JP2005261946A - Guidance mechanism for positioning subject in imaging collecting beam - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To position manually a table for supporting a patient in a medical imaging device. <P>SOLUTION: A medical imaging assembly has a radiation sensor (250), a supporting body (200), the table (100) for supporting the patient, and can determine a relative movement of the table/the sensor to set a region-of-interest area (350) to the center (45) of the collection beam (400) by displaying the position of the region-of-interest area. Data processing starts from one image irradiation, and other geometric factors (455 and 800) passing through the region-of-interest area are considered by using a geometric straight line (450) passing through the region-of-interest area, and next, the intersection positions of this straight line and the other geometric factors are found at three-dimension to position the region-of-interest area. The data processing calculates the relative movement of the table (100)/the sensor (250), which are necessary to place the region-of-interest area to the center (458) of the collection beam (400) moved newly, based on this geometric position of the region-of-interest area. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to an object positioning guidance mechanism in an imaging collection beam. Specifically, embodiments of the present invention relate to medical imaging devices and manual positioning of a table that supports a patient whose images are to be captured using such devices.

Health care workers face daily difficulties in this regard, particularly with respect to imaging portals that can move according to several degrees of freedom around a movable table. The difficulty is mainly to focus the collection beam on the specific point where the image is needed, such as the heart or coronary artery in the case of cardiac imaging. Apart from issues of work comfort, healthcare professionals can also reduce the application of radiation doses (mainly x-rays) to patients and, in some cases, the dose of contrast agents injected into the body. I am only interested in that.

  In modern practice, a healthcare professional moves the image sensor and collection portal from one image sampling position (projection) to the next. This means that the table itself must be moved. At the required location, the healthcare worker moves the region of interest to the center of the collection beam. This centering takes place, i.e. after a small number of required images have been taken for this, e.g. by fluoroscopy, the medical worker injects a contrast agent to collect the required images.

  This centering operation is very redundant. In a normal table, only longitudinal, lateral and vertical movements are mechanically possible. Since acquisition is usually performed obliquely from the table, it is necessary to repeatedly search for each of these three degrees of freedom to reach the final position, which is the center of the acquisition beam. Thus, health care workers need to focus on this procedure, but need to be able to focus on other situations as well, especially on the patient.

  U.S. Pat. No. 4,633,494 discloses a positioning assist device by placing a point in the center of an image. After the health care worker places this point, the device displays the movement of the table to be moved. However, these means apply to devices in which the sensor is only placed completely vertically on the table, and two degrees of freedom, the longitudinal and lateral translation of the table, are driven against this centering. In other words, it must be driven in a direction that is necessarily perpendicular to the axis of the sensor.

  In currently used medical imaging, the acquisition is typically tilted with respect to the surface of the table. As a result, it is necessary to move the table in a manner that is not completely orthogonal to the beam. This causes the required image to change as the distance to the sensor is changed, and this change has a significant geometric effect on the image. Therefore, it is difficult to set such a correction method in the case of oblique collection.

There is also a unique problem with existing “spin” techniques, ie collections that are performed automatically and continuously by movement of the collection portal. In this case, the imaging region (eg, heart) must generally be located at the geometric isocenter of the collection device so that the heart is located at the center of the beam regardless of the position of the device. In rotation collection, the isocenter is the point at the intersection of the three rotation axes of the portal. The isocenter projection is therefore always very close to the center of the image. Currently, the heart is positioned at the isocenter and then moved forward of the table by performing continuous lateral positioning and then performing fluoroscopic acquisition to adjust the longitudinal and vertical position of the table. Perspective collection is performed, and the horizontal position of the table is adjusted at this time. These operations are time consuming and require a large amount of ionization for the patient.
U.S. Pat. No. 4,633,494

  Embodiments of the present invention seek to overcome the various drawbacks described above, ie, generally to facilitate centering of the imaging area facing the medical imaging sensor.

