Radiation imaging diagnostic equipment with improved scouting capabilities

Abstract

To obtain high-quality radiological images. [Solution] A radiological image acquisition method for acquiring radiological images of a portion of a patient, the radiological image acquisition method including the steps of: positioning the patient within an analysis area; setting an imaging start position so that the portion of the patient to be diagnosed is included between the imaging start position and the imaging end position; acquiring successive images from the imaging start position to the imaging end position using a radiation beam; and combining the successive images to generate a composite scouting image.

Description

[Technical Field]

[0001] The present invention relates to a radiological imaging diagnostic device with an improved scouting function. [Background technology]

[0002] A radiological image acquisition device includes a bed for supporting a patient, a control station for controlling the device's functions, and a gantry, which is a device having a cavity suitable for inserting the patient's portion to be analyzed and for radiological imaging of the patient. Within the gantry, the radiological image acquisition device includes a radiation source that emits radiation (e.g., X-rays) in response to commands and a detector that detects the radiation that has passed through the portion of the patient to be analyzed. The device then transmits signals to visualize the patient's internal anatomical structures. When a specific body part needs to be visualized, it may be useful to first "scout" the area to be imaged. Scouting is the process of acquiring a preview or overview image to assess the size and shape of the diagnostic area and plan subsequent image acquisition. Summary of the Invention [Problem to be solved by the invention]

[0003] However, in the techniques described in the above publications, when a particular region of the body needs to be visualized, it may be beneficial to first "scout" the region to be imaged, which is the process of obtaining a preview or overview image to assess the size and shape of the region of diagnostic interest and to plan subsequent image acquisition.

[0004] An object of the present invention is to provide a technique for solving the above-mentioned problems. [Means for solving the problem]

[0005] In one aspect, the disclosed embodiments provide a method for imaging a portion of a patient using radiation. The method includes the steps of positioning the patient within an analysis region and setting an imaging start position. A region of the patient to be diagnosed is included between the imaging start position and the imaging end position. The method further includes the step of acquiring a series of images using a radiation beam, starting from the imaging start position and ending at the imaging end position. The method further includes the step of combining the series of images to form a composite scouting image.

[0006] Implementations can include one or more of the following features.

[0007] The predetermined spacing is between about 8 mm and about 12 mm or between about 4 mm and about 6 mm. The radiation beam is cone-shaped or fan-shaped. The end position is set when setting the start position or is determined by the operator when acquisition is stopped. The method further includes selecting a stack thickness or a radiation beam thickness.

[0008] The method can further include acquiring a computed tomography image generated at least in part based on the composite scouting image. The method can further include performing a surgical procedure based on the composite scouting image. The scouting image can be an image of the patient's entire body.

[0009] The image acquisition step is performed using a gantry having a rotatable ring on which a radiation source generating a radiation beam and a detector are disposed, and is performed at a predetermined rotation angle. A plurality of composite scouting images are acquired at each of the predetermined rotation angles. The radiological image acquisition method may include acquiring a computed tomography image created at least in part based on the plurality of composite scouting images.

[0010] In another aspect, the disclosed embodiments provide a radiological image acquisition device including a gantry defining an analysis region in which at least a portion of a patient is positioned. The radiological image acquisition device further includes a radiation source adapted to emit radiation that passes through at least a portion of the patient. The radiation defines a central axis of propagation. The radiological image acquisition device further includes a detector arranged to detect the radiation and generate a data signal based on the detected radiation. The radiological image acquisition device further includes a gantry rotation device including a ring to which the radiation source and the detector are attached and a rotation bearing for rotating the ring. The radiological image acquisition device further includes a controller adapted to continuously rotate the ring with the gantry rotation device and acquire images from data signals continuously received from the detector while the radiation source and the detector attached to the ring continuously receive radiation, thereby scanning at least a portion of the patient. The radiological image acquisition device further includes a movement mechanism for moving the gantry and a sensor system for triggering image acquisition at defined intervals as the gantry moves.

[0011] Implementations may include one or more of the following features.

[0012] The predetermined distance interval is between about 8 mm and about 12 mm or between about 4 mm and about 6 mm. The radiation image acquisition device may further include a bed with a patient head support system. The radiation image acquisition device may further include a pole system connected to the gantry, the pole system including a camera and capable of folding away from the analysis region. The sensor system may include a laser track having discrete steps or notches spaced at predetermined intervals. [Effects of the Invention]

[0013] According to the present invention, a high-quality radiation image acquisition device can be provided. [Brief explanation of the drawings]

[0014] [Figure 1]1 is a diagram illustrating a radiation image acquisition device according to an embodiment of the present invention. [Figure 2A] 1 is a partial cross-sectional view of a radiation image acquisition device according to an embodiment of the present invention. [Figure 2B] FIG. 2 is a diagram showing a light source subassembly of a radiation image acquisition device according to an embodiment of the present invention. [Figure 2C] 1 is a table containing predetermined relationships for configuring an X-ray source, according to an embodiment of the present invention. [Figure 2D] 1 is a partial cross-sectional view of a perforated laser track ring according to an embodiment of the present invention. [Figure 3A] 2 is a diagrammatic view of a gantry subassembly with a cutting section according to one embodiment of the radiological image acquisition device shown in FIG. 1. [Figure 3B] FIG. 3B is a perspective view of the gantry subassembly shown in FIG. 3A. [Figure 4A] 2 shows another partial cross-sectional view of the radiation image acquisition device of FIG. 1. [Figure 4B] 4B shows a partial perspective view of an embodiment of a gantry rotation device of the radiological image acquisition apparatus shown in FIG. 4A. [Figure 4C] 4C shows another partial perspective view of the embodiment of the horizontal rotation device of the radiation image acquisition device shown in FIG. 4B. [Figure 5] 1 shows a graph of controlling the emission of X-rays by a radiation source and the acquisition of an image by a radiation detector of a radiological image acquisition device according to an embodiment of the present invention. [Figure 6A] 2 illustrates a matrix mode of a flat panel sensor subassembly of the imaging device of FIG. 1 in accordance with an embodiment of the present invention. [Figure 6B] 2 illustrates a linear sensor mode of the flat panel sensor subassembly of the imaging device of FIG. 1 in accordance with an embodiment of the present invention. [Figure 7] 1 is a flowchart illustrating an imaging procedure according to an embodiment of the present invention. [Figure 8A] 1 shows an example of a composite scouting image for a clinical animal patient according to an embodiment of the present invention. [Figure 8B]1 illustrates a patient and a fan beam radiation beam field at successive positions along the length of the patient, according to an embodiment of the present invention. [Figure 8C] 10 illustrates a track located on the underside of a gantry transport mechanism that generates trigger signals at known geometric positions of the gantry, according to an embodiment of the present invention. [Figure 9A] 1 is a diagram illustrating the difference in beam width used in images acquired during scouting and CT images, in accordance with an embodiment of the present invention. [Figure 9B] 1 is a diagram illustrating the difference in beam width used in images acquired during scouting and CT images, in accordance with an embodiment of the present invention. [Figure 10] FIG. 1 illustrates a pole system mounted to a gantry and including a camera, according to an embodiment of the present invention. [Figure 11] FIG. 1 illustrates a pole system mounted to a gantry and including a camera, according to an embodiment of the present invention. [Figure 12A] FIG. 1 illustrates a head positioning system according to an embodiment of the present invention. [Figure 12B] FIG. 1 illustrates a head positioning system according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, embodiments of the present invention will be described in detail by way of example with reference to the drawings. However, the components described in the following embodiments are merely examples and are not intended to limit the technical scope of the present invention.

