Patent Application
20230165549
This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2021-192395, filed on Nov. 26, 2021; the entire contents of which are incorporated herein by reference.
Embodiments described herein relate generally to a structure, an X-ray diagnostic apparatus, and a method.
An X-ray diagnostic apparatus is an apparatus for acquiring an X-ray image depicting the internal structure of a subject by causing an X-ray emitter to irradiate the subject with X-rays, and causing an X-ray detector to detect the X-rays transmitted through the subject. Generally speaking, the X-rays emitted from the X-ray emitter often form a cone beam. For example, when an X-ray tube is installed as the X-ray emitter, the X-rays are emitted in a fan-like shape diverging from an X-ray focal point positioned at the anode of the X-ray tube.
When an X-ray image is captured using a cone X-ray beam, the magnification of the region included in the X-ray image of the subject changes depending on a source-to-image-receptor distance (SID) and a source-to-object distance (SOD).
Specifically, the magnification becomes higher with a shorter SID or SOD. When the region included in the X-ray image is a lesion, such a change in the magnification may become a cause of an overestimation or an underestimation of the lesion.
Embodiments will now be explained in detail with reference to some drawings.
A configuration of an X-ray diagnostic apparatus 1 will now be explained with reference to
The X-ray tube 101 is an example of an X-ray emitter. The X-ray tube 101 is a vacuum tube with a cathode having a filament and an anode having a target. The X-ray tube 101 generates X-rays by emitting thermal electrons from the filament toward the target, and causing the thermal electrons to collide with the target, using the high voltage applied by the X-ray high voltage device 107. The X-ray high voltage device 107 applies a high voltage to the X-ray tube 101 under the control of the processing circuitry 111.
The X-ray aperture 102 includes, for example, aperture blades for demarcating a range to be irradiated with the X-rays emitted from the X-ray tube 101. The aperture blades are made of an X-ray shielding material such as lead and tungsten. The X-ray aperture 102 has four aperture blades, for example. With such a configuration, the X-rays emitted from the X-ray tube 101 travel through the aperture formed by the four aperture blades, and the subject P is irradiated with the X-rays. In the example illustrated in
The structure 103 is positioned between the X-ray tube 101 and the subject P, and enables the subject P to be irradiated with a parallel X-ray beam. The structure 103 will be described later in detail.
The X-ray detector 104 is an example of an X-ray detector. The X-ray detector 104 is an X-ray flat panel detector (FPD), for example. The X-ray detector 104 detects the X-rays emitted from the X-ray tube 101 and transmitted through the X-ray aperture 102, the structure 103, and the subject P. The X-ray detector 104 provides a detection signal corresponding to a detected X-ray dose to the processing circuitry 111.
The stand 105 is a mechanism that supports some or all of the components included in the X-ray diagnostic apparatus 1, when an image of the subject P who is standing is to be captured. In
The input interface 108 is provided as a mouse, a keyboard, a trackball, a switch, a button, a joystick, a touchpad enabling an input operation to be made by touching the operation surface, a touchscreen that is an integration of a display screen and a touchpad, a non-contact input circuitry using an optical sensor, and a voice input circuitry, for example. The input interface 108 receives various input operations from a user, and supplies electrical signals corresponding to the received input operations to the processing circuitry 111.
The display 109 is provided as a display device, such as a liquid crystal display or a cathode ray tube (CRT) display. The display 109 displays various types of information supplied from the processing circuitry ill.
The memory 110 is a storage device including, for example, a random access memory (RAM), a semiconductor memory element such as a flash memory, a hard disk, or an optical disc. The memory 110 stores therein various types of information supplied from the processing circuitry 111. The memory 110 also stores therein a computer program to be executed by the processing circuitry 111.
The processing circuitry 111 is implemented as an arithmetic processing unit such as a central processing unit (CPU) and a micro-processing unit (MPU). For example, the processing circuitry 111 functions as a control function 111a, an image processing function 111b, and an output function 111c, by reading and executing computer programs stored in the memory 110. The image processing function 111b is an example of an image processing unit.
