RADIOLOGICAL IMAGING DEVICE WITH IMPROVED SCOUTING FUNCTIONALITY

A radiological image is acquired of a part of a patient by positioning the patient within an analysis zone of the radiologic imaging device and setting an imaging start location. The part of the patient to be diagnosed is included between the start location and an end location. A series of images is acquired with a radiologic beam beginning at the start location and continuing until the end location is imaged. The images in the series of images are stitched together to form a composite scouting image.

BACKGROUND

A radiological imaging device may include a bed on which a patient is placed, a control station able to control the functioning of the device, and a gantry—a device with a cavity in which the portion of the patient to be analyzed is inserted and is suitable to perform the radiological imaging of the patient. Inside the gantry, the radiological imaging device includes a source suitable to emit radiation, such as X-rays, on command and a detector suitable to receive the radiation after it has traversed the portion of the patient to be analyzed. The device then sends a signal suitable to permit visualization of the internal anatomy of the patient. Sometimes, given the need to visualize specific parts of the body, it may be beneficial to first “scout” the area to be imaged. Scouting involves taking a preview or an overview image to assess the size and shape of the area to be diagnosed to plan a subsequent image acquisition.

SUMMARY

In one aspect, the disclosed embodiments provide a method to acquire a radiological image of a part of a patient. The method includes positioning the patient within an analysis zone and setting an imaging start location. The part of the patient to be diagnosed is included between the start location and an end location. The method further includes acquiring with a radiological beam a series of images beginning at the start location and continuing until the end location is imaged. The method further includes stitching together the images in the series of images to form a composite scouting image.

The pre-determined distance interval may be between about 8 mm and about 12 mm or between about 4 mm and about 6 mm. The radiological beam may be cone shaped or fan shaped. The end location may be set when the start location is set or may be determined when the acquiring is stopped by an operator. The method may further include selecting a thickness of a stack or a thickness of the radiological beam.

The method may further include acquiring a computed tomography image based at least in part on the composite scouting image. The method may further include performing a surgical procedure based on the scouting image. The scouting image may be of the whole body of the patient.

The acquiring may be performed using a gantry having a rotatable ring to which a source that produces the radiological beam and a detector are positioned, and the acquiring may be performed at a defined rotation angle. A plurality of composite scouting images may be acquired, each at respective defined rotation angle. The method may further include acquiring a computed tomography image based at least in part on the plurality of composite scouting images.

In another aspect, the disclosed embodiments provide a radiological imaging device including a gantry defining an analysis zone in which at least a part of a patient is placed. The device further includes a source suitable to emit radiation that passes through the at least part of the patient, the radiation defining a central axis of propagation. The device further includes a detector arranged to receive the radiation and to generate data signals based on the radiation received. The device further includes a gantry rotation apparatus that includes a ring to which the source and the detector are mounted and a rotational bearing member configured to rotate the ring. The device further includes a controller adapted to acquire an image from data signals received continuously from the detector while the gantry rotation apparatus continuously rotates the ring and the source emitting the radiation and the detector receiving the radiation that are mounted to the ring, so as to scan the at least part of the patient. The device further includes a translational mechanism that translates the gantry and a sensor system to trigger acquisition of images at a defined interval as the gantry translates.

The pre-determined distance interval may be between about 8 mm and about 12 mm or between about 4 mm and about 6 mm. The device may further include a bed including a patient head support system. The device may further include a pole system attached to the gantry, the pole system including cameras and capable of being folded out of the analysis zone. The sensor system may include a laser-tracked track with discrete steps or notches that are spaced according to said defined interval.

Where considered appropriate, reference numerals may be repeated among the drawings to indicate corresponding or analogous elements. Moreover, some of the blocks depicted in the drawings may be combined into a single function.

DETAILED DESCRIPTION

While imaging a patient, it may be beneficial to first “scout” the area to be imaged. Scouting involves taking a preview or an overview image to assess the size and shape of the area to be diagnosed to plan a subsequent image acquisition. A method for improved radiological imaging using scouting is described below. This method includes setting an imaging start location and an imaging end location, where the part of the patient to be diagnosed is included between the start and end locations. The method then acquires a series of images beginning at the start location and continuing a pre-determined distance interval until the end location is imaged and then stitches together the images to form a single scouting image. This improved scouting image can be used to plan more detailed imaging or a surgical procedure. This system overcomes the problems in prior art systems of scout images not being detailed or extensive enough. Furthermore, the embodiments disclosed herein overcome precision problems arising in other approaches due to deficiencies in mechanical precision and deformation problems arising in other approaches due to deficiencies in software processing.

Reference is now made toFIG.1, which is a three-dimensional perspective view of an embodiment of radiological imaging device1that performs long scouting and other tasks. Radiological imaging device1maybe used to perform two- and three-dimensional scans on a patient's body. Radiological imaging device1includes a gantry20having a housing99. Gantry20defines a preferred axis of extension20a(shown inFIG.2B). The gantry also includes a transportation mechanism25and a control unit30.

