Method for controlling a computed tomography system and control device

Abstract

This invention relates to a method for controlling a computed tomography (CT) system (1), comprising the following steps: defining an examination area (U) of an examination object (6); defining a certain number of interference structures, wherein the interference structures are structures located within the beam path of the CT system (1) and reflecting or absorbing X-ray radiation with an intensity exceeding the tolerance range; calculating the beam path of the X-rays (R) of the CT examination of the examination area (U), and determining the interference angle range (W) of the beam path passing through the interference structure (S) and the gantry (2) of the CT system where the examination area (U) is located; performing CT recording while the gantry (2) rotates, and recording CT data (D); reconstructing an image dataset (B) from the CT data (D) without omitting the determined interference angle range (W); and outputting the image dataset (B). This invention also relates to a control device and a CT system.

Description

Technical Field

[0001] The present invention relates to a method and a control device for controlling a computed tomography (CT) system, and a computed tomography (CT) system. Background Technology

[0002] In locally confined anatomical structures, such as the chest, CT scans ("CT": computed tomography) may not provide a sufficient number of projection angles for displaying the desired anatomical structures using conventional recording techniques and image reconstruction. In such cases, numerous projections through the spine are used to visualize the chest, axilla, and anterior chest wall; these projections are high-dose and potentially susceptible to artifacts, such as sclerosis artifacts.

[0003] Furthermore, a specialized placement aid (substantially pressure-free, “suspended” display) is necessary, especially during (female) chest imaging. However, this results in less than ideal placement for female patients compared to routine data acquisition and reconstruction (off-center placement).

[0004] Without a dedicated placement aid, a range of examinations may experience a decline in image quality, such as lateral placement in liver interventions.

[0005] Cross-sectional techniques (such as flat-panel CT) used to monitor interventional and radiotherapy placements exhibit the same fundamental problems as conventional CT techniques, differing only in the significant cone-beam projection issue.

[0006] Taking CT-based chest imaging as an example, there are dedicated chest CT scanners. However, due to the technical and physical limitations of the system, it is impossible to visualize the chest wall and axilla using the applied techniques. Similarly, it is impossible to simultaneously visualize both breasts, and this can negatively impact clinical use for dynamic examinations (such as contrast agent dynamics). Furthermore, such systems currently cannot (as is possible in MRI) simultaneously image the chest and perform interventional procedures into the chest.

[0007] Currently, personalized placement aids are only used to address this issue. In the field of CT-based chest imaging, similar to MRI, there are customized imaging placement aids, or, in the case of a dedicated chest scanner, appropriate structural measures for chest placement. Summary of the Invention

[0008] One object of the present invention is to disclose an alternative and more convenient method and corresponding apparatus for controlling a computed tomography system, thereby avoiding the aforementioned drawbacks.

[0009] This objective is achieved by the method according to claim 1, the control device according to claim 10, and the computed tomography system according to claim 12.

[0010] The method of this invention is used to control a computed tomography (CT) system. It allows for improved image quality and also reduces the dose to the patient, especially when using high-resolution CT techniques (e.g., photon counting techniques). The method provides for monitoring image artifacts with a relatively low radiation dose, particularly when recording anatomical regions where high-resolution and low-contrast behavior is favorable for diagnostic statements.

[0011] The method includes the following steps:

[0012] - Define the inspection area for the object being inspected.

[0013] - Define a certain number of interfering structures, where each interfering structure is located within the beam path of the computed tomography system and reflects or absorbs X-ray radiation with an intensity exceeding the tolerance range.

[0014] - Calculate the X-ray beam path for the CT scan of the examination area, and determine the range of interference angles of the beam path through interfering structures and the gantry of the computed tomography system in the examination area.

[0015] - Perform CT recording and record CT data while the gantry is rotating.

[0016] - Reconstructing the image dataset from CT data while omitting the measured interference angle range.

[0017] - Output image dataset.

[0018] The object of examination can theoretically be any body, and the examination area can be a part or the entire body. Preferably, the object of examination is a person, and the examination area is an organ or body region. The examination area is usually defined before the examination.

