DE102009008700A1 - Method for producing X-ray images of patient, involves balancing effect of deformation in X-ray images by processing two-dimensional X-ray images or reconstructing two-dimensional X-ray images to three-dimensional volume image - Google Patents

Abstract

The method involves processing two-dimensional X-ray images of an investigation object by an image processing unit, and determining deformation of a patient support device and/or an adjustable C-arm in all directions. An effect of deformation in the X-ray images is partly balanced by processing the two-dimensional X-ray images or reconstructing the two dimensional X-ray images to a three-dimensional volume image while loading the two dimensional X-ray images. An independent claim is also included for an X-ray unit for producing an X-ray image of an investigation object.

Description

The The invention relates to a method for generating X-ray images according to the claim 1 and an X-ray machine for performing a Such method according to the claim 11th

With Novel C-arm based X-ray machines can not only 2D X-ray images but also 3D volume images are generated by a while Rotation of the C-arm around a subject at different Angulations 2D X-ray images and then reconstructed into a 3D volumetric image. Furthermore you can with C-arm x-ray equipment during an interventional Intervention 2D X-ray images recorded and with spatial Information, eg. With a previously created 3D volume image, also from other modalities or with graphics drawn in the volume.

at The C-arm-based X-ray machines can be used in the During the generation and processing of the X-ray images, z. B. in the Processing 2D X-ray images or the reconstruction of 3D volume images, but also in the superposition of 2D X-ray images and 3D volume images stiffness-related plant-specific influencing factors the radiographs adversely affect and create errors in the overlay.

It It is an object of the present invention to provide a method which improves the quality of recorded with a C-arm X-ray machine X-ray images, especially in the reconstruction of 3D volume images and the overlay of 2D X-ray images with 3D volume images, possible. Furthermore, it is an object of the invention, one for the implementation of the Method suitable X-ray device to provide.

The The object is achieved by a method for creating X-ray images according to the claim 1 and of an X-ray device according to the claim 11. Advantageous embodiments of the invention are each the subject the associated Dependent claims.

at the method according to the invention for creating X-ray images an examination object with an X-ray machine, comprising an adjustable C-arm, which is an x-ray detector and an X-ray source holds, a system control device, an image processing unit, a Patient positioning device and at least one deformation determination device, will be at least an x-ray of the examination object and by means of the image processing unit processed, at least one deformation of the patient support device and / or the C-arm and at least one effect of the deformation on the x-ray during processing of the X-ray image considered and at least partially offset. By the method according to the invention become stiffness-related influencing factors, in particular the influence the weight of the patient on the patient bed and / or the impact the weight of the C-arm components on the C-arm and corrected if necessary. The weight of the patient and that Weight for example from X-ray and x-ray detector to lead to deformations of the X-ray machine. These Deformations are determined by the method according to the invention and serve as a basis for a correction of the rigidity-related plant-specific influencing factors. This can significantly improve the quality of the created X-ray pictures achieved become.

To An embodiment of the invention is a plurality of 2D X-ray images of the examination subject at different positions of the wearer relative taken to the examination subject and by means of the image processing unit reconstructed into a 3D volumetric image and it becomes at least one Effect of deformation on at least one X-ray image during reconstruction of the 3D volume image and at least partially offset. Especially during the reconstruction of volume images from several X-ray images have a stiffness-related effect Influencing factors strongly on the quality of the reconstructed volume image. Because the 2D X-ray images be recorded at different angulations of the C-arm and this in each case different for different angulations deformed, the errors in the volume image are generally not reproducible. The invention provides a way to prevent errors and therefore the quality of the volume image to improve significantly.

To A further embodiment of the invention is at least a 2D X-ray image of the examination object and by means of the image processing unit with a z. B. previously created 3D volume image superimposed and it will at least one Effect of deformation on the 2D X-ray image during the overlay considered and at least partially offset. The application of such overlay methods is mainly used in interventional procedures. Here can be mistakes in the overlays to damage and injury to the patient. For this reason, the use of the invention is particularly advantageous.

Advantageously, a deformation of the patient support device in all three spatial directions is determined. That way, the effect can be The deformation can be determined and compensated with particular precision.

To Another embodiment of the invention are by means of the Patient support device arranged strain gauges resistance changes measured and used to determine the deformation. Strain gauges are commercially available Components that are easily and effortlessly installed and applied can be. A particularly precise Measuring method of such strain gauges is based on the measurement of resistance changes.

Conveniently, a deformation of the C-arm in all three spatial directions is determined. On In this way, the effect of deformation can be determined very precisely and be balanced.

