JP2010246794A - X-ray imaging device - Google Patents

Abstract

An object of the present invention is to set an optimum X-ray condition in accordance with an irradiation area of X-rays to be changed without intervention of an operator during imaging or fluoroscopy of a subject.
An X-ray irradiating means for irradiating X-rays B, an X-ray setting means for setting X-ray conditions of the X-ray irradiating means, and an image for acquiring an X-ray image transmitted through a subject. The acquisition unit 7, the light receiving area measuring unit 56 that measures the X-ray light receiving area that passes through the subject M, the light amount measuring unit 57 that measures the transmitted light amount of the X-ray that passes through the subject M, and the light receiving area are changed. Control the light receiving area changing means 80 and 81, the calculating means 58 for calculating the unit area transmitted light amount from the light receiving area and the transmitted light amount, the storage means 59 for storing the preset unit area optimum amount, and the X-ray setting means 51. The control means 52 sets the X-ray condition so that the unit area transmitted light amount is within the optimum unit area amount in accordance with the displacement of the light receiving area.
[Selection] Figure 1

Description

  The present invention relates to an X-ray image apparatus that acquires an X-ray image of a subject by irradiating the subject with X-rays from an X-ray irradiation means.

  The X-ray imaging apparatus is an apparatus that acquires an X-ray image of a subject by irradiating the subject with X-rays from an X-ray irradiation unit. The X-ray imaging device determines whether the X-ray dose to be irradiated is large or small, and inputs X-ray conditions such as the X-ray tube voltage before irradiating the subject with X-rays. Set. Based on this input setting, the high voltage generator is operated to control the X-ray irradiation means (for example, Patent Document 1). As described above, the operator sets the X-ray condition before the imaging, so that the subject is irradiated with the X-ray having the optimum dose.

  By the way, during imaging or fluoroscopy with an X-ray imaging apparatus, the irradiation area of X-rays to be irradiated may be changed so that X-rays are not irradiated to a predetermined part of the subject. Then, the operator changes the X-ray condition set before imaging in accordance with the change of the irradiation area, and performs input setting again so as to obtain an optimal X-ray dose. That is, when the irradiation area is reduced, the X-ray dose is reduced accordingly, and when the irradiation area is increased, the X-ray dose is increased. Therefore, every time the irradiation area is changed during imaging, the operator needs to input and set the X-ray conditions again, and the subject may be irradiated with an inappropriate dose of X-rays due to an input error. .

JP 2003-203797 A

  Therefore, in view of the above problems, the problem to be solved by the present invention is optimal in accordance with the X-ray irradiation area to be changed without intervention of an operator during imaging or fluoroscopy of the subject. Another object of the present invention is to provide an X-ray image apparatus that can be set to various X-ray conditions.

In order to solve the above problems, an X-ray imaging apparatus according to the present invention provides:
X-ray irradiation means for irradiating X-rays, X-ray setting means for setting X-ray conditions of the X-ray irradiation means, image acquisition means for acquiring an X-ray image that passes through the subject, and transmission through the subject Light receiving area measuring means for measuring the X-ray light receiving area, light quantity measuring means for measuring the transmitted light quantity of the X-ray transmitted through the subject, light receiving area changing means for changing the light receiving area, and the unit from the light receiving area and the transmitted light quantity A calculation means for calculating the area transmitted light amount, a storage means for storing a preset unit area optimum amount, and a control means for controlling the X-ray setting means,
The control means sets the X-ray condition so that the unit area transmitted light amount is within the unit area optimum amount according to the displacement of the light receiving area.

Preferably, the light receiving area changing means includes an irradiation angle changing means for changing an X-ray irradiation angle irradiated from the X-ray irradiation means, and a collimator for changing an X-ray irradiation field irradiated from the X-ray irradiation means,
The light receiving area measuring means calculates the light receiving area based on the irradiation angle and the opening amount of the collimator.

Preferably, the X-ray irradiation means includes an imaging mode in which X-rays are intermittently irradiated onto the subject and imaged, and a fluoroscopy mode in which the X-rays are continuously irradiated on the subject to perform fluoroscopy.
The unit area optimum amount is set for each of the photographing mode and the fluoroscopic mode.