[0019] A number of interfering structures are defined prior to the examination. These can be a single structure or multiple structures. Interfering structures are located within the beam path of the computed tomography (CT) system, i.e., they are irradiated by X-ray radiation and either reflected or absorbed. However, not all structures are considered interfering structures; only those whose reflection or absorption intensity exceeds a tolerance range (e.g., above or below predetermined limits) are considered interfering structures. The tolerance range of the structure, or the corresponding material and dimensions, are predefined. In the case of humans, bone material, for example, can be interfering, and larger bones, such as the spine in particular, can be considered interfering structures. However, parts of the patient's bed or where assistive devices are placed can also be considered interfering structures. Essentially, the physician knows which structures will interfere with the image. These structures can be defined as "interfering structures" in this method. Preferred interfering structures have a known location in the body or examination area and are image regions with high Hounsfield units. However, air can also constitute an interfering structure. In this case, the image region with the lowest Hounsfield units is preferred as the interfering region.

[0020] If the interfering structures are known, then their locations are essentially also known. For example, in the case of humans, the skeletal structure is known, and even if it is not possible to observe the inside of the human body (at this time), the location of the spine, which is an exemplary interfering structure, can be easily specified.

[0021] Using the known locations of the interfering structures and the defined location of the examination area, the beam path of the X-rays for the CT scan can now be calculated. Note that the X-ray source remains off. Only the theoretical path is determined. Preferably, the patient (or subject of examination) is positioned such that the number of interfering structures is (significantly) located at an eccentric position at an isogonal point.

[0022] The calculated beam paths are then used to determine whether they pass through the interfering structure and the inspection area. The angle at which X-rays emitted by the X-ray source pass through the interfering structure and the inspection area is called the "interference angle," and the range of the interference angle is called the "interference angle range." Therefore, the interference angle range is the angular range that the rotating gantry can occupy within which X-rays will pass through the interfering structure and the inspection area. It is preferable that the X-rays only pass through the interfering structure after passing through the inspection area. Therefore, these angular ranges are preferably not considered interference angle ranges.

[0023] Once the interference angle range is determined, CT recording can be performed using a rotating gantry, and CT data (i.e., basic images) can be recorded during the process.

[0024] The image dataset is then reconstructed based on the CT data. The determined interference angle ranges are omitted. Note that it is not necessary to omit all interference angle ranges. For example, when there are two separate examination areas, the first interference angle range can be omitted when reconstructing the first image dataset for the first examination area, and the second interference angle range can be omitted when reconstructing the second image dataset for the second examination area.

[0025] Dose reduction can be achieved by shutting off the X-ray source within the interference angle range during recording.

[0026] The reconstructed image dataset is then output. For example, it can be displayed for direct diagnosis or stored for subsequent diagnosis.

[0027] Therefore, this method essentially removes certain regions from CT data that might impair the image. It should be noted in this regard that reconstruction typically requires a recording angle slightly larger than 180°. Therefore, it is advantageous that, in the case of opposing interference angle ranges, the smaller interference angle range is not considered as the interference angle range. Alternatively, CT data for the interference angle range can be simulated or calculated (e.g., using appropriately trained artificial intelligence) and used for reconstruction.

[0028] By utilizing the interference angle range, the necessary projection can be defined for the examination area while avoiding projections that limit image quality and thus lead to low dose efficiency. Specifically, for example, beam paths through the skeletal spine can be avoided. This can occur in both sequential and helical recording.

[0029] The control device for controlling a computed tomography imaging system according to the present invention is preferably designed for implementing the method according to the present invention. The control device comprises the following components:

[0030] - Inspection unit, designed to define the inspection area of ​​the object being inspected.

[0031] - Interference structure unit, designed to define a certain number of interference structures, wherein the interference structures are structures located within the beam path of the computed tomography system and reflect or absorb X-ray radiation with intensity exceeding the tolerance range.

[0032] - A computational unit is designed to calculate the beam path of X-rays from a CT scan of the examination area and to determine the interference angle range of the computed tomography (CT) system gantry, within which the beam path passes through interfering structures and the examination area.

[0033] - The data interface is designed to output control commands for performing CT recordings while the gantry is rotating, and to receive CT data.

[0034] - The reconstruction unit is designed for: reconstructing image datasets from CT data in a slim and lightweight design that omits the measured interference angle range.

[0035] - Data interface, designed to output image datasets.

[0036] The functionality of the components has been described in detail above in the context of the method according to the present invention.

[0037] The computed tomography system according to the invention is designed, either by including the control device of the invention or alternatively or additionally, for implementing the method according to the invention. Preferably, the CT system includes a flat panel detector.