  Embodiments of the present invention include a radiation sensor, a means for supporting the sensor, a means for supporting a subject to be imaged, and a means for generating relative movement between the sensor support means and the subject support means. And a data processing means capable of determining relative movement of the table / sensor such that the region of interest is in the center of the collection beam by display of the location of the region of interest. In an embodiment of the invention, the processing means uses a geometric line passing through the region of interest from a single image exposure, taking into account another geometric element passing through the region of interest, It is designed to determine the position of the region of interest by determining the position of the intersection of elements in three dimensions. In an embodiment of the present invention, the processing means, based on knowledge of the geometric position of the region of interest, calculates the relative movement of the table / sensor necessary to place the region of interest at the center of the newly moved collection beam. Can be calculated.

  Other features, objects and advantages of the present invention and its embodiments will be better understood when the following detailed description is read with reference to the accompanying drawings.

  FIG. 1 shows an assembly that includes a table 100, a collection portal 200 with a sensor 250, and a subject 300 (eg, a patient) that is placed on the table 100 and from which an optimal image of the heart 350 is to be taken. Yes. FIG. 1 shows a table 100 shown in two successive positions after being centered to form two successive orientations of the portal. In this exemplary embodiment, these two table locations are selected at the initiative of a healthcare professional in an initial procedure, which includes providing the device with accurate location information of a region of interest 350 on the patient's body. In a healthcare professional, this initial acquisition phase involves selecting a first direction of irradiation and the patient so that the region of interest 350 (in this case the heart) is centered on the acquisition beam 400 relative to this direction. Including placing 300. This first acquisition stage is therefore conventional and one or several fluoroscopic image exposures necessary for such a central arrangement can be used in this variant as well.

  Once the region of interest 350 is centered in the beam 400, the health care professional can perform an automated operation performed by the processor or memory of the device with the portal 200, the optical sensor 250, and a series of position sensors distributed on the table 100. The steps can be controlled, including storing the current exact geometric position of the portal 200, sensor 250, and table 100. Based on this memory, the assembly knows the path of the main axis 450 of the selected beam 400 so that the region of interest 350 passes through the geometric line at the center of the beam 400, ie the center of the sensor 250 and It can be estimated that it is arranged on a straight line 450 perpendicular to this.

  The healthcare worker can then perform the second stage for different directions of the sensor 250, again in the same way as the first stage. Thus, the second stage requires a new positioning of the table 100 by the medical practitioner, and the region of interest 350 is first offset from the beam 400 as the beam 400 is moving, and again the central axis 450 of the beam. Be on top. When repositioned in the center of the beam 400, the medical practitioner can inform the assembly that the region of interest 250 is located in the center of the beam 400. Based on the 3D reading of the position of sensor 250 and table 100, the assembly may deduce that region of interest 350 is now placed on a second geometric line 455 that is different from the first line. it can.

  FIG. 2 shows these two straight lines 450 and 455 here in the coordinate system of the table 100 (the drawing of FIG. 1 is shown in the general coordinate system). In FIG. 2, the two straight lines 450 and 455 actually intersect at a region of interest 350 that has been specifically targeted by the healthcare professional during the two phases described above.

  If these two axes 450 and 455 are known, the assembly calculates the intersection of the two lines in three dimensions to estimate the position of the region of interest 350 relative to the table 100. As a result, the assembly will be accurately aware of the positioning of the region of interest 350 and will provide the health care professional with the appropriate positioning results in subsequent steps, as will be described below.

  In FIG. 3, the sensor 250 is placed in a third position where an image of interest can be supplied. The sensor 250 moves over the portal 200 so that the heart 350 of the patient 300 is offset laterally from the central axis 458 of the beam 400. The assembly then estimates the position of the heart 350 relative to the new position of the beam 400 using the position of the optical sensor 250 provided by the corresponding position sensor and the position of the heart 350 based on the position of the table 100. To do. The assembly then estimates the distance that the heart 350 is away from the central axis 458 of the beam 400 and calculates the required amount of movement of the table 100 so that the heart 350 is positioned on the central axis of the beam 400. .

