DE102009004897A1 - Method for recording three-dimensional reconstructed data sets of organ of patient, involves recording two-dimensional data in visual field, and reconstructing three-dimensional data sets from two-dimensional image data - Google Patents

Abstract

The method involves recording two-dimensional radioscopic images of an object below projection angles of greater than 15 degrees. A central point of an interesting area is marked by an operator in the two-dimensional images. A visual field extended around the central point and/or a midpoint derived from the central point is displayed for recording two-dimensional image data formed due to three-dimensional reconstruction. The two-dimensional data in the visual field is recorded based on authentication of a user. Three-dimensional data sets are reconstructed from the two-dimensional image data.

Description

The The invention relates to a method for receiving a three-dimensional Reconstruction data set of a region of interest within a to be recorded object, in particular a patient, with a X-ray equipment with a C-arm, which is pivotable around a patient table.

The Create three-dimensional data sets from a plurality of two-dimensional ones Projection images are in particular of computed tomography devices (CT devices) ago known. For some time, however, too X-ray equipment with a pivotable about a patient table C-arm, on the opposite a radiation source and a radiation detector are arranged, known, which are adapted to receive projection images, those for the determination of CT-like three-dimensional reconstruction records can be used. there the C-arm is pivoted about the object to be recorded, in particular around a midpoint within the region of interest, to obtain image data, which then similar to the computer tomography can be reconstructed. The fundamental Procedures are known and need not be discussed here become.

X-ray equipment with a C-arm, however, have some disadvantages compared to normal computed tomography devices on. One of these disadvantages is the limited field of view. While one CT gantry provides a field of view of about 500-700 mm is a three-dimensional Recording with a C-arm-based system usually on a field of view limited by about 250 mm.

Therefore a very accurate positioning of the patient is necessary to ensure that the area of interest is also fully in the obtained three-dimensional reconstruction data set visible is. Trusted x-ray equipment thereby on the eye measure of User. In doing so, the patient table is moved with the patient, that the region of interest is located approximately in the isocenter of the C-arm, where also an anterior-posterior and a lateral positioning take place can. Then it is checked by a test run, whether collision-free the image data can be recorded. This is not the case, a new positioning is required.

But even when recording the image data due to the device geometry actually done can, is often not sure that actually the entire one of interest Area in the resulting three-dimensional reconstruction data set is included. Since only a very small field of view is available, is a very exact positioning to fully exploit this field of view required in the "trial and error "method, that is based purely on judgment, particularly error prone is. For example, it can when taking pictures in the abdomen area to come that parts of the area of interest are not displayed correctly can be.

Of the The invention is therefore based on the object of specifying a method with a reliable one and in terms of field of view improved recording three-dimensional Reconstruction records with an X-ray device can be done with C-arm.

• – Aufnahme von zwei zweidimensionalen Durchleuchtungsbildern des Objekts unter unterschiedlichen Projektionswinkeln, insbesondere um mehr als 15 Grad versetzt,
• – Markierung eines zentralen Punktes des interessierenden Bereichs durch einen Benutzer in den zweidimensionalen Bildern,
• – Anzeige eines sich um den zentralen Punkt und/oder einen davon abgeleiteten Mittelpunkt erstreckenden Blickfelds für die Aufnahme der der dreidimensionalen Rekonstruktion zugrunde liegenden Bilddaten,
• – nach Bestätigung des Benutzers Aufnahme der zweidimensionalen Bilddaten in dem von dem Benutzer bestätigten Blickfeld und,
• – Rekonstruktion eines dreidimensionalen Bilddatensatzes aus den zweidimensionalen Bilddaten.

To solve this problem, the following steps are provided according to the invention in a method of the type mentioned in the introduction:

• Taking two two-dimensional fluoroscopic images of the object at different projection angles, in particular offset by more than 15 degrees,
• Marking a central point of the region of interest by a user in the two-dimensional images,
• Display of a field of view extending around the central point and / or a center derived therefrom for recording the image data on which the three-dimensional reconstruction is based,
• Upon acceptance of the user, capturing the two-dimensional image data in the field of view confirmed by the user and
• - Reconstruction of a three-dimensional image data set from the two-dimensional image data.

