Attenuation correction in positron emission tomography

Abstract

For attenuation correction in positron emission tomography (PET), three-dimensional image data (5) of a multitude of hardware components are obtained for use in a PET scan using a PET system (1). Based on the three-dimensional image data (5), an associated attenuation map is generated for each hardware component of the multitude. A subset of the multitude of hardware components, arranged within a predefined field of view of the PET system (1) during a PET scan, is selected. Based on the attenuation maps of this subset of hardware components, a common attenuation map is generated. Attenuation-corrected PET image data are then generated from the PET scan data using this common attenuation map.

Description

[0001] The present invention relates to a computer-implemented method for attenuation correction in positron emission tomography (PET), and to a method for attenuation correction in PET, wherein such a computer-implemented method is carried out. The invention further relates to a data processing system for carrying out such a computer-implemented method, a PET system with such a data processing system, and a corresponding computer program product for carrying out the computer-implemented method.

[0002] In a PET scanner—whether a standalone PET scanner without a combination with another imaging modality such as computed tomography (CT) or magnetic resonance imaging (MR), or in PET-CT or MR-PET systems—the gamma quanta are slowed down by matter located between the signal source at the point in space where electron-positron annihilation occurs and two gamma quanta are emitted in opposite directions, and the gamma detectors. The gamma detectors are equipped, for example, with crystals of lutetium yttrium oxoorthosilicate (LYSO) or lutetium oxyorthosilicate (LSO), which act as scintillators by converting the gamma quanta into optical photons. Photodetectors, such as CMOS detectors, can then convert these photons into electrons.

[0003] The aforementioned attenuation negatively impacts PET signal quality and, if unavoidable, usually requires post-processing correction. Attenuation maps are used for this correction. These maps exist for hardware components such as the patient table or local MR coils, as well as for the patient. Typically, three-dimensional image data is acquired with a separate CT scanner to generate the attenuation maps for the hardware components. After acquisition, this image data is converted into attenuation maps and stored, for example, as voxel data resolved in three spatial directions. Each voxel contains the spatially resolved attenuation of the PET data by the hardware components, for instance, in the form of the so-called LAC value (linear attenuation coefficient).This approach, for example, exploits the fact that there is an approximately linear relationship between the attenuation of gamma quanta and CT image data.

[0004] After the PET scan is performed, the determined PET counts are subsequently increased according to the LAC value of the respective voxel.

[0005] The attenuation maps for the hardware components are transformed to perform attenuation correction, among other things to convert them into the reference coordinate system of the PET system. However, this transformation is very time-consuming, which is particularly disadvantageous because it takes place during the PET scan.

[0006] It is an object of the present invention to provide a way to accelerate the attenuation correction in a PET examination with respect to hardware components, in particular during the PET measurement time.

[0007] This problem is solved by the subject matter of the independent patent claim. Advantageous further developments and preferred embodiments are the subject matter of the dependent claims.

[0008] The invention is based on the idea of ​​generating and transforming an associated individual attenuation map for a large number of potentially relevant hardware components, storing the transformed attenuation maps, and selecting a subset of the potentially relevant hardware components for the specific upcoming or completed PET examination and generating a common attenuation map based on the corresponding transformed attenuation maps, which is then used for attenuation correction of the PET data, in particular for measurement time.

[0009] According to one aspect of the invention, a computer-implemented method for attenuation correction in positron emission tomography (PET) is described. Three-dimensional image data from a plurality of hardware components are obtained for use in PET examinations using a PET system. Depending on the three-dimensional image data, a corresponding attenuation map is generated for each hardware component in the plurality of hardware components. For each hardware component in the plurality of hardware components, a transformation rule is determined, which includes a coordinate transformation between a coordinate system corresponding to the generation of the respective three-dimensional image data and a reference coordinate system of the PET system. A plurality of transformed attenuation maps is generated by transforming the attenuation maps of the plurality of attenuation maps using the respective transformation rule.The transformed attenuation maps of the numerous hardware components are stored on a data carrier. After the transformed attenuation maps are stored on the data carrier, an examination configuration for the PET scan is obtained. Depending on the examination configuration, a subset of the numerous hardware components is selected, whereby the hardware components of this subset are, or will be, or at least partially, arranged within a predefined field of view of the PET system during the PET scan. Based on the transformed attenuation maps of the subset of hardware components, a combined attenuation map is generated. PET data resulting from the PET scan are then obtained.Based on the PET data, attenuation-corrected PET image data are generated using the common attenuation map.

[0010] Unless otherwise specified, all steps of the computer-implemented method can be performed by a data processing system comprising at least one data processing device. In particular, the at least one data processing device is configured or adapted to perform the steps of the computer-implemented method. For this purpose, the at least one data processing device may, for example, store a computer program containing instructions which, when executed by the at least one data processing device, cause the at least one data processing device to perform the computer-implemented method. The computer-implemented method may also be implemented wholly or partly in hardware. The terms "data processing system" and "at least one data processing device" may be used interchangeably here and in the following. This also applies to corresponding derivatives.

[0011] In the event that the at least one data processing device comprises two or more data processing devices, certain steps performed by the at least one data processing device can also be understood as different data processing devices performing different steps or different parts of a step. In particular, it is not necessary for each data processing device to perform the steps. In other words, the execution of the steps can be distributed among the two or more data processing devices.