[0016] [First embodiment] The following describes embodiments of the present invention in detail. However, it will be understood by those skilled in the art that embodiments of the present invention may be practiced without these specific details. In other instances, well-known methods, procedures, components, and circuits have not been described in detail so as not to obscure the present invention.

[0017] When imaging a patient, it may be beneficial to first "scout" the area to be imaged. Scouting refers to the procedure of acquiring a preview or overview image to assess the size and shape of the diagnostic area and plan subsequent image acquisition. An improved method for radiological imaging using scouting is described below. This method includes setting a start and end position for image acquisition so that the patient region of interest is included between the start and end positions. Images are then acquired at predetermined distance intervals, starting from the start position and ending at the end position, and these images are combined to form a single scouting image. This improved scouting image can be used for more detailed imaging and surgical planning. This system overcomes the problem of conventional systems where the scouting image is not detailed or comprehensive. Furthermore, the embodiments disclosed herein overcome the accuracy issues caused by lack of mechanical precision and distortion issues caused by lack of software processing in other approaches.

[0018] FIG. 1 is a three-dimensional perspective view illustrating an embodiment of a radiological image acquisition device 1 for performing long-range scouting and other tasks. The radiological image acquisition device 1 is used to perform two-dimensional and three-dimensional scans of a patient's body. The radiological image acquisition device 1 includes a gantry 20 having a housing 99. The gantry 20 defines a preferred extension axis 20a (shown in FIG. 2B). The gantry 20 also includes a transport mechanism 25 and a control unit 30.

[0019] The control unit 30 is mounted on the gantry 20 (FIGS. 1, 3A, and 3B) and can control the gantry 20 by sending data and command signals to the gantry 20 using communication means. In some embodiments, the control unit 30 is housed in a separate unit (not shown), such as a workstation cart, or is comprised of multiple components, such as a first component mounted on the gantry 20 and a second component housed in a separate unit. These examples are merely illustrative, and in other embodiments, the control unit 30 may be located in positions or locations other than those described above.

[0020] The gantry 20 can be mounted on a transport mechanism 25 (e.g., a cart) and configured to be transported to a desired location. In one embodiment, the transport mechanism 25 includes at least four wheels 24 attached to the transport mechanism 25 via brackets 22. In a preferred embodiment, the brackets 22 are V-shaped (as shown in FIG. 1 ) to accommodate different wheel 24 sizes while maintaining the transport mechanism 25 as close to the floor as possible. Furthermore, the V-shaped brackets allow the diameter of each wheel 24 to be substantially equal to, or preferably substantially larger than, the distance between the transport mechanism 25 and the floor. This allows the distance between the transport mechanism 25 and the floor to remain constant. Because the distance between the transport mechanism 25 and the floor is typically small, the size of the gantry 20 can be large. However, other suitable shapes for the brackets 22 or other means for securing the wheels 24 to the transport mechanism 25 can also be used.

[0021] FIG. 2A is a more detailed three-dimensional perspective view of the gantry 20 and associated components of the radiological image acquisition device 1. The housing 99 of the gantry 20 contains various components for performing a radiological scan. These components include a radiation source 21 (e.g., an X-ray source) having a central axis of radiation 21a (shown in FIG. 2B) and a radiation detector 102 that receives radiation emitted from the radiation source 21. The gantry 20 further defines an analysis region 20b (FIG. 3A) in which the patient's entire body or a specific body part to be imaged is positioned during scanning. In some embodiments, the gantry 20 includes a laser positioning system including at least one horizontal laser 72 and one vertical laser 74 (FIGS. 3A and 3B).

[0022] The radiation source 21 emits radiation capable of penetrating the patient's body and interacting with tissues and fluids present within the patient's body. In one embodiment, the radiation source 21 emits ionizing radiation, more specifically, X-rays. In some embodiments, the radiation image acquisition device 1 includes a collimator positioned adjacent to the radiation source 21 to limit the radiation to the radiation detector 102 and adjust the radiation field to align with the position of the radiation detector 102.

[0023] FIG. 2B shows a detailed perspective view of the radiation source 21 and its associated components. As noted above, the collimator 76 used to restrict radiation to the radiation detector 102 includes an X-ray filter (not shown), e.g., a bowtie filter, positioned between the radiation source 21 and the radiation detector 102. The X-ray filter modifies the shape of the radiation beam (e.g., X-rays) emitted from the radiation source 21 in the direction of the radiation source's central axis of propagation 21a, which extends perpendicular to the plane of the drawing. The X-ray filter is therefore shown as a point at the intersection 21a of axis 20a and axis 38. Specifically, the X-ray filter alters the energy of the radiation along the central axis of propagation 21a relative to the periphery of the radiation beam by absorbing low-power X-rays near the periphery of the radiation beam, thereby altering the energy distribution of the radiation along axes 20a and 38 before the X-rays pass through the patient. In one embodiment, the X-ray filter comprises a sheet material (e.g., aluminum and / or copper) of a predetermined thickness suitable for absorbing radiation. The thickness of the radiation absorbing sheet is determined along the central axis of propagation 21a.