  As described above, the X-ray imaging apparatus according to the present invention includes a light amount measuring unit that measures the transmitted light amount of X-rays that pass through the subject, a light receiving area measuring unit that measures the light receiving area, and a unit from the transmitted light amount and the light receiving area. Calculation means for calculating the area transmitted light amount, storage means for storing a preset unit area optimum amount, and control means for controlling the X-ray setting means. Then, the control unit sets the X-ray condition so that the unit area transmitted light amount is within the unit area optimum amount according to the displacement of the light receiving area.

It is a block diagram which shows an X-ray imaging device. It is a figure for demonstrating the measuring method of a light reception area. It is a figure for demonstrating the measuring method of a light reception area. It is a flowchart figure for demonstrating the control method of a X-ray imaging device.

  Therefore, during the X-ray imaging or fluoroscopy, even if the operator changes the X-ray light receiving area irradiated to the subject so that the predetermined part of the subject is not irradiated with X-rays, the control means Since the X-ray conditions are set so that the unit area transmitted light amount is within the optimal unit area according to the displacement of the area, there is no need for the operator to input and set the X-ray conditions again. The subject is not irradiated with an inappropriate dose of X-rays.

  Embodiments of an X-ray imaging apparatus according to the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 is a block diagram showing an X-ray imaging apparatus. 2 and 3 are diagrams for explaining a method of measuring the light receiving area. FIG. 4 is a flowchart for explaining a control method of the X-ray imaging apparatus.

  As shown in FIG. 1, the X-ray imaging apparatus includes a top plate 4 formed of an X-ray transmissive material. A subject (for example, a patient) M is placed on the top 4. The X-ray imaging apparatus includes an X-ray tube (X-ray irradiation means) 1 that irradiates a subject M with X-rays B. The X-ray tube 1 includes a collimator 2 that shields a part of the irradiated X-ray and defines an irradiation field. The X-ray imaging apparatus includes an X-ray detector 3 that detects X-rays transmitted through the subject M. The X-ray detector 3 includes, for example, an FPD (flat panel X-ray detector).

  The X-ray imaging apparatus includes a tube voltage generator 5. The tube voltage generator 5 sets a tube voltage generator 50 that gives a tube voltage V and a tube current I to the X-ray tube 1 and an X-ray condition (tube voltage V, tube current I, etc.) that the tube voltage generator 50 gives. An X-ray setting unit 51. The X-ray imaging apparatus includes an image acquisition unit 7. The image acquisition unit 7 includes an image reading unit 70 that reads a transmission X-ray detection signal detected by the X-ray detector 3, and an image processing unit 71 that processes read data from the image reading unit 70 to generate image data. An image memory 72 for storing image data from the image processing unit 71, and a monitor 72 connected to the image memory 72 for displaying an X-ray image.

  The X-ray imaging apparatus includes an irradiation angle changing unit 80 that changes the irradiation angle of the X-ray B by rotating the X-ray tube 1 at an angle. The irradiation angle changing unit 80 includes, for example, a pulse motor having an output shaft connected to the X-ray tube 1. The X-ray imaging apparatus includes a collimator driving unit 81 that drives the collimator 2 to change the X-ray irradiation field. The collimator driving unit 81 includes, for example, a slide mechanism such as a rail and a motor that slides the collimator 2 along the vertical axis and the horizontal axis.

  The X-ray imaging apparatus includes an operation unit 8 for operating driving of the irradiation angle changing unit 80 and the collimator driving unit 81. The operator operates the irradiation angle changing unit 80 and the collimator driving unit 81 with the operation unit 8 while observing the X-ray image displayed on the monitor 73 so that the predetermined part of the subject M is not irradiated with the X-ray B. Further, the position of the X-ray B irradiated to the subject M is moved, or the irradiation field of the X-ray B irradiated to the subject M is changed. Therefore, the irradiation angle changing unit 80 and the collimator driving unit 81 can change the light receiving area (light receiving area) of the X-ray B that passes through the subject M (light receiving area changing means).

