JP3491563B2 - X-ray equipment - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plurality of imaging positions set along the body axis of a subject, and an X-ray imaging condition set in advance for each imaging position. More particularly, the present invention relates to a technique for easily setting appropriate X-ray imaging conditions while suppressing an exposure dose. 2. Description of the Related Art Conventionally, as an X-ray imaging apparatus, as shown in FIG. 8, an X-ray tube 51 and an image intensifier (X-ray detection) for detecting transmitted X-rays from a subject M are used. vessel)
The X-ray imaging units 54 provided at both ends of the C-arm 53 in such a manner that the X-ray imaging units 52 face each other with the subject M interposed therebetween are sequentially set along the body axis Z of the subject M by step feed. While sequentially moving to the shooting positions Pa to Pe,
X set in advance for each of the photographing positions Pa to Pe
X-rays are emitted from the X-ray tube 51 to the subject M at each of the imaging positions Pa to Pe according to the X-ray imaging conditions, and transmitted X-rays are detected by the image intensifier (I / I tube) 52 to perform X-ray imaging. There are devices configured to be performed. [0003] In the case of FIG. 8, the imaging is repeatedly executed at each of the imaging positions Pa to Pe according to the X-ray imaging conditions programmed by the operator in advance with respect to the standard subject, and the hips of the subject M are set. A wide region of interest from the to the foot is immediately photographed. And usually, each shooting position Pa
The X-ray imaging conditions in Pe are different from each other. Because, for a thick and thick waist, a good quality X-ray image is obtained at a tube voltage of about 100 kV, while for a thin and thin toe, a good quality X-ray image is obtained at a tube voltage of about 60 kV. This is because, when the region of interest is wide, appropriate X-ray imaging conditions at the imaging position differ between the positions. [0004] However, the above-mentioned conventional X-ray imaging apparatus has a problem that the X-ray imaging conditions are often not appropriate. Since the X-ray imaging conditions programmed in advance based on the standard body are not suitable for the subject M having a large deviation from the standard body, the operator modifies the program for the subject M having a large deviation from the standard body. Must. However, intuitively grasping the exact difference between the standard body and the subject M and accurately modifying the program requires abundant experience and is not easy. If the number of shooting positions is different, the program will be different, but since the number of shooting positions (number of steps) is not constant, for example, as in the case of adults and infants, the program for all cases where the number of shooting positions is different Must be prepared, and programming of the X-ray imaging conditions itself is troublesome and not easy. On the other hand, instead of using the X-ray imaging conditions based on the standard body, each imaging position P of the subject M to be imaged is
Although it is actually performed to set the X-ray imaging conditions for each of the imaging positions Pa to Pe based on the results obtained by actually performing the X-ray test exposure before a main imaging in a to Pe. ,
In the case of this method, there is another problem that the exposure dose is increased by the amount of the test irradiation. [0006] The present invention has been made in view of such circumstances, and an object of the present invention is to provide an X-ray imaging apparatus capable of easily setting appropriate X-ray imaging conditions while suppressing an exposure dose. And In order to solve the above-mentioned problems, an X-ray imaging apparatus according to the present invention is provided such that an X-ray tube and an X-ray detector face each other with a subject interposed therebetween. X-ray imaging means, and an imaging position changing means for changing the imaging position of the subject by step-by-step feeding along the body axis of the object one by one, and a predetermined X-ray imaging time is set for each imaging position. The X-ray tube irradiates the subject with X-rays from the X-ray tube at each imaging position according to X-ray imaging conditions that are at least one of the X-ray tube voltage and the X-ray tube current, and transmits X-rays from the subject with an X-ray detector. In an X-ray imaging apparatus configured to perform X-ray imaging by detecting
Corresponding imaging condition storage means for storing a correspondence between X-ray fluoroscopy conditions performed prior to X-ray imaging to determine an imaging position and the X-ray imaging conditions, and both ends determined by performing X-ray fluoroscopy A photographing position storing means for storing the respective photographing positions, and the X-ray photographing conditions corresponding to the X-ray fluoroscopic conditions at the time of determining the photographing positions at both ends are read out from the corresponding photographing condition storing means, and the photographing positions at the both ends are read out. The X-ray detector overlaps a certain width between adjacent photographing positions based on both-end position photographing condition setting means to be set as X-ray photographing conditions and the intermediate photographing position of the X-ray photographing conditions of each