JP6432602B2 - X-ray fluoroscopic equipment - Google Patents

Description

  The present invention relates to an X-ray fluoroscopic imaging apparatus that acquires an X-ray image by irradiating a subject with X-rays, and in particular, X-ray irradiation that can capture suitable X-ray images corresponding to various physiques of the subject. The present invention relates to a technique for determining conditions.

  At medical sites, X-ray fluoroscopic apparatuses that capture X-ray images of a subject by irradiating the subject with X-rays are used (see, for example, Patent Documents 1 and 2). As shown in FIG. 4, the conventional X-ray fluoroscopic apparatus 101 includes a top plate 103, an X-ray tube 105, an X-ray detector 107, an image generation unit 109, and an X-ray irradiation control unit 111. Yes.

  The top plate 103 places the subject M in a horizontal posture. The X-ray tube 105 irradiates the subject M with X-rays. The X-ray tube 105 and the X-ray detector 107 are arranged to face each other with the top plate 103 interposed therebetween. The X-ray detector 107 detects X-rays that are transmitted through the subject M from the X-ray tube 105, converts the detected X-rays into electrical signals, and outputs them as X-ray detection signals. As an example of the X-ray detector 107, an image intensifier (Image Intensifier), a flat panel type detector (FPD: Flat Panel Detector), or the like is used.

  The image generation unit 109 is provided after the X-ray detector 107, and generates an X-ray image in which an image of the subject M is projected based on the output X-ray detection signal. The X-ray irradiation control unit 111 is connected to the X-ray tube 105, and controls the tube voltage and tube current of the X-ray tube 105, thereby irradiating the X-ray dose from the X-ray tube 105 and the timing of irradiating X-rays. Control etc. The tube voltage and tube current of the X-ray tube 105 controlled by the X-ray irradiation control unit 111 are hereinafter referred to as “X-ray irradiation conditions”.

  Even if the X-ray conditions are constant, when the body thickness (subject thickness) of the subject M increases, the X-ray dose transmitted through the subject M decreases, and when the subject thickness decreases, the transmitted X-ray dose increases. . Therefore, the luminance of the X-ray image acquired by X-ray imaging may not be optimal for diagnosis due to the change in the subject thickness. Therefore, in order to maintain the quality of the X-ray image to be imaged, the X-ray irradiation conditions in X-ray imaging (hereinafter referred to as “X-ray imaging conditions”) are set to the subject thickness before X-ray imaging. It is important to adjust in advance accordingly (see, for example, Patent Document 3).

  Here, a mechanism for adjusting the imaging conditions according to the thickness of the subject in the conventional apparatus will be described. In the conventional fluoroscopic imaging apparatus 101, a body thickness detection unit 113 is provided after the X-ray irradiation control unit 111, and an imaging condition calculation unit 115 is provided after the body thickness detection unit 113. The body thickness detection unit 113 detects the body thickness of the subject M based on the tube voltage of the X-ray tube 105 and the luminance of the X-ray image generated by the image generation unit 109. The imaging condition determination unit 115 determines appropriate X-ray imaging conditions according to the body thickness of the subject.

  In order to adjust the imaging conditions, first, X-ray fluoroscopy is performed by continuously irradiating the subject M with weak X-rays from the X-ray tube 105, and the image generation unit 109 generates an X-ray fluoroscopic image. At this time, luminance information of the X-ray fluoroscopic image is transmitted from the image generation unit 109 to the X-ray irradiation control unit 111 as needed. Next, the X-ray irradiation control unit 111 performs feedback control on the X-ray irradiation conditions in the X-ray fluoroscopy (hereinafter referred to as “X-ray fluoroscopy conditions”) so that the luminance of the X-ray fluoroscopic image becomes a predetermined value A. Adjust by. As shown in FIG. 5A, the value of the X-ray fluoroscopic condition where the luminance of the X-ray image is A corresponds to the subject thickness on a one-to-one basis. Therefore, when the subject thickness increases, the value of the X-ray fluoroscopic condition where the luminance of the X-ray image is A increases (FIG. 5, solid line portion).

  When the brightness of the X-ray image reaches a predetermined value A, information related to the value of the X-ray fluoroscopic condition is transmitted from the X-ray irradiation control unit 111 to the body thickness detection unit 113. The body thickness detection unit 113 detects the value of the corresponding subject thickness based on the value of the X-ray fluoroscopic condition where the luminance of the X-ray fluoroscopic image is A. As an example, when the value of the X-ray fluoroscopic condition in which the luminance of the X-ray image is A is Va, the body thickness detection unit 113 sets the corresponding subject thickness value Ta based on the graph of FIG. To detect. Information on the value of the subject thickness is transmitted from the body thickness detection unit 113 to the imaging condition determination unit 115.