  According to the first calculation method embodiment, the assembly allows the movement of the table 100, which can be purely horizontal (arrow 510), so that it is desirable to only move in the longitudinal and lateral directions of the table 100. calculate. The results of these calculations are displayed on the display screen in the form of a control window 600 comprising fixed points 610 and moving points 620. This type of window 600 may form part of the main screen of the assembly control computer or may be represented in the form of a specific small screen. The fixed point 610 at the center of the window 600 represents the region of interest 350 (in this case the heart) to be imaged, in other words the center of the heart in this case. The movement point 620 represents the central axis of the beam 400.

  In this case, when the table 100 moves horizontally, the movement point 620 (the center of the beam 400) moves away from or approaches the region of interest 350 (the window center 610). Thus, the table 100 moves until these two points 610 and 620 match.

  According to another embodiment, the assembly includes a guide that can be used to provide the shortest possible movement. This movement includes a movement that reduces the distance in a direction perpendicular to the axis of the beam 400 (represented by arrow 520 in FIG. 3). In this case, the table 100 also needs to move vertically.

  Guidance is by a window 600 similar to the window shown above in horizontal movement (longitudinal and lateral) and by an additional window 700 itself that includes a fixed element 710 and an element 720 that moves freely in the height direction. Given. These elements 710 and 720 symbolize the actual height of the table 100 and the respective required height, ie the actual height of the heart 300 and the height of the center of the beam 400 transmitted in close proximity to the heart. Represents. In this case, the moving element 720 and the fixed element 710 include horizontal segments in which the fixed element is at an intermediate height of the window 700 and the moving element moves vertically. When these two elements match, the table 100 has the required height.

  According to the third embodiment, the positioning guidance of the heart 350 can be selected not only on the central axis 450 of the beam 400 but also at the distance d of the sensor 250 at an ideal distance. This distance d is usually 40 cm. The two windows 600 and 700 shown above allow direct movement of the table 100. Placing the patient at this distance d from the receiver provides an optimal situation, minimizing the amount of radiation delivered to the patient during subsequent irradiation, minimizing the need for geometric expansion, The result is a significant reduction in risk for certain portions of the region of interest 350 located outside the illuminated region.

  The assembly also allows for the final movement of the table 100, thereby positioning the heart 350 at the center of the system (isocenter), thus eliminating the need for additional movement of the table other than a collision.

  In one variation, the assembly includes a sensor that increases the distance between the optical sensor 250 and the patient's body 300 and is used to detect an optimal separation from the region of interest 350 and also includes the patient 200 and the detector. It is used to stop the approaching movement between 250 before the collision occurs. Thus, at any location on sensor 250, the health care worker's job is simplified, eliminating the need for a normally manual, continuous positioning operation with respect to the associated illumination prior to obtaining the required image.

  The assembly performs the simple geometric calculation shown above using a three-dimensional geometric model in which the sensor 250 and its main axis 450 are modeled, and the table 100 and the patient region of interest 350 are modeled, In addition, the three-dimensional models of the various physical systems present in the assembly, specifically the components of the portal 200 that support the sensor 250, are similarly modeled. In this way, any collisions between the table 100 and the portal 200 and / or the receiver 250 are detected before these collisions occur during the proposed movement. Thus, the assembly reduces the risk of physical collisions between the various parts of the assembly and / or between the patient's body 300 and these parts.

  The assembly can also determine whether the region of interest 350 can be centered on the beam 200 at a predetermined location of the sensor 250.

  When a potential collision is detected, the assembly signals the possibility of this collision.

  If necessary, a “spin” method can be introduced. “Spin” includes the control of a series of automatic acquisitions of continuous irradiation simultaneously with the movement of the sensor 250 around the patient 300. To achieve this, the region of interest 350 (in this case the heart) must always be placed on the main axis 450 path of the beam 400 and the table 100 does not need to move during acquisition. Thus, the patient's heart 750 must be placed at a point called the isocenter, defined as being at the intersection of the three rotation axes of the portal 200. The isocenter is thus mechanically defined by the structure of the assembly. Commercially available X-ray portals include three axes of rotation with common intersections.