The high voltage generator 5 includes a control unit 52 that controls the X-ray setting unit 51 to change and set the X-ray condition of the X-ray B to be irradiated. The high voltage generator 5 includes an irradiation angle measurement unit 53 that measures the irradiation angle θ of the X-ray B from the X-ray tube 1, an irradiation field measurement unit 54 that measures the opening amount S ₂ of the collimator 2, and an X-ray tube and a throw distance measuring unit 55 for measuring the distance L ₁ between 1 and the X-ray detector 3. The irradiation angle measurement unit 53 includes, for example, an angle sensor connected to a pulse motor or the like of the irradiation angle changing unit 80. The irradiation field measurement unit 54 performs measurement based on, for example, a horizontal position sensor connected to the slide mechanism of the collimator driving unit 81. Moreover, the irradiation distance measurement part 55 measures based on the raising / lowering position sensor connected to the X-ray tube 1 and the X-ray detector 3, for example.

High-voltage generator 5 includes a light receiving area measuring unit 56 for measuring a receiving area (light-receiving area) S ₁ of the X-ray B transmitted through the subject M. Receiving area measuring unit 56, the irradiation distance measuring unit distance determined in 55 _L 1, the distance _{L 2} between the X-ray focal point 1a and collimator 2 of the X-ray tube 1, irradiation field measuring unit 54 with the obtained opening amount _S 2, based on the irradiation angle θ obtained in the irradiation angle measuring unit 53 calculates the light receiving area S _1.

As Figures 2 and 3, the light receiving area _{S 1,} the distance _{L 1,} the distance _{L 2,} the opening amount _{S 2,} based on the irradiation angle theta, is calculated from the following equation (1). FIG. 2 shows the case where θ = 0.
S ₁ = ((L ₁ / L ₂ ) ² × S ₂ ) / cos θ (1)
In addition, although said (1) Formula is a formula approximated in order to speed up calculation speed, the formula calculated | required in detail may be sufficient.

  The high voltage generator 5 includes a light amount measuring unit 57 that measures the transmitted light amount P of the X-ray B that passes through the subject M. For example, the light amount measurement unit 57 measures the transmitted light amount P based on the pixel value acquired from the X-ray detector 3. Therefore, the light amount measuring unit 57 measures the transmitted light amount P that is displaced according to the body thickness of the subject M. The transmitted light amount P can be measured based on the CT value in the X-ray CT apparatus.

High-voltage generator 5 includes a calculating unit 58 for receiving area S ₁ measured by the light receiving area measuring unit _56, based on the amount of transmitted light P measured by the light quantity measuring unit 57 calculates a unit area transmitted light amount A _m. The unit area transmitted light amount _Am is a transmitted light amount per unit area, and is calculated from the following equation (2). Unit area transmitted light amount A _m, the operator since displaced according to the light receiving area S ₁ be changed by operating the operation unit 8 calculates example each time for each predetermined time unit Delta] t.
A _m = P / S ₁ (2)

High-voltage generator 5 includes a storage unit 59 for storing a unit area optimal amount A _b previously set. The unit area optimum amount _Ab is the optimum transmitted light amount P of X-rays that pass through the subject M per unit area. Unit area optimal amount A _b is not a unique value can be a value having a predetermined allowable range. The unit area optimum amount _Ab is different depending on an imaging mode in which X-rays are intermittently irradiated to the subject and imaging and a fluoroscopy mode in which X-rays are continuously irradiated on the subject to perform fluoroscopy. Is set. Since the X-ray irradiation time (imaging time) for the subject M is different between the imaging mode and the fluoroscopic mode, the unit area optimum amount _Ab can be set in consideration of the irradiation time. Therefore, each unit area optimum amount _Ab is selected according to the photographing mode and the fluoroscopic mode.

The high voltage generator 5 includes a comparison unit 60 connected to the calculation unit 58 and the storage unit 59. Comparing unit 60, the unit area transmitted light amount A _m obtained in calculator 58, the unit area optimal amount A _b from the storage unit 59 is input. The comparison unit 60, calculated by comparing the unit area transmitted light amount A _m and the unit area optimal quantity A _b measured, as follows (3), for example, the light amount difference A _c for each predetermined time unit Δt To do.
A _c = A _m −A _b (3)

The comparison unit 60 is connected to a control unit 52 that changes and sets the X-ray conditions of the irradiated X-rays. Then, the control unit 52, as light amount difference A _c is 0, change set X-ray condition for each predetermined time unit Delta] t, to adjust the unit area transmitted light amount A _m. For example, the unit area optimal amount A _b is the time that is set as the pixel value 600, the unit area transmitted light amount A _m of measurement so that the pixel value 600, change set the X-ray condition. Thus, every time the light receiving area S ₁ is displaced, automatically without the intervention of an operator, the X-ray dose that transmits through the subject M to the unit light receiving area can be optimized.