[0038] Most of the aforementioned components of the control device can be implemented, in whole or in part, as software modules within the processor of a corresponding computing system. The advantage of primarily software implementation is that existing computing systems can be easily modified via software updates to operate according to the invention. In this regard, the task is also addressed by a corresponding computer program product having a computer program that can be directly loaded into the computing system, having program segments to implement the steps of the method according to the invention when the program is implemented in the computing system, at least the steps that can be implemented by a computer. In addition to the computer program, such a computer program product may, if necessary, include additional components, such as documentation and / or additional parts, such as hardware components, such as hardware keys (dongles, etc.) for using the software.

[0039] It should be noted that performing CT recording corresponds to transmitting relevant control commands and receiving CT data. This method can be implemented, in particular, by a computer.

[0040] Computer-readable media, such as memory sticks, hard disks, or other removable or fixed-mount data carriers, can be used to transport to or store at or within a computing system or control device, wherein program segments of a computer program that are readable and executable by the computing system are stored in the computer-readable medium. For this purpose, the computing system may, for example, have one or more cooperating microprocessors, etc.

[0041] Further particularly advantageous designs and modifications of the invention are derived from the dependent claims and the following description, wherein claims of one class of claims may also be modified in part similar to claims of another class of claims and description, and features of different embodiments or variations may in particular be combined to form new embodiments or variations.

[0042] According to a preferred method, CT data are recorded without considering the measured interference angle range. Preferably, the X-ray source used for recording is switched off within the interference angle range, or at least its radiation power is reduced. Therefore, the total dose is reduced. Preferably, dose modulation is performed as the beam parameters (e.g., kilovolt setting or reference mAs) change.

[0043] If it is desirable to improve the image while keeping the total dose constant, it is preferable to determine the beam parameters, particularly the accelerating voltage and / or current intensity of the X-ray source, for the entire recording based on the entire 360° angular range minus the interference angular range.

[0044] According to a preferred method, the following angular range is considered the interference angular range: Within this angular range, the X-ray beam from the gantry's X-ray source first passes through the interfering structure and then through the inspection area. Because the beam is typically conical, these interference angular ranges have a more severe impact on recording than their respective opposing angular ranges, where X-ray radiation first passes through the inspection area and then irradiates the interfering structure. The latter angular range can be considered the angular range used for reconstruction (and recording).

[0045] According to the preferred method, the interference structure is defined based on the topogram of the object under inspection, the camera recording of the object under inspection, or the model of the object under inspection.

[0046] The object of inspection is preferably a human or animal body, and the interfering structure is part of a skeleton, placement aid, or frame.

[0047] According to the preferred method, the object to be examined is positioned using a placement aid. Then, preferably, an interference structure is defined based on the position and form of the placement aid. Therefore, in this case, the placement aid is the interference structure. Preferably, the isoangular points of the examination area are defined after the object to be examined is positioned using the placement aid. Preferably, this definition is performed automatically using image recognition or communication between the placement aid and the computed tomography system.

[0048] According to the preferred method, the object to be inspected is secured using a fixing device. Then, the interfering structure is preferably defined based on the position and form of the fixing device. Therefore, in this case, the fixing device (e.g., a screw, plate, or other rigid body) is the interfering structure. The interfering structure is preferably also defined automatically using image recognition or communication between the fixing device and the computed tomography system.

[0049] In practice, after a dedicated placement aid is introduced into the scanner via manual input, image recognition, or direct communication between the placement aid and the scanner, calibration of a new isogonal point can be performed based on the anatomical structure of interest. In the case of chest visualization, a predefined target area can be transmitted to the CT scanner, such as the volume of the thoracic cavity or the location or extent of the chest. The same applies to fixation devices.

[0050] In this regard, preferred control devices include a positioning unit designed to determine the position of the placement aid and / or fixing device. Preferably, the positioning unit is designed to estimate the position based on an image and / or to receive and evaluate information about the placement aid.

[0051] According to the preferred method, within the scope of determining the interference angle range, the following check is performed: by considering the entire 360° angle range minus the interference angle range, the remaining angle range superimposed with the remaining angle range rotated by approximately 180° is checked to see if it has a continuous 360° angle range. Therefore, it essentially checks whether at least 180° is available for reconstruction. Note that this check does not necessarily have to be performed by rotating and superimposing copies of the remaining angle range. However, this checking process is advantageous if the remaining angle range has a complex structure. If a gap should exist in such a superposition case, then 180° cannot be used for reconstruction, i.e., information is lacking in this case.