With the method according to the invention is a user given an aid for the first time, one possible allow exact definition of the field of view by the user depending on the choice of the central point in the 2D representation already shown which field of view he can expect in three dimensions. This is possible, there in principle It is known how big that is maximum possible Field of view of the X-ray device for such three-dimensional Reconstruction records is. It should be noted that basically a user of course to make a new selection of a central point. It can that is to say at a glance, for example, the area of interest Completely can be included. Fehlaufnahmen, which then a part of the area of interest has been recorded, so can be reduced. The user is the size of the three-dimensional field of view always aware.

Only two two-dimensional fluoroscopic images, which are at an angle to one another, are used for the method according to the invention stand, needed. Conveniently, this angle is more than 15 °, as have proven particularly advantageous two offset by substantially 90 ° two-dimensional fluoroscopic images, which are therefore perpendicular to each other. Such fluoroscopic images are particularly easy to create when a biplane X-ray device is used as the X-ray device. The angled fluoroscopic images make it possible to define the central point of the region of interest.

To The marking by the user is now, as already mentioned, in inventive method one around the central point and / or one derived from it Midpoint extending field of view for recording the three dimensional Reconstruction underlying image data displayed. Here is to consider that, although the basic extent of the field of view in the X-ray device is known, but it is often not possible for a variety of reasons, any point as isocenter or midpoint of the following Select image data recording. So are x-ray equipment known for the only one or a few movements of the C-arm for recording three-dimensional datasets calibrated. On the other hand, due to the geometry of the X-ray equipment Rotary movements not in every position, for example, the patient table also really perform. Therefore, according to the invention can also be provided be that from the central point a midpoint is derived for the an image data recording possible is. Then get So the user not only information about the field of view of the selected him central point, but at the center, where a shot too indeed possible is. How later will be explained in more detail If necessary, it may be necessary to move parts before shooting the X-ray device, for example, the patient table, yet to adjust. Also These geometry parameters can be included in the determination of the center and the surrounding field of view be determined immediately and, for example, for the user to manual Approach issued or even for automatic approach to one Control unit of the X-ray device passed become. This will be described below with reference to the patient table even closer be executed.

is the user agrees, so in particular the entire interest Area included in the field of view, the user can confirm and it finally happens the capture of the two-dimensional image data in the user's confirmed Field of view. After all is still the three-dimensional image data set from the two-dimensional Image data reconstructed, after which he brought to display, for example can be and / or stored for further analysis.

In order to the definition of the central point in three-dimensional space too is unique, it can be provided that the first by the user central point in one of the fluoroscopic images is marked after which his selection of the central point in the other fluoroscopic image automatically restricted is that always results in a unique three-dimensional point. For example, in the case of two perpendicular fluoroscopic images remains after setting a point in a fluoroscopic image for definite definition in the other fluoroscopic image only one more line left. This can be displayed to the user, for example, or his input options can restricted accordingly so that he, for example, has a cursor with which he makes the markings only move along this straight line.

As already mentioned, it is a particular advantage of the method according to the invention that the user is always made aware of how far the maximum possible field of vision reaches, so that he can recognize whether the area of interest is covered. It is also possible, as already mentioned, for the user to reject the marking of a central point and mark a new central point. However, with particular advantage, it can also be provided that a field of view that is possible with this point is already faded in during the marking of the central point. Even before the point has been marked, for example, assuming that the marker is made where the cursor is at the moment, it will already display a field of view that would be possible at this central point. So it is constantly updated online, what the boundaries of the field of vision look like. Such a consideration need not be limited to the possible central point, but also the derivation of the center can already be carried along during the marking process. This display can also be continued in such a way that a display already takes place in the other fluoroscopic image. Thus, it can be provided that the central point in one of the fluoroscopic images is first marked by the user, whereby, with or during the marking of the central point in the one fluoroscopic image, a consequent restriction of the field of view in the second fluoroscopic image is automatically determined and displayed. So if the user makes his choice in the first fluoroscopic image, it can be determined from this, how large the field of view can still be in the second fluoroscopic image. In the above already drawn example of the two orthogonal fluoroscopic images So there would be an extending strip around the straight line on which the central point can lie. The user is thus ensured an ideal overview.