To A further embodiment of the invention is based on the deformation a caused by the deformation of the patient bed distortion of the examination object on the at least one X-ray image determined and considered. Such a distortion is for example due to a deformed Patient couch caused because the patient at one end of the radiograph is stored at a distance lower than at the other end. This is particularly crucial when a large area of the patient is up the X-ray image should be displayed. From the strength of the deformation, the Size of the distance calculated and from this the distortion is determined.

In Advantageously, based on the deformation of a by the deformation the patient couch caused offset or a shift the imaged examination subject on the at least one X-ray image determined and considered. One such offset or displacement appears, for example on a laterally recorded X-ray image of an examination subject on a deformed patient bed. Shall have multiple x-rays or an x-ray and a volume image superimposed which are created in differently deformed patient bed were, it comes to big Errors. Is the offset or displacement based on the deformation calculated, the offset or the shift may be on the corresponding X-ray photograph corrected and thus a flawless overlay created.

To An embodiment of the invention is the distortion or the offset or the shift on the X-ray image corrected in particular by means of image processing. The image processing can by applying an algorithm to the x-ray image, a distortion or for example, by negatively shifting the offset or displacement correct.

The Inventive X-ray device for creation of x-rays an examination object has an adjustable C-arm, which a X-ray detector and an X-ray source holds, a system control device, an image processing unit and a patient support apparatus comprising at least a deformation determining device for determining the deformation the patient support device and / or the C-arm, wherein the Image processing unit is adapted to an effect of deformation during processing of the X-ray image too consider and at least partially offset. Expediently, the x-ray device has a calculation unit which is adapted to at least one effect of the deformation to determine.

To An embodiment of the invention comprises the deformation determining device at least one strain gauge on. Strain gages are commercial Components that are easy and effortless to install and apply can.

Conveniently, is for a determination of the deformation of the patient support device of at least one strain gauge on the patient support device arranged.

Conveniently, is for a determination of the deformation of the C-arm of the at least one strain gauge arranged on the C-arm.

To Another embodiment of the invention is the strain gauge from a x-ray transparent Material formed. This is particularly advantageous when the strain gauge is placed on the patient support device. Through a Radiotransparent Material is it possible the strain gauge at a particularly favorable for the measurement Place to place without him a disturbing figure on the x-ray generated.

The Invention and further advantageous embodiments according to features the subclaims become below with reference to schematically illustrated embodiments explained in the drawing, without that's a limitation the invention to these embodiments he follows. Show it:

1 a side view of a deformed by the patient's weight patient bed;

2 a view of an inventive X-ray device with deformation determining devices on the patient bed;

3 a sequence of a method according to the invention for the production of X-ray images;

4 a sequence of a method according to the invention for reconstructing a 3D volume image;

5 a view of a deformed by the weight of X-ray and X-ray detector C-arm;

6 a view of a C-arm with multiple deformation determining devices;

7 a view of a strain gauge, and

8th a sequence of a method according to the invention for superimposing a 2D X-ray image and a 3D volume image.

In the 1 is shown as a patient couch 10 by the weight and weight of a patient 11 is deformed. The table top of the patient bed 10 Depending on the cantilever length l, the material from which it was produced, and the weight forces involved, it is deformed at its cantilevered end by the amount d.

In the 5 is shown as the weight of an X-ray 14 and the weight of an X-ray detector 15 to a deformation of a C-arm 13 lead, with the respective deformation at different angulations of the C-arm 13 is different.

In the 2 is an inventive X-ray machine with a C-arm 13 , which is an X-ray source 14 and an X-ray detector 15 holds, and with a patient bed 10 shown. The C-arm may, for example, be arranged on a robot arm or another adjustable suspension and is preferably movable and rotatably mounted in several spatial directions. In order to determine a deformation of the patient table, at least one, in particular several, strain gauges 12 at the patient table 10 arranged. One or more strain gauges are arranged, for example, on the cantilevered end of the patient couch; but it can also be arranged on other areas of the patient bed one or more strain gauges. The positions of the strain gauges 12 serve here only as an example and can be selected as needed.

The X-ray machine also has a system controller 16 , an image processing unit 17 for example in the form of an image system and a calculation unit 18 on. control Panel 16 , Image processing unit 17 and calculation unit 18 can also be arranged together in one unit. The strain gauges are, for example, via a data line with the calculation unit 18 or the Control Panel 16 connected in order to forward the measured deformations can. By means of the calculation unit or the system control, the deformation can then be used to determine or calculate what effect the deformation has on the X-ray image and / or how great the effect actually is. From this it can then be determined how the effect can be corrected or at least reduced from the X-ray image. This information is then sent to the image processing unit 17 passed, which performs the correction.

