JP7533692B2 - X-ray detection device and X-ray imaging device - Google Patents

Description

The present invention relates to an X-ray detection device and an X-ray imaging device.

For example, an X-ray imaging device is known that includes an X-ray tube that generates X-rays, a tabletop on which a subject (e.g., a patient) is placed, and an X-ray detection unit that is positioned opposite the X-ray tube with the subject in between (see, for example, Patent Document 1).

The subject moves to the imaging room where the X-ray device is located. The operator (e.g., a radiologist) only needs to determine the subject's position. This is because the positional relationship between the X-ray tube and the X-ray detection unit is determined in advance.

However, there are cases where the subject cannot move to the imaging room. A mobile cart that can move to the subject's room is known as an X-ray imaging device that can be used in such cases (see, for example, Patent Document 2).

For X-ray imaging using a mobile cart, a flat panel X-ray detector (FPD) is used to detect the X-rays emitted from the X-ray tube.

JP 2010-134295 A JP 2003-220032 A

However, when taking X-rays using a mobile cart, the FPD is placed between the patient and the bed. In other words, the operator needs to align the FPD with the patient.

However, because the FPD is placed behind the subject, the operator must align the FPD with the subject while making it difficult to see the FPD. This not only makes the alignment process more difficult, but also puts the accuracy of the alignment at risk. Furthermore, a decrease in the accuracy of alignment can lead to more frequent reimaging.

To assist in the alignment of the FPD with the subject, a method is known in which a device that generates a magnetic field is placed around the FPD, and the generated magnetic field is analyzed to detect the position and tilt of the FPD. However, the generation of the magnetic field is highly dependent on the surrounding environment, such as the bed frame, so the surrounding environment is limited. Furthermore, there is a risk that the alignment work will become difficult due to the increase in the weight and size of the FPD.

The present invention aims to provide an X-ray detection device and an X-ray imaging device that can facilitate alignment work and improve alignment accuracy.

In order to achieve the above object, the X-ray detection device of the present invention comprises:
a surface through which X-rays are incident on a detection element that detects X-rays;
a plurality of light emitting units provided on an edge of the surface and arranged symmetrically with respect to a center line passing through a center position of the surface , the plurality of light emitting units having substantially the same light intensity;
An X-ray detection device comprising :
a light detection unit that detects light from the plurality of light emitting units;
a center position detection unit that detects a center position of the X-ray detection device based on a detection result by the light detection unit;
Equipped with.

The present invention makes it possible to facilitate alignment work and improve alignment accuracy.

Schematic diagram of a medical cart FIG. 2 is a plan view of an FPD according to an embodiment of the present invention, seen from the front side; A diagram showing the light intensity of the light-emitting part along the horizontal direction FIG. 1 is a block diagram showing a configuration of an X-ray imaging apparatus according to an embodiment of the present invention. A diagram showing a leakage light pattern that indicates a specific light intensity of the leakage light from behind the subject. FIG. 1 is a diagram for explaining detection of the center position of an FPD in the X direction; A diagram showing a leakage light pattern that indicates a specific light intensity of the leakage light from behind the subject. FIG. 1 is a diagram for explaining detection of tilt around the Z axis of an FPD; A diagram showing the intensity of light leaking from behind the subject. FIG. 1 is a block diagram showing a configuration of an X-ray imaging apparatus according to a first modified example. FIG. 11 is a block diagram showing a configuration of an X-ray imaging apparatus according to a second modified example. FIG. 1 shows the inclinations of an FPD around the X-axis, Y-axis, and Z-axis. FIG. 1 shows the inclinations of the FPD and the X-ray tube around the X-axis, the Y-axis, and the Z-axis. A diagram showing the inclination of the FPD and the X-ray tube around the X-axis.

The following describes an embodiment of the present invention with reference to the drawings.

In this embodiment, an X-ray imaging device 1 is described that is composed of a mobile cart 2 and a portable X-ray detection device 100 (FPD). Figure 1 is a schematic diagram of the mobile cart 2 and the FPD 100.