  Here, as shown in FIG. 5B, the value of the X-ray imaging condition in which the brightness of the X-ray image is optimal for diagnosis in the X-ray imaging corresponds to the subject thickness on a one-to-one basis. The imaging condition determination unit 115 detects an appropriate X-ray imaging condition in which the luminance of the X-ray image acquired by X-ray imaging becomes a predetermined value B according to the value of the subject thickness. As an example, when the object thickness value transmitted to the imaging condition determining unit 115 is Ta, the imaging condition determining unit 115 sets the X corresponding to the object thickness value Ta based on the graph of FIG. A value Wa of the radiographing condition is detected. Thus, by performing X-ray fluoroscopy prior to X-ray imaging, appropriate X-ray imaging conditions can be determined in advance.

JP 2006-288813 A JP 2006-247250 A JP 2000-261724 A

However, the conventional example having such a configuration has the following problems.
That is, in the conventional X-ray fluoroscopic apparatus, there is a limit to the magnitude of the tube voltage that can be applied to the X-ray tube. That is, as shown in FIG. 5A, the X-ray fluoroscopic condition cannot be raised to a predetermined value Vb or more when detecting the subject thickness. Therefore, the value of the subject thickness that can be accurately detected by the body thickness detection unit 113 is limited to a certain value Tb or less corresponding to the X-ray fluoroscopic condition Vb.

  Therefore, when the object thickness is a value equal to or greater than Tb, for example, Tc, as shown by the two-dot chain line in FIG. However, the actual X-ray fluoroscopic conditions are limited to Vb or less. That is, when the subject thickness is equal to or greater than Tb, an accurate value of the subject thickness cannot be detected by fluoroscopy. As a result, since appropriate X-ray imaging conditions cannot be detected, there is a concern that it becomes difficult to capture a high-quality X-ray image suitable for diagnosis.

  Further, when it is determined that the subject thickness is thin, it is necessary to set the X-ray fluoroscopic condition to a small value in order to detect the subject thickness. In this case, since the image quality of the X-ray fluoroscopic image is deteriorated due to the shortage of the X-ray dose, it is difficult to accurately measure the luminance value of the X-ray fluoroscopic image. Therefore, although the actual luminance value is not the predetermined value A, the luminance value of the X-ray fluoroscopic image may be mistaken for the predetermined value A. Accordingly, in the conventional example, when the subject thickness is thin, the accuracy of the detected subject thickness is low, and there is a concern that it may be difficult to detect an X-ray imaging condition capable of capturing a high-quality X-ray image. The

  The present invention has been made in view of such circumstances, and provides an X-ray fluoroscopic apparatus capable of generating a high-quality X-ray image suitable for diagnosis regardless of the thickness of the subject. Objective.

In order to achieve such an object, the present invention has the following configuration.
That is, the X-ray fluoroscopic apparatus according to the present invention detects an X-ray source that irradiates a subject with X-rays, and detects X-rays that are irradiated from the X-ray source and transmitted through the subject and convert them into light. An image intensifier, a light transmittance adjusting means for adjusting the transmittance of the light converted by the image intensifier, and a signal for detecting the light adjusted by the light transmittance adjusting means and converting it into an electrical signal A conversion unit; an image generation unit configured to generate an X-ray image based on the electrical signal converted by the signal conversion unit; and a luminance of the X-ray image generated by the image generation unit in X-ray fluoroscopy to a predetermined value. The X-ray irradiation condition comprising the tube voltage and tube current of the X-ray source, and the control means for controlling the light transmittance adjusted by the light transmittance adjusting means and the X controlled by the control means Irradiation conditions and Based on the light transmittance, body thickness detection means for detecting the body thickness of the subject, and the X-ray in X-ray imaging based on the body thickness of the subject detected by the body thickness detection means Imaging condition determining means for determining the irradiation condition and the light transmittance, and a second relation table associating the body thickness of the subject with each of the X-ray irradiation condition and the light transmittance in X-ray imaging A second related table storage means for storing the X-ray irradiation conditions and the light transmittance in X-ray imaging by referring to the second related table. It is characterized by.

According to the X-ray fluoroscopic apparatus of the present invention, the control means is a light that is converted by the image intensifier so that the luminance of the X-ray image generated by the image generation means becomes a predetermined value in the X-ray fluoroscopy. The transmittance and X-ray irradiation conditions are controlled. Then, based on the X-ray irradiation conditions controlled by the control means and the light transmittance, the body thickness detection means detects the body thickness of the subject. By providing such a configuration, even if the X-ray irradiation conditions cannot be changed any more, the luminance of the X-ray image can be adjusted by further changing the light transmittance. Therefore, even if the X-ray irradiation condition cannot be changed due to the body thickness of the subject, the control means can change the light transmittance to control the luminance of the X-ray image to a predetermined value. As a result, the body thickness detection means can accurately determine the body thickness of the subject corresponding to a wider variety of subject physiques.

  The imaging condition determining means determines an X-ray irradiation condition and light transmittance in X-ray imaging based on the body thickness of the subject detected by the body thickness detecting means. The body thickness detecting means can accurately detect the body thickness of the subject corresponding to a variety of physiques of the subject. Therefore, the imaging condition determining means can appropriately determine the X-ray irradiation conditions and the light transmittance in the X-ray imaging. Therefore, it is possible to capture suitable X-ray images corresponding to a variety of physiques of subjects.