[0024] In another embodiment, multiple X-ray filters (not shown) may be stored at different positions on the gantry 20. Each X-ray filter in the multiple X-ray filters may differ from the others at least in shape and may also differ in material (e.g., aluminum and / or copper) and / or sheet thickness. The control unit 30 may drive a motor drive mechanism (not shown) provided in the gantry 20 to remove a selected X-ray filter (e.g., selected by the control unit 30 as described below) from the storage location and position the selected X-ray filter in front of the radiation source 21.

[0025] In another embodiment, the radiological equipment operator inputs patient-specific information (e.g., the type of imaging diagnostic procedure to be performed on the patient (e.g., fluoroscopy, tomography, or radiography), the type of patient (e.g., human or animal), the patient's weight, the type of tissue to be imaged, etc.) into the control unit 30. Based on the input information, the control unit 30 automatically sets the optimal radiation dose to be applied to the patient by the radiological image acquisition device 1. Furthermore, the control unit 30 determines the X-ray emission energy and / or the type of X-ray filter to be placed in front of the radiation source 21 based on a predetermined relationship between the patient-specific information. An example of such a predetermined relationship is shown in the table of FIG. 2C and is defined according to a look-up table, a conditional branching algorithm, and / or a mathematical formula implemented in the control unit 30. Thus, the radiological image acquisition device 1 can perform the selected imaging procedure while maintaining optimal image quality at an X-ray dose that is safe for the patient and the operator. The X-ray emission energy depends on parameters such as the X-ray tube voltage, the X-ray tube current, and the exposure time.

[0026] For example, the control unit 30 can determine the operating parameters of the radiation source 21 based on a predefined relationship between patient information, the selected radiological imaging procedure, the X-ray radiation energy, and the material and thickness of the X-ray filters among the multiple X-ray filters arranged in the gantry. An example of such a predefined relationship is shown in the table of FIG. 2C. For example, if an operator specifies that a high-resolution computed tomography (CT) scan be performed on hard tissue (e.g., the thoracic region) when inputting patient-specific information into the control unit 30, the control unit 30 can use a lookup table (e.g., FIG. 2C) to determine the operating parameters of the radiation source 21 corresponding to the specification. Specifically, using the lookup table of FIG. 2C, the control unit 30 can determine that the above input corresponds to the operating parameters of the radiation source 21 being 100 kV, 60 mA, 5 ms, and an X-ray filter made of a 3 mm thick aluminum sheet and a 0.2 mm thick copper sheet. As another example, if the operator specifies via control unit 30 that high-resolution tomography be performed on soft tissue (e.g., the abdominal region), control unit 30 will consult the look-up table of Figure 2C to determine that the above inputs correspond to radiation source 21 operating parameters of 60 kV, 60 mA, 10 ms and an X-ray filter made of a 2 mm thick aluminum sheet. Such variables can be adjusted depending on the scan target.

[0027] In yet another embodiment, radiation source 21 emits radiation in a cone-shaped or fan-shaped beam using a collimator 76 with an adjustable beam shape. Collimator 76 includes at least two, preferably four, movable plates 78 that surround the X-ray radiation area and thus substantially block the radiation, as shown in FIG. 2B . Using a motorized mechanism (not shown) controlled by control unit 30, an operator can position movable plates 78 of collimator 76 in an open configuration, a slit configuration, or a position intermediate between the two configurations. Using a motorized mechanism controlled by control unit 30, an operator can also position movable plates 78 along a movement axis that is substantially perpendicular to central propagation axis 21 a and substantially perpendicular or parallel to expansion axis 20 a.

[0028] In some embodiments, the motor drive mechanism includes at least one independent motor for each movable plate 78 and an additional motor for the X-ray filter. When the collimator 76 is set in the open configuration, radiation from the radiation source 21 is not blocked and propagates in a cone shape along the central propagation axis 21a (those skilled in the art will understand that the term "cone" as used herein broadly includes geometric shapes having circular or non-circular bases (e.g., square or rectangular)). However, when the collimator 76 is configured as a slit, a portion of the radiation from the radiation source 21 is blocked, and the unblocked radiation therefore propagates along the central propagation axis 21a in the shape of a fan (i.e., a cross-section of the cone radiation) disposed in a plane perpendicular to the axial extension 20a. Thus, in one embodiment, the operator can configure the collimator 76 to cause the radiation source 21 to emit either a cone beam or a fan beam, and use the radiation image acquisition device 1 to perform different types of imaging, such as cone beam tomography or fan beam tomography.

[0029] In another embodiment, the shape of the beam of radiation emitted from the radiation source 21 can be modified by placing a filtering means (not shown) above the radiation source 21 to modify the characteristics of the beam before the radiation reaches the target. In particular, in one embodiment, the radiation source 21 can use a filtering means to emit multiple fan-shaped beams of radiation. The use of multiple fan-shaped beams can improve the quality of the scanned image, such as by reducing light scattering compared to a cone-shaped radiation emission. In yet another embodiment, the filtering means can include, for example, one or more filters, one or more grids, or an adjustable aperture. In yet another embodiment, the filtering means can include one or more stackable filters or stackable grids. In some embodiments, the filtering means is movable. In an embodiment, an anti-scatter grid is placed on the flat panel sensor, thereby affecting the characteristics of the received radiation after passing through the patient and before reaching the sensor.

[0030] In one embodiment, a laser positioning system including a horizontal laser 72 and a vertical laser 74 (see FIGS. 3A and 3B) is used in combination with an adjustable bed. Activated by the control unit 30, the laser positioning system projects visual markers onto the patient to facilitate positioning the patient on the bed within the analysis zone 20b. Further details are described in U.S. Provisional Patent Application Nos. 61 / 932,034 and 61 / 944,956, which are incorporated herein by reference in their entireties.