As already mentioned, It may happen that not every user-selected central point may be suitable for image data recording. Then, for example be provided that under consideration a collision model of the X-ray device Determines whether at the central point marked by the user as the center of the current position of the patient table a Recording of image data possible is, and this information is displayed to the user. For example can also be a coloring the field of view shown by this represented in red becomes. Then the user becomes aware that he - at least at the moment Setting the X-ray device, especially the patient table - there make no recording can.

In particularly advantageous embodiment of the method according to the invention However, it can be provided that a center of a possible Recording process of the three-dimensional reconstruction underlying Patient table position defining image data taking into account a patient table position Collision model of the X-ray device is determined so that a distance of the center and the central Punktts becomes minimal, after which the resulting field of vision and optionally the midpoint displayed to the user becomes. It is therefore also checked in this embodiment, which possible near the central point located suitable centers a shift of the patient table can be achieved. There, as already described, collisions of device parts may occur this is not necessarily for Any point marked by the user central point possible, so that with the inventive method but in any case, the center can be found closest to the one the central point lies. Thus, as already mentioned above, degrees of freedom become the X-ray device, like the patient table position, to take care as much as possible to be able to correspond exactly to the user's request. The user will immediately brought to the notice, whether with the due to the system conditions modified choice the field of vision still meets its requirements. is If not, he can try another, for example central point to define. In an expedient further embodiment, after the patient table position is known anyway provided be that after confirmation the center of the surrounding field of view by the user of Patient table automatically before recording the image data in the determined patient table position is moved. So that's not it tedious manual patient table movement more necessary because of the procedure itself the optimal table position (XYZ position) has been determined and also the setting is done automatically. This will continue to make mistakes reduced, the effort is reduced and with greater certainty of area of interest.

Yet It can also happen that, for example, not the entire maximum available Field of view by a user be needed. Then can be provided be that the field of view is reduced by a user. For example, you can the limitations of the field of view by a user inside be moved to indicate the field of view actually required by him. These additional Information given by the user may be up various ways are used to advantage. So can be provided be that limitations of the field of view by the user during the Recording the image data through the use of collimators are taken into account and / or reconstructs only the reduced field of view of the user becomes. For example, you can restrictions result in an upper or lower side in an actual collimation of the X-ray beam, while left-right restrictions or Adjustments due to truncation artifacts only in the Reconstruction will be considered. That actually needed Field of view for The 3D reconstruction can thus advantageously before the image data recording already defined, allowing additional manual adjustments for a second Reconstruction after the first reconstruction with the maximum Field of view are no longer necessary. Thus, the time until the three-dimensional reconstruction data set with the desired largest spatial resolution in terms of the desired Field of view is obtained, greatly reduced.

All in all offers the method according to the invention so a useful one Aid for recording three-dimensional reconstruction image data sets with an X-ray device with a C-arm, the ideal information of the user recording errors practically excludes, reduces the effort and thus greatly reduces the time consumption.

Further Advantages and details of the present invention will become apparent from the embodiments described below and based on the drawings. Showing:

1 a flow chart of the method according to the invention,

2 an X-ray device with a C-arm in a first position,

3 one in the position off 2 recorded X-ray image,

4 the X-ray device in a second position of the C-arm,

5 one in the in 3 shown position transmitted fluoroscopic image, and

6 a sketch to limit the possible field of view in perpendicular to each other radiographic images.

1 shows a flowchart of the method according to the invention. The method according to the invention is used to record and reconstruct a three-dimensional reconstruction data record, wherein an area of interest in a patient, for example an organ, is to be recorded. For this, it is first necessary to find as little effort as possible and exactly one center or isocenter for recording the two-dimensional image data underlying the reconstruction (projection images) in such a way that the region of interest can also be completely captured by the field of view of the x-ray device for such recordings.