  In addition, the X-ray fluoroscopic apparatus according to the present invention stores a first relation table that associates each of the X-ray irradiation conditions and the light transmittance controlled by the control unit with the body thickness of the subject. It is preferable that a first related table storage unit is provided, and the body thickness detecting unit detects the body thickness of the subject by referring to the first related table.

  According to the fluoroscopic imaging apparatus according to the present invention, the body thickness detection unit detects the body thickness of the subject by referring to the first related table. The first association table associates each of the X-ray irradiation conditions and the light transmittance controlled by the control unit with the body thickness of the subject. That is, by referring to the first relation table, the body thickness detection means can more quickly detect an accurate value of the body thickness of the subject corresponding to the X-ray irradiation condition and the light transmittance. Therefore, it is possible to reduce the time required for generating a high-quality X-ray image.

  Further, in the X-ray fluoroscopic apparatus according to the present invention, the first related table may include the X-ray irradiation condition according to the body thickness of the subject when the body thickness of the subject is within a predetermined range. And the body thickness of the subject and the X so that the light transmittance changes according to the body thickness of the subject when the body thickness of the subject is outside a predetermined range. It is preferable to associate the irradiation condition with the light transmittance.

  According to the X-ray fluoroscopic imaging apparatus of the present invention, the first related table indicates that the X-ray irradiation conditions change according to the body thickness of the subject when the body thickness of the subject is within a predetermined range. In addition, the body thickness of the subject is associated with the X-ray irradiation conditions and the light transmittance. When the body thickness of the subject is out of a predetermined range, the body thickness of the subject and the X-ray irradiation so that the light transmittance changes according to the body thickness of the subject. Correlate conditions and light transmittance

  When the object thickness is thicker than the predetermined range, the X-ray irradiation condition reaches the upper limit value, and therefore the X-ray irradiation condition cannot be further increased. Even in such a case, the brightness of the X-ray image can be adjusted to be higher by further controlling the light transmittance. Therefore, the control means can control the luminance of the X-ray image to a predetermined value by adjusting the light transmittance even when the subject thickness is thicker than the predetermined range. As a result, the body thickness detecting means can detect an accurate value of the subject thickness corresponding to the subject having a thicker body thickness.

  On the other hand, when the subject thickness is thinner than a predetermined range, even if the X-ray irradiation conditions are constant, the luminance of the X-ray image can be adjusted to be low by controlling the light transmittance low. Therefore, the control means can control the luminance of the X-ray image to a predetermined value without excessively reducing the X-ray irradiation conditions even when the body thickness of the subject is thinner than the predetermined value. Therefore, it is possible to avoid a situation in which the luminance detection accuracy of the X-ray image is lowered due to the deterioration of the image quality of the X-ray image due to the decrease in the X-ray irradiation conditions. Therefore, when the subject thickness is thin, the control means can more accurately control the brightness of the X-ray image to a predetermined value, so that the body thickness detection means can accurately detect the subject even with a thinner body thickness. The specimen thickness value can be detected.

  The imaging condition determining means determines an X-ray irradiation condition and light transmittance in X-ray imaging based on the body thickness of the subject detected by the body thickness detecting means. The body thickness detection means can accurately detect the value of the body thickness of the subject for a wider range of body thicknesses of the subject. Therefore, the imaging condition determining means can appropriately determine the X-ray irradiation conditions and the iris diaphragm opening in X-ray imaging. Therefore, it is possible to capture suitable X-ray images corresponding to a variety of physiques of subjects.

  In addition, the X-ray fluoroscopic apparatus according to the present invention stores a second relation table that associates the body thickness of the subject with the X-ray irradiation conditions and the light transmittance in X-ray imaging. Preferably, the imaging condition determining unit determines the X-ray irradiation condition and the light transmittance in X-ray imaging by referring to the second related table.

  According to the X-ray fluoroscopic apparatus according to the present invention, the imaging condition determining means determines the X-ray irradiation conditions and the light transmittance in the X-ray imaging by referring to the second related table. The second relation table associates the body thickness of the subject with the X-ray irradiation conditions and the light transmittance in X-ray imaging. That is, the imaging condition determining means refers to the body thickness of the subject detected by the body thickness detecting means and the second related table, so that the appropriate X-ray irradiation conditions and light transmittance in X-ray imaging can be determined more quickly. Can be determined. Therefore, it is possible to reduce the time required for generating a high-quality X-ray image.

  Further, in the X-ray fluoroscopic apparatus according to the present invention, the control unit is configured to perform the X-ray fluoroscopy in the X-ray fluoroscopy so that the luminance of the X-ray image generated by the image generation unit by X-ray fluoroscopy becomes a predetermined value. It is preferable to control the beam irradiation conditions and the light transmittance.

  According to the X-ray fluoroscopic apparatus according to the present invention, the control means controls the X-ray irradiation conditions and light transmission in X-ray fluoroscopy so that the luminance of the X-ray image generated by X-ray fluoroscopy has a predetermined value. Control the rate. In this case, the body thickness detection means detects the body thickness of the subject by performing X-ray fluoroscopy to irradiate X-rays with a relatively low dose. Accordingly, the X-ray dose received by the subject can be reduced when determining appropriate X-ray irradiation conditions and light transmittance in X-ray imaging.