[0031] Returning to the drawings, and with particular reference to FIGS. 3A and 3B, an embodiment of the gantry 20 of the radiological image acquisition device 1 is shown. As described above, a laser positioning system is mounted on the gantry 20 and includes at least one horizontal laser 72 and / or at least one vertical laser 74. The horizontal laser 72 projects a horizontal visual marker 73 to assist the operator in adjusting the patient's height and inclination, and the vertical laser 74 projects a top-down marker 75 to assist the operator in aligning the patient to a lateral center position relative to the gantry 20. The operator adjusts the patient's position by observing the patient's position relative to the projected laser markers 73 and 75, i.e., the patient's position relative to the analysis zone 20b. The operator then manually repositions the patient on the bed by adjusting the bed's controls (not shown in FIGS. 3A and 3B) until the patient is in a suitable position for image acquisition. In one embodiment, two horizontal lasers 72 are provided, diagonally intersecting each other to define a horizontal marker segment. In this embodiment, two horizontal lasers project visual markers at opposite angles to each other along an inclined axis.

[0032] In some embodiments, in the analysis region 20b, the radiation detector 102 is positioned opposite the radiation source 21 and the collimator 76 to detect radiation that has passed through the region of the patient's body under examination. Upon receiving radiation, the radiation detector 102 converts the received radiation into corresponding electrical signals and forwards the signals to the control unit 30 at a particular frame rate. The received data signals are processed by the control unit 30 to obtain an image. How the radiation from the radiation source and the detection of radiation by the detector are controlled is described in detail below.

[0033] In one embodiment, the gantry 20 includes a gantry rotation device 40 (FIGS. 4A-4C) for rotating the radiation source 21 and the radiation detector 102 about an extension of the axis 20a, enabling the radiological image acquisition device 1 to perform a rotational scan of a portion of a patient positioned in the analysis region 20b (FIG. 1). In another embodiment, the gantry rotation device 40 rotates the radiation (X-ray) source 21 and the radiation detector 102 at high speed about the gantry bore axis 100 (FIG. 1) to acquire a volumetric scan of the patient. Using the gantry rotation device 40, high-speed rotation of the source and detector about the gantry bore axis 100 (i.e., extension axis 20a) can be achieved with high stability and minimal slippage.

[0034] In some embodiments, the gantry rotation device 40 includes a gantry source / detector ring 103 ( FIG. 4B ) to which the radiation sources 21 and radiation detectors 102 are attached, and a stationary ring (not shown) that connects the gantry source / detector ring 103 to the transport mechanism 25. In one embodiment, the gantry source / detector ring 103 can be cantilevered to the stationary ring.

[0035] The gantry rotation device 40 further includes a rotation motor 105 (or gantry shaft rotation motor) integrated with the stationary ring (FIGS. 4B-4C), a gearbox 106 (or gantry shaft rotation gearbox) driven by the motor 105, and a rotation bearing 107 (or gantry shaft rotation bearing) interposed between the rings. The rotation bearing 107 includes a low-friction bearing member and is connected to the gearbox 106. The rotation bearing 107, housed within the gantry 20, drives the rotation of the gantry source / detector ring 103 through rotational contact between the rotation bearing 107 and the gantry source / detector ring 103. In particular, the motor 105 drives the gearbox 106, which rotates the rotation bearing 107, thereby rotating the gantry source / detector ring 103 relative to the stationary ring through contact between these two members (in embodiments, a drive belt arrangement may be used). The operation of the motor 105 and the rotation bearing 107 is controlled by the control unit 30. In some embodiments, it is desirable to minimize slip between the rotational bearing 107 and the gantry source / detector ring 103 so that these two components rotate substantially synchronously and minimize loss of control of the rotation. In other embodiments, it is desirable to increase the amount of friction between the rotational bearing 107 and the gantry source / detector ring 103 to minimize slip between these components. The amount of friction can be achieved, for example, by fabricating these components from materials with a desired coefficient of friction or by applying various coatings or texturing to one or both of these components.

[0036] In one embodiment, the gantry 20 further includes a perforated laser track ring 108 (FIGS. 2A and 2D) integrated with the gantry source / detector ring 103 to record data regarding the rotation of the gantry source / detector ring 103 about the bore axis 100 of the gantry 20. As the gantry 20 rotates about the bore axis 100, laser emitters and detectors (not shown) are used to detect the apertures (e.g., uniformly and angularly spaced perforations spaced approximately 0.5 degrees apart) in the perforated laser track ring 108 to record data regarding the rotation of the gantry 20. By recording data regarding the rotation of the gantry 20, various software programs integrated into the control unit 30 can be used to monitor and analyze the orientation and velocity of the gantry source / detector ring 103, thereby reducing slip and potential errors in the rotation of the gantry 20. In another embodiment, detecting the apertures in the perforated laser track ring 108 can minimize slip between the rotation bearing 107 and the gantry source / detector ring 103.

[0037] In some embodiments, the rotational motion of the gantry source / detector ring 103 is controlled in a standard closed-loop manner, where as the gantry source / detector ring 103 rotates, the laser emitter / detector outputs a pulse each time an opening in the perforated laser track ring 108 is detected. To determine if a positioning error of the gantry source / detector ring 103 has occurred (e.g., due to motion slip), the desired rotational motion of the gantry source / detector ring 103 is defined as angle Θ.

[0038] The following is a method for minimizing slippage between the rotational bearings 107 of the gantry 20 and the gantry source / detector ring 103. The method begins by applying an accelerated rotation to the gantry of the device. The gantry is a device having a cavity into which the portion of the patient to be analyzed is inserted and suitable for performing radiographic imaging of the patient. The gantry contains a radiological imaging device with a radiation source that emits radiation, such as x-rays, under command-controlled motion. Once the gantry source / detector ring 103 reaches a certain rotational speed, pulses are continuously counted to track the actual angular position of the gantry source / detector ring 103 (represented by angle β). The actual angular position of the gantry source / detector ring 103 can be calculated from the following equation: β=Θ-α+Δ where Δ corresponds to a relatively small angle equivalent to several pulses. When the gantry source / detector ring 103 reaches angle β, it decelerates and stops by following the velocity curve used in the acceleration phase in the opposite direction. This ensures that the angular extent of this deceleration phase is substantially equal to α. In this embodiment, the final angular position of the gantry source / detector ring 103 during rotation is substantially equal to Θ + Δ. This is because Δ serves to ensure that the final number of pulses, if extra pulses are allowed, is equal to or greater than the desired number of pulses.