[0052] Preferably, when the remaining angular range is less than 360°, for the missing angular range, simulated data simulating the recording within the missing angular range is added to the CT data before reconstructing the image dataset. Alternatively or additionally, since the interfering angular range is actually known before recording, the missing angular range can be removed from this certain number of interfering angular ranges. For this purpose, it is preferable to determine the degree of interference in the missing angular range and the angular range rotated 180° relative to it, and remove angular ranges with lower interference levels from the interfering angular ranges. This is preferably an angular range in which X-rays pass through the examination area first and then irradiate the interfering structure.

[0053] According to a preferred method, two or more inspection regions of the object to be inspected are defined. The interference angle ranges of the two inspection regions are preferably measured separately. If the light beam path passes through both the interfering structure and the associated inspection region, the interference angle range is associated with the inspection region. Then, omitting the measured interference angle ranges of the associated inspection regions, an image dataset is reconstructed separately for each inspection region. Therefore, if, for example, an interfering structure is defined, and there exists a first interference angle range for a first inspection region and a second interference angle range for a second inspection region, an image dataset is reconstructed for the first inspection region omitting the first interference angle range, and for the second inspection region omitting the second interference angle range.

[0054] Preferably, it is determined which interference angle ranges are identical to the area being examined. Then, CT data can be recorded without omitting identical interference angle ranges. If multiple areas may exist, the individual interference angle ranges can be separated. Therefore, the X-ray source should not be turned off within the interference angle range, as this may result in insufficient data for reconstructing the area being examined. However, if shared interference angle ranges exist, the X-ray source can be turned off to reduce the overall dose. Therefore, it is best to turn off the X-ray source used for recording within the same interference angle range, or at least reduce its radiation power.

[0055] Therefore, optimization can be performed on multiple areas to be examined. For example, the number of projections required for image acquisition of contrast agents from both breasts will differ from the number required for the individual manifestation of the breast lesion to be biopsied. In any case, reconstruction is performed individually and is best based on optimal projection onto a single target volume.

[0056] Also preferably, the image dataset is reconstructed from two different projection sets. In the contrast agent dynamics example, acquisition can be optimized to meet the need for simultaneous acquisition of both breasts. Image reconstruction can preferably be based on a single optimized projection, which can then be combined again into a single image. For these different projection sets, two different interference angle ranges can exist, so features of the two examination regions can also be applied here.

[0057] According to a preferred method, a combination of data sparsity reconstruction techniques and iterative solution methods is used when reconstructing the image dataset. To represent structures, particularly the structure of the biopsy needle, it is preferable to augment the projection without requiring full data acquisition, which is essential for detailed representation of chest tissue. This method is known in the prior art and is used, for example, in CT to calculate data beyond the area fully captured by the detector (extended field of view). These techniques are particularly advantageous for the method of the present invention if the X-ray source is shut off within the interference angle range, i.e., from which no CT data is recorded.

[0058] According to the preferred method, the examination area is the chest or lungs. The preferred interfering structure is the spine.

[0059] It should be noted that interfering structures do not necessarily have to absorb or reflect large amounts of radiation. On the contrary, depending on the type of examination, interfering structures may reflect or absorb very small amounts of radiation (i.e., less than a predetermined limit). For example, in the case of a biopsy of the iliac crest, a projection containing a large amount of skeletal information is preferred, while a projection containing a large amount of soft tissue information is omitted. Interfering structures can be defined here using prior knowledge and / or localization images.

[0060] For specialized reconstructions (e.g., scaled spine), a combination of conventional dose modulation and selective projection selection (omitting the interference angle range) is also preferred. Therefore, image quality can be improved while maintaining beam efficiency. This method can also be used to replace or complement previous methods for improving image quality. For example, based on information from localization images, foreign bodies can be identified in the examined object and defined as interfering structures. An interference angle range can then be defined for this foreign body, for example, to avoid artifacts, such as metal artifacts. For instance, when displaying the lungs, projection can be omitted based on foreign bodies that have penetrated the lungs. This differs significantly from iterative artifact reduction because in the proposed method, there is already a precise understanding of the introduced foreign body, and the expected projection can be filtered out. Attached Figure Description

[0061] The invention will then be described and explained in more detail again with reference to the accompanying drawings and embodiments. Here, the same parts are given the same reference numerals in different drawings. These drawings are generally not to scale. Here:

[0062] Figure 1 A general schematic diagram of a CT system is shown, which has an embodiment of a control device according to the invention for implementing the method.