Control unit30is mounted on gantry20(as shown inFIGS.1,3A, and3B) and is capable of controlling gantry20by transferring data and command signals to gantry20using communication means. In some embodiments, control unit30maybe housed in a stand-alone unit (not shown) such as, for example, a workstation cart, or may be formed of multiple parts, such as a first part mounted on gantry20and a second part housed in a stand-alone unit. These examples are merely illustrative in nature, and, in other embodiments, control unit30maybe located at other positions and locations besides those described above.

Gantry20maybe mounted onto transportation mechanism25(e.g., a cart) in order to be transported to a desired location. In one embodiment, transportation mechanism25includes at least four wheels24that are mounted to transportation mechanism25via brackets22. In one preferred embodiment, brackets22are v-shaped (as shown inFIG.1) to accommodate wheels24of varying sizes, while still maintaining transportation mechanism25as close to the floor as possible. Moreover, the v-shaped brackets allow the diameter of each wheel24to be substantially equal or, preferably, substantially greater than the distance between transportation mechanism25and the floor, which helps to maintain a constant distance between transportation mechanism25and the floor. The distance between transportation mechanism25and the floor is typically small, thus allowing the size of gantry20to increase. However, a person skilled in the art would understand that any other suitable shape for brackets22and/or any other means of attaching wheels24to transportation mechanism25can be used as well.

FIG.2Ashows a more detailed, three-dimensional perspective view of gantry20and associated components of radiological imaging device1. Housing99of gantry20includes the various components used to perform the radiological scan. These components include a radiation source21(e.g., X-ray source) with a central axis of propagation21a(shown inFIG.2B), a radiation detector102that receives the radiation emitted by radiation source21. Gantry20further defines an analysis zone20bin which the patient's entire body or a particular body part to be imaged is placed during scanning. In some embodiments, gantry20also includes a laser positioning system that includes at least one horizontal laser72and one vertical laser74(FIGS.3A and3B).

Radiation source21emits radiation capable of traversing the patient's body and can interact with the tissues and fluids present inside the patient's body. In one embodiment, radiation source21emits ionizing radiation, more particularly, X-rays. In some embodiments, radiological imaging device1includes a collimator adjacent to radiation source21to constrain the radiation on radiation detector102and to modify the radiation field in order to adjust it to the position of radiation detector102.

FIG.2Bshows a more detailed, perspective view of radiation source21and its associated components. As mentioned above, collimator76, which is used to constrain the radiation on radiation detector102, includes an X-ray filter (not shown) positioned between radiation source21and radiation detector102, e.g., a bowtie filter. The X-ray filter modifies the shape of the radiation beam (e.g., X-ray) emitted from radiation source21in a direction of a central axis of propagation21a,which extends in a direction orthogonal to the plane of the figure and, therefore, is depicted as a point at the vertex of axes20aand38. Specifically, the X-ray filter modifies the energy of the emitted radiation along central axis of propagation21a,relative to outer edges of the radiation beam, by absorbing the low power X-rays near the outer edges of the radiation beam, thereby modifying the energy distribution of the emitted radiation along axes20aand38, prior to the X-rays traversing the patient. In one embodiment, the X-ray filter includes a sheet material (e.g., aluminum and/or copper sheet) of predetermined thickness suitable for absorbing the radiation. The thickness of the radiation-absorbing sheet is determined along central axis of propagation21a.

In another embodiment, a plurality of X-ray filters (not shown) may be stored at different locations in gantry20. Each X-ray filter of the plurality of X-ray filters differs from the others at least in terms of shape and may also differ in terms of the material (e.g., aluminum and/or copper) and/or the thickness of the sheet. Control unit30can cause a motorized mechanism (not shown) provided within gantry20to retrieve a selected X-ray filter (e.g., selected by control unit30in a manner to be described further herein below) from storage and position the selected X-ray filter in front of radiation source21.

In another embodiment, the radiological device operator inputs patient-specific information, for example, the types of imaging procedures (e.g., fluoroscopy, tomography, or radiography) to be performed on the patient, the species of the patient (e.g., human or animal), the patient's weight, tissue type to be imaged or the like, into control unit30. Based on the inputted information, control unit30automatically configures an optimal radiation dosage to be used on the patient by radiological imaging device1. Moreover, based on some predetermined relationships among the different patient specific information, control unit30determines the emission energy of the X-rays and/or the type of X-ray filter to be placed in front of radiation source21. Examples of such predetermined relationships are shown in the table ofFIG.2C, which are defined in accordance with lookup tables, conditional statement algorithms, and/or mathematical formulas implemented on control unit30. Accordingly, radiological imaging device1can perform the selected imaging procedure with an X-ray dosage that is safe for the patient, as well as the operator, while maintaining optimal image quality. The emission energy of the X-rays depends on parameters, such as X-ray tube voltage, X-ray tube current, and exposure time.