In order to on the patient table arranged strain gauges in the X-ray image are not visible they are positioned at the table so that they are not in the beam path the X-ray source lie. Advantageously, the strain gauges are made of one X-ray transparent Material formed.

In order to determine a deformation of the C-arm, at least one, in particular several, strain gauges 12 on the C-arm 13 arranged as in the 5 is shown, the strain gauges are distributed over the C-arm and at least one strain gauge each near the X-ray source 14 and a respective strain gauge next to the X-ray detector 15 is arranged. The positions of the strain gauges 12 serve here only as an example and can be selected as needed. In order to measure the deformation particularly well, it is advantageous to arrange some strain gauges at the respective ends of the C-arm.

A typical strain gauge 12 is in the 7 shown. The strain gauge has, for example, a measuring grid film made of resistance wire which has been laminated on a thin plastic substrate, etched and provided with electrical connections. The measuring principle of such strain gauges 12 is generally the following: Strain gauges change their electrical resistance during deformation, so when stretched, the resistance increases and when compressed it is reduced. The change of resistance is achieved by integration of the strain gauge 12 detected in an electrical circuit. Depending on the change in resistance, conclusions are drawn about the deformation. In addition, there are also strain gauges that use piezoelectric, voltage-optical or capacitive measuring principles. To detect deformations in different spatial levels, multiple strain gauges in different Rich arranged or so-called rosette strain gauges are used.

In the 3 a sequence of a method according to the invention is shown. An X-ray image of an examination subject is recorded by means of an X-ray apparatus (step 20 ). In addition, at least one deformation of the patient support device or the C-arm is determined (step 21 ), for example, by means of one or more strain gauges, the respective deformation is measured. For example, in the case of the patient bed, the deformation can be measured simultaneously with the acquisition of the X-ray image in order to obtain a particularly accurate measurement. In the case of the C-arm, for example, it is possible to fall back on measurements that have already been taken in a calibration process with a correspondingly identical position of the C-arm.

After the measurement and recording are performed, at least one effect of the deformation on the X-ray image is determined (step 22 ). For example, in the case of measuring the deformation of the patient couch 10 a distortion caused by the deformation or an offset or a displacement of the imaged examination subject on the X-ray image can be calculated. Such a calculation can be carried out by the calculation unit based on information about the deformation as well as about further geometric information of the X-ray device. Such geometric information may include the position of X-ray and X-ray detector, the position and size of the patient couch, the size of the examination subject, the size of the X-ray detector, and so on.

Subsequently, the effect is corrected during the processing of the X-ray image (step 23 ), for example, by applying an algorithm of image processing to the X-ray image. In the case of an offset or a displacement, the imaged examination object can be displaced on the X-ray image in the opposite direction of the offset or of the displacement; in the case of distortion, an equalization algorithm can be applied to the X-ray image or to parts of the X-ray image.

The Deformation of the C-arm can be done using one or more strain gauges before taking an x-ray or even once as a calibration process in different angulations and Positions with different distances between X-ray emitters and x-ray detector be determined. The C-bow deformations can be per system than over the Running time to be consistently assumed, as long as the static conditions do not change. In different systems, the deformation but different be. Therefore, be preferred for each system determines the deformations of the C-arm once and z. B. involved in the calibration process.

The Table deformation, however, can not be consistent over the term because they are weighted by the patient, the position of the patient Patients and the cantilever length l of the table is dependent. Deformations are recaptured and included in each shot.

In the 4 or the 8th a method in the case of a 3D reconstruction of a volume image from a plurality of x-ray images or a superimposition of a volume image with an x-ray image is shown. Following the correction of the X-ray images or a 3D volume image is reconstructed (step 24 ) or a superposition of a volume image with the X-ray image (step 25 ) carried out. The X-ray image to be superimposed may, for example, be a live X-ray image during an interventional procedure, the superimposed volume image may also have been recorded and transmitted by another imaging device.

at an overlay 3D volume images and 2D X-ray images be through the inventive method Inaccuracies, so z. B. that the volume image is not congruent with the x-ray image is balanced, giving an additional 2D / 3D registration can be saved. Overall, it comes through the inventive method in an overlay to improve the overlay accuracy, to higher quality Investigations and improving the workflow for the user.

• – zumindest ein Röntgenbild des Untersuchungsobjekts aufgenommen und mittels der Bildverarbeitungseinheit verarbeitet wird,
• – zumindest eine Verformung der Patientenlagerungsvorrichtung oder des C-Bogens ermittelt wird, und
• – zumindest ein Effekt der Verformung auf das Röntgenbild bei der Verarbeitung des Röntgenbilds berücksichtigt und zumindest teilweise ausgeglichen wird.