photographing position at both ends. And an intermediate position imaging condition setting means for obtaining and setting the X-ray imaging condition of such an intermediate imaging position. [Operation] The operation of the X-ray imaging apparatus according to the present invention is as follows. In the case of the X-ray imaging apparatus according to the present invention, X-ray fluoroscopic conditions (X-ray fluoroscopic conditions) performed prior to X-ray imaging to determine an imaging position, X-ray tube voltage and X-ray during X-ray imaging Correspondence with the X-ray imaging condition, which is at least one of the tube currents, is stored in advance in the corresponding imaging condition storage means, and when imaging is performed, first, X-ray fluoroscopy is performed and both ends of the imaging position are determined. Each imaging position is determined and stored in the imaging position storage means, and the X-ray imaging conditions corresponding to the X-ray fluoroscopy conditions at the time of determining each imaging position at both ends are set by the both-end position imaging condition setting means. The X-ray imaging condition of the imaging position is read from the corresponding imaging condition storage means and set. Also,
The intermediate position, in which the X-ray detector overlaps a certain width between adjacent image positions, based on the X-ray image conditions of the respective image positions at both ends and the position of the intermediate image position, by the intermediate position image condition setting means. Is determined and set. The intermediate photographing position (position)
Is usually automatically calculated based on the photographing positions at both ends, but may be set by the operator. When the X-ray imaging is started, the X-ray imaging is executed one after another according to the X-ray imaging conditions set in advance from the imaging position at one end to the imaging position at the other end along the body axis of the subject. Will be done. In other words, according to the present invention, if the correspondence between the X-ray fluoroscopic conditions and the X-ray radiographic conditions is stored in advance in the corresponding radiographic condition storage means, the X-ray fluoroscopic conditions at the time of determining each radiographic position at both ends are stored. The X-ray imaging conditions of each of the two imaging positions are automatically read out from the corresponding imaging condition storage means and set, and the X-ray imaging conditions of the intermediate imaging position are also set to the X-ray imaging of each of the two imaging positions. It is automatically determined and set based on the conditions and the position of the intermediate shooting position. By making good use of the correspondence between X-ray fluoroscopy conditions and X-ray imaging conditions, it is possible to determine the appropriate X-ray imaging conditions according to the situation of the subject to be actually imaged without using test exposure. In addition, the number of photographing positions is determined automatically, and it is not necessary to set the photographing position for each case. Next, an embodiment of the X-ray imaging apparatus according to the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an overall configuration of an X-ray imaging apparatus according to an embodiment, and FIG. 2 is a schematic diagram showing a situation of X-ray imaging by the embodiment apparatus. The X-ray imaging apparatus according to the embodiment illustrated in FIG. 1 includes an imaging system that detects X-ray irradiation to the subject M and transmitted X-rays from the subject M accompanying the X-ray irradiation, and a transmission X-ray detection signal. An X-ray image is created and displayed based on the control system, and the control system controls the movement of the imaging system. Usually, the imaging system and the control system have separate installation rooms. Hereinafter, a specific configuration of the X-ray imaging apparatus according to the embodiment will be described in the order from the imaging system side to the control system side. As shown in FIG. 1, an X-ray tube 1 and an I / I tube 2 for detecting transmitted X-rays from a subject M are provided on the imaging system side to transfer the subject M on a top plate 3 to the subject. C in the form of facing each other
An X-ray imaging unit 5 provided at both ends of the arm 4 is provided. The X-ray imaging unit 5 is supported by a movable supporter 7 arranged to run on a rail 6,
It moves along the longitudinal direction of the top plate 3 (the direction perpendicular to the paper surface). In the case of the former X-ray imaging unit 5, transmitted X-rays from the subject M generated by X-ray irradiation by the X-ray tube 1 are I
It is configured to be detected by the I tube 2, converted to an electric signal by a TV camera (not shown) installed at the rear of the I · I tube 2, and then transmitted as a video signal to the control system side. I have. In the case of the latter movable supporter 7, an electric motor 7a and a position sensor 7b are mounted, and upon receiving a drive signal from the photographing position control section 8, the electric motor 7a
The movable supporter 7 travels on the rail 6 as the vehicle rotates, and the position of the X-ray imaging unit 5 that changes along the body axis Z of the subject M with the travel of the movable supporter 7 is a position sensor. 7b. On the photographing system side, as shown in FIG.
