decreases from time (t3) to time (t4).

(Step 12)
From time (t1) to time (t2) and from time (t3) to time (t4), long images created by joining perspective image frames differ in the number of fluoroscopic image frames added, so the image density differs. Displayed on the display unit 80 as a long image. Here, a long image from time (t1) to time (t2) and from time (t3) to time (t4) is defined as a long image at the end. Therefore, the examiner uses the operation unit 120 to select whether to correct the long image (whether to delete the long image at the end). If the long image at the end is not deleted, the operation ends.

(Step 13)
When the operation unit 120 selects to correct the long image (delete the long image at the end), the image processing unit 112 deletes the long image at the end from the entire long image. The image processing unit 112 extracts only the long image from time (t2) to time (t3) when the added number of fluoroscopic image frames is constant by deleting the long image at the end from the entire long image. Is done. The display unit 80 can display a long image having a uniform density from time (t2) to time (t3). Then, the operation ends.

  Note that (Step 5) and (Step 6) may be omitted, and the drive start position and the image collection start position may be matched. Therefore, since the examiner moves the video system to the image collection start point while checking the X-ray irradiation range, the visibility of the image collection start position is improved. Further, since the drive start position and the image collection start position are the same, the collection of the fluoroscopic image starts from the drive start position. Therefore, the creation time of the long image can be shortened.

  The image storage unit 114 can store the fluoroscopic image obtained in real time from the image processing unit 112 as a moving image together with the acquisition time information, and also stores the long image obtained from the image processing unit 112 together with the acquisition time information. be able to.

  By outputting a fluoroscopic image or a long image from the image storage unit 114, the display unit 80 can display a fluoroscopic image or a long image. Further, by outputting the long image together with the fluoroscopic image from the image storage unit 114 in accordance with the acquisition time information, the display unit 80 can display the long image together with the fluoroscopic image on the same screen. Therefore, the examiner can confirm the acquisition process of the long image together with the fluoroscopic image. For example, the examiner can confirm the injection state of the contrast agent with a fluoroscopic image and a long image.

As described above, according to the present embodiment, it is possible to create a long image using a fluoroscopic image, and it is possible to suppress exposure of the subject more than to create a long image using a captured image obtained by X-ray imaging. .
Further, according to the present embodiment, since a long image is created by superimposing a plurality of fluoroscopic images, it is possible to display a long image with little influence of joints. Specifically, since the number of images constituting the long image is large, more image information can be acquired, and thus a long image with high joining accuracy can be created. Therefore, the examiner can make an accurate diagnosis.

  In addition, according to the present embodiment, since the X-ray dose is low because a fluoroscopic image is used, it is possible to diagnose a large number of subjects 100 such as a side bay examination.

  Further, according to the present embodiment, since a long image can be created without stopping the movement of the video system, it takes less time than creating a long image using an image taken by X-ray imaging. Therefore, the burden on the subject 100 can be reduced.

(Variable X-ray dose to reduce exposure)
Next, Example 2 will be described with reference to FIGS. The difference from the first embodiment is that the X-ray dose can be varied in order to further reduce the exposure.
FIG. 5 (a) is a graph showing the relationship between the number of added sheets F (t) and the time T at a point where an arbitrary time has elapsed from the image collection start position. FIG. 5B is a graph showing the relationship between the number of fluoroscopic image frames H (t) and time T added when creating a long image for one fluoroscopic image frame.

Here, the length Lmm of one fluoroscopic image frame (the same direction as the moving direction of the video system), the moving speed V (t) mm / s of the video system, and the fluoroscopic image frame rate as f / s (frame / sec) To do. The total number of fluoroscopic image frames H (m) irradiated to an arbitrary fluoroscopic image frame m (time t (m-1) to t (m)) constituting a long image should be expressed by the following equation (1). Can do.

例えば、透視画像フレーム1枚の長さLを400mm、速度Vを100mm/s、透視画像フレームレートを30f/sとした時の総透視画像フレーム数H(m)は、数2の通りとなる。ただし、F(t)が一定となる領域のみで構成されるm枚目の透視画像フレームの加算フレーム数である。

For example, when the length L of one fluoroscopic image frame is 400 mm, the speed V is 100 mm / s, and the fluoroscopic image frame rate is 30 f / s, the total number of fluoroscopic image frames H (m) is as follows: . However, it is the number of frames added to the m-th perspective image frame constituted only by the region where F (t) is constant.

透視画像フレーム1枚に対してNのX線線量を照射していたとすると、透視画像フレーム1枚分に相当する映像系の移動時に照射されるX線線量は、H(m)枚の透視画像フレームが加算されているので、その総X線線量N(m)は、数3のようになる。

Assuming that one fluoroscopic image frame is irradiated with N X-ray doses, the X-ray dose irradiated when moving the video system corresponding to one fluoroscopic image frame is H (m) fluoroscopic images. Since the frames are added, the total X-ray dose N (m) is as shown in Equation 3.