The invention can be briefly summarized in the following way: To improve the quality of X-ray images, a method for generating X-ray images of an examination subject with an X-ray apparatus comprising an adjustable C-arm, which holds an X-ray detector and an X-ray source, a system control device, an image processing unit Patient storage device and at least one deformation determination device, provided

• At least one X-ray image of the examination subject is taken and processed by means of the image processing unit,
• - At least one deformation of the patient support device or the C-arm is determined, and
• - At least one effect of the deformation on the X-ray image in the processing of the X-ray image is taken into account and at least partially compensated.

Claims (18)

Method for generating X-ray images of an examination subject with an X-ray apparatus, comprising an adjustable C-arm ( 13 ), which has an X-ray detector ( 15 ) and an x-ray source ( 14 ), a system control device ( 16 ), an image processing unit ( 17 ), a patient support device and at least one deformation determination device, wherein - at least one x-ray image of the examination object is recorded (step 20 ) and by means of the image processing unit ( 17 ) is processed, - at least one deformation of the patient support device and / or the C-arm ( 13 ) is determined (step 21 ), and - at least one effect of the deformation on the X-ray image during the processing of the X-ray image is taken into account and at least partially compensated (step 23 ). The method of claim 1, wherein a plurality of 2D X-ray images of the examination subject at different positions of the C-arm ( 13 ) recorded relative to the examination subject and by means of the image processing unit ( 17 ) are reconstructed into a 3D volume image and at least one effect of the deformation on at least one X-ray image during the reconstruction of the 3D volume image is taken into account and at least partially compensated. Method according to claim 1, wherein at least one 2D X-ray image of the examination subject is recorded and recorded by means of the image processing unit (1). 17 ) is superimposed with a 3D volume image and at least considered an effect of the deformation on the 2D X-ray image in the superposition and at least partially compensated. Method according to one of the preceding claims, wherein a deformation of the patient support device in all three Spaces is determined. Method according to claim 4, wherein strain gauges arranged on the patient support device ( 12 ) Resistance changes are measured and from this the deformation is determined. Method according to one of the preceding claims, wherein a deformation of the C-arm ( 13 ) is determined in all three spatial directions. Method according to one of the preceding claims, wherein additional 2D X-ray images recorded and superimposed with the 3D volume image and the effect in the overlay considered and is at least partially offset. The method of claim 4, wherein based on the deformation a caused by the deformation of the patient support device Distortion of the examination object on the at least one X-ray image determined and considered becomes. The method of claim 4, wherein based on the deformation a caused by the deformation of the patient support device Offset or displacement of the imaged subject on the at least one x-ray picture determined and considered becomes. Method according to one of claims 8 or 9, wherein the distortion or the offset or the displacement on the X-ray image in particular by means of an image processing is corrected. X-ray machine for generating X-ray images of an examination subject, with an adjustable C-arm ( 13 ), which has an X-ray detector ( 15 ) and an x-ray source ( 14 ) with a system control device ( 16 ), with an image processing unit ( 17 ) and a patient support device, comprising at least one deformation determination device for determining the deformation of the patient support device and / or the C-arm, wherein the image processing unit ( 17 ) is adapted to take into account and at least partially compensate for an effect of the deformation during the processing of the X-ray image. X-ray apparatus according to claim 11 with a calculation unit ( 18 ), wherein the calculation unit is adapted to determine the at least one effect of the deformation. X-ray apparatus according to claim 11 or 12, wherein the system control device ( 16 ) is adapted to control the X-ray apparatus in such a way that a plurality of 2D X-ray images of the examination subject are at different positions of the C-arm (FIG. 13 ) recorded relative to the examination subject and by means of the image processing unit ( 17 ) are reconstructed into a 3D volume image, and wherein the image processing unit ( 17 ) is adapted to take into account the effect of the deformation in the reconstruction of the 3D volume image and at least partially compensate. X-ray apparatus according to one of the preceding claims, wherein the X-ray apparatus is designed to record 2D X-ray images and the image processing unit ( 17 ) is adapted to superimpose the 2D X-ray images with a 3D volume image and is adapted to take into account and at least partially compensate for the effect of the deformation in the superimposition. X-ray apparatus according to one of the preceding claims, wherein the deformation determination device comprises at least one strain gauge ( 12 ) having. X-ray apparatus according to one of the preceding claims, wherein the at least one strain gauge ( 12 ) is arranged on the patient support device and designed to measure a deformation of the patient support device. X-ray apparatus according to one of the preceding claims, wherein the at least one strain gauge ( 12 ) on the C-arm ( 13 ) and for measuring a deformation of the C-arm ( 13 ) is trained. X-ray apparatus according to one of the preceding claims, wherein the strain gauge ( 13 ) is formed of an X-ray transparent material.