This will be done first in one step 1 taken two two-dimensional fluoroscopic images, which are at an angle to each other, in this case 90 °. This is done by the 2 - 3 explained in more detail. It shows 2 the X-ray device designed for carrying out the method according to the invention 2 with the C-arm 3 at which a radiation source 4 and a radiation detector 5 are arranged opposite each other, and the patient table 6 on which already a patient 7 in which the area of interest lies 8th contained in a first position of the C-arm 3 , In this position of the C-arm 3 can be a fluoroscopic image 9 be included as it is in 3 is shown by way of example. It shows a coronal view of the patient's torso 7 , Also indicated here is the area of interest 8th ,

Another position of the C-arm 3 the X-ray device 2 shows 4 , The fluoroscopic image taken in this position 10 ( 5 ) is perpendicular to the fluoroscopic image 9 and, in this example, shows a sagittal view of the patient's torso 7 again with the indicated area of interest 8th ,

The in step 1 recorded fluoroscopic images 9 and 10 are now displayed, for example via a suitable display device, a monitor, a user in particular at the same time.

In one step 11 Now the user marks a central point 12 in the fluoroscopic images 9 . 10 , This is done by first, for example via a cursor controlled by an input device, in the fluoroscopic image 9 the central point 12 marked. The inventive method conductive control unit 13 the X-ray device 2 then automatically determines which allowed options for unambiguously defining the central point 12 in the second fluoroscopic image 10 still remain. The movement possibilities of the cursor are in the picture 10 then restricted accordingly, so that a unique three-dimensional point 12 is defined.

Already while the point is being marked by the user, so the cursor in the fluoroscopic images 9 and 10 is moved, can be displayed how large the maximum (two-dimensional) field of view around the central point 12 Look out, giving the user an assistance in setting the point 12 is given. It is particularly advantageous if after or even already during the marking of the central point 12 in the fluoroscopic image 9 also in the fluoroscopic image 10 the extent to which this choice restricts a possible field of view is displayed. This is going through 6 explained in more detail. There is indicated the anatomy 14 of the patient 7 with the area of interest 8th shown centrally. This area 8th is also in the first fluoroscopic image 9 shown. A central point 12 now determines a maximum field of view 15 in the plane of this fluoroscopic image 9 What - as mentioned - the user can also be displayed immediately. For this limitation already follows - even if the point 12 is not fully defined in three-dimensional space - a limitation 16 the possible field of view in the plane of the fluoroscopic image 10 , In this case, it is still a possible strip 17 that's about the straight line 18 extends on which the point 12 in the fluoroscopic image 10 can still be set.

Of the So user can already while estimate the marking process, what consequences for the field of vision and in particular with regard to the person of interest Range by his selection in about.

Now, it is true that not every user selectable central point 12 inevitably represents a point as the center around which the C-arm 3 in shooting the two-dimensional image data underlying the three-dimensional reconstruction, is suitable. While it may still be necessary on the one hand, the patient table 6 In all three spatial directions to move to bring the central point in the isocenter, also geometric restrictions with regard to a possible risk of collision must be considered. Not at all patient table positions, therefore, the image data recording can be done without that there are collisions. It is therefore not enough to determine a patient table position, so that the central point 12 also forms the center of the image data recording, but it must also be checked whether a collision-free recording is possible.

This is possible via a in the control unit 13 stored collision model, the possibilities of movement of the components of the X-ray device 2 describes and thus gives the possibility to determine whether a planned movement of the C-arm 3 leads to collisions.

With the help of these tools will now be in one step 19 of the method according to the invention, after the three-dimensional position of the central point 12 is known, a collision-free recording enabling patient table position determined that defines a center for the image data recording, the closest possible to the central point 12 lies. It is therefore minimized this distance, it should be noted that it can of course also occur that both points coincide. An example of such from the central point 12 derived midpoint 20 is in the fluoroscopic pictures 9 . 10 in the 3 and 5 shown. The middle-point 20 can be seen very close to the user-marked central point 12 , At the central point 12 is thus not immediately an image data recording possible what the user can be communicated.