透視画像フレームを加算することは、その加算分だけX線線量を被検体100に照射することになる。そこで、本実施例では、被検体100の被曝を抑えるために、制御部118は、透視画像フレーム1枚分の長尺画像に必要な総X線線量N(m)を所定値(被曝上限値)に設定する。そして、制御部118は、透視画像フレーム1枚当りに必要なX線線量をN(m)／H(m)として算出する。制御部118は、このX線線量のX線条件を高電圧発生部108及びX線発生部60に設定する。
なお、操作部120により所定値(被曝上限値)を任意に設定することができる。

Adding the fluoroscopic image frames irradiates the subject 100 with the X-ray dose by the added amount. Therefore, in this embodiment, in order to suppress the exposure of the subject 100, the control unit 118 sets the total X-ray dose N (m) necessary for the long image for one fluoroscopic image frame to a predetermined value (exposure upper limit value). ). Then, the control unit 118 calculates the X-ray dose necessary for one fluoroscopic image frame as N (m) / H (m). The control unit 118 sets the X-ray condition of the X-ray dose in the high voltage generation unit 108 and the X-ray generation unit 60.
The operation unit 120 can arbitrarily set a predetermined value (exposure upper limit value).

  Next, the operation of the second embodiment will be described with reference to FIG. Since the difference from the first embodiment is step 7, only step 7 will be described.

(Step 7)
In the first embodiment, the control unit 118 sets the X-ray conditions to the high voltage generation unit 108 and the X-ray generation unit 60 based on the steady-state speed (V1) of the video system, but can be changed as in the second embodiment. It is. Specifically, the control unit 118 presets the total X-ray dose N (m) necessary for a long image for one fluoroscopic image frame as a predetermined value (exposure upper limit value). Then, the control unit 118 calculates the X-ray dose necessary for one fluoroscopic image frame as N (m) / H (m). Then, based on the calculated X-ray dose, the control unit 118 sets the X-ray conditions including the tube current flowing through the X-ray tube, the tube voltage, the imaging time, and the like in the high voltage generation unit 108 and the X-ray generation unit 60. To do.

  As described above, according to the present embodiment, the total X-ray dose N (m) required for a long image for one fluoroscopic image frame is set to a predetermined value (exposure upper limit value) in advance, and the object 100 is All X-ray doses can be reduced.

(Density gain)
Here, Example 3 will be described with reference to FIGS. The difference from the first embodiment and the second embodiment is that a density gain for making the density of the long image uniform is set in each perspective image frame.
As shown in FIG. 6 (a), the long image created by joining the perspective image frames is displayed on the display unit 80 as a long image having a different density because the number of additions of the perspective image frames is different. . For example, the first long image from the left end of m = 1 is created with only the perspective image frame 1. In addition, the second long image from the left end of m = 1 is created by the perspective image frame 1 and the next perspective image frame 2. The seventh long image from the left end of m = 1 is created from the perspective image frame 1 to the perspective image frame 7.

  FIG. 7A is a graph showing the relationship between the number of fluoroscopic image frames H (t) and time T added when creating a long image for one fluoroscopic image frame. FIG. 7 (b) is a graph showing the relationship between density gain G (t) and time T.

  The image processing unit 112 performs processing for making the density of the long image uniform due to the difference in the number of fluoroscopic image frames added. Specifically, the image processing unit 112 multiplies a portion with a small number of fluoroscopic image frames to be added (for example, the first long image from the left end of m = 1) by a high density gain G (t) coefficient, A low density gain G (t) coefficient is multiplied by a portion having a large number of fluoroscopic image frames to be added (for example, the seventh long image from the left end of m = 1). Here, the image processing unit 112 performs a process for equalizing the density of the long image as in Expression 4 when the required density α is obtained.

よって、図6(b)に示すように、透視画像フレームの加算枚数の違いによる長尺画像の濃度を均一に保つことができる。

Therefore, as shown in FIG. 6B, the density of the long image due to the difference in the number of fluoroscopic image frames added can be kept uniform.

  Next, the operation of the third embodiment will be described with reference to FIG. Since points different from the first embodiment are steps 12 and 13, only steps 12 and 13 will be described.

(Step 12)
Therefore, the examiner uses the operation unit 120 to select whether or not to correct the long image (whether or not to correct the density gain of the long image). If the density gain of the long image is not corrected, the operation ends.

(Step 13)
When the operation unit 120 is selected to correct the long image (correct the density gain of the long image), the image processing unit 112 equalizes the density of the long image due to the difference in the added number of fluoroscopic image frames. Process to keep in. The display unit 80 can display a long image with uniform density based on the long image output from the image processing unit 112. Then, the operation ends.
As described above, according to the present embodiment, a long image with a uniform density can be displayed on the display unit 80, and the examiner can perform an accurate diagnosis.