The control function 111a, for example, controls an irradiation of the subject P with X-rays. Specifically, the control function 111a controls to supply a high voltage from the X-ray high voltage device 107 to the X-ray tube 101, and controls to open the aperture in the X-ray aperture 102.
The image processing function 111b generates an X-ray image of the subject P based on the X-rays detected by the X-ray detector 104, for example. Specifically, the X-ray detector 104 outputs the detection signal corresponding to an X-ray dose detected thereby, and the image processing function 111b generates an X-ray image using the detection signal received from the X-ray detector 104.
The output function 111c displays the X-ray image generated by the image processing function 111b on the display 109, or sends the X-ray image to an external image storage device so as to store therein the X-ray image, for example.
The X-ray diagnostic apparatus 1 having the configuration described above irradiates the subject P with a parallel X-ray beam. With this, an SID- or SOD-dependent change in the magnification can be avoided, and this contributes to an improvement in the accuracy of interpretations of the image, and to reductions in the sizes of the apparatus and examination room.
An emission of a parallel X-ray beam by the X-ray diagnostic apparatus 1 will now be explained with reference to
As illustrated in
Although the acrylic material 103a is used as an example of a scatterer, any material may be selected as long as the material is capable of scattering X-rays. In
The structure 103 will now be explained more in detail with reference to
At this time, as illustrated as the X-ray R1 in
By contrast, as illustrated as X-rays R2 and R7 in
Some of the X-rays having become incident on the acrylic material 103a are scattered by the acrylic material 103a, as illustrated as X-rays R3, R4, R5 and R6 in
As illustrated in
At this time, compared with the X-ray R1, the X-ray R3 and the X-ray R6 take long paths to transmit through the acrylic material 103a, and therefore, are subjected to greater attenuations. Among the scattered X-rays, the X-rays R3 and R6 are scattered components scattered in the predetermined angle, and have low coefficient rates, compared with those of the components transmitted through the acrylic material 103a and the grid 103b without being scattered, e.g., X-ray R1. Therefore, the X-ray detector 104 detects a higher X-ray dose in the central region that includes the X-ray axis (the path of the X-ray R1 in
Hence, the acrylic material 103a may be configured to have a convex-shaped portion on an incidence surface where the X-rays emitted from the X-ray tube 101 become incident, as illustrated in
Alternatively, as illustrated in
For example, the image processing function 111b can perform a correction for eliminating the systematic error in the pixel values corresponding to the respective detected positions based on a correction X-ray image (calibration image) captured in advance. Such a correction X-ray image is captured without the subject P placed between the X-ray tube 101 and the X-ray detector 104. Such a correction X-ray image is data representing the extraction of the systematic error in an X-ray dose distribution or an X-ray energy distribution, with the effect of transmission through the subject P eliminated. The correction X-ray image may be captured for each condition, e.g., a tube voltage or a tube current for the X-ray tube 101, the degree by which the X-ray aperture 102 is opened, an SID, or an SOD. The memory 110 may store therein the correction X-ray images captured for these different conditions, respectively. To correct an X-ray image captured from a subject P, the image processing function 111b can make a correction for eliminating the systematic error in the pixel values at the respective detected positions by using a correction X-ray image captured under the same condition as the X-ray image to be corrected.
By providing the structure 103, the dose of X-rays with which the subject P is irradiated becomes reduced. This is because some of the X-rays emitted from the X-ray tube 101 are absorbed or scattered by the acrylic material 103a or blocked by the grid 103b. Taking this reduction of the X-ray dose into consideration, the output from the X-ray tube 101 may be set high, or a sensitive X-ray detector 104 may be provided, compared with those used when the structure 103 is not provided.
As described above, the structure 103 is disposed between the X-ray tube 101 and the subject P. The acrylic material 103a scatters the X-rays emitted from the X-ray tube 101. Among the X-rays scattered by the acrylic material 103a, the grid 103b transmits the X-rays at the predetermined angle. With this, the structure 103 according to the embodiment can emit X-rays in the form of a parallel beam.
It is also possible to capture an X-ray image using a cone X-ray beam, instead of a parallel X-ray beam. However, in such a case, the magnification of the region included in the X-ray image of the subject changes depending on the SID or the SOD.