[0039] In another embodiment that minimizes slip between the rotational bearing 107 and the gantry source / detector ring 103, the values ​​of α, β, Θ, and Δ are defined in a similar manner. However, in this embodiment, a standard velocity loop is used. Furthermore, in this embodiment, a velocity shape (e.g., trapezoidal or S-shaped) is defined for the point-to-point motion of the gantry source / detector ring 103 from zero (0) to Θ, and the relationship between the angle β and the desired angular velocity is calculated. A counter is incremented for each detected pulse, allowing tracking of the angle β. When the counter reaches the desired angular velocity, i.e., β = Θ - α + Δ, and the last desired pulse is detected, the rotation of the gantry source / detector ring 103 is completely stopped. Therefore, in this embodiment, no extra stroke Δ is required to implement the method.

[0040] Detection of the apertures (i.e., perforations) in the perforated laser track ring 108 can also be used to drive emission of radiation via the radiation source 21. In particular, in one embodiment, detection of each aperture in the perforated laser track ring 108 via a laser emission / detector combination as the ring rotates about the bore axis 100 can drive emission of radiation via the radiation source 21. Alternatively, detection of every second, every third, every fourth, etc. aperture in the perforated laser track ring 108 via a laser emission / detector combination can drive emission of radiation via the radiation source 21.

[0041] In another embodiment, the emission of X-rays by the radiation source 21 and the acquisition of images by the radiation detector 102 of the radiation image acquisition device 1 are controlled according to the graph in FIG. 5. In this embodiment, an optical converter located at a fixed position on the gantry 20 outputs a precise signal (as shown in FIG. 5) depending on the required resolution relative to the mechanical position of the gantry source / detector ring 103. The precise signal provided by the optical converter is generated each time the optical converter detects an opening, or every second, third, etc., in the perforated laser track ring 108. The number of openings detected in the perforated laser track ring 108 depends on the desired resolution of the scanned image (e.g., 720 pulses per rotation). The signal from the optical converter is used as a trigger signal or flat panel trigger input, as shown in FIG. 5, to drive the acquisition of the radiation detector 102 (e.g., a flat panel sensor). This causes the radiation detector 102 to generate a dedicated signal, or X-ray enable (FIG. 5), indicating that the panel is ready for irradiation by the X-ray source.

[0042] Continuing with the embodiment with reference to FIG. 5, when the signal generated by the radiation detector 102 or X-ray enable (FIG. 5) goes high, the internal electronic circuitry of the radiation image acquisition device 1 drives the X-ray source or X-ray output of FIG. 5 to generate the desired exposure time. When the signal from the radiation detector 102 or X-ray enable (FIG. 5) goes low, the radiation detector 102 (e.g., a flat panel sensor) is not illuminated. If the detector is illuminated with this signal low (e.g., disabled), artifacts may appear in the acquired image, causing a degradation of image quality. Therefore, in this embodiment, the internal electronic circuitry of the radiation image acquisition device 1 is configured to prevent this degradation of image quality. However, while the above embodiment uses a single optical transducer, multiple optical transducers can be provided to optimize image scanning by the radiation image acquisition device 1. Furthermore, in another embodiment, the radiation detector 102 is not illuminated when the output signal goes high or low, thus changing, thereby achieving up to 1440 pulses per rotation.

[0043] The specific components and configuration of the gantry rotation device 40 in the above-described embodiments of the radiological image acquisition device 1 may be varied without departing from the spirit of the present invention. In alternative embodiments, for example, the gantry rotation device 40 may include at least one of horizontal or vertical wheels in guide tracks, a base with wheel seats for the gantry, treads, gears, an electric rotation motor, an air-separated, magnetically balanced, or lubricated contact ring, a direct drive motor, or a manually operated device. Additionally, a volumetric scan of the patient, or at least a portion of the patient, may alternatively be acquired, for example, using a scan tube (e.g., a CT scan tube) or a C-arm or robotic arm sensor and source mount.

[0044] Next, an embodiment of the radiation detector 102 is shown. In this embodiment, the radiation detector 102 includes at least one flat panel sensor 32f (shown in FIGS. 6A and 6B) that includes an array of pixels. Different positions of the flat panel sensor 32f (e.g., left, center, right) can be read. The flat panel sensor 32f is operable in multiple independent readout modes, including a matrix mode (FIG. 6A) and a linear sensor mode (FIG. 6B). The independent readout modes of the flat panel sensor 32f are selectable by the control unit 30. In this embodiment, operating the flat panel sensor 32f in the matrix mode is referred to as a first active configuration, and operating the flat panel sensor 32f in the linear sensor mode is referred to as a second active configuration of the radiation detector 102.

[0045] In a first active configuration (i.e., the matrix mode shown in FIG. 6A), flat panel sensor 32f outputs signals to control unit 30 corresponding to radiation detected by pixels within an area of ​​photosensitive surface 32g of flat panel sensor 32f (FIG. 6A). In this embodiment, photosensitive surface 32g has substantially the same extent as the entire array of pixels of flat panel sensor 32f. The matrix mode of the flat panel sensor is suitable for performing at least tomography and fluoroscopy.

[0046] In a second active configuration (i.e., linear sensor mode, as shown in FIG. 6B), the flat panel sensor 32f outputs signals to the control unit 30 corresponding to radiation detected by a subset of pixels within the area of ​​the photosensitive surface 32h of the flat panel sensor 32f (FIG. 6A). The photosensitive surface 32h of the flat panel sensor 32f effectively functions as a linear sensor. Specifically, in this embodiment, the photosensitive surface 32h has a frame rate ranging from approximately 10 to 300 frames per second, and its width is substantially greater than its length. In the illustrated example, the length of the photosensitive surface 32h is defined in a direction substantially parallel to the extension axis 20a, and the width of the photosensitive surface 32h is defined in a direction substantially perpendicular to the extension axis 20a and the central propagation axis 21a. Other configurations are possible in embodiments, such as a configuration in which the length and width of the photosensitive surface 32h are positioned at a defined angle (e.g., 90 degrees) relative to the extension axis 20a.