As shown in FIG. 1, the mobile cart 2 is equipped with an X-ray tube 3 and a console 4 (corresponding to the "alarm unit" of the present invention). The mobile cart 2 can be moved to an operating room, an intensive care unit (ICU), etc. An FPD 100 is used for X-ray photography using the mobile cart 2.

The FPD 100 is inserted between the subject 10 and the bed 20. The operator aligns the FPD 100 with the subject 10. In this embodiment, aligning the FPD 100 with the subject 10 means aligning the position of the subject 10 with the center position of the FPD 100.

The operator also aligns the FPD 100 with the X-ray tube 3. In this embodiment, aligning the FPD 100 with the X-ray tube 3 means matching the inclination of the X-ray tube 3 with the inclination of the FPD 100 (making the X-ray tube 3 and the FPD 100 face-to-face). Note that this embodiment will be described assuming that the position of the X-ray tube 3 and the center position of the FPD 100 are aligned.

The X-axis, Y-axis, and Z-axis are depicted in Figure 1. In the following explanation, the left-right direction in Figure 1 is referred to as the X-direction or horizontal direction, the left direction is referred to as the "+X direction" or "left side", and the right direction is referred to as the "-X direction" or "right side". Additionally, the up-down direction in Figure 1 is referred to as the Y-direction or front-back direction, the up direction is referred to as the "+Y direction" or "front side", and the down direction is referred to as the "-Y direction" or "back side". Additionally, the direction perpendicular to the paper surface in Figure 1 is referred to as the Z-direction or vertical direction, the front direction is referred to as the "+Z direction" or "front side", and the back direction is referred to as the "-Z direction" or "back side".

In this embodiment, the FPD 100 is provided with, in order from the front side (+Y direction), an upper cover 110, a scintillator layer 120 (see FIG. 2A), an X-ray detection element (not shown), a substrate (not shown), a support (not shown), and a lower cover 130. The scintillator layer 120 converts X-ray energy into light. The X-ray detection element detects the light from the scintillator layer 120. X-ray detection elements are arranged on the back side (-Y direction) of the scintillator layer 120.

In this embodiment, the upper surface of the scintillator layer 120 is referred to as the "detection surface." The outer frame 112 of the upper cover 110 is referred to as the "periphery of the detection surface." In the following description, the central axis of the detection surface 120 in the horizontal direction (X direction) is referred to as the "horizontal central axis." The central axis of the detection surface 120 in the vertical direction (Z direction) is referred to as the "vertical central axis."

Figure 2A is a plan view of the FPD 100 as viewed from the front side. As shown in Figure 2A, the periphery 112 of the detection surface 120 has a left edge 114L, a right edge 114R, a front edge 114F, and a rear edge 114B. The left edge 114L is located to the left of the horizontal central axis A1 and extends in the vertical direction. The right edge 114R is located to the right of the horizontal central axis A1 and extends in the vertical direction. The left edge 114L and the right edge 114R are located symmetrically with respect to the horizontal central axis A1.

The near side edge 114F is located in front of the vertical center axis A2 and extends in the horizontal direction. The far side edge 114B is located behind the vertical center axis A2 and extends in the horizontal direction. The near side edge 114F and the far side edge 114B are located symmetrically with respect to the vertical center axis A2.

The FPD 100 is equipped with light-emitting units 140. The light-emitting units 140 are arranged around the periphery 112 of the detection surface 120 so as to emit light from the surface. The light-emitting units 140 are, for example, light-emitting diodes (LEDs) or organic electroluminescence (OELs). A diffusion plate is disposed on the upper surface side of the light-emitting units 140. The directionality of LEDs is stronger than that of organic ELs. For this reason, the diffusion plate is effectively used to diffuse the LED light.

The left light-emitting unit 140L, which is located on the left edge 114L, is disposed over the entire front surface of the left edge 114L.

The right light-emitting unit 140R, which is located on the right edge 114R, is disposed over the entire front surface of the right edge 114R.

The front light emitting unit 140F arranged on the front edge 114F is arranged over the entire front surface of the front edge 114F.

The rear light-emitting unit 140B arranged on the rear edge 114B is arranged over the entire surface of the rear edge 114B.