  In the X-ray fluoroscopic apparatus according to the present invention, the light transmittance adjusting means is an iris diaphragm, and the iris diaphragm adjusts the light transmittance by adjusting the opening of the iris diaphragm. Is preferred.

  According to the X-ray fluoroscopic apparatus of the present invention, the light transmittance adjusting means is an iris diaphragm, and the iris diaphragm adjusts the light transmittance by adjusting the opening of the iris diaphragm. The amount of light converted by the image intensifier is adjusted according to the opening of the iris diaphragm and detected by the signal conversion means. Therefore, the control means can suitably control the luminance of the X-ray image by adjusting the opening of the iris diaphragm. As a result, the body thickness detection means can accurately detect the body thickness of the subject. The imaging condition determining means can accurately determine appropriate conditions for each of the X-ray irradiation conditions and the iris diaphragm opening in the X-ray imaging.

  According to the X-ray fluoroscopic apparatus according to the present invention, the control unit controls the transmittance of light converted by the image intensifier and the X-ray irradiation condition so that the luminance of the X-ray image becomes a predetermined value. Then, based on the X-ray irradiation conditions controlled by the control means and the light transmittance, the body thickness detection means detects the body thickness of the subject. By providing such a configuration, even if the X-ray irradiation conditions cannot be changed any more, the luminance of the X-ray image can be adjusted by further changing the light transmittance. Therefore, even if the X-ray irradiation condition cannot be changed due to the body thickness of the subject, the control means can change the light transmittance to control the luminance of the X-ray image to a predetermined value. As a result, the body thickness detection means can accurately determine the body thickness of the subject corresponding to a wider variety of subject physiques.

  The imaging condition determining means determines an X-ray irradiation condition and light transmittance in X-ray imaging based on the body thickness of the subject detected by the body thickness detecting means. The body thickness detecting means can accurately detect the body thickness of the subject corresponding to a variety of physiques of the subject. Therefore, the imaging condition determining means can appropriately determine the X-ray irradiation conditions and the light transmittance in the X-ray imaging. Therefore, it is possible to capture suitable X-ray images corresponding to a variety of physiques of subjects.

It is a functional block diagram explaining the structure of the X-ray fluoroscopic apparatus which concerns on an Example. It is a flowchart explaining the process of operation | movement of the X-ray fluoroscopic apparatus which concerns on an Example. It is a figure explaining the mechanism which determines X-ray imaging conditions in an Example. (A) is a graph showing the relationship between X-ray fluoroscopic conditions and subject thickness, and (b) is a graph showing the relationship between subject thickness and X-ray imaging conditions. It is a functional block diagram explaining the structure of the X-ray fluoroscopic apparatus which concerns on a prior art example. It is a figure explaining the mechanism which detects X-ray imaging conditions in a prior art example. (A) is a graph showing the relationship between X-ray fluoroscopic conditions and subject thickness, and (b) is a graph showing the relationship between subject thickness and X-ray imaging conditions.

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

<Description of overall configuration>
As shown in FIG. 1, the X-ray fluoroscopic apparatus 1 according to the embodiment includes a top plate 3 on which a subject M that takes a horizontal posture is placed, and an X-ray tube 5 that irradiates the subject M with X-rays. And an image intensifier 7 (hereinafter referred to as “I / I tube 7”) for detecting X-rays irradiated to the subject M and transmitted therethrough. The X-ray tube 5 and the I / I tube 7 are disposed to face each other with the top plate 3 interposed therebetween. The X-ray tube 5 is provided with a collimator 9 that limits the X-rays emitted from the X-ray tube 5 to a cone shape that is a pyramid.

  The I / I tube 7 detects X-rays that are transmitted through the subject M from the X-ray tube 5 and converts them into visible light. A TV camera 11 is provided behind the I / I tube 7, and an iris diaphragm 13 is provided between the I / I tube 7 and the TV camera 11. The TV camera 11 further converts the visible light converted by the I / I tube 7 into an electrical signal and outputs it as an X-ray detection signal. The X-ray tube 5 corresponds to the X-ray source in the present invention, and the TV camera 11 corresponds to the signal conversion means in the present invention.

  The iris diaphragm 13 is an optical element, and adjusts the amount of light incident on the television camera 11 from the I / I tube 7 through the iris diaphragm 13 by changing the aperture of the diaphragm. That is, as the aperture of the iris diaphragm 13 increases, the amount of light incident on the television camera 11 increases, so the output of the X-ray detection signal increases.

  The X-ray fluoroscopic apparatus 1 includes an X-ray irradiation control unit 15, an iris control unit 17, an image generation unit 19, a monitor 21, a luminance value detection unit 22, a body thickness detection unit 23, and an imaging condition determination. Unit 25 and main control unit 27. The X-ray irradiation control unit 15 is connected to the X-ray tube 5, and controls the X-ray irradiation conditions, that is, the tube voltage and tube current of the X-ray tube 5 to control the dose of the X-ray 5 a irradiated from the X-ray tube 5. , And the timing for irradiating the X-ray 5a. The X-ray irradiation conditions in X-ray fluoroscopy are hereinafter referred to as “X-ray fluoroscopy conditions”, and the X-ray irradiation conditions in X-ray radiography are hereinafter referred to as “X-ray radiography conditions”.