[0047] The second active configuration of the flat panel sensor 32f is useful for performing fan-beam tomography. Referring to FIG. 2B, fan-beam tomography can be performed by shaping radiation emitted from the radiation source 21 into a fan-shaped beam, for example, using a collimator 76. However, by selecting a portion (i.e., a subset) of the flat panel sensor 32f as the radiation-sensitive surface, the flat panel sensor 32f can operate in multiple modes. Furthermore, by selecting a subset of the flat panel sensor 32f as the radiation-sensitive surface, switching from fan-beam imaging to cone-beam imaging can be easily achieved without changing the operation of the radiation source 21 or physically replacing components of the radiographic image acquisition device 1. That is, for a cone-shaped radiation beam, operating the flat panel sensor 32f in a linear sensor mode results in a photosensitive surface 32h that is effectively sensitive only to the fan-shaped cross-section of the cone-shaped radiation beam. Therefore, when the radiation source 21 emits a cone-shaped radiation beam, cone-beam tomography can be performed using the control unit 30. For example, matrix mode and fan beam tomography of flat panel sensor 32f can be performed via control unit 30 by selecting, for example, linear sensor mode of flat panel sensor 32f.

[0048] The pixel array size of photosensitive surfaces 32g and 32h of flat panel sensor 32f can be predefined in the hardware, firmware, software, or other control means of flat panel sensor 32f. In one embodiment, flat panel sensor 32f can be a model operable in a matrix mode to provide photosensitive surface 32g with, for example, a 1096x888 or 2192x1776 pixel array. In such a case, the flat panel sensor can also be separately operated in a linear sensor mode to provide photosensitive surface 32h with, for example, a 1816x60 pixel array.

[0049] In some embodiments, the flat panel sensor 32f can be mounted to a panel motion system 35 including guides 34 and a motorized transport mechanism 36 (FIGS. 6A and 6B). The panel motion system 35 is adapted to move the flat panel sensor 32f along an axis 38 that is substantially perpendicular to both the extension axis 20a and the central axis of propagation 21a. In one embodiment, during a linear mode of operation of the panel sensor 32f, the axis 38 is held parallel to the width of the sensitive surface 32h of the panel sensor 32f.

[0050] Referring to FIG. 7, a process 700 for scanning at least a portion of a patient using the radiographic image acquisition device 1 will be described. In step 702, the radiographic image acquisition device 1 is initialized to perform the scanning process. Next, in step 704, the operator positions the patient on the bed. In some embodiments, the operator activates a laser positioning system (including laser 72 and laser 74 shown in FIGS. 3A and 3B ) to project a horizontal visual marker 73 to assist the operator in adjusting the height and tilt of the patient relative to the gantry 20. The laser positioning system can also project a top-down marker 75 to assist the operator in adjusting the patient laterally relative to the gantry 20.

[0051] Additionally, in step 704, the operator may operate the control unit 30 to specify imaging parameters, such as the region of the body to be scanned. In some embodiments, the operator enters patient information (e.g., species, weight, and / or tissue type to be imaged) into the control unit 30 and instructs the control unit 30 to automatically set the appropriate radiation dose based on the patient information.

[0052] Next, a scouting procedure is performed. As noted above, scouting generally involves acquiring preview or overview images for assessing the size, shape, and precise location of the region of diagnostic interest. The innovation in this regard in embodiments of the present disclosure is acquiring a series of images along the length of the patient region and then merging these images into a single scouting image in a geometrically reliable manner.

[0053] Figure 8A shows an example of a composite scouting image for a clinical animal patient. The scouting image is, in a sense, a flattened preview image of the portion of the patient being imaged. In this example, the composite image is formed from approximately 220 scouting images acquired over a 900 mm scouting acquisition (i.e., a scouting process with a linear gantry travel distance of 900 mm). From each individual scouting image formed over the 900 mm scouting acquisition, a section approximately 4 mm in the direction of linear gantry travel (i.e., approximately 4 mm in the direction of linear gantry travel) is extracted from the images used to generate the composite scouting image. The composite scouting image can be used, for example, to determine the number of stacks required to perform the desired CT acquisition.

[0054] Figure 8B shows a schematic diagram of a patient 800 and radiation beam fields (in this example, fan-shaped beams) 810a, 810b, 810c, and 810d at sequential positions along the patient's length. The beam fields overlap, allowing stitching to generate a full-length composite scouting image. Image stitching is the process of processing individual images to generate a single composite image using various computer vision and machine learning software tools, such as OpenCV (an open-source computer vision library). Collimating the beams reduces radiation dose and generates the final scouting image using only the useful portion of each image. In contrast, triangular region 810e represents the radiological exposure area of ​​an equivalent uncollimated cone beam.

[0055] Thus, referring to FIG. 7 , in step 706, the operator sets the start and end positions for the scouting acquisition. In step 708, the operator captures images to be stitched into the scouting image. To generate the images to be stitched, the gantry acquires images while moving linearly from the start position to the end position in a controlled manner along axis 100 (see FIG. 1 ). In an embodiment, the operator can stop image generation before reaching the end position. If the velocity is constant, images can be stitched based on the calculated distance traveled by the gantry. However, this method is ineffective when the gantry is accelerating or decelerating. Therefore, an alternative method for generating these images is to move the gantry in discrete motor steps. However, this method can significantly increase acquisition time.

[0056] In embodiments, the combined images may be generated by triggering the panel sensor and radiation source at a sequence of defined geometric positions, where images are acquired at the specified positions regardless of the acceleration and / or velocity of the gantry.