The imaging positions PA (for example, five) set along the body axis Z of the subject M (to be described in detail later).
Is stored in the photographing position memory 9 and the position sensor 7 is stored in the photographing position memory 9.
A determination switch unit 10 for issuing a command to store the detected position of b as a photographing position, and a travel switch unit 11 for traveling control of the movable supporter 7 are provided.
A display monitor 12 on which a line image is projected on a screen is also provided. Further, during execution of X-ray imaging, the imaging position control unit 8 performs X-ray imaging based on the set position of the imaging position stored in the imaging position memory 9 and the detection position of the position sensor 7b, for example, as shown in FIG. The running of the movable supporter 7 is controlled so that the line imaging unit 5 is moved stepwise to the photographing positions PA to PE in order. Next, the description will proceed to the control system side. On the control system side, first, an image signal processing unit 13 that performs image signal processing necessary for a video signal as an X-ray image, an X-ray image memory 14 that stores the X-ray image created by the image signal processing unit 13,
An image printing unit 15 for printing an X-ray image on a sheet and outputting it as an X-ray photograph as necessary, and a display monitor 16 for displaying the X-ray image on a screen are provided. The video signal is converted into a digital signal by A / D conversion on either the control system side or the imaging system side, and then image signal processing is performed. On the control system side, an irradiation control unit 17 which includes a high-voltage power supply and supplies necessary power to the X-ray tube 1 is provided.
And a computer (CPU) 18 for performing calculations and command signals necessary for operating the apparatus, and a keyboard 19 for performing input operations (for example, an input operation for starting photographing) required for operating the apparatus.
In addition to the above, there are provided a fluoroscopy luminance determination unit 20 that functions as an automatic luminance control during X-ray fluoroscopy, and an exposure timer unit 21 that performs automatic exposure control during X-ray imaging. In the case of the apparatus of the embodiment, a hand switch HS is provided on the photographing system so that the photographing system can also perform an input operation for starting photographing. The control system is provided with a corresponding imaging condition memory 22 for storing the correspondence between X-ray fluoroscopic conditions and X-ray imaging conditions as one characteristic configuration. The X-ray imaging conditions corresponding to the X-ray fluoroscopic conditions at the time of determining each of the imaging positions at both ends determined by performing X-ray fluoroscopy are defined as the X-ray imaging conditions of each of the imaging positions at both ends. Both end position imaging condition setting means for reading from the condition memory 22 and setting it in the X-ray imaging condition memory 23 is provided. The end position photographing condition setting means is mainly configured by the CPU 18 and a control program for operating the CPU. The characteristic configuration will be specifically described below with reference to the drawings. In the following, it is assumed that the region of interest to be imaged is from the waist to the toe of the subject M, and that the X-ray imaging conditions are the same except for the tube voltage (tube current, exposure time, etc.). That is, although the exposure dose differs greatly between X-ray fluoroscopy and X-ray imaging, there is a difference between an appropriate tube voltage in X-ray fluoroscopy and an appropriate tube voltage in X-ray imaging as shown in FIG. Good correspondence is seen. In both X-ray fluoroscopy and X-ray imaging, the tube voltage is large at the thick and thick region of interest, such as the waist,
There is the same tendency that it is higher than the tube voltage at the thin and thin site of interest, such as the toes. Then, the correspondence between the tube voltage at the time of X-ray fluoroscopy and the tube voltage at the time of X-ray photography shown in FIG. On the other hand, in the case of the apparatus of the embodiment, in the X-ray fluoroscopy performed to determine the photographing positions at both ends, the luminance determination unit 20 during fluoroscopy is used.