For example, control unit30can perform the aforementioned determination of X-ray emission energy and/or select an X-ray filter type based on predetermined relationships (e.g., defined in accordance with lookup table(s), conditional statement algorithm(s), and/or mathematical formula(s) implemented on control unit30, although these examples are not limiting) between the patient information, the radiological imaging procedure selected to be performed, the X-ray emission energy, and the materials and thicknesses of the X-ray filters available in the plurality of X-ray filters located inside the gantry. Examples of such predetermined relationships are shown in the table ofFIG.2C. By way of example and not of limitation, if while inputting the patient specific information in control unit30, an operator specifies that a high-resolution computed tomography (CT) scan is to be performed on hard tissues (e.g., the thorax region), control unit30can determine the operating parameters of radiation source21for such specification using a lookup table (for example,FIG.2C). Specifically, using the lookup table ofFIG.2C, control unit30can determine that the aforementioned input correlates to operating parameters for radiation source21of 100 kV and 60 mA for 5 ms, and for the X-ray filter with a 3 mm thick aluminum sheet and a 0.2 mm thick copper sheet. As another example, if an operator specifies (by way of control unit30) that high-resolution tomography is to be performed on soft tissues (e.g., an abdominal region), control unit30determines, via the lookup table ofFIG.2C, that the aforementioned input correlates to operating parameters for radiation source21of 60 kV and 60 mA for 10 ms and an X-ray filter with a 2-mm thick sheet of aluminum. Such variables can be adjusted depending on the target being scanned.

In yet another embodiment, radiation source21emits either a cone-shaped beam or a fan-shaped beam of radiation using collimator76, which can modify the beam shape. Collimator76, as shown inFIG.2B, includes at least two movable plates78, preferably, four movable plates, surrounding the area of X-ray emission and, therefore, substantially blocking the radiation. An operator can place movable plates78of collimator76in an open configuration, a slit configuration or in between those two configurations using a motorized mechanism (not shown) controlled by control unit30. The operator can also configure movable plates78along an axis of translation that is substantially perpendicular to central axis of propagation21aand substantially perpendicular or parallel to axis of extension20a,using the motorized mechanism controlled by control unit30.

In some embodiments, the motorized mechanism includes at least one independent motor for each movable plate78and an additional motor for the X-ray filter. When collimator76is configured in the open configuration, radiation from radiation source21is not blocked and travels along central axis of propagation21ain the shape of a cone (one of ordinary skill in the art would understand that the term “cone,” as used throughout the present description, broadly includes geometries having a circular or a non-circular base, e.g., square or rectangular). However, when collimator76is configured as a slit, a portion of the radiation of radiation source21is blocked, and thus the unblocked radiation propagates along central axis of propagation21ain the shape of a fan (i.e., a cross-section of the cone-shaped radiation) oriented in a plane perpendicular to axis of extension20a.Thus, in one embodiment, an operator may configure radiation source21to emit either a cone-shaped beam or a fan-shaped beam by virtue of collimator76, and perform different types of imaging with radiological imaging device1, for example, cone-beam tomography or fan-beam tomography, respectively.

In another embodiment, the shape of the beam of radiation emitted by radiation source21can be modified by positioning a filtering means (not shown) on top of radiation source21to affect the characteristics of the beam of radiation before it reaches the target. In particular, in one embodiment, radiation source21can emit radiation in a plurality of fan-shaped beams of radiation by using the filtering means. By using a plurality of fan-shaped beams, the image quality of the scanned image can be improved due to, inter alia, reduction of light scattering as compared to cone-shaped radiation emission. In yet another embodiment, the filtering means includes, for example, one or more filters, one or more grids, or an adjustable diaphragm. In addition, in another embodiment, the filtering means can include one more stackable filters or stackable grids. In some embodiments, the filtering means is movable. In embodiments, an anti-scatter grid may be positioned on the flat panel sensor, thereby affecting the characteristics of the received radiation after it has passed through the patient—but before it has reached the sensor.

In one embodiment, the laser positioning system, which includes horizontal laser72and vertical laser74(seeFIGS.3A and3B), is used in conjunction with an adjustable bed. The laser positioning system, when activated by control unit30, projects visual markers onto the patient in order to facilitate positioning of the patient on a bed within analysis zone20b.Further details can be found in U.S. Provisional Patent Application Nos. 61/932,034 and 61/944,956, which are incorporated herein by reference in their entireties.

Referring again to the drawings and more particularly toFIGS.3A and3B, which shows an embodiment of gantry20of radiological imaging device1. As mentioned above, the laser positioning system is mounted on gantry20and includes at least one horizontal laser72and/or at least one vertical laser74. Horizontal laser72projects horizontal visual markers73to aid the operator in adjusting the height and inclination of the patient, and vertical laser74projects a top-down marker75to aid the operator in adjusting the lateral centering of the patient with respect to gantry20. The operator adjusts the positioning of the patient by observing the position of the patient with respect to projected laser markers73and75, and thus with respect to analysis zone20b.The operator then manually repositions the patient on the bed by adjusting controls of the bed (not shown inFIGS.3A and3B) until the patient is in the correct position for imaging. In one embodiment, two mutually oblique horizontal lasers72are provided in order to reciprocally intersect and define a horizontal marker segment. In the embodiment, the two horizontal lasers project visual markers at opposite angles to each other along an inclined axis.