  In the prior art, the medical staff needs to place the region of interest 350 at the isocenter position by several successive image exposures in several directions, so that the region of interest is placed at the isocenter position. The patient's position must be readjusted many times. By such a process for geometrical identification of the location of the region of interest 350, the assembly comprising a model of assembly self-configuration and table configuration allows medical personnel to place the region of interest 350 at the isocenter of the system. Lead. To accomplish this, the assembly shows the isocenter of the device in the form of a movable cross 620 (the region of interest identified above is represented by a fixed point 610) and of the moving segment 720 4 includes the window of FIG. 4 representing the isocenter height in form (the identified heart height is in the form of a fixed segment 710). Thus, the user is guided horizontally by the first window 600 and vertically by the second window 700, and the isocenter of the assembly, which is known in advance by the assembly, is geometrically determined by the assembly during the aforementioned pre-stage. To be aligned with the region of interest 350 of the patient being positioned. Once the heart 350 is positioned at the isocenter of the assembly, a “spin” acquisition can begin.

  An assembly that utilizes a geometric model of the structure of the assembly itself can simulate the movement of the portal 200 and sensor 250 around the table 100 during the required “spin”, and between these different elements. A collision can be detected and a signal is first sent so that the health care professional can modify or limit the required “spin” trajectory.

  This is the case for certain obese (and therefore thick) patients, or for irradiation in, for example, an angular arrangement of the tail or head. Conventionally, detection of such an unfeasible route requires an initial operation that is particularly difficult to recognize the situation.

  By reducing the risk of collision, the assembly facilitates the use of a small C-tree support 200. Furthermore, in the past, when using a large C-arm, “spin” could only be considered easy, and this was the only method that did not require shifting the beam 400 relative to the isocenter, With this assembly, accurate positioning can be guided at the isocenter, thus enabling a series of equal and reliable collections using a small C-arm.

  According to another embodiment, the table 100 comprises a moving means such as a motor, which activates the movement using a method similar to that described above after the movement necessary to shut off the main axis of the beam is identified. .

  Two steps have been described above, including performing the two illuminations that the assembly uses to estimate the position of the region of interest 350 on the table 100 by the intersection of the two axes indicated by these illuminations. The assembly can also provide 3D geometric identification of the region of interest 350 using another means directed by the health care professional.

  Thus, in addition to the effective positioning of the heart on the axis 450 of the beam 400 during at least one irradiation, a straight line through the region of interest 350 can be manually identified from the image showing the region of interest 350. A variation slightly offset from the center of the image (close to the illumination) is also possible. The required axis position then looks like the required offset of the displayed image.

  Thus, the assembly can identify the geometric axis 450 through the region of interest 350. The assembly places the region of interest 350 in its model by repeating the operation or by intersecting this axis with another geometric element.

  In another embodiment shown in FIG. 5, an intersection between two geometric elements is used, and the assembly can identify the location of the region of interest 350 by this intersection. Again, one of the two elements is the main axis 450 of the receiver 250 during pre-irradiation. However, the second geometric element includes a plane 800 parallel to the table 100. Thus, the position of the heart 350 is the intersection of the horizontal plane 800 and the axis passing through this plane, and an inclined intersection is sufficient.

  This horizontal plane 800 is signaled to the assembly using a variety of possible techniques. The first involves asking the health care professional to physically measure the height of the heart 350 (of the region of interest) relative to the table 100, particularly in response to the patient's obesity. Thus, this height h can be entered manually to allow the device to recognize the height position of the plane 800 through the heart. When the position of the table 100 is recognized by a position sensor associated with the table, the assembly estimates the height of the heart.

  According to another approach, the assembly automatically identifies this height h as the default height corresponding to the expected average. Therefore, the knowledge of the center position of the heart 350 is an approximate value.

  According to a third approach, the heart 350 includes additional elements such as a catheter. The assembly then comprises means for identifying the position of the catheter, using this means, for example, by additional movement (eg on the screen) of a health care professional who is a surgeon, or completely automatically on the catheter relative to the table 100 Can be measured.

  An additional configuration is proposed as a variant when collected in a fixed direction and single irradiation is performed. Therefore, the image is converted under the control of the user, and the image when the table 100 is correctly arranged is displayed. For example, this transformation under user control is an approximation that assumes that the imaging region is a plane parallel to the plane of the image and passes through a three-dimensionally identified point representing the region of interest 350. This transformation requires only a simple modification to the image as an approximation. Thus, only a simple modification of the image (translation and enlargement and / or reduction) is performed. Regions that do not form part of this first irradiation cannot be shown.