[0063] Figure 2 The interference structure and interference angle range are shown.

[0064] Figure 3 A sequence diagram showing one possible order of the method of the present invention is provided.

[0065] Figure 4 An example of a method according to the invention for recording two inspection areas is shown. Detailed Implementation

[0066] Figure 1 An embodiment of a computed tomography (CT) system 1 with a radiation detector 4 and a radiation source 5 is shown. The radiation source 5 is configured to irradiate the radiation detector 4 with radiation. The CT system 1 shown includes a gantry 2 with a rotating body 3. The rotating body 3 includes an X-ray source 5 as the radiation source 5 and a radiation detector 4 configured to detect X-ray radiation.

[0067] The rotating body 3 can rotate about the rotation axis 8. The patient 6 is located on the treatment bed 7 and can move along the rotation axis 8 via the gantry 2. The patient 6's head is placed on the placement aid 1. The computing processing unit 9 is configured to control the imaging system 1 and / or to generate an image dataset based on the signals detected by the radiation detector 4.

[0068] The (raw) X-ray image dataset of the object 6 is typically recorded from multiple angles with one energy beam each using a radiation detector 4, resulting in two or more raw datasets. The (final) image dataset can then be reconstructed based on the (raw) X-ray image datasets using mathematical methods, such as filtered back projection or iterative reconstruction methods.

[0069] The computing processing unit 9 serves as a control device 9 for controlling the CT system 1. Input device 10 and output device 11 are connected to the computing processing unit 9. Input device 10 and output device 11 can, for example, enable user interaction or represent the generated image dataset B.

[0070] Control device 9 here includes a data interface 12 for receiving CT data, outputting control commands, and outputting reconstructed image datasets (see also [reference]). Figure 3 ).

[0071] In addition to the data interface 12, the control device also includes an inspection unit 13, an interference structure unit 14, a calculation unit 15, a reconstruction unit 16, and in this example, a positioning unit 17.

[0072] The examination unit 13 is used to define the examination area U for the patient 6. This represents an area that may be suitable for examination of the chest or lungs. In simple cases, the examination area can be defined by manual input. However, the examination unit 13 can also define tools for defining the examination area U in an image, or tools for defining the examination area U according to the regulations used for the examination.

[0073] Interference structure unit 14 defines a number of interference structures S, wherein the interference structures S are structures located within the beam path of the computed tomography imaging system 1 and reflect or absorb X-ray radiation with an intensity exceeding the tolerance range. It can be predetermined, for example, which structures within the human body will be considered interference structures S (e.g., the spine), and then it can be determined which interference structures S might interfere with the measurement of the examination area U. These interference structures are defined as (related) interference structures S.

[0074] The computation unit 15 is used to calculate the beam path of the X-ray R for CT examination of the examination area U, and to determine the interference angle range W of the gantry 2 of the computed tomography system. Within this interference angle range, the beam path passes through the interference structure S and the examination area U. Geometric calculations can be easily performed using the known positions of the X-ray sources 5, their known beam paths, and the known positions of the defined interference structures.

[0075] As described above, the data interface 12 is used to output control commands to perform CT recording while the rotating body 3 of the gantry 2 is rotating, and to receive CT data D.

[0076] Using reconstruction unit 16, image dataset B can be reconstructed from CT data D without omitting the measured interference angle range W.

[0077] Subsequently, data interface 12 is used to output the reconstructed image dataset B.

[0078] In this example, the control device 9 also includes a positioning unit 17, which is designed to determine the position of the placement aid 1. The positioning unit 17 is specifically designed to estimate the position based on images and / or to receive and evaluate information about the placement aid 1.

[0079] Figure 2 The interfering structure S (here, the spine) and the range of the interfering angle W are shown. It can be assumed that the observer moves along... Figure 1 The axis of rotation is observing the head of patient 6. Here, patient 6 is positioned slightly off-center in gantry 2, so that the examination area U is centered around the left chest. The spine (which is actually not visible) is represented here as the interfering structure S. X-ray source 5 and its cone-shaped X-ray R are shown above patient 6. During recording, the X-ray source rotates around patient 6. When it is within the interference angle range W, the X-ray R passes through the spine first and then through the examination area U. This is undesirable, so the interference angle range W is omitted from the recording (or at least from the reconstruction).