In some embodiments, in analysis zone20bradiation detector102is located opposite radiation source21and collimator76to detect radiation once it has traversed the portion of the patient's body to be examined. Once the radiation is received, radiation detector102converts the received radiation into equivalent electrical signals and transfers the signal to control unit30at a particular frame rate. Once received, control unit30processes the data signals to acquire images. One method of controlling the emission of radiation by the source and the detection of the radiation by the detector will be described more fully below.

In one embodiment, gantry20includes a gantry rotation apparatus40(FIGS.4A-4C) to rotate radiation source21and radiation detector102together around axis of extension20ato allow radiological imaging device1to perform a rotational scan of the portion of the patient that has been placed in analysis zone20b(FIG.1). In another embodiment, gantry rotation apparatus40rotates radiation (X-ray) source21and radiation detector102rapidly around the axis100of the bore of the gantry (FIG.1) to obtain a volumetric scan of a patient. The rapid rotation of the source and the receiving device about bore axis100of the gantry (namely, axis of extension20a) using gantry rotation apparatus40, can be accomplished with great stability while minimizing slippage.

In some embodiments, gantry rotation apparatus40includes a gantry source/detector ring103(FIG.4B) to which radiation source21and radiation detector102are mounted, and a static ring (not shown) connecting gantry source/detector103ring to transportation mechanism25. In one embodiment, gantry source/detector ring103can be attached to the static ring in a cantilever manner.

Gantry rotation apparatus40further includes a rotational motor105or gantry axis rotation motor (FIGS.4B-4C) that is integral with the static ring, a gearbox106or gantry axis rotation gearbox that is driven by motor105, and a rotational bearing107or gantry axis rotation bearing interposed between the rings. Rotational bearing107includes a low-slip bearing member and is connected to gearbox106. Rotational bearing107, which is housed inside of gantry20, drives the rotation of gantry source/detector ring103via a rotational contact of rotational bearing107to gantry source/detector ring103. In particular, motor105drives gearbox106, which in turn rotates rotational bearing107, which thus rotates, with respect to the static ring, gantry source/detector ring103through contact between these two members (in embodiments, a drive belt arrangement may be used). Operation of motor105and, thus, rotational bearing107can be controlled by control unit30. In some embodiments, it is preferred to minimize slippage between rotational bearing107and gantry source/detector ring103, such that these two members rotate substantially in unison, and the loss of control over the rotation is minimized. In some other embodiments, the amount of friction between rotational bearing107and gantry source/detector ring103is desired to be increased in order to minimize the slippage between these members. The amount of friction can be increased by, for example, producing these members out of materials having desired coefficients of friction or by adding various coatings or texturing to one or both of these members to achieve a desired coefficient of friction.

In one embodiment, gantry20further includes a perforated, laser-tracked ring108(FIGS.2A and2D) integrated with gantry source/detector ring103that records data relating to rotation of gantry source/detector ring103about bore axis100of gantry20. A laser emitter and a detector (not shown) that detects openings (e.g., perforations uniformly and angularly spaced, e.g., by about 0.5 degrees) in the perforated, laser-tracked ring108as the ring rotates around bore axis100are used to record data relating to the rotation of gantry20. By recording the data relating to the rotation of gantry20, both the orientation and the speed of gantry source/detector ring103can be monitored and analyzed using various software embedded in control unit30, which in turn can reduce slippage and potential errors in the rotation of gantry20. In another embodiment, by detecting the openings in perforated, laser-tracked ring108, the slippage between rotational bearing107and gantry source/detector ring103can be minimized.

In some embodiments, the rotational motion of gantry source/detector ring103is controlled by a standard closed-loop method. In this closed loop method, as gantry source/detector ring103rotates, the laser emitter/detector provides pulses as the openings in perforated, laser-tracked ring108are detected. In order to determine whether an error in the positioning of the gantry source/detector ring103has occurred due to, for example, motion slippage, the desired motion of rotation of gantry source/detector ring103is defined as an angle ⊖.

Following is a method to minimize slippage between rotational bearing107and gantry source/detector ring103of gantry20. The method starts with applying accelerating rotation on gantry source/detector ring103until gantry source/detector ring103reaches a desired velocity (with any suitable velocity shape). As gantry source/detector ring103accelerates up to the desired velocity, pulses are counted in order to compute the real or actual angular span or displacement (α), which occurs during the accelerated motion. Once gantry source/detector ring103reaches a constant velocity of rotation, the pulses are continuously counted in order to track the real angular position (given by angle β) of gantry source/detector ring103. The real angular position of gantry source/detector ring103can be calculated from the following formula:

β=⊖−α+Δ,where Δ corresponds to a relatively small angle equivalent to a few pulses. Once gantry source/detector ring103reaches the angular position of β, it is subjected to a deceleration to bring it to a stop following the velocity curve used in the acceleration phase in reverse, so that the angular span during this deceleration phase is substantially equal to α. In this embodiment, the final angular position of gantry source/detector ring103is substantially equal to ⊖+Δ during rotation, since the role of Δ is to ensure that the final number of pulses is at least equal to the desired number of pulses, given that an extra pulse is acceptable.