  It will be understood that in any of the disclosed embodiments and equivalents thereof, positioning or positioning of the assembly or any portion thereof can be performed manually, semi-automatically, or automatically regardless of the described method. .

  Those skilled in the art will recognize that various modifications may be made in the function and / or method and / or results and / or structure and / or steps of the disclosed embodiments and equivalents without departing from the scope and extension of the invention. Can be done or suggested. Further, the reference numerals in the claims corresponding to the reference numerals in the drawings are merely used for easier understanding of the present invention, and are not intended to narrow the scope of the present invention. Absent. The matters described in the claims of the present application are incorporated into the specification and become a part of the description items of the specification.

The figure which shows two steps | paragraphs in the geometric determination of the region of interest by two continuous image irradiation. The figure which shows the axis | shaft of these two image irradiation with respect to the to-be-photographed object. FIG. 2 is a diagram illustrating a subsequent stage in table movement in relation to FIG. 1. FIG. 2 shows a guide window for such movement in connection with FIG. The figure which shows the deformation | transformation form of the step of the geometric identification of the region of interest by the intersection of a plane and a center irradiation axis.

Explanation of symbols

100 table 250 sensor 300 patient 350 region of interest 458 geometric element 510 parallel path 540 path leading region of interest to isocenter

Claims (22)