With the function described above, an appropriate tube voltage is automatically set so that the intensity of the video signal becomes an appropriate level and a high quality fluoroscopic image is displayed on the screens of the display monitors 12 and 16. The end position imaging condition setting means applies the X-ray tube voltage information for determining the imaging positions at both ends to the correspondence between the two tube voltages in FIG. ) Is configured to perform the reading and setting, and will be specifically described below with reference to the drawings. FIG. 4 is a schematic diagram showing the state of the X-ray imaging unit at the time of reading and setting the X-ray imaging conditions of the imaging positions at both ends. FIG. 5 is a flowchart showing the process of reading and setting the X-ray imaging conditions of the imaging positions at both ends. It is. [Step S1] Operate the traveling switch unit 11 to move the movable supporter 7, and move the X-ray imaging unit 5 toward the waist for setting the photographing position at one end as shown by the solid line in FIG. . [Step S2] X-ray fluoroscopy of the waist is started by operating the console 19 or the hand switch HS, and a fluoroscopic image is displayed on the screens of the display monitors 12 and 16. [Step S3] While checking the see-through state on the screen of the display monitor 12 or the display monitor 16, the traveling switch unit 11 is operated to finely adjust the position of the X-ray imaging unit 5 and
The position of the line imaging unit 5 is accurately adjusted to a desired position. [Step S4] By operating the decision switch section 10, the current position detected by the position sensor 7b is recorded in the photographing position memory 9 as the photographing position PA at one end, and the CPU 18 converts the current position into the X-ray fluoroscopic tube voltage. Corresponding X-ray imaging tube voltage corresponds to imaging condition memory 2
2, and the read voltage is stored in the X-ray imaging condition memory 23 as a tube voltage (X-ray imaging condition) at the imaging position PA. [Step S5] The movable supporter 7 is operated by operating the traveling switch unit 11, and the X-ray imaging unit 5 is moved to the other end by setting the photographing position at the other end, as shown by the dashed line in FIG. Move to [Step S6] X-ray fluoroscopy of the toes is started by operating the console 19 or the hand switch HS, and the fluoroscopic images are displayed on the screens of the display monitors 12 and 16. [Step S7] While observing the see-through image on the screen of the display monitor 12 or the display monitor 16, the position of the X-ray imaging unit 5 is finely adjusted by operating the feed switch unit 11 to accurately position the X-ray imaging unit 5. To the desired position. [Step S8] By operating the decision switch section 10, the current position detected by the position sensor 7b is recorded in the photographing position memory 9 as the photographing position PE on the other end side and corresponds to the tube voltage of X-ray fluoroscopy. The X-ray imaging tube voltage is read from the corresponding imaging condition memory 22, and the read voltage is set to the tube voltage (X
X-ray imaging condition) is stored in the X-ray imaging condition memory 23. This completes the process of reading and setting the X-ray imaging conditions of the imaging positions PA and PE at both ends. On the control system side, as another characteristic configuration, the X-ray imaging conditions of the intermediate imaging position located between the imaging positions PA and PE at both ends are set in the imaging position PA set above. , PE, and intermediate position imaging condition setting means for automatically obtaining the values based on the X-ray imaging conditions of the PEs and the positions of the respective intermediate imaging positions and setting them in the X-ray imaging condition memory 23. The intermediate position photographing condition setting means is also configured mainly by the CPU 18 and a control program for operating the CPU, but will be specifically described below with reference to the drawings. FIG. 6 is a schematic diagram showing the state of the X-ray imaging unit at the time of obtaining and setting the X-ray imaging conditions of the intermediate imaging position, and FIG. 7 shows the process of reading and setting the X-ray imaging conditions of the intermediate imaging position. It is a flowchart. [Step F1] First, the CPU 18 determines the intermediate photographing positions PB, PC, P based on the photographing positions PA, PE and the size of the I / I tube 2, as shown in FIG.
Calculate D. As shown in FIG. 2, the detection surface of the I / I tube 2 is overlapped by a fixed width between the adjacent photographing positions so that the position of the intermediate photographing position is adjusted so that the photographing omission does not occur between the adjacent photographing positions. It is determined. [Step F2] The calculated intermediate photographing positions PB, PC and PD are sent to the photographing position memory 9 and recorded. [Step F3] The CPU 18 sets the voltage value Vx for the tube voltage of each of the intermediate photographing positions PB, PC and PD.