In another embodiment of minimizing slippage between rotational bearing107and gantry source/detector ring103, the values of α, β, ⊖, and Δ are defined in the same manner. However, in this embodiment, a standard velocity loop is used. Moreover, in this embodiment, a velocity shape is defined (e.g., trapezoidal or S-shaped) for the point-to-point motion of gantry source/detector ring103from zero (0) to ⊖, and a relationship between angle β and the desired angular velocity is computed. For each detected pulse, a counter is incremented, allowing for the tracking of angle β. Once the counter reaches the desired angular velocity, i.e., β=⊖−α+Δ, such that the last desired pulse is detected, the rotation of gantry source/detector ring103is definitively stopped. Thus, in this embodiment, the extra stroke Δ is not needed to implement the method.

The detecting of the openings (i.e., perforations) in perforated, laser-tracked ring108can also be used to drive the emission of the radiation via radiation source21. In particular, in one embodiment, the detection of each opening in perforated, laser-tracked ring108via the laser emitter/detector combination as the ring rotates around bore axis100can be used to drive the emission of the radiation via radiation source21. Alternatively, detecting every other opening, or every third opening, or every fourth opening, etc., in perforated, laser-tracked ring108via the laser emitter/detector combination can be used to drive the emission of the radiation via radiation source21.

According to another embodiment, the emission of X-rays by radiation source21and the acquisition of images via radiation detector102of radiological imaging device1are controlled according to the graph ofFIG.5. In this embodiment, an optical transducer, provided on a fixed position of gantry20, gives an accurate signal (as shown inFIG.5) for each mechanical position of gantry source/detector ring103with respect to the required resolution. The accurate signal provided by the optical transducer is generated as each opening, or every other opening, or every third opening, etc. in perforated, laser-tracked ring108is detected via the optical transducer. The number of openings detected in perforated, laser-tracked ring108depends upon the desired resolution of the scanned images (e.g., 720 pulses per revolution). The signal from the optical transducer is used to generate a trigger signal or Flat Panel Trigger Input, as shown inFIG.5, to drive radiation detector102(e.g., the flat panel sensor) acquisition. Accordingly, radiation detector102generates a dedicated signal or the X-Ray Enable (inFIG.5) to indicate that the panel is ready to be irradiated by the X-ray source.

Continuing with the embodiment with respect toFIG.5, when the signal generated by radiation detector102or the X-Ray Enable (inFIG.5) goes high, the internal electronics circuitry of radiological imaging device1drives the X-Ray source or the X-Ray Output inFIG.5to produce an irradiation of the desired duration. In the event that the signal from radiation detector102or the X-Ray Enable (inFIG.5) goes low, radiation detector102(e.g., the flat panel sensor) should no longer be irradiated. Irradiation of the detector when this signal is low (e.g., disabled) lead to artifacts in the acquired images, which in turn can lead to poor image quality. Accordingly, in this embodiment, the internal electronics circuitry of radiological imaging device1prevents it from producing poor quality images. Although, the embodiment described above utilizes a single optical transducer, multiple optical transducers can be provided in order to optimize the scanning of images by radiological imaging device1. Furthermore, in yet another embodiment, radiation detector102shall no longer be irradiated when the output signal gets high or low and, therefore, changes, in order to have up to1440pulses per revolution.

The specific components and configuration of gantry rotation apparatus40of the embodiment of radiological imaging device1, as discussed above, can be altered without departing from the spirit of the invention. In another embodiment, for example, gantry rotation apparatus40can include at least one of horizontal or vertical wheels in a guide track, a base with a wheel seat for the gantry, treads, gears, an electric rotational motor, air-separated, magnetically-balanced or lubricated contacting rings, direct-drive motors, or manual manipulation. Moreover, a volumetric scan of the patient or at least a portion of the patient can alternatively be obtained, for example, by way of a scanning tube (e.g., CT scanning tube) or by using C-arm or robotic arm sensors and source mounts.

Next is an embodiment of radiation detector102. In this embodiment, radiation detector102includes at least one flat panel sensor32f(as shown inFIGS.6A and6B) that includes an array of pixels. Different positions of flat panel sensor32f(e.g., left, middle, right) may be read. Flat panel sensor32fis capable of operating in multiple independent read-out modes, including a matrix mode (FIG.6A) and a linear sensor mode (FIG.6B). The independent read-out modes of flat panel sensor32fare selectable by control unit30. In this embodiment, operating flat panel sensor32fin the matrix mode is referred to as the first active configuration, and operating flat panel sensor32fin the linear sensor mode is referred to as the second active configuration of radiation detector102, respectively.

In the first active configuration (i.e., the matrix mode, as shown inFIG.6A), flat panel sensor32foutputs signals to control unit30corresponding to the radiation detected by the pixels in a region of sensitive surface32gof flat panel sensor32f(FIG.6A). In one embodiment herein, sensitive surface32gis substantially coextensive with the entire array of pixels of flat panel sensor32f.The matrix mode of the flat panel sensor is suitable for performing at least tomography and fluoroscopy.