[0080] Figure 3 A sequence diagram illustrating a possible sequence of methods for controlling a computed tomography system 1 according to the present invention is shown, for example... Figure 1 As shown.

[0081] In step I, the examination area U and the interfering structure S for patient 6 were defined. In this example, the interfering structure is the spine, such as... Figure 2 As shown.

[0082] In step II, the interference angle range W of the gantry 2 of the computed tomography system 1 is determined by calculating the beam path of the X-ray R passing through the interference structure S and the inspection area U.

[0083] In step III, CT recording is performed simultaneously with the rotation of gantry 2 (i.e., the rotation of its rotating body 3). During this process, CT data D is recorded. It can be assumed that, to reduce the dose, the X-ray source 5 is switched off within the interference angle range W.

[0084] In step IV, the image dataset B is reconstructed from the CT data D without omitting the measured interference angle range W, and then output.

[0085] Figure 4An example of the recording method of the present invention is shown. Two examination regions U1 and U2 are defined on patient 6, and interference angle ranges W1 and W2 for each examination region U1 and U2 are determined. If the beam path passes through the interference structure S and the associated examination region U1 and U2, the interference angle ranges W1 and W2 are associated with the examination region U1 and U2. Then, an image dataset B is reconstructed separately for each examination region U1 and U2, omitting the determined interference angle ranges W1 and W2 for the associated examination regions U1 and U2.

[0086] In this case, the interference angle ranges W1 and W2 do not overlap. This means that the X-ray source is not turned off when recording CT data, because the reconstructed 360° data can be used for at least one examination area U1, U2.

[0087] If there is an interference angle range W (the same interference angle range W) associated with the two inspection areas U1 and U2, the X-ray source 5 used for recording can be turned off within that interference angle range W.

[0088] Finally, it should be reiterated that the accompanying drawings described in the above description are merely embodiments, and those skilled in the art can modify the embodiments in different ways without departing from the scope of the invention. Furthermore, the use of the indefinite articles "a" or "an" does not preclude the possibility that the relevant feature may appear multiple times. The terms "unit" and "device" also do not preclude the possibility that the relevant component may consist of multiple interacting sub-components, which may also be spatially distributed if necessary. The expression "a certain number" should be understood as "at least one". Regardless of the grammatical gender of the specific term, individuals with male or female gender identities are also included in the terminology.

Claims

1. A method for controlling a computed tomography system (1), comprising the following steps: - Define the inspection area (U) of the inspection object (6). - Define a certain number of interference structures (S), wherein the interference structures (S) are structures located within the beam path of the computed tomography system (1) and that reflect or absorb X-ray radiation with an intensity exceeding the tolerance range. - Calculate the beam path of the X-ray (R) of the CT examination of the examination area (U) and determine the interference angle range (W) of the gantry (2) of the computed tomography system, in which the beam path passes through the interference structure (S) and the examination area (U). - CT recording is performed while the gantry (2) is rotating, and CT data (D) is recorded. - The image dataset (B) is reconstructed from the CT data (D) without omitting the measured interference angle range (W). - Output the image dataset (B).

2. The method of claim 1, wherein the CT data (D) is recorded with the measured interference angle range (W) omitted.

3. The method according to claim 2, wherein the X-ray source (5) for recording is turned off within the interference angle range (W), or at least the radiation power of the X-ray source is reduced.

4. The method of claim 2, wherein the beam parameters are determined for the entire recording based on the entire 360° angular range minus the interference angular range (W).

5. The method according to claim 4, wherein the beam parameters are the accelerating voltage and / or current intensity of the X-ray source (5).

6. The method according to any one of claims 1 to 5, wherein the following angle range is considered as the interference angle range (W): when in the angle range, the beam of the X-ray source (5) of the gantry (2) passes first through the interference structure (S) and then through the inspection area (U).

7. The method according to any one of claims 1 to 5, wherein the interference structure (S) is defined based on the positioning image of the object under inspection (6), the camera recording of the object under inspection (6), or the model of the object under inspection (6).

8. The method according to claim 7, wherein the object of inspection (6) is a human or animal body, and the interference structure (S) is a skeleton, a placement aid (L), or part of the frame (2).