  The iris control unit 17 is connected to the iris diaphragm 13, and controls the aperture of the iris diaphragm 13 to transmit light incident on the TV camera 11 from the I / I tube 7 through the iris diaphragm 13. Control the rate.

  The image generation unit 19 is provided in the subsequent stage of the television camera 11 and generates an X-ray image based on the X-ray detection signal output from the television camera 11. The monitor 21 displays various X-ray images generated by the image generation unit 19. The luminance value detection unit 22 is provided in the subsequent stage of the image generation unit 19 and detects the luminance value of the X-ray image generated by the image generation unit 19. The body thickness detector 23 is based on the X-ray irradiation conditions controlled by the X-ray irradiation controller 15 and the aperture of the iris diaphragm 13 controlled by the iris controller 17 (hereinafter referred to as “iris aperture”). Thus, the body thickness of the subject M is detected.

  The imaging condition determination unit 25 is provided in the subsequent stage of the body thickness detection unit 23, and based on the body thickness of the subject M detected by the body thickness detection unit 23, the X-ray imaging conditions and the iris opening in the X-ray imaging are determined. decide. The image generation unit 19 corresponds to the image generation means in the present invention. The body thickness detector 23 corresponds to the body thickness detector in the present invention. The photographing condition determining unit 25 corresponds to the photographing condition determining means in the present invention.

  The main control unit 27 comprehensively controls the X-ray irradiation control unit 15, the iris control unit 17, and the body thickness detection unit 23. Further, the brightness of various X-ray images generated by the image generation unit 19 is detected. The input unit 29 is used to input an operator's instruction, and examples thereof include a keyboard input type panel and a touch input type panel. The storage unit 31 stores various images generated by the image generation unit 19. The storage unit 31 stores various related tables in advance. The main control unit 27 corresponds to the control means in the present invention. The storage unit 31 corresponds to the first related table storage unit and the second related table storage unit in the present invention.

<Description of related table>
Here, a related table stored in advance in the storage unit 31 will be described. The storage unit 31 stores a related table T1 and a related table T2. The relation table T1 indicates that the X-ray fluoroscopic conditions and the iris opening are set such that the luminance value of the image generated by X-ray fluoroscopy is a predetermined value A for each body thickness (subject thickness) of the subject M. It is recorded in association with the combination of degrees.

  The upper part of FIG. 3A is a graph showing the relationship between the X-ray fluoroscopic conditions recorded in the association table T1 and the subject thickness. The lower part of FIG. 3A is a graph showing the relationship between the iris diaphragm and the subject thickness recorded in the association table T1. As an example, when the subject thickness is Ta, the luminance value of the X-ray fluoroscopic image is predetermined by performing X-ray fluoroscopy under the condition that the X-ray fluoroscopic condition is Va and the iris opening degree is Pa. Value A. The association table T1 corresponds to the first association table in the present invention.

  In the association table T2, combinations of X-ray imaging conditions and iris opening degrees are recorded so that an image generated by X-ray imaging becomes an optimal image for diagnosis for each subject thickness. The upper part of FIG. 3B is a graph showing the relationship between the X-ray imaging conditions and the subject thickness recorded in the association table T2. The lower part of FIG. 3B is a graph showing the relationship between the iris diaphragm and the subject thickness recorded in the association table T2. That is, when the subject thickness is Ta, an X-ray image that is optimal for diagnosis is generated by performing X-ray imaging under the condition that the X-ray imaging condition is Wa and the iris opening is Qa. The The association table T2 corresponds to the second association table in the present invention.

<Description of operation>
Next, the operation of the X-ray fluoroscopic apparatus 1 according to the embodiment will be described. FIG. 2 is a flowchart for explaining the operation of the X-ray fluoroscopic apparatus according to the embodiment.

Step S1 (Generation of X-ray fluoroscopic image)
First, after placing the subject M on the top 3, the collimator 9 is controlled to set the X-ray irradiation field. Then, the operator operates the input unit 29 to input an instruction to irradiate the subject M with the X-ray 5a from the X-ray tube 5 by X-ray fluoroscopy. The main control unit 27 outputs a control signal to the X-ray irradiation control unit 15 and the iris control unit 17 in accordance with the input instruction. The X-ray irradiation control unit 15 controls the X-ray irradiation condition (X-ray transmission condition) in X-ray fluoroscopy to the reference value Va according to the control signal. The iris control unit 17 controls the iris opening to the reference value Pa according to the control signal.

  The I / I tube 7 detects the X-ray 5 a that passes through the subject M and converts it into light, and the amount of light is adjusted according to the iris opening of the iris diaphragm 13. The television camera 11 detects light that has passed through the iris diaphragm 13 and outputs an X-ray detection signal. The image generation unit 19 generates an X-ray fluoroscopic image of the subject M based on the X-ray detection signal.