In the present case, in the case of the fluoroscopic images 9 . 10 the user is shown how big the maximum field of view 21 when shooting with this (possible) center point 20 is. For the user, therefore, it is immediately apparent in the example shown that the area of interest 8th in the field of vision 21 is still included as desired, although the midpoint 20 in this example from the central point 12 differs.

After the determination of the center 20 , the field of vision 21 and the corresponding display in the step 19 of the method according to the invention can now in step 22 the user the maximum field of view 21 Restrict according to his needs. For example, it can move the lateral boundaries inward. Something of the kind - as in the case presented here - makes sense if the area of interest is smaller than that of the field of vision anyway 21 covered area, so that also reconstruction time can be saved. These restrictions are also displayed to the user on the monitor.

Finally, the user needs in one step 23 confirm his selection.

It should be noted that the user, of course, at any time his choice of the central point 20 or even his limitation of the field of vision 21 can change again until a satisfactory condition for him is reached. Due to the various display options, it is always possible for him to assess the settings with regard to the recording goals.

In one step 24 Then, if necessary, the patient table is moved to the determined patient table position. This is done automatically by the X-ray device 2 , no further manual intervention is required.

In step 25 are then under pivoting of the C-arm 3 the two-dimensional image data underlying the reconstruction was recorded. The specific center 20 lies in the center of the rotary motion. Limitations of the field of vision 21 up and down as they may be in step by the user 23 have been desired are taken into account in the adjustment of the collimators.

In step 26 Finally, the three-dimensional reconstruction image data set is determined in the field of view defined by the user. Naturally, the restrictions of the maximum field of view defined by the user are also important 21 one.

Then you can the obtained three-dimensional reconstruction data set is displayed and also be saved.

Claims (12)

A method for capturing a three-dimensional reconstruction data set of a region of interest within an object to be recorded, in particular a patient, with an X-ray device with a C-arm, which is pivotable about a patient table, comprising the following steps: taking two two-dimensional fluoroscopic images of the object at different projection angles, in particular displaced by more than 15 degrees, - marking of a central point of the region of interest by an operator in the two-dimensional images, - display of a focal point extending around the central point and / or a center derived therefrom for recording the three-dimensional reconstruction Image data, - after confirmation of the user recording the two-dimensional image data in the field of view confirmed by the user and - Reconstruction of a three-dimensional image data set from the two-dimensional image data. Method according to claim 1, characterized a user makes a new selection of a central point. Method according to claim 1 or 2, characterized that two two-dimensional by 90 degrees offset Transmitted fluoroscopic images are recorded. Method according to one of the preceding claims, characterized characterized in that a biplane X-ray device used becomes. Method according to one of the preceding claims, characterized characterized in that by the user first the central point in one of the fluoroscopic images is marked, after which his selection the central point in the other fluoroscopic image automatically is restricted so that always results in a unique three-dimensional point. Method according to one of the preceding claims, characterized that already during marking the central point one possible with this point Field of view is displayed. Method according to claim 6, characterized that by the user first the central point is highlighted in one of the fluoroscopic images, being with or during the marking of the central point in the one fluoroscopic image a consequent limitation of the field of view is automatically determined in the second fluoroscopic image and is displayed. Method according to one of the preceding claims, characterized that under consideration a collision model of the X-ray device Determines whether at the central point marked by the user as the center of the current position of the patient table a recording of the image data possible and this information is displayed to the user. Method according to one of the preceding claims, characterized characterized in that one is a midpoint of a possible Recording process based on the three-dimensional reconstruction taking into account underlying image data defining patient table position a collision model of the X-ray device is determined so that a distance of the center and the central Punktts becomes minimal, after which the resulting field of view and optionally the midpoint displayed to the user become. Method according to claim 9, characterized that after the confirmation the center of the surrounding field of view by the user of Patient table automatically before recording the image data in the determined patient table position is moved. Method according to one of the preceding claims, characterized characterized in that the field of view is reduced by a user becomes. Method according to claim 11, characterized that the field of view limitations by the user during the Recording the image data through the use of collimators are taken into account and / or reconstructs only the reduced field of view of the user becomes.