In the second active configuration (i.e., linear sensor mode, as shown inFIG.6B), flat panel sensor32foutputs signals to control unit30corresponding to the radiation detected by the subset of pixels in a region of sensitive surface32hof flat panel sensor32f(FIG.6A). Sensitive surface32hof flat panel sensor32ffunctions effectively as a linear sensor. Specifically, in this embodiment, sensitive surface32hhas a frame rate in the range of approximately 10 to 300 frames per second and a width that is substantially greater than its length. In the example depicted, the length of sensitive surface32his defined in a direction substantially parallel to axis of extension20a,wherein the width of sensitive surface32his defined in a direction substantially perpendicular to axis of extension20aand central axis of propagation21a.In embodiments, other configurations are possible, such as having the length and width of the sensitive surface32horiented at a defined angle, e.g., 90 degrees, relative to the axis of extension20a.

The second active configuration of flat panel sensor32fis useful for performing fan beam tomography. As described with reference toFIG.2B, fan beam tomography can be performed by shaping the radiation emitted by radiation source21into a fan-shaped beam using, for example, collimator76. However, by selecting a portion (i.e., a subset) of flat panel sensor32fas a radiation sensitive surface, flat panel sensor32fcan operate in multiple modes. Moreover, switching from fan beam imaging to cone beam imaging can be easily achieved by selecting a subset of flat panel sensor32fas a radiation-sensitive surface, without altering the operation of radiation source21or physically interchanging any components of radiological imaging device1. That is, for a cone-shaped beam of radiation, operating flat panel sensor32fin the linear sensor mode will provide sensitive surface32hthat is effectively sensitive only to a fan-shaped cross-section of the cone-shaped beam of radiation. Accordingly, when the radiation source21emits a cone-shaped beam of radiation, cone beam tomography can be performed using control unit30. For example, the matrix mode of flat panel sensor32fand fan beam tomography can be performed by selecting via control unit30, for example, the linear sensor mode of flat panel sensor32f.

The pixel array size of sensitive surfaces32gand32hof flat panel sensor32fcan be predefined in hardware, firmware, software, or other control means of the panel sensor32f.In one embodiment, flat panel sensor32fmay be a model which can operate in a matrix mode that provides a sensitive surface32ghaving, e.g., a 1096×888 or a 2192×1776 array of pixels. In such a case, the flat panel sensor may also separately operate in a linear sensor mode that provides a sensitive surface32h, having, e.g., an 1816×60 array of pixels.

In some embodiments, flat panel sensor32fcan be mounted on a panel motion system35that includes guides34and a motorized transportation mechanism36(FIGS.6A and6B). Panel motion system35is suitable for moving flat panel sensor32falong an axis38, which is substantially perpendicular to both axis of extension20aand central axis of propagation21a.In one embodiment, during the linear mode of operation of the panel sensor32f,axis38remains parallel to the width of the sensitive surface32hof the panel sensor32f.

A process700of scanning at least a portion of a patient using radiological imaging device1will now be described with reference toFIG.7. In operation702, radiological imaging device1initializes itself to perform the scanning process. Next, in operation704, the operator positions the patient on a bed. In some embodiments, the operator may activate the laser positioning system (including lasers72and74, as shown inFIGS.3A and3B), which projects horizontal visual markers73to assist the operator in adjusting the height and inclination of the patient in reference to gantry20. The laser positioning system may also project a top-down marker75to assist the operator in laterally adjusting the patient in reference to gantry20.

Additionally, in operation704, the operator may operate control unit30to specify imaging parameters, such as the portion of the body on which to perform a scan. In some embodiments, the operator also inputs patient information (e.g., species, weight, and/or tissue type to be imaged) to control unit30and commands control unit30to automatically configure radiological imaging device1to select the appropriate radiation dose based on the patient information.

Next, the scouting procedure is performed. As mentioned above, scouting generally involves taking a preview or an overview image to assess the size, shape, and exact placement of the area to be diagnosed. The innovation in this aspect of the disclosed embodiments is to take a series of images along the length of an area of a patient and then merge the images into a single scouting image in a geometrically reliable way.

FIG.8Ashows an example of a composite scouting image for a clinical animal patient. The scouting image is, in a sense, a flat preview of a portion of the patient to be imaged. In this example, the composite image is formed from about 220 scouting images acquired a 900 mm scouting acquisition, i.e., a scouting process in which the distance of the linear movement of the gantry is 900 mm. From each individual scouting image formed along the 900 mm scouting acquisition, a portion of about 4 mm (i.e., about 4 mm in the direction of linear movement of the gantry) is taken from the image to be used to produce the composite scouting image. The composite scouting image may be used to determine, inter alia, the number of stacks required to perform a desired CT acquisition.