9. The method according to any one of claims 1 to 5, wherein the object to be inspected (6) is placed by means of a placement aid (L) or fixed by means of a fixing device, and an interference structure (S) is defined based on the position and form of the placement aid (L) or the fixing device.

10. The method according to claim 9, wherein the isogonal points of the inspection area (U) are defined after the inspection object (6) is placed with the aid of the placement aid (L).

11. The method according to claim 10, wherein the isogonal points of the examination area (U) are automatically defined by means of image recognition or by means of communication between the placement aid (L) and the computed tomography system (1).

12. The method according to any one of claims 1 to 5, wherein, Within the scope of measuring the interference angle range (W), examine whether the remaining angle range, superimposed with the remaining angle range rotated by 180°, has a continuous 360° angle range by subtracting the interference angle range (W) from the entire 360° angle range.

13. The method of claim 12, wherein, in the case that the remaining angular range is less than 360°, before reconstructing the image dataset (B), for the missing angular range, simulated data is added to the CT data (D), the simulated data simulating the recording in the missing angular range, and / or the missing angular range is removed from a number of interfering angular ranges (W), wherein the degree of interference in the missing angular range and the degree of interference in an angular range rotated 180° relative to the missing angular range are determined, and angular ranges with a lower degree of interference are removed from the interfering angular ranges (W).

14. The method according to any one of claims 1 to 5, wherein two or more inspection areas (U1, U2) of the inspection object (6) are defined, and interference angle ranges (W1, W2) are determined for each of the two inspection areas (U1, U2), wherein if the beam path passes through the interference structure (S) and the inspection area (U1, U2), the interference angle ranges (W1, W2) are associated with the relevant inspection area (U1, U2), and in the absence of the determined interference angle ranges (W1, W2) of the relevant inspection areas (U1, U2), the image dataset (B) is reconstructed separately for each inspection area (U1, U2).

15. The method of claim 14, wherein determining which interference angle ranges (W) associated with the examination areas (U1, U2) are the same, and recording the CT data (D) without omitting the same interference angle ranges (W).

16. The method of claim 14, wherein the X-ray source (5) for recording is turned off within the same interference angle range (W), or at least the radiation power of the X-ray source is reduced.

17. The method according to any one of claims 1 to 5, wherein, When reconstructing the image dataset (B), a combination of data sparsity reconstruction techniques and iterative solution methods is used.

18. The method of claim 17, wherein projection is incorporated to represent the structure.

19. The method according to any one of claims 1 to 5, wherein the examination area (U) is the chest or lung, and wherein the interfering structure (S) is the spine.

20. A control device (9) for controlling a computed tomography system (1), comprising: - An inspection unit (13) is designed to define the inspection area (U) of the inspection object (6). - An interference structure unit (14) is designed to: define a certain number of interference structures (S), wherein the interference structures (S) are structures located within the beam path of the computed tomography system (1) and reflect or absorb X-ray radiation with intensity exceeding the tolerance range. - A computing unit (15) is designed to: calculate the beam path of the X-ray (R) of the CT examination of the examination area (U) and determine the interference angle range (W) of the gantry (2) of the computed tomography system, in which the beam path passes through the interference structure (S) and the examination area (U). - A data interface (12) is designed to: output control commands for performing CT recording while the gantry (2) is rotating, and to receive CT data (D). - A reconstruction unit (16) is designed to reconstruct an image dataset (B) from the CT data (D) without omitting the determined interference angle range (W). - A data interface (12) is designed to output the image dataset (B).

21. The control device according to claim 20, comprising a positioning unit (17) designed to determine the position of a placement aid (L) or a fixing device.

22. The control device according to claim 21, wherein the positioning unit (17) is designed to estimate the position based on an image and / or to receive and evaluate information of the placement aid (L).

23. A computed tomography system (1) comprising a control device (9) according to any one of claims 20 to 22 and / or designed to perform the method according to any one of claims 1 to 19.

24. A computer program product comprising instructions that, when executed by a computer, cause the computer to perform the steps of the method of any one of claims 1 to 19, wherein performing a CT recording corresponds to transmitting corresponding control instructions and receiving CT data (D).

25. A computer-readable storage medium comprising instructions that, when executed by a computer, cause the computer to perform the steps of the method of any one of claims 1 to 19, wherein performing a CT recording corresponds to transmitting corresponding control instructions and receiving CT data (D).

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