[0057] FIG. 8C illustrates a track 820, for example, located on the bottom surface of transport mechanism 25, with discrete steps or notches, for example, spaced 5 mm or 10 mm apart. Smaller or larger spacings can also be used, such as about 4 mm to about 6 mm or about 8 mm to about 12 mm. In an embodiment, track 820 is located near a component of the gantry linear motion system, such as linear bearing 830, which, in an embodiment, may be in the form of a ball-bearing screw. This arrangement generates trigger signals at known geometric locations on a portion of the gantry. The trigger signals allow images to be accurately acquired at these known locations. Images acquired in this manner are geometrically reliable, and therefore each pixel can be associated with a linear spatial location with a defined precision.

[0058] In step 710 (see FIG. 7), the operator selects the stack or beam thickness. Regarding stacks, the operator can specify the stack position and number. The number of stacks may be limited by the control unit to ensure a proper acquisition workflow, taking into account the system's technical specifications. Regarding beams and beam thickness, the operator can select cone beams or fan beams with different thicknesses. For example, beam thicknesses of 20 mm, 50 mm, or 100 mm may be selected, as well as other intervals. In embodiments, the system can suggest beam sizes based on patient information (such as species, imaging target, weight, or other characteristic information). Additionally, the system can suggest beam sizes based on the type of imaging task. For example, when imaging soft tissue objects, the system suggests a thinner beam because higher image contrast is required. As another example, when imaging hard tissue objects, a larger beam size is suggested because sufficient contrast already exists. The stack thickness is related to the beam thickness determined by the control unit. Generally, a beam wider than the capture range (the range that can be captured by the sensor) cannot be emitted. This is because the device is adapted to emit only the radiation necessary to obtain the desired image. In embodiments, the system may perform acquisitions that acquire multiple stacks. Further, in embodiments, the beam size and stack size may vary from one stack to another to acquire a desired target image with an optimal beam size for a particular patient.

[0059] In general, fan beams reduce dose and improve CT image quality. Using a fan beam improves image quality by reducing scattering artifacts that affect projection data. After the reconstruction process, this means that images acquired with a thinner beam have better soft tissue contrast, reduced coupling artifacts, and more reliable gray-level values ​​(i.e., Hounsfield Unit (HU) values).

[0060] To obtain better images, acquisition should be performed as quickly as possible to reduce motion artifacts and as frequently as possible to minimize scattering and improve geometric accuracy. An acquisition frequency of 24–28 Hz is appropriate for 2x2 scouting, while approximately 8 Hz is appropriate for 1x1 scouting and digital radiography (DR). 1x1 means treating each pixel on the flat panel as a single pixel (maximum resolution > data volume > reduced frame rate). On the other hand, 2x2 binning treats four pixels as a single unit, resulting in reduced resolution (data volume > increased frame rate). For 2x2 binning, for example, if 28 images can be acquired per second and the trigger interval is 5 mm, the acquisition speed can reach a maximum of 140 mm / s. In embodiments, binning other than the 1x1 and 2x2 described above is possible depending on the technical specifications and capabilities of the panel source couple and may change over time as technology advances. These speeds and frequencies are merely examples and are not intended to limit the invention. The beam should be as collimated as possible to reduce the radiation dose delivered to the patient. In another embodiment, if the patient moves, an audible alarm is emitted to alert the operator and / or the patient. The alarm is also displayed on the operator's monitor.

[0061] Once a scouting image is acquired, the operator or medical professional reviews it and determines whether another scouting image or a more detailed cross-sectional image should be acquired. Generally, scouting images can be acquired at any fixed rotation angle of the gantry. The operator may want to acquire this type of image at a specific angle depending on the patient's anatomy and the purpose of the imaging diagnosis. In some cases, images may be acquired at multiple angles to identify the exact location to scan. Displaying one or more images simultaneously helps the operator identify the exact location to scan.

[0062] In step 712, the operator begins acquiring CT images. Figures 9A and 9B illustrate the difference in beam width used in the images acquired during scouting and the CT image. In Figure 9A, the image acquired during scouting uses a narrow beam at a specific location (here, 910 mm). To achieve such a narrow beam, the collimator is closed, for example, about 20 mm (or, for example, in a range from about 15 mm to about 25 mm). In Figure 9B, the CT image uses a wider beam, capturing an area ranging from about 835 mm to about 985 mm, centered at the linear location (910 mm) in Figure 9A.

[0063] In step 714, the control unit 30, in response to the operator-specified imaging parameters described above, controls the gantry rotation device to rotate the source 21 and detector so as to align the central axis of propagation 21a with respect to the patient and / or bed. Furthermore, if the operator instructed the control unit 30 to automatically configure the radiological image acquisition device 1 to use an appropriate radiation dose in operation 704, the control unit 30 configures the source 21 and collimator 76 as necessary as described above to prepare to deliver such radiation dose. Once the central axis of propagation 21a reaches the desired tilt, the radiological image acquisition device 1 begins scanning in operation 716.

[0064] In step 716, during scanning of the patient's body, the gantry rotation device 40 rotates the gantry source / detector ring 103 so that the radiation source 21 and the radiation detectors 102 rotate together. This allows the radiation to scan the entire analysis region 20b being imaged. As the gantry source / detector ring 103 continues to rotate, the radiation source 21 emits radiation. After passing through the patient's body, this radiation is detected by the radiation detectors 102, which then send corresponding electrical signals to the control unit 30.

[0065] Operation 716 will now be described for the case where the radiation detector 102 includes a flat panel sensor 32f and a photosensor surface 32h operating in a linear sensor mode. During a scan, the radiation source 21 emits pulsed radiation that passes through the patient's body and strikes the photosensor surface 32h of the flat panel sensor 32f. As the gantry source / detector ring 103 rotates, the flat panel sensor 32f detects the radiation during the rotation and sends corresponding electrical signals to the control unit 30. The control unit 30 then receives signals for the entire imaged area and processes the signals to obtain an image of the scanned portion of the patient.

[0066] In one embodiment, one or more additional scans can be performed, as desired by the operator. For each additional scan, the gantry is moved along axis 100 by the gantry linear motion system to a new location. Further scanning procedures are then performed in a manner similar to that described above, i.e., the gantry source / detector ring 103 rotates while the radiation source 21 emits radiation and the flat panel sensor 32f continuously outputs signals to the control unit 30. In this manner, multiple scans can be obtained, each scan being as wide as the width of the photosurface 32h. The multiple scans are provided to the control unit 30 in operation 718 for graphical reconstruction.