Step S2 (adjustment of fluoroscopic conditions and iris opening)
The data of the fluoroscopic image generated by the image generation unit 19 is transmitted to the luminance value detection unit 22. The luminance value detection unit 22 detects the luminance value of the X-ray fluoroscopic image and compares it with a predetermined luminance value A stored in advance. As an example of a method in which the luminance value detection unit 22 detects the luminance value of the X-ray fluoroscopic image, an average value of luminance values in a predetermined region, which is a part of the X-ray fluoroscopic image, is used as the luminance value of the X-ray fluoroscopic image. And a method of detecting as.

  3A, the combination of the reference value Va for the X-ray fluoroscopic condition and the reference value Pa for the iris opening is a value corresponding to the object thickness Ta. Therefore, when the luminance value of the fluoroscopic image matches the predetermined luminance value A, it can be determined that the body thickness of the subject M placed on the top 3 is Ta. On the other hand, when the luminance value of the X-ray fluoroscopic image is lower than the predetermined luminance value A, it is determined that the subject thickness is larger than Ta, and when the luminance value of the X-ray fluoroscopic image is higher than the predetermined luminance value A, the subject thickness is determined. Can be determined to be smaller than Ta.

  The main control unit 27 adjusts the X-ray fluoroscopic condition and the iris opening degree by feedback control based on the result of comparison by the luminance value detection unit 22. That is, the main control unit 27 outputs a control signal to the X-ray irradiation control unit 15 and the iris control unit 17 according to the luminance value of the X-ray fluoroscopic image. The X-ray irradiation control unit 15 changes the X-ray fluoroscopic condition according to the luminance value of the X-ray fluoroscopic image, and the iris control unit 17 changes the iris opening degree according to the luminance value of the X-ray fluoroscopic image.

  Then, returning to step S1, an X-ray transmission image is generated again, and the luminance value of the X-ray fluoroscopic image is compared with a predetermined luminance value A. In this way, the steps S1 and S2 are repeated until the luminance value of the X-ray fluoroscopic image reaches the predetermined value A. When the luminance value of the fluoroscopic image reaches the predetermined value A, the process proceeds to step S3.

  The X-ray fluoroscopic conditions and the iris opening are adjusted as follows. When the luminance value of the X-ray fluoroscopic image is lower than the predetermined value A, the X-ray fluoroscopic condition is first made larger than Va while maintaining the iris opening degree at Pa (FIG. 3A, F1). If the luminance value of the X-ray fluoroscopic image does not reach the predetermined value A even if the X-ray fluoroscopic condition reaches the upper limit value Vb, the iris opening degree is made larger than Pa while maintaining the value of the X-ray fluoroscopic condition at Vb. (FIG. 3 (a), F2). In this case, the amount of light incident on the television camera 11 is increased by increasing the iris opening, so that the luminance value of the X-ray fluoroscopic image is further increased. Therefore, the luminance value of the X-ray fluoroscopic image can be adjusted to the predetermined value A even when the subject M is thicker than the subject thickness Tb corresponding to the upper limit value Vb of the X-ray fluoroscopic conditions. .

  On the other hand, when the luminance value of the X-ray fluoroscopic image is higher than the predetermined value A, the X-ray fluoroscopic condition is first made smaller than Va while maintaining the iris opening at Pa (FIGS. 3A and 3). If the brightness value of the X-ray fluoroscopic image does not reach the predetermined value A even if the X-ray fluoroscopic condition becomes Vc, the iris opening is made smaller than Pa while maintaining the value of the X-ray fluoroscopic condition at Vc (FIG. 3 (a), F4). In this case, since the amount of light incident on the television camera 11 is reduced by reducing the iris opening, the luminance value of the X-ray fluoroscopic image is reduced. Further, since the value of the X-ray fluoroscopic condition is maintained at Vc, it is possible to prevent a situation in which the X-ray dose is insufficient because the tube voltage or the like is excessively lowered. Therefore, in the embodiment, it is possible to reduce the luminance value of the X-ray fluoroscopic image while avoiding the deterioration of the image quality of the X-ray fluoroscopic image due to the insufficient X-ray dose.

Step S3 (detection of subject thickness)
When the luminance value of the X-ray fluoroscopic image becomes a predetermined value A, information on the X-ray fluoroscopic condition and the iris opening degree is transmitted from the main control unit 27 to the body thickness detection unit 23. The body thickness detection unit 23 refers to the association table T1 stored in the storage unit 31, and detects the value of the subject thickness based on the information of the X-ray fluoroscopic condition and the iris opening degree. Information on the value of the subject thickness is transmitted from the body thickness detection unit 23 to the imaging condition determination unit 25.

  As an example, a case will be described in which the X-ray fluoroscopic condition is Vb and the brightness value of the X-ray fluoroscopic image is a predetermined value A under the condition that the iris opening is Pb. In this case, the body thickness detector 23 refers to the association table T1 and detects the corresponding subject thickness value. As indicated by the symbol J in the graph of FIG. 3A, the subject thickness corresponding to the condition where the X-ray fluoroscopic condition is Vb and the iris opening is Pb is Td. Therefore, the body thickness detection unit 23 determines that the body thickness of the subject M actually placed on the top 3 is Td and detects information on the subject thickness Td. Then, the body thickness detection unit 23 transmits information on the subject thickness Td to the imaging condition determination unit 25.