Is calculated according to the following complementary formula using the tube voltages Va and Vb of the photographing positions PA and PE. Normally, the tube voltage Va
Is about 100 kV, and the tube voltage Vb is about 60 kV.
In the following equation, Lab represents the distance between the photographing positions PA and PE, and Lx represents the distance between the photographing position PE and the intermediate photographing position for which the voltage value Vx is to be calculated. Vx = (Va−Vb) × Lx ÷ Lab + Vb [Step F4] Photographing positions PB, P
Each tube voltage Vx obtained for each of C and PD is used as an X-ray imaging condition for each of the intermediate imaging positions PB, PC, and PD.
It is stored in the line imaging condition memory 23. This completes the process of obtaining and setting the X-ray imaging conditions of the intermediate imaging positions PB to PD. As described above, according to the X-ray photographing apparatus of the embodiment, the X-ray photographing conditions of the photographing positions PA and PE at both ends are stored in the corresponding photographing condition memory in accordance with the X-ray fluoroscopic conditions at the time of determining the photographing positions at both ends. 22 are automatically read and set, and the intermediate photographing positions PB to PD
X-ray imaging conditions are also the respective imaging positions PA and PE at both ends.
Are automatically determined and set based on the X-ray imaging conditions and the positions of the intermediate imaging positions PB to PD. As described above, when the setting of the X-ray imaging conditions at each of the five imaging positions PA to PE is completed, the process immediately shifts to the X-ray imaging. In the apparatus of the embodiment, when the operation shifts to X-ray imaging, first, the X-ray imaging unit 5
Is returned to the photographing position PA, X-ray photography is performed under the conditions set in the photographing position PA, and then, as shown in FIG. 2, the photographing position PB → the photographing position PC → the photographing position PD → the photographing Position PE
And the X-ray imaging unit 5 sequentially moves by step feed to change the photographing position in order, and the photographing positions PB to
X-ray imaging is performed according to the conditions set by the PE. The present invention is not limited to the above embodiment, but can be modified as follows. (1) In the case of the embodiment, the X-ray imaging unit is a so-called floor traveling type, but an apparatus having a configuration in which the X-ray imaging unit is a so-called ceiling traveling type is a modified example. (2) In the case of the embodiment, the X-ray detector is I · I
As a modified example, an apparatus in which the X-ray detector is a tube but is an X-ray surface sensor such as a flat panel X-ray sensor in which a large number of semiconductor X-ray detection elements are arranged vertically and horizontally is mentioned. . (3) A modified example of the apparatus of the embodiment is a DSA (Digital Subtraction Angiography) type apparatus capable of angiographic imaging. In the case of this modified example, the setting of the X-ray imaging condition of the imaging position is performed in the same manner as in the previous embodiment. When performing X-ray imaging, X-ray imaging is usually performed at each imaging position in the state where no contrast medium is injected, and then X-ray imaging is sequentially performed again at each imaging position with the contrast medium injected. Then, subtraction processing (subtraction processing) is performed between the X-ray image in the contrast agent non-injected state and the X-ray image in the contrast medium injected state for each same imaging position. It should be noted that the X-ray imaging in the state where the contrast medium is not injected may be such that the imaging position is changed from the forefoot to the waist, contrary to the X-ray imaging in the state where the contrast medium is injected. (4) In the case of the embodiment, the luminance judging section 2 at the time of fluoroscopy
0 and the exposure timer unit 21 are configured to perform luminance judgment or automatic exposure control based on a video signal obtained by the I / I tube 2, but a photomultiplier that detects irradiation X-rays separately from the I / I tube 2 Is provided on the imaging system side, and an apparatus having a configuration in which the luminance determination unit 20 during exposure or the exposure timer unit 21 performs luminance determination or automatic exposure control based on the output signal of the photomultiplier is a modified example. (5) In the case of the embodiment apparatus, only the tube voltage is different between the X-ray imaging conditions of each imaging position. An apparatus having a configuration in which other parameters such as a tube current also change is cited as a modification. (6) In the case of the embodiment, the imaging position is changed by the step feed of the X-ray imaging unit. However, the top plate on which the subject is placed is stepped by the step feed. An apparatus having a configuration in which the photographing position is changed is mentioned as a modification. As is clear from the above description, according to the X-ray imaging apparatus of the present invention, at least the X-ray fluoroscopic conditions and at least the X-ray tube voltage and the X-ray tube current at the time of X-ray imaging. If the correspondence with one of the X-ray imaging conditions is stored in the corresponding imaging condition storage means in advance, the X-rays at each of the imaging positions at both ends are then determined according to the X-ray fluoroscopic conditions at the time of determining each of the imaging positions at both ends. The photographing conditions are automatically read out from the corresponding photographing condition storage means and set, and the X-ray photographing conditions of the intermediate photographing position where the X-ray detector overlaps a certain width between the adjacent photographing positions are also set at both ends. Are automatically determined and set based on the X-ray imaging conditions of each imaging position and the position of the intermediate imaging position.