Next, a series of X-ray imaging methods will be described with reference to FIG.
First, the operator stores the unit area optimal amount _{A b} in the storage unit 59 (step S1). As described above, the unit area optimal amount A _b can be set different values between the shooting mode and the fluoroscopic mode. Then, the operator operates the operation unit 8 to drive the irradiation angle changing unit 80 and the collimator driving unit 81, thereby preventing X-rays from being irradiated to a predetermined part of the subject M (step S2). With the driving of the irradiation angle changing unit 80 and the collimator drive unit 81, the light receiving area measuring unit 56, based on the above (1), it measures the light receiving area S ₁ (step S3). Further, the light quantity measurement unit 57 measures the transmitted light quantity P of the X-ray B that passes through the subject M (step S4).

A light receiving area S ₁ obtained by the light receiving area measuring unit 56, based on the amount of transmitted light P obtained in light amount measurement unit 57, calculation unit 58, from the above equation (2), calculates a unit area transmitted light amount A _m (Step S5). Then, the unit area transmitted light amount A _m obtained in calculator 58, based on the the unit area optimal amount A _b stored in the storage unit 59, comparing unit 60, as described above (3), the unit area transmission calculating a light amount difference _{a c} of the light amount _{a m} and the unit area optimal amount _{a b} (step S6). And the control part 52 changes and sets the X-ray conditions of the X-ray setting part 51 so that the light quantity difference _Ac may be set to 0 (step S7). By repeating the above steps S2~S7 for each predetermined unit time Delta] t, the operator drives the irradiation angle changing unit 80 and the collimator drive unit 81, each time changing the light receiving area S _1, interposed operator X-rays with optimal X-ray conditions can be automatically irradiated to the subject without the need for re-input setting of the X-ray conditions by the operator, and the subject is irradiated with an inappropriate dose of X-rays due to an input error. There is nothing to do.

  Furthermore, the X-ray image apparatus according to the present invention can be applied to a film-type X-ray imaging apparatus. In that case, the X-ray detector 3 includes an X-ray film for photographing the subject M and an area sensor for detecting X-rays. The area sensor is connected to the light amount measurement unit 57 and is configured to measure the transmitted light amount P of X-rays that pass through the subject M.

1 X-ray tube (X-ray irradiation means)
2 collimator 3 X-ray detector 5 high voltage generator 7 image acquisition unit 51 X-ray setting unit 52 control unit 56 light receiving area measurement unit 57 light quantity measurement unit 58 calculation unit 59 storage unit 80 irradiation angle change unit 81 collimator drive unit

Claims (3)

X-ray irradiation means for irradiating X-rays, X-ray setting means for setting X-ray conditions of the X-ray irradiation means, image acquisition means for acquiring an X-ray image that passes through the subject, and transmission through the subject A light receiving area measuring means for measuring a light receiving area of the X-ray, a light quantity measuring means for measuring a transmitted light quantity of the X-ray transmitted through the subject, a light receiving area changing means for changing the light receiving area, the light receiving area and the light receiving area A calculating means for calculating the unit area transmitted light amount from the transmitted light amount, a storage means for storing a preset unit area optimum amount, and a control means for controlling the X-ray setting means,
The X-ray imaging apparatus characterized in that the control means sets the X-ray condition so that the unit area transmitted light amount is within the unit area optimum amount according to the displacement of the light receiving area. The light receiving area changing means includes an irradiation angle changing means for changing an X-ray irradiation angle irradiated from the X-ray irradiation means, and a collimator for changing an X-ray irradiation field irradiated from the X-ray irradiation means,
The X-ray imaging apparatus according to claim 1, wherein the light receiving area measuring unit calculates the light receiving area based on the irradiation angle and an opening amount of the collimator. The X-ray irradiating means includes an imaging mode in which X-rays are intermittently irradiated and imaged, and a fluoroscopic mode in which X-rays are continuously irradiated to the subject and seen through.
The X-ray imaging apparatus according to claim 1, wherein the optimal unit area amount is set for each of the imaging mode and the fluoroscopy mode.

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