The light-emitting units 140 are arranged symmetrically with respect to a center line passing through the center position of the detection surface 120. Specifically, the left light-emitting unit 140L and the right light-emitting unit 140R are arranged symmetrically with respect to the horizontal center axis A1. The front light-emitting unit 140F and the back light-emitting unit 140B are arranged symmetrically with respect to the vertical center axis A2.

As shown in FIG. 3, the medical cart 2 is equipped with a light leakage detection unit 210, an extraction unit 220, a center position detection unit 230, and an inclination detection unit 235.

The leakage light detector 210 is disposed on the X-ray tube 3 side (see FIG. 1). The leakage light detector 210 is, for example, an image sensor such as a CCD. The leakage light detector 210 generates an electrical signal according to the light intensity of the light emitter 140.

In this embodiment, the leak light detection unit 210 is disposed above the subject 10 (in the +Y direction). Diffused light and surface emission from the light emitting unit 140 cause leak light to occur from behind the subject 10. The leak light detection unit 210 detects the leak light from behind the subject 10.

Figure 2B is a diagram showing the light intensity of the light emitter 140 along the horizontal direction (X direction) when there is no obstruction such as the subject 10 on the front side (+Y direction) of the FPD 100. Note that the positions a, b, c, d, e, f, and m shown in Figure 2B correspond to the positions a, b, c, d, e, f, and m in the horizontal direction shown in Figure 2A. Position a is the position of the left end (left edge 114L) of the left light emitter 140L. Position b is the position of the right end of the left light emitter 140L. Position c is the position of the left end of the right light emitter 140R. Position d is the position of the right end (right edge 114R) of the right light emitter 140R. Position m is the center position of the PDF 100.

As shown in FIG. 2A, the area between a-b and the area between c-d are areas with the highest light intensity. These areas correspond to the light-emitting unit 140. FIG. 2A shows a left leakage light pattern PLL, a right leakage light pattern PLR, a front leakage light pattern PLF, and a back leakage light pattern PLB, which indicate the specific light intensities of the leakage light from the left light-emitting unit 140L, the right light-emitting unit 140R, the front light-emitting unit 140F, and the back light-emitting unit 140B.

The area to the left of position a (+X direction) is an area that indicates the light intensity of the leaked light on the left light-emitting unit 140L side. Additionally, the area to the right of position d (-X direction) is an area that indicates the light intensity of the leaked light on the right light-emitting unit 140R side. As shown in FIG. 2B, the light intensity of the leaked light on the left light-emitting unit 140L side decreases from position a toward the left. Additionally, the light intensity of the leaked light on the right light-emitting unit 140R side decreases from position d toward the right. Note that the specific light intensity at a position distanced L1 to the left of position a, and the specific light intensity at a position distanced L1 to the right of position d are obtained by experimental results or simulation.

To align the position of the subject 10 with the center position of the FPD 100, there is alignment in the X direction and alignment in the Z direction. The directionality is different in both alignments, but the alignment method is the same. Therefore, below, we will explain alignment in the X direction, and omit the explanation of alignment in the Z direction.

In addition, to align the tilt of the FPD 100 with the tilt of the X-ray tube 3, there is tilt alignment around the X-axis and tilt alignment around the Z-axis. In both tilt alignments, the tilt axes are different, but the method of tilt alignment is the same. Therefore, below, tilt alignment around the Z-axis will be explained, and explanation of tilt alignment around the X-axis will be omitted.

Figure 4 shows a leakage light pattern that indicates a specific light intensity from the leakage light from behind the subject 10. Figure 4 shows a case where the subject 10 is on the front side (+Y direction) of the FPD 100. In this case, the extraction unit 220 extracts a left leakage light pattern PLL that indicates a specific light intensity from the leakage light on the left light emitter 140L side. The extraction unit 220 extracts a right leakage light pattern PLR that indicates a specific light intensity from the leakage light on the right light emitter 140R side.

The center position detection unit 230 detects the center position of the FPD 100 in the X direction based on the left leakage light pattern PLL and the right leakage light pattern PLR.