An imaging assembly comprising:
Means (250) for providing a radiation sensor;
Means (200) for providing a support for the sensor;
Means (100) for providing an analyte support;
Means for generating relative movement between means (100) for providing the analyte support and means (200) for providing a support for the sensor;
Processing means capable of determining relative movement of the subject / sensor such that the region of interest (350) is at the center (450) of the collection beam (400) by displaying the position of the region of interest (350); Using a geometric line (450) through the region of interest (350) from a single image exposure, considering another geometric element (455, 800) through the region of interest (350), then this line (450) and the other geometric element (455, 800) are located in three dimensions to locate the region of interest (350), and this geometrical region of interest (350) Based on the knowledge of the position, the object support (100) / sensor support (250) necessary to place the region of interest (350) in the center (458) of the newly moved collection beam (400). ) Relative shift And processing means for calculating,
An imaging assembly comprising:   Either the geometric straight line (450) or the another geometric element (455, 800) is formed from a central axis (450) of the collection beam (400) when positioned. The assembly described in.   3. An assembly according to claim 1 or claim 2, wherein the further geometric element (455, 800) is formed from a central axis (455) of the collection beam (400) when positioned.   Assembly according to any one of the preceding claims, wherein the further geometric element (455, 800) is formed from a plane (800) substantially parallel to the subject support (100).   The assembly according to claim 4, wherein the plane (800) parallel to the subject support (100) is identified by inputting a body thickness (h) of the subject (300).   The means according to claim 4 or 5, comprising means for identifying the position of an external element of the body of the subject (300) as an index of the height (h) of the plane (800) parallel to the subject support (100). An assembly according to any one of the above.   Means for controlling movement of at least one of the elements in the object support (100) and the sensor support (250), and means for controlling means for controlling movement corresponding to the positioning calculation result. An assembly according to any one of the claims.   The assembly of claim 1, comprising means for collecting said geometric line (450) and said another geometric element (455, 800) for each of these two acquisitions to be manually controlled.   Any of the preceding claims, wherein the geometric line (450) and / or the another geometric element (455, 800) includes a straight line identified as a desired center of the image as an adjacent illumination offset. The assembly according to one.   Assembly according to any one of the preceding claims, wherein the calculating means identifies the occurrence of a collision during the relative movement of the analyte support (100) / sensor support (250).   A form of window (600) that includes a fixed element (610) and a moving element (620), each representing one of the positions of the region of interest (350) and the central axis (450) of the beam (400) An assembly according to any one of the preceding claims, comprising means for displaying positioning calculation results at.   One window includes two points, one of which is a two-dimensional movement point (620) within the window (600), and the other of the points is a fixed point (610) of the window; A moving element (each representing the position of the central axis (450) of the beam (400) and the position of the region of interest (350) across the beam, the other window representing the height of the patient (300)). The assembly according to claim 11, comprising two windows (600, 700) comprising 720) and a fixing element (710) representing the height required for the subject.   6. A method according to any one of the preceding claims, comprising means for guiding the relative movement along a shortest path (520) for positioning a region of interest (350) on a central axis (450) of the beam (400). Assembly.   Assembly according to any one of the preceding claims, comprising means for guiding the relative movement along a path (510) parallel to the plane of the object support (100).   Assembly according to any one of the preceding claims, comprising means for guiding the relative movement along a path (540) leading the region of interest (350) to an optimal distance (d) from the sensor (250). .   Assembly according to any one of the preceding claims, comprising means for guiding the relative movement along a path (540) leading the region of interest (350) to an isocenter of movement of the assembly. Means for generating relative movement between the object support means (100) and the sensor support means (200);
Processing means capable of determining relative movement of the subject / sensor such that the region of interest (350) is at the center (450) of the collection beam (400) by displaying the position of the region of interest (350); Using a geometric line (450) through the region of interest (350) from a single image exposure, considering another geometric element (455, 800) through the region of interest (350), then this line (450) and the other geometric element (455, 800) are determined in three dimensions to locate the region of interest (350), and this geometry of the region of interest (350) Based on the knowledge of the position, the object support (100) / sensor support (250) necessary to place the region of interest (350) in the center (458) of the newly moved collection beam (400). ) Relative shift And processing means for calculating,
A method of operating a data processing system comprising: Generating a relative movement between means (100) for providing the analyte support and means (200) for providing a support for the sensor;
A processing step in which the relative movement of the subject / sensor can be determined by position indication of the region of interest (350) such that the region of interest (350) is at the center (450) of the collection beam (400), Using a geometric line (450) through the region of interest (350) from a single image exposure, considering another geometric element (455, 800) through the region of interest (350), then this line (450) and the other geometric element (455, 800) are located in three dimensions to locate the region of interest (350), and this geometrical region of interest (350) Based on the knowledge of the position, the object support (100) / sensor support (250) necessary to place the region of interest (350) in the center (458) of the newly moved collection beam (400). ) Relative shift And the processing stage to calculate,
A computer apparatus including means for executing When run on a computer,
Generating relative movement between means (100) for providing the analyte support and means (200) for providing a support for the sensor;
A processing step in which relative indication of the subject / sensor can be determined by position indication of the region of interest (350) such that the region of interest (350) is at the center (450) of the collection beam (400), Using a geometric line (450) through the region of interest (350) from a single image exposure, considering another geometric element (455, 800) through the region of interest (350), then this line (450) and the other geometric element (455, 800) are located in three dimensions to locate the region of interest (350), and this geometrical region of interest (350) Based on the knowledge of the position, the object support (100) / sensor support (250) necessary to place the region of interest (350) in the center (458) of the newly moved collection beam (400). ) Relative shift And the processing stage to calculate,
A computer program comprising code means for executing When run on a computer,
Generating a relative movement between means (100) for providing the analyte support and means (200) for providing a support for the sensor;
A processing step in which the relative movement of the subject / sensor can be determined by position indication of the region of interest (350) such that the region of interest (350) is at the center (450) of the collection beam (400), Using a geometric line (450) through the region of interest (350) from a single image exposure, considering another geometric element (455, 800) through the region of interest (350), then this line (450) and the other geometric element (455, 800) are located in three dimensions to locate the region of interest (350), and this geometrical region of interest (350) Based on the knowledge of the position, the object support (100) / sensor support (250) necessary to place the region of interest (350) in the center (458) of the newly moved collection beam (400). ) Relative shift And the processing stage to calculate,
A computer program on a carrier that carries code that performs the.   A product for use in a computer system comprising a computer readable medium embodying computer readable program code means for performing the steps of claim 1. A machine-readable program storage device tangibly embodying a program of instructions executable by a machine for performing the steps of the method of claim 1.

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