(Variable X-ray dose for long images with uniform density)
Here, Example 4 will be described with reference to FIGS. The difference from the first to third embodiments is that the X-ray dose is made variable according to the region of interest (for example, body thickness) of the subject 100.

  For example, the body part and the lower limb part of the subject 100 have different body thicknesses. Therefore, if fluoroscopic images are acquired on the trunk and lower limbs of the subject 100 under the same X-ray conditions, the image density of the fluoroscopic image frames may be different. Therefore, the control unit 120 can also set the X-ray condition in the high voltage generation unit 108 and the X-ray generation unit 60 based on the region of interest of the subject 100.

  Specifically, as shown in FIG. 8 (b), time (t1) to time (t3 ′) is the timing of irradiating the body part of the subject 100 with X-rays, and time (t3 ′) to time ( t4) is the timing of irradiating the lower limb of the subject 100 with X-rays. Therefore, the control unit 120 includes the high-voltage generation unit 108 and the X-ray dose α (mAs) from time (t1) to time (t3 ′), which is the timing of irradiating the body of the subject 100 with X-rays. Set to X-ray generator 60. Therefore, the control unit 120 includes the high voltage generation unit 108 and the X-ray dose β (mAs) from time (t3 ′) to time (t4), which is the timing of irradiating the lower limb of the subject 100 with X-rays. Set to X-ray generator 60.

  As described above, according to the present invention, the X-ray dose can be varied according to the region of interest (for example, body thickness) of the subject 100. Therefore, a long image with a uniform density can be displayed on the display unit 80, and the examiner can make an accurate diagnosis.

  10 Stand unit, 20 Support arm unit, 30 Support frame, 40 Top plate, 50 Post unit, 60 X-ray generation unit, 70 X-ray detection unit, 80 Display unit, 100 Subject, 108 High voltage generation unit, 112 Image processing Unit, 114 Image storage unit, 118 Control unit, 120 Operation unit, 130 Drive unit

Claims (14)

  An X-ray generation unit that irradiates the subject with X-rays, an X-ray detection unit that detects an X-ray signal based on the X-rays transmitted through the subject, the X-ray generation unit, and the X-ray detection unit Based on the detected position information, a drive unit that moves the video system, a position sensor that detects position information of the video system, and a plurality of fluoroscopic image frames based on the X-ray signals obtained by the X-ray detection unit An X-ray diagnostic apparatus comprising: an image processing unit that creates a long image by adding together, and a display unit that displays the long image.   The X-ray diagnostic apparatus according to claim 1, wherein the X-ray generation unit emits X-rays at a preset time interval.   The X-ray generation unit sets an X-ray condition including an X-ray time interval, a tube current, a tube voltage, and an imaging time for pulse irradiation of the X-ray based on the moving speed of the video system. The X-ray diagnostic apparatus according to claim 1, wherein X-ray irradiation is performed under an X-ray condition.   4. The X-ray diagnostic apparatus according to claim 3, wherein the moving speed of the video system is a steady speed of the video system.   The X-ray diagnostic apparatus according to claim 1, wherein the image processing unit sequentially superimposes the luminance values of the plurality of fluoroscopic image frames in accordance with the position of the video system from which the fluoroscopic image frame is acquired. .   The image processing unit adds the fluoroscopic image frames sequentially obtained by shifting the moving amount based on the moving amount of the video system for one X-ray irradiation of the X-ray generating unit, and creates the long image The X-ray diagnostic apparatus according to claim 1, wherein:   The X-ray diagnostic apparatus according to claim 1, wherein the driving unit moves the video system so that the video system has a steady speed at an image acquisition start position where the acquisition of the fluoroscopic image frame is started. .   The X-ray diagnostic apparatus according to claim 1, wherein the image processing unit creates the long image by deleting the long image at an end portion having a different density.   The X-ray diagnostic apparatus according to claim 1, further comprising an image storage unit that stores a fluoroscopic image obtained from the image processing unit as a moving image together with acquisition time information, and stores the long image together with the acquisition time information. .   The X-ray diagnostic apparatus according to claim 1, wherein the display unit displays the long image together with the fluoroscopic image on the same screen.   The X-ray generation unit sets an X-ray dose of one fluoroscopic image frame based on a total X-ray dose necessary for a long image of the one fluoroscopic image frame. The X-ray diagnostic apparatus described.   The X-ray diagnostic apparatus according to claim 1, wherein the image processing unit sets a density gain for making the density of the long image uniform in each fluoroscopic image frame.   The X-ray diagnostic apparatus according to claim 1, wherein the X-ray generation unit varies the X-ray dose according to a region of interest of the subject.   Irradiating X-rays, detecting an X-ray signal based on the X-ray, adding a plurality of fluoroscopic image frames based on the X-ray signal based on position information, and creating a long image; A long image creating method comprising: displaying an image.

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