Detection of the center position of the FPD 100 in the X direction by the center position detector 230 will be described with reference to Fig. 5. As shown in Fig. 5, a point spaced a distance L1 to the right from the left leakage light pattern PLL (the position of the left edge 114L) is defined as Pa. A point spaced a distance L1 to the left from the right leakage light pattern PLR (the position of the right edge 114R) is defined as Pd. Thus, the center position Pm in the X direction of the FPD 100 is expressed by the following equation (1).
Pm=(Pa+Pd)/2...(1)

Next, detection of the relative tilt between the X-ray tube 3 and the FPD 100 will be described with reference to FIG. 6. FIG. 6 is a diagram showing a leakage light pattern that indicates a specific light intensity among the leakage light from behind the subject 10. The tilt detection unit 235 detects whether the left leakage light pattern PLL and the right leakage light pattern PLR are symmetrical. When the left leakage light pattern PLL and the right leakage light pattern PLR are asymmetrical as shown in FIG. 6, the tilt detection unit 235 detects that the X-ray tube 3 is tilted around the Z axis with respect to the FPD 100.

Next, detection of the relative tilt angle between the X-ray tube 3 and the FPD 100 will be described with reference to Fig. 7. As shown in Fig. 7, the distance between the left leakage light pattern PLL and the right leakage light pattern PLR is L3. When there is no relative tilt around the Z axis between the X-ray tube 3 and the FPD 100, the distance between the left leakage light pattern PLL and the right leakage light pattern PLR is a value (L0+2L1) obtained by adding the length L0 (design value) of the FPD 100 in the X direction and two distances L1. As a result, the relative tilt angle θ between the X-ray tube 3 and the FPD 100 around the Z axis is expressed by the following formula (2).
θ=cos ^-1 (L3/(L0+2×L1))...(2)

The tilt detection unit 235 detects the relative tilt angle θ around the Z axis between the X-ray tube 3 and the FPD 100 based on the distance L3 between the left leakage light pattern PLL and the right leakage light pattern PLR.

The console 4 displays the center position of the FPD 100 in the X direction detected by the center position detection unit 230, and the relative tilt angle between the X-ray tube 3 and the FPD 100 detected by the tilt detection unit 235.

When taking chest X-rays using the mobile cart 2, the FPD 100 is inserted between the subject 10 and the bed 20. In other words, the FPD 100 is hidden behind the subject 10. The operator aligns the FPD 100 with the subject 10. If alignment is not performed sufficiently and the alignment accuracy decreases, this will lead to an increased frequency of re-imaging.

According to the FPD 100 of the above embodiment, the left light emitter 140L and the right light emitter 140R are arranged symmetrically with respect to the lateral central axis A1. This allows the operator to visually confirm the presence or absence of lateral positional deviation of the FPD 100 relative to the subject 10 based on the intensity of the leakage light on the left light emitter 140L side and the intensity of the leakage light on the right light emitter 140R side.

Next, the positional deviation of the FPD 100 will be described with reference to FIG. 8. FIG. 8 is a diagram showing the intensity of leakage light from behind the subject 10. As shown in FIG. 8, the leakage light is strong on the left light-emitting unit 140L side and weak on the right light-emitting unit 140R side, so the operator can visually confirm the positional deviation of the FPD 100 to the left relative to the subject 10.

The X-ray imaging device 1 according to the above embodiment includes a leakage light detection unit 210 that detects leakage light from the light emitting unit 140 leaking from behind the subject 10 toward the X-ray tube 3, an extraction unit 220 that extracts a leakage light pattern that indicates a predetermined light intensity from the leakage light, a center position detection unit 230 that detects the center position of the FPD 100 based on the leakage light pattern, and a console 4 that notifies the center position of the FPD 100 in the X direction detected by the center position detection unit 230. This allows the operator to easily align the position of the subject 10 with the center position of the FPD 100 in the X direction based on the notified center position of the FPD 100 in the X direction.

Next, a first modified example of the X-ray imaging device 1 according to the present embodiment will be described. Note that in the first modified example as well, the alignment of the position of the X-ray tube 3 with the center position of the FPD 100 in the X direction will be described.