By making good use of the correspondence between fluoroscopy conditions and X-ray imaging conditions, appropriate X-ray imaging conditions according to the situation of the subject to be actually imaged can be automatically determined without using test exposure. Since it is not necessary to set each of the cases where the number of imaging positions is different, it is possible to easily set appropriate X-ray imaging conditions while suppressing the exposure dose.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram illustrating an overall configuration of an X-ray imaging apparatus according to an embodiment. FIG. 2 is a schematic diagram showing a situation of X-ray imaging by the embodiment device. FIG. 3 is a graph showing a correspondence relationship between a tube voltage for fluoroscopy and a tube voltage for X-ray imaging. FIG. 4 is a schematic diagram showing a situation when X-ray imaging conditions are set for imaging positions at both ends. FIG. 5 is a flowchart showing a process of setting X-ray imaging conditions of imaging positions at both ends. FIG. 6 is a schematic diagram showing a situation when an X-ray imaging condition is set at an intermediate imaging position. FIG. 7 is a flowchart illustrating a setting process of an X-ray imaging condition of an intermediate imaging position. FIG. 8 is a schematic diagram showing a state of X-ray imaging by a conventional device. [Description of References] 1 X-ray tube 2 I-I tube 5 X-ray imaging unit 7 Movable supporter 7 b Position sensor 8 Imaging position control unit 9 Imaging position memory 10 Decision switch unit 18 CPU ( Computer) 22 ... Corresponding imaging condition memory M ... Subjects PA to PE ... Imaging position Z ... Body axis

Claims (1)

(57) Claims 1. An X-ray imaging means provided with an X-ray tube and an X-ray detector facing each other with a subject interposed therebetween, and an imaging position of the subject is set. A photographing position changing unit that changes step by step along the body axis of the sample one after another,
X that is at least one of the X-ray tube voltage and the X-ray tube current at the time of X-ray imaging that is set in advance for each imaging position
The X-ray tube irradiates the subject with X-rays at each imaging position according to the X-ray imaging conditions, and transmits X-rays from the subject with X-rays.
In an X-ray imaging apparatus configured to execute X-ray imaging by detecting with a X-ray detector, a condition of X-ray fluoroscopy performed prior to X-ray imaging to determine an imaging position and the X-ray imaging Corresponding radiographing condition storage means for storing the correspondence with the conditions, radiographing position storage means for storing each radiographic position at both ends determined by performing fluoroscopy, and radiographic conditions at the time of determining each radiographic position at both ends The both-end position photographing condition setting means for reading out the X-ray photographing conditions corresponding to the above from the corresponding photographing condition storage means and setting the X-ray photographing conditions at each photographing position at both ends, and the X-ray photographing conditions at each photographing position at both ends And the intermediate imaging position, the X-ray detector is positioned at the intermediate imaging position such that the X-ray detector overlaps a certain width between adjacent imaging positions.
An X-ray imaging apparatus, comprising: an intermediate position imaging condition setting means for obtaining and setting X-ray imaging conditions.