Step S4 (Determination of X-ray imaging conditions and iris opening)
The imaging condition determination unit 25 determines each of the iris opening and the X-ray imaging conditions in X-ray imaging based on the subject thickness information transmitted from the body thickness detection unit 23. At this time, the imaging condition determination unit 25 detects the X-ray imaging conditions and the iris opening with reference to the related table T2 stored in the storage unit 31. As indicated by a symbol J in the graph of FIG. 3B, when the object thickness is Td, the X-ray imaging condition is Wb, and the iris opening is generated by X-ray imaging under the condition that the iris opening is Qb. The X-ray photographed image is an optimal image for diagnosis. Thus, the optimal combination is determined for each of the iris opening and the X-ray imaging conditions in X-ray imaging.

Step S5 (Generation of X-ray image)
After the X-ray imaging conditions and the iris opening are determined, an X-ray imaging image is generated. That is, the operator operates the input unit 29 and inputs an instruction to irradiate the subject M with X-rays 5a from the X-ray tube 5 by X-ray imaging. The main control unit 27 outputs a control signal to the X-ray irradiation control unit 15 and the iris control unit 17 in accordance with the input instruction. When it is determined that the subject thickness is Td, the iris control unit 17 controls the iris opening to Qb according to the control signal. The X-ray irradiation control unit 15 controls the X-ray imaging condition to Wb according to the control signal, and causes the X-ray tube 5 to emit X-rays. The image generation unit 19 generates an X-ray image of the subject M based on the X-ray detection signal. The X-ray image is displayed on the monitor 21. With the generation of the X-ray image, all the series of steps are completed.

<Effects of Configuration of Example>
As described above, according to the X-ray fluoroscopic apparatus according to the embodiment, determination of appropriate X-ray imaging conditions and the like by feedback control can be performed for a wider range of subject thicknesses. Hereinafter, effects of the configuration according to the embodiment will be described.

  In the X-ray fluoroscopic apparatus according to the conventional example, when the subject thickness is detected based on the luminance value of the X-ray fluoroscopic image, the luminance value of the X-ray fluoroscopic image is changed by changing only the value of the X-ray fluoroscopic condition. Control to a predetermined value A. Then, the subject thickness is detected with reference to the relationship between the X-ray irradiation condition and the subject thickness when the luminance value of the X-ray fluoroscopic image is A.

  However, since the tube voltage that can be applied to the X-ray tube is limited due to the standards of the X-ray fluoroscopic apparatus, the X-ray irradiation condition can be increased to a predetermined value Vb or more as shown in FIG. Can not. Therefore, when the subject thickness is larger than the subject thickness value Tb corresponding to the upper limit value Vb of the fluoroscopic condition, the luminance value of the fluoroscopic image is always lower than the predetermined value A. Therefore, the value of the object thickness that can be accurately detected in the conventional example is limited to Tb or less.

  In the conventional example, when the subject thickness is thin, it is necessary to excessively reduce the tube voltage in order to set the luminance value of the X-ray fluoroscopic image to a predetermined value. When the tube voltage is excessively reduced, the image quality of the X-ray fluoroscopic image is deteriorated due to the shortage of the X-ray dose, so that it is difficult to accurately measure the luminance value of the X-ray fluoroscopic image. Therefore, even if the actual luminance value is not the predetermined value A, the luminance value of the X-ray fluoroscopic image may be mistaken for the predetermined value A. Therefore, in the conventional example, when the subject thickness is thin, the accuracy of the detected subject thickness is low, and there is a concern that it is difficult to detect an X-ray imaging condition capable of capturing a high-quality X-ray image. The That is, in the X-ray fluoroscopic imaging apparatus according to the conventional example, the range of the subject thickness that can accurately detect suitable X-ray imaging conditions is narrow.

  Therefore, in the X-ray fluoroscopic apparatus according to the embodiment, the I / I tube is used as the X-ray detection unit, and the brightness value of the X-ray fluoroscopic image is controlled by changing the iris opening in addition to the X-ray irradiation conditions. It has a configuration. In such a configuration, as shown in FIG. 3A, even when the value of the X-ray fluoroscopic condition reaches the upper limit value Vb, the brightness of the X-ray fluoroscopic image is increased by further increasing the iris opening degree. The value can be further increased. Therefore, even when the subject thickness is thicker than Tb, the luminance value of the X-ray fluoroscopic image can be controlled to the predetermined value A, so that an accurate subject thickness value can be detected. As a result, even when the body thickness of the subject M is thicker than Tb, it is possible to detect the X-ray imaging conditions and the iris opening that can capture a high-quality X-ray image.