The X-ray imaging device 1 according to the first modified example includes a learning unit 240 as shown in FIG.
For example, depending on the state in which the illumination in the room is reflected by the FPD 100, it may be difficult for the leakage light detector 210 to detect leakage light, which may cause the center position detector 230 to erroneously detect the center position in the X direction of the FPD 100. As a result, for example, the deviation between the position of the subject 10 and the center position in the X direction of the FPD 100 may exceed the allowable range. In this case, the center position in the X direction of the FPD 100 is corrected.

The learning unit 240 stores the leak light pattern in correspondence with the corrected center position of the FPD 100 in the X direction.

The center position detection unit 230 compares the leakage light pattern extracted by the extraction unit 220 with the leakage light pattern stored in the learning unit 240, and if both leakage light patterns are similar, detects the center position of the FPD 100 (the corrected center position of the FPD 100) that corresponds to the leakage light pattern stored in the learning unit 240.

According to the above-mentioned variant example 1, the center position of the FPD 100 is accurately detected regardless of the surrounding environment when the leakage light detection unit 210 detects leakage light, so that the accuracy of alignment between the FPD 100 and the subject 10 can be further improved.

Next, Modification 2 will be described with reference to FIG. 10 and FIG. 11A to FIG. 11C. FIG. 11A is a diagram showing the tilt of FPD 100 around the X-axis, Y-axis, and Z-axis. FIG. 11B is a diagram showing the tilt of FPD 100 and X-ray tube 3 around the X-axis, Y-axis, and Z-axis. FIG. 11C is a diagram showing the tilt of FPD 100 and X-ray tube 3 around the X-axis.

In the above embodiment, the relative tilt angle between the X-ray tube 3 and the FPD 100 is detected by the tilt detection unit 235, but the present invention is not limited to this. As shown in FIG. 10, the X-ray imaging device 1 according to the second modification includes a first angle sensor 310, a second angle sensor 320, an angle difference detection unit 330, and a control unit 340.

As shown in FIG. 11A, the first angle sensor 310 detects the tilt angle θx around the X axis, the tilt angle θy around the Y axis, and the tilt angle θz around the Z axis of the FPD 100. As the first angle sensor 310, a known sensor such as an acceleration sensor or a magnetic sensor is used.

As shown in Figures 11A and 11B, the second angle sensor 320 detects the tilt angle φx around the X-axis, the tilt angle φy around the Y-axis, and the tilt angle φz around the Z-axis of the X-ray tube 3. As with the first angle sensor 310, the second angle sensor 320 may be a known sensor such as an acceleration sensor or a magnetic sensor.

The angle difference detection unit 330 detects the tilt of the X-ray tube 3 around the X-axis relative to the FPD 100 based on the difference between the tilt angle θx of the FPD 100 around the X-axis detected by the first angle sensor 310 and the tilt angle φx of the X-ray tube 3 around the X-axis detected by the second angle sensor 320.

The angle difference detection unit 330 detects the tilt of the X-ray tube 3 around the Y axis relative to the FPD 100 based on the difference between the tilt angle θy of the FPD 100 around the Y axis detected by the first angle sensor 310 and the tilt angle φy of the X-ray tube 3 around the Y axis detected by the second angle sensor 320.

The angle difference detection unit 330 detects the tilt of the X-ray tube 3 around the Z axis relative to the FPD 100 based on the difference between the tilt angle θz of the FPD 100 around the Z axis detected by the first angle sensor 310 and the tilt angle φz of the X-ray tube 3 around the Z axis detected by the second angle sensor 320.

The relative tilt between the FPD 100 and the X-ray tube 3 will be described below with reference to FIG. 11C. FIG. 11C is a diagram showing the tilt angle θz of the FPD 100 around the X-axis and the tilt angle φz of the X-ray tube 3 around the X-axis.

As shown in FIG. 11C, when there is a difference between tilt angle θx and tilt angle φx (θx-φx=α), when there is no difference between tilt angle θy and tilt angle φy (θy-φy=0), and when there is no difference between tilt angle θz and tilt angle φz (θz-φz=0), the angle difference detection unit 330 detects the tilt α of the X-ray tube 3 around the X-axis relative to the FPD 100. The control unit 340 notifies the console 4 of information on the tilt α of the X-ray tube 3 relative to the FPD 100. The operator tilts the X-ray tube 3 based on the notified information.