FIG.8Bshows a patient800and schematic drawing of the radiological beam fields (in this example, a fan-shaped beam)810a,810b,810c,810dat successive locations along the length of the patient. The beam fields overlap, allowing a full-length composite scouting image to be generated via stitching. Stitching of the images involves processing the separate images using various available computer vision and machine learning software tools, e.g., OpenCV (Open Source Computer Vision Library), to produce a single composite image. Collimating the beam allows the radiation dose to be reduced so that only the useful part of each image is used to generate the final scouting image. In contrast, the triangular region810erepresents a radiologic field of an equivalent uncollimated cone beam.

Accordingly, referring again toFIG.7, in operation706, the operator sets the start and end locations for the scouting acquisition. In operation708, the operator acquires the images to be stitched into the scouting image. To generate the images to be stitched, the gantry is advanced linearly, in a direction of axis100(seeFIG.1), in a controlled manner from the start location to the end location while the images are being taken. In embodiments, the generation of the images can be stopped by the operator before the end location is reached. If the speed is constant, then the images can be stitched based on the calculated distance the gantry has traveled. This method does not work as well if the gantry is accelerating or decelerating, so another way to generate these images is by advancing the gantry by discrete motor steps—although this may significantly increase acquisition time.

In embodiments, the images to be stitched together may be generated by triggering the panel sensor and the radiation source at a series of defined geometric positions, in which case the images may be acquired at specified position regardless of the acceleration and/or speed of the gantry.

FIG.8Cshows a track820positioned, e.g., on the underside of the transportation mechanism25, with discrete steps or notches that are spaced, for example, 5 mm or 10 mm apart. Smaller or larger intervals may also be used, such as about 4 mm to about 6 mm or about 8 mm to about 12 mm. In embodiments, the track820is positioned in proximity to components of the gantry linear motion system, such as the linear bearing830, which, in embodiments, may be in the form of a ball bearing screw. Such an arrangement allows a trigger signal to be produced at known geometric positions of the gantry. The trigger signal allows images to be acquired precisely at these known positions. The images obtained in this manner are geometrically reliable and, consequently, each pixel can be related to a linear spatial position with a defined precision.

In operation710(seeFIG.7), the operator selects the stacks or beam thickness. Regarding the stacks, the operator can select the position and number of stacks. The number of stacks can be limited by the control unit to ensure proper acquisition workflows, taking into account the technical specifications of the system. Regarding beams and beam thickness, the operator can select a cone beam of varying thickness or a fan beam. For example, beam thicknesses of 20 mm, 50 mm, or 100 mm can be selected—other intervals may also be used. In embodiments, a beam size can be suggested by the system based on patient information, such as species, imaging target, weight, or other characterizing information. Furthermore, a beam size can be suggested by the system based on the type of imaging task. For example, if a soft-tissue target is being imaged, more image contrast is needed, so a thinner beam is suggested by the system. As a further example, if a hard tissue target is being imaged, then enough contrast is already present and therefore a larger beam size is suggested. Stack thickness is related to beam thickness as determined by the control unit. In general, it is not possible to emit a wider beam than the acquired one, i.e., wider than can be captured by the sensor, because the machine is adapted to emit only the radiation needed to achieve the desired images. In embodiments, the system can perform an acquisition in which multiple stacks are acquired. Furthermore, in embodiments, the size of the beam and of the stacks may vary between one stack and the others to acquire the desired target image with optimal beam size for a particular patient.

In general, a fan beam will reduce the dose and improve CT image quality. Image quality is improved using a fan beam due to reduced scatter artifacts that affect projection data. After the reconstruction process, this means that images acquired with a thinner beam have improved soft-tissue contrast, reduced cupping artifacts, and more reliable gray level values, i.e., Hounsfield unit (HU) values.

To obtain better images, the acquisition should be performed as fast as possible to reduce movement artifacts and at the highest frequency as possible to obtain the most collimated images with less scatter and better geometry. Acquisition frequency may be between 24 and 28 Hz for 2×2 scouting, and approximately 8 Hz for 1×1 scouting and digital radiography (DR). 1×1 means that each pixel in the flat panel is considered as a single pixel (maximum resolution>more data>slower frame rate). In binning 2×2 instead, 4 pixels are considered as an entity, therefore you have less resolution (>less data>higher frame rate) For the 2×2 scouting, this means that, for example, 28 images can be acquired each second and therefore the acquisition speed could be up to 140 mm/s for a triggering interspace of 5 mm. In embodiments, scouting other than the 1×1 and 2×2 discussed above, may be implemented depending on the technical specifications and capabilities of the panel source couple, and this may vary over time as technologies improve. These speeds and frequencies are merely examples and do not serve to limit the invention. To reduce the amount of radiation being emitted to the patient, the beam should be as collimated as possible. In another embodiment, if the patient moves, a sound may be emitted alerting the operator and/or the patient. An alert may also be shown on the operator's monitor.

Once the scouting image is acquired, an operator or healthcare provider will review the scouting image and determine if another scouting image is needed or if a more detailed tomographic image should be taken. In general, scouting images can be acquired at any fixed rotation angle of the gantry. Operators may want to acquire this type of image at a specific angle based on the anatomy of the patient and the imaging objective. In some cases, a number of angles may be acquired to better find the exact position to be scanned. One or more images can be shown together to help the operator to find out the exact position to be scanned.