  Further, when it is determined that the subject thickness is smaller than Tc, the brightness value of the X-ray fluoroscopic image is reduced by lowering the iris opening while maintaining the X-ray fluoroscopic condition constant (FIG. 3A). F4). In this case, since it is possible to prevent the tube voltage from being excessively lowered, it is possible to avoid deterioration of the image quality of the X-ray fluoroscopic image. As a result, since the luminance value of the X-ray fluoroscopic image can be controlled to the predetermined value A more reliably, the X-ray imaging conditions and iris capable of capturing a high-quality X-ray image even when the subject thickness is smaller than Tc. It is possible to accurately detect the opening. As described above, the X-ray fluoroscopic apparatus according to the embodiment can determine appropriate X-ray imaging conditions and the like by feedback control for a wider range of the subject thickness.

  The present invention is not limited to the above embodiment, and can be modified as follows.

  (1) In the embodiment described above, in step S1, the reference value of the X-ray fluoroscopic condition is Va and the reference value of the iris opening is Pa, but each reference value is a combination corresponding to an arbitrary subject thickness. You may change suitably. For example, an X-ray fluoroscopic image may be generated using the X-ray fluoroscopic condition Vc and the iris opening degree Pc corresponding to the case where the subject thickness is 0 as a reference value (FIG. 3A, symbol K). In this case, the X-ray fluoroscopic condition or the iris opening degree is increased from each reference value. Then, the actual subject thickness is detected based on the combination of the X-ray fluoroscopic condition and the iris opening when the luminance value of the X-ray fluoroscopic image reaches the predetermined value A.

  (2) In the above-described embodiment, the iris opening is maintained at a constant value when the X-ray fluoroscopic condition is changed in step S2, but the iris opening is appropriately changed while changing the X-ray fluoroscopic condition. It may be. When the subject thickness is determined to be equal to or less than Tc, the X-ray fluoroscopic condition is maintained constant by changing the iris opening, but the X-ray fluoroscopic image quality is not deteriorated while changing the iris opening. A configuration in which the X-ray fluoroscopic conditions are appropriately changed may be employed.

  (3) The configuration according to the above-described embodiment can be applied not only to the X-ray fluoroscopic apparatus related to the medical field but also to the industrial field and the nuclear field. In particular, since the apparatus according to the embodiment can accurately detect X-ray imaging conditions even for a thin subject, it is possible to more suitably perform a nondestructive inspection on a thin layer substrate or the like.

1 X-ray fluoroscopic apparatus
5 ... X-ray tube (X-ray source)
7: Image intensifier 11: TV camera (signal conversion means)
DESCRIPTION OF SYMBOLS 13 ... Iris diaphragm 15 ... X-ray irradiation control part 17 ... Iris control part 19 ... Image generation part (image generation means)
22 ... Luminance value detection unit 23 ... Body thickness detection unit (body thickness detection means)
25 ... Shooting condition determining unit (shooting condition determining means)
27: Main control unit (control means)
31... Storage unit (first relation table storage means, second relation table storage means)

Claims (4)

An X-ray source for irradiating the subject with X-rays;
An image intensifier that detects X-rays emitted from the X-ray source and transmitted through the subject and converts them into light;
Light transmittance adjusting means for adjusting the transmittance of the light converted by the image intensifier;
Signal converting means for detecting the light adjusted by the light transmittance adjusting means and converting it into an electrical signal;
Image generating means for generating an X-ray image based on the electrical signal converted by the signal converting means;
In X-ray fluoroscopy, an X-ray irradiation condition consisting of a tube voltage and a tube current of the X-ray source, and the light transmittance adjusting unit so that the luminance of the X-ray image generated by the image generating unit becomes a predetermined value. Control means for controlling the light transmittance adjusted by the control means, body thickness detection means for detecting the body thickness of the subject based on the X-ray irradiation conditions controlled by the control means and the light transmittance;
An imaging condition determining unit that determines the X-ray irradiation condition and the light transmittance in X-ray imaging based on the body thickness of the subject detected by the body thickness detecting unit ;
In X-ray imaging, comprising: a second related table storage means for storing a second related table that associates the body thickness of the subject with each of the X-ray irradiation conditions and the light transmittance;
The X-ray fluoroscopic imaging apparatus , wherein the imaging condition determining means determines the X-ray irradiation condition and the light transmittance in X-ray imaging by referring to the second related table . The X-ray fluoroscopic apparatus according to claim 1,
A first relation table storage means for storing a first relation table that associates each of the X-ray irradiation conditions and the light transmittance controlled by the control means with the body thickness of the subject;
The X-ray fluoroscopic imaging apparatus, wherein the body thickness detecting means detects the body thickness of the subject by referring to the first related table. The X-ray fluoroscopic apparatus according to claim 2,
In the first relation table, when the body thickness of the subject is within a predetermined range, the X-ray irradiation condition changes according to the body thickness of the subject, and the body thickness of the subject is predetermined. An X that associates the body thickness of the subject, the X-ray irradiation conditions, and the light transmittance so that the light transmittance changes according to the body thickness of the subject when out of the range. A fluoroscopic imaging device. The X-ray fluoroscopic apparatus according to any one of claims 1 to 3 ,
The light transmittance adjusting means is an iris diaphragm;
An X-ray fluoroscopic apparatus in which the iris diaphragm adjusts the transmittance of the light by adjusting an opening of the iris diaphragm.

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