When θx-φx=0, θy-φy=0, and θz-φz=0, the control unit 340 notifies the console 4 that there is no tilt of the X-ray tube 3 relative to the FPD 100.

According to the above-mentioned variant 2, the operator can orient the X-ray tube 3 directly toward the FPD 100 based on the relative inclination between the X-ray tube 3 and the FPD 100.

Next, a third modified example will be described. In the above embodiment, the central position detection unit 230 detects the central position of the FPD 100 based on the leakage light pattern. If the X-ray tube 3 does not face the subject 10, in other words, for example, if the X-ray tube 3 is not directly above the subject 10, the leakage light detection unit 210 arranged on the X-ray tube 3 side cannot detect the leakage light leaking from behind the subject 10 from directly above, and there is a risk of erroneously detecting the leakage light pattern.

The medical cart 2 in the third modified example is therefore equipped with a subject imaging unit that images the subject 10. The imaging surface of the subject imaging unit is oriented in the same direction as the X-ray irradiation surface of the X-ray tube 3. Based on whether the subject 10 is in the center of the image captured by the subject imaging unit, it is possible to easily check whether the leak light detection unit 210 can detect leak light leaking from behind the subject 10 from directly above. This eliminates the risk of erroneous detection of the leak light pattern.

According to the third modification, by providing a subject imaging section, erroneous detection of the leakage light pattern can be prevented, making it easier to align the position of the subject 10 with the center position of the FPD 100.

The subject imaging unit in the third modification may be the leak light detection unit 210. The control unit 340 may also cause the console 4 to notify guidance information for orienting the X-ray tube 3 directly to the subject 10 (for positioning the X-ray tube 3 directly above the subject 10).

In the above embodiment, it has been described that the position of the X-ray tube 3 and the center position of the FPD 100 are aligned. By using the subject imaging section in the above modification example 3, it is possible to easily align the position of the X-ray tube 3 and the center position of the FPD 100. This is for the following reasons. By using an image of the subject 10 captured by the subject imaging section, the X-ray tube 3 can be positioned directly above the subject 10. The position of the subject 10 can be aligned with the center position of the FPD 100 based on the left leakage light pattern PLL and the right leakage light pattern PLR. This makes it possible to align the position of the X-ray tube 3 with the center position of the FPD 100.

In the above embodiment and each modified example, the light-emitting unit 140 is arranged symmetrically with respect to the lateral central axis A1, but the present invention is not limited to this. For example, the light-emitting unit 140 is arranged around the detection surface 120. In this case, the center position detection unit 230 detects the center position of the FPD 100 based on the predetermined arrangement position of the light-emitting unit 140.

In addition, the above embodiments are merely examples of the implementation of the present invention, and the technical scope of the present invention should not be interpreted in a limiting manner based on them. In other words, the present invention can be implemented in various forms without departing from its gist or main characteristics.

Reference Signs List 1 X-ray device 2 Medical cart 3 X-ray tube 4 Console 10 Subject 20 Bed 100 FPD
110 Upper cover 112 Outer frame 114B Back edge 114F Front edge 114L Left edge 114R Right edge 120 Detection surface (scintillator layer)
130 Lower cover 140 Light emitting unit 140B Back side light emitting unit 140F Front side light emitting unit 140L Left side light emitting unit 140R Right side light emitting unit 210 Leakage light detection unit 220 Extraction unit 230 Center position detection unit 235 Tilt detection unit 240 Learning unit 310 First angle sensor 320 Second angle sensor 330 Angle difference detection unit 340 Control unit

Claims (2)

a surface through which X-rays are incident on a detection element that detects X-rays;
a plurality of light emitting units provided on an edge of the surface and arranged symmetrically with respect to a center line passing through a center position of the surface , the plurality of light emitting units having substantially the same light intensity;
An X-ray detection device comprising :
a light detection unit that detects light from the plurality of light emitting units;
a center position detection unit that detects a center position of the X-ray detection device based on a detection result by the light detection unit;
An X-ray imaging device comprising: 2. The X-ray imaging apparatus according to claim 1, wherein information relating to a position of the subject and a central position of the X-ray detection device is notified based on the subject and the detected central positions of the X-ray detection device.