To suppress the effect of magnification while using a cone X-ray beam, for example, it is possible to ensure a longer SID or SOD, as illustrated in
By contrast, by enabling the X-rays to be emitted in the form of a parallel beam using the structure 103, it is possible to eliminate the effect of magnification and to improve the accuracy of interpretations. In addition, the sizes of the apparatus and the examination room can be reduced because there is no need to extend the SID or the SOD.
In a second embodiment, modifications related to the configuration of the X-ray diagnostic apparatus 1 will be explained.
In
For example, the X-ray diagnostic apparatus 1 may be provided with a stand 112 instead of the holder 106, as illustrated in
The X-ray diagnostic apparatus 1 may also be provided with a stand 113 and an arm 114, as illustrated in
Explained in
In the example illustrated in
In the example illustrated in
The X-ray diagnostic apparatus 1 may also be configured to irradiate the subject P who is seated with the X-rays, as illustrated in
The X-ray diagnostic apparatus 1 may also be disposed in a small examination room, as illustrated in
Explained in a third embodiment is an example in which an X-ray image is captured by scanning the range to be included in the X-ray image. In other words, explained below is an example in which an X-ray image is captured by irradiating a part of the range to be included in the X-ray image of the subject P with X-rays, while shifting the position being irradiated with the X-rays, instead of capturing the X-ray image by irradiating the entire range to be included in the X-ray image all at the same time with the X-rays.
In
Therefore, the X-ray diagnostic apparatus 1 moves the X-ray tube 101, the X-ray aperture 102, and the structure 103 in the directions indicated by the arrows in
The term “processor” used in the above explanation means circuitry such as a CPU, a graphics processing unit (GPU), an application-specific integrated circuit (ASIC), and a programmable-logic device (e.g., a simple programmable-logic device (SPLD), a complex programmable-logic device (CPLD), and a field programmable-gate array (FPGA)). If the processor is a CPU, for example, the processor implements a function by reading and executing a computer program stored in a memory. If the processor is an ASIC, for example, instead of storing the computer program in a memory, the function is directly incorporated into the processor circuit, as a logic circuit. The processors in the embodiment are not limited to a configuration in which each of the processors is implemented as a single circuit, but may also have a configuration in which a combination of a plurality of independent circuits are configured as a single processor, and the function may be implemented thereby. Furthermore, the function may be implemented by integrating a plurality of elements in the drawings into a single processor.
It has been explained so far that a single memory stores therein computer programs corresponding to the respective processing functions of the processing circuitry. However, embodiments are not limited thereto. For example, a plurality of memories may be deployed in a distributed manner, and the processing circuitry may be configured to read the computer programs from the respective memories. Instead of storing the computer programs in a memory, it is also possible to use a configuration in which the computer programs are directly incorporated into the processor circuitry. In such a case, the processor implements the functions by reading and executing the computer programs incorporated in the circuitry.
The elements included in each of the apparatuses according to the embodiments described above are functional and conceptual representations, and do not necessarily need to be physically configured as illustrated in the drawings. In other words, the specific configurations in which the apparatuses are distributed or integrated are not limited to those illustrated in the drawings, and may also be configured by functionally or physically distributing or integrating the whole or a part of the apparatuses in any units, based on various loads and utilization conditions. Furthermore, the processing functions executed by each of the apparatus may be implemented, in whole or in part, as a CPU and a computer program parsed and executed by the CPU, or as hardware using wired logic.
The method explained in the embodiments described above may also be implemented by causing a computer such as a personal computer or a workstation to execute a computer program. This computer program may be distributed over a network such as the Internet. The computer program may also be recorded a computer-readable non-transitory recording medium such as a hard disk, a flexible disk (FD), a compact disc read-only memory (CD-ROM), a magneto-optical disk (MO), and a digital versatile disc (DVD), and executed by causing a computer to read the computer program from the recording medium.
According to at least one of the embodiments described above, it is possible to emit X-rays as a parallel beam.
While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2021-192395 | Nov 2021 | JP | national |