[0067] In step 718, the control unit 30 performs a graphical reconstruction of the region to be imaged using the measurements made by the radiation detector 102. The multiple scans acquired by the flat panel sensor 32f in step 716 are reconstructed into a single overall image in a manner that minimizes edge effects in overlapping areas of the multiple images. The gantry linear motion system therefore enables the flat panel sensor 32f to provide an overall radiation image that is wider than the photosurface 32h. The process then proceeds to step 720, where it ends. The operator can repeat the entire process, or portions thereof, to acquire additional scans, if desired.

[0068] Other operations or sequences of operations for acquiring scouting images and CT images are contemplated in addition to the operations illustrated in Figure 7. Furthermore, the actual order of operations in the flowchart of Figure 7 is not limiting, and operations may be performed in any practical order.

[0069] In another embodiment, as shown in FIGS. 10 and 11 , the gantry includes a pole system 1100 containing one or more cameras 1110 that provide patient motion compensation during imaging procedures. Because some patients (e.g., horses) are large, the cameras can be obstructive when the patient enters and exits the gantry. The pole system 1100 is hinged and foldable, as shown in FIG. 11 , allowing the cameras to be moved away from the gantry to provide space for patient entry and exit (or for CT acquisition). Only one of the cameras needs to be moved; the other camera remains fixed and available for motion compensation. The pole system 1100 has a symmetrical structure and can be installed on the right or left side of the gantry depending on site limitations. The pole system 1100 can be constructed of carbon or other lightweight materials. In an embodiment, the pole system 1100 is adapted to minimize vibration and resonance by employing an overconstrained mechanical structure.

[0070] In another embodiment, as shown in Figures 12A and 12B, the radiological image acquisition device 1 includes a patient positioning system 1200. Such a system can include one or more patient supports 1210 (shown in detail in Figure 12B). The V-shaped configuration of these patient supports can immobilize the patient's head and support the patient to reduce movement. The patient support 1210 can include a recess 1220 to maintain its position on the bed.

[0071] Aspects of the present invention may be embodied in the form of a system, a computer program product, or a method. Likewise, aspects of the present invention may be embodied in hardware, software, or a combination of both. Aspects of the present invention may be embodied as a computer program product stored in the form of computer-readable program code recorded on one or more computer-readable mediums.

[0072] The computer-readable medium may be a computer-readable storage medium, which may be, for example, an electronic, optical, magnetic, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof.

[0073] The computer program code in embodiments of the present invention can be written in any suitable programming language. The program code can be executed on a single computer or on multiple computers. The computer can include a processing unit in communication with a computer-usable medium, the computer-usable medium including a set of instructions, the processing unit designed to execute the set of instructions.

[0074] The above discussion is intended to explain the principles and various embodiments of the present invention. Many variations and modifications will become apparent to those skilled in the art once the above disclosure is fully appreciated. It is intended that the following claims be interpreted to embrace all such variations and modifications.

Claims

1. 1. A method for acquiring a radiographic image of a portion of a patient, comprising: placing a patient within an analysis region; setting the imaging start position so that the part of the patient to be diagnosed is included between the imaging start position and the imaging end position; acquiring successive images from the imaging start position to the imaging end position using a radiation beam; combining the successive images to generate a composite scouting image; A method for acquiring a radiological image, comprising:

2. The radiation image acquiring method according to claim 1 , wherein the distance from the imaging start position to the imaging end position is about 8 mm to about 12 mm.

3. The radiation image acquiring method according to claim 1 , wherein the distance from the imaging start position to the imaging end position is about 4 mm to about 6 mm.

4. The method of claim 1 , wherein the radiation beam is cone-shaped.

5. The method of claim 1 , wherein the radiation beam is fan-shaped.

6. The radiographic image acquiring method according to claim 1 , wherein the imaging end position is set based on the imaging start position.

7. The radiographic image acquiring method according to claim 1 , wherein the imaging end position is determined when imaging is stopped by an operator.

8. The method of claim 1 further comprising the step of selecting a stack thickness or a radiation beam intensity.

9. 10. The method of claim 1 further comprising the step of acquiring a computed tomography image based at least in part on said composite scouting image.

10. The method of claim 1 , further comprising the step of performing surgery based on the composite scouting image.

11. The radiation image acquiring method according to claim 1 , wherein the composite scouting image is an image of the whole body of a patient.

12. The method of claim 1 , wherein the acquisition is performed using a gantry including a rotatable ring on which a light source generating a radiation beam and a detector are arranged, and the acquisition is performed at a defined rotation angle.

13. 13. The method of claim 12, wherein a plurality of composite scouting images are acquired at predetermined rotation angles.

14. 14. The method of claim 13, further comprising acquiring a computed tomography image based at least in part on the plurality of composite scouting images.

15. a gantry defining an analysis volume in which at least a portion of the patient is positioned; a radiation source that emits radiation that passes through at least a portion of the patient, the radiation defining a central axis of propagation; a detector that detects the radiation and generates a data signal based on the detected radiation; a gantry rotating ring on which the radiation source and the detector are mounted, and a rotation bearing for rotating the gantry rotating ring; a controller that continuously rotates the gantry rotating ring and the radiation source and the detector mounted on the gantry rotating ring to scan at least a portion of the patient while acquiring images from data signals continuously detected by the detector; a linear bearing for moving the gantry; a sensor system that triggers the capture of images at predetermined intervals as the gantry moves; A radiation image acquisition device comprising:

16. The radiation image acquisition device according to claim 15 , wherein the predetermined interval is from about 8 mm to about 12 mm.

17. The radiation image acquisition device according to claim 15 , wherein the predetermined interval is about 4 mm to about 6 mm.

18. 16. The radiographic image acquisition device of claim 15, further comprising a bed including a patient head support system.

19. 16. The radiographic image acquisition device of claim 15, further comprising a pole system attached to the gantry, the pole system including a plurality of cameras and foldable from the analysis region.

20. 16. The radiographic image acquisition device of claim 15, wherein the sensor system includes a laser track having discrete steps or notches spaced at predetermined intervals.

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