In operation712, the operator begins to acquire the CT image.FIGS.9A and9Billustrate the difference in beam width used for an image acquired during scouting versus a CT image. InFIG.9A, the image taken during scouting uses a narrow beam at a specific location—here it is shown as 910 mm. The collimator is closed to achieve such a narrow beam, e.g., about 20 mm (or, e.g., in a range of about 15 mm to about 25 mm). InFIG.9B, the CT image uses a wider beam and images a field of about 150 mm, centered around the linear position (910 mm) ofFIG.9A, which would be between about 835 mm and about 985 mm.

In operation714control unit30responds to the aforementioned operator-specified imaging parameters and controls the gantry rotation apparatus, so as to rotate source21and the detector in order to orient central axis of propagation21ain relation to the patient and/or bed. Moreover, if the operator commands control unit30to automatically configure radiological imaging device1to use an appropriate radiation dose in operation704, control unit30configures source21and collimator76, if necessary, in the manner described above, so as to be prepared to provide such a dose. Once central axis of propagation21ahas reached the desired inclination, radiological imaging device1starts scanning at operation716.

In operation716, during scanning of the patient's body, gantry rotation apparatus40rotates gantry source/detector ring103so that radiation source21and radiation detector102rotate together, thereby permitting the radiation to scan the entire analysis zone20bto be imaged. As the rotation of gantry source/detector ring103continues, radiation source21emits radiation. Such radiation, after traversing the patient's body, is detected by radiation detector102, which in turn sends a corresponding electrical signal to control unit30.

The manner in which operation716is performed in a case in which radiation detector102includes a flat panel sensor32foperating in a linear sensor mode with sensitive surface32hwill now be described. During a scan, radiation source21emits pulsed radiation, which traverses the patient's body and hits sensitive surface32hof flat panel sensor32f.As gantry source/detector ring103rotates, flat panel sensor32fdetects radiation during such rotation and sends corresponding electrical signals to control unit30. Accordingly, control unit30receives a signal for the entire zone imaged and processes the signal to acquire an image of the scanned part of the patient.

In one embodiment, if desired by the operator, one or more additional scans may be performed. For each additional scan, the gantry can be translated along axis100by the gantry linear motion system to a new position. Next, a further scanning procedure is performed in the manner described above, that is, gantry source/detector ring103is rotated while radiation source21emits radiation and flat panel sensor32fcontinuously outputs a signal to control unit30. In this manner, a plurality of scans can be acquired, each scan being as wide as the sensitive surface32h.The plurality of scans is then provided to control unit30for graphic reconstruction at operation718.

In operation718, control unit30carries out the graphic reconstruction of the zone being imaged using the readings performed by radiation detector102. The plurality of scans acquired in operation716by flat panel sensor32fcan be reconstructed into one overall image in a manner that minimizes edge effects in overlapping regions of the plurality of images. Thus, by virtue of the gantry linear motion system, flat panel sensor32fcan provide an overall radiological image that is wider than sensitive surface32h.The process then continues to operation720and ends. The operator may repeat the process or a portion thereof to acquire additional scans, as desired.

Besides the operations shown inFIG.7, other operations or series of operations are contemplated to acquire scouting and CT images. Moreover, the actual order of the operations in the flowchart inFIG.7is not intended to be limiting, and the operations may be performed in any practical order.

In another embodiment, shown inFIGS.10and11, the gantry includes a pole system1100that includes one or more cameras1110that provide motion compensation for the patient during an imaging procedure. Because some patients (e.g., horses) are large, the cameras may get in the way of the patient entering or exiting the gantry. Pole system1100is hinged and foldable, as shown inFIG.11, so that the camera can be moved out of the way of the gantry providing more space for the patient's entry and exit (or to perform a CT acquisition). Only one of the cameras needs to be moved, so the other camera can remain stationary and can be used for motion correction. Pole system1100maybe symmetrical, allowing it to be mounted on the right or left side of the gantry depending on specific site restrictions. Pole system1100maybe made of carbon or other lightweight material. In embodiments, the pole system1100is adapted to minimize oscillations and resonance by using an over-constrained mechanical configuration.

In another embodiment, shown inFIGS.12A and12B, radiological imaging device1includes a patient positioning system1200. Such a system may include one or more patient supports1210(shown in detail inFIG.12B). The v-shape of these patient supports allows the head to be held in place to contain the patient and reduce motion. Patient support1210may include a recess1220that allows it to be held in position on the bed.

Aspects of the present invention may be embodied in the form of a system, a computer program product, or a method. Similarly, aspects of the present invention may be embodied as hardware, software, or a combination of both. Aspects of the present invention may be embodied as a computer program product saved on one or more computer-readable media in the form of computer-readable program code embodied thereon.

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

Computer program code in embodiments of the present invention may be written in any suitable programming language. The program code may execute on a single computer or on a plurality of computers. The computer may include a processing unit in communication with a computer-usable medium, where the computer-usable medium contains a set of instructions, and where the processing unit is designed to carry out the set of instructions.