[0012] Each embodiment of the computer-implemented method results in a corresponding embodiment of an attenuation correction method for PET that is not purely computer-implemented, by including corresponding steps for generating the three-dimensional image data from the multitude of hardware components. Furthermore, each embodiment of the computer-implemented method results in a corresponding embodiment of a method for performing a PET scan that is not purely computer-implemented, by including corresponding steps for generating the PET data using the PET system, i.e., for performing the PET scan using the PET system. These two extensions can also be combined by including the steps for generating the three-dimensional image data and the steps for performing the PET scan.

[0013] The three-dimensional image data includes, in particular, a three-dimensional image dataset for each of the numerous hardware components. The three-dimensional image data, or the image datasets for the individual hardware components, can correspond, for example, to CT or PET datasets that were previously recorded or acquired. In the case of PET datasets, these are independent of the PET scan and the resulting PET data.

[0014] The PET system can be, for example, a pure PET system without any other imaging modality, or a PET-CT system, or an MR-PET system.

[0015] The numerous hardware components are those that can potentially be used in a PET scan using the PET system. These can include, in particular, a patient table, aids for securing or fixing the patient, or, especially in MR-PET systems, local coils, i.e., local MR radiofrequency coils, which can be placed or attached directly to the body of the patient being examined. It is also possible to determine multiple attenuation maps for the same hardware component, but with different configurations or spatial orientations relative to other components, for example, a PET detector of the PET system or the patient table. In this case, different configurations or spatial orientations of the same hardware component can be treated as different hardware components within the framework of the method according to the invention.

[0016] The selection of the subset of hardware components is made according to the specified examination configuration of the PET system for the PET examination to be performed.

[0017] The individual attenuation maps for the hardware components within the multitude of hardware components only need to be generated, transformed, and stored once and can then be used for specific PET scans. If the specific scan configuration is known, particularly which hardware components will actually be used, the corresponding subset of hardware components is selected accordingly. Based on the selected transformed attenuation maps, a common attenuation map is then generated, which can be used for all relevant hardware components within the subset for the specific PET scan. This can be done during the PET scan, whereas the actual initial calculation and transformation of the individual attenuation maps takes place beforehand.Selecting the subset and generating the common attenuation map is significantly less computationally intensive than the initial generation and transformation of the attenuation maps for the individual hardware components. Furthermore, the former does not require any additional imaging, which would also be correspondingly time-consuming. According to the invention, these time-consuming steps are performed upstream.

[0018] It should be noted that when generating the common attenuation map, particular attention is paid to the position or location of the individual hardware components of the subset in relation to each other or to the PET scanner itself, as intended for the PET examination, whereby this information may also be specified in the examination configuration.

[0019] The PET data can be, for example, raw PET data, such as the corresponding PET counts. This raw PET data can then be corrected based on the common attenuation map, and the PET image data can then be generated from the corrected raw PET data using a known PET reconstruction technique. However, it is also possible that the PET data are already reconstructed PET image data. In this case, this PET image data can be attenuation-corrected based on the common attenuation map to generate the attenuation-corrected PET image data.

[0020] It should be noted that the described steps for attenuation correction according to the computer-implemented method of the invention relate only to the correction of attenuation by the relevant hardware components, but not to the correction of attenuation effects due to the patient's body itself. In other words, the proposed computer-implemented method of the invention can be supplemented by known methods for attenuation correction with respect to the influence of the patient's body.

[0021] The attenuation map for a given hardware component can, for example, be a three-dimensional array of voxels, with a corresponding attenuation correction value stored for each voxel. The attenuation correction value can, in particular, be a LAC value. To determine the attenuation correction value, it is specifically exploited that the three-dimensional image data directly allows for a deduction of the attenuation correction value. If the three-dimensional image data is, for example, CT image data, it is utilized that the attenuation of X-ray quanta used in the CT scan is approximately directly proportional to the attenuation of gamma quanta in the PET scan. The attenuation correction values ​​of the attenuation maps, both here and in the following, always refer to the attenuation of gamma quanta in the PET scan, unless otherwise stated.If the three-dimensional image data is also generated by the same or a different PET system, the corresponding attenuation map or attenuation correction values ​​can be read directly from the three-dimensional image data.

[0022] The coordinate system used to generate the three-dimensional image data determines, in particular, the position and orientation of the respective hardware component within the three-dimensional image data. However, this coordinate system can differ from the reference coordinate system of the PET system; in other words, the corresponding hardware component in the PET data may have a different position and orientation relative to the reference coordinate system of the PET system than relative to the coordinate system used to generate the three-dimensional image data. This fact is addressed through transformation in appropriate embodiments.

[0023] In the case of an MR-PET system, the transformation rule may also include a coordinate transformation from the reference coordinate system of the MR scanner to the reference coordinate system of the PET detector.

[0024] By decoupling the generation and transformation of the individual attenuation maps for the individual hardware components from their application during the PET scan, as described in the invention, the time required for subsequent attenuation correction during or after the actual PET scan can be significantly reduced. Tests have shown that, in a typical application, a time saving of more than a factor of 50 can be achieved. However, the actual time saving depends on the number of hardware components actually used in the PET scan, their characteristics, and other factors.

[0025] According to at least one embodiment, the transformed attenuation maps are generated and stored on the data carrier before the PET scan. In particular, the transformed attenuation maps are thus retained for the PET scan and one or more further PET scans.

[0026] According to at least one embodiment, after the transformed attenuation maps have been stored on the data carrier, a further examination configuration for a further PET examination is obtained. Depending on this further examination configuration, another subset of the multitude of hardware components is selected, which are arranged in the field of view of the PET system during the further PET examination. Depending on the transformed attenuation maps of this further subset of hardware components, another common attenuation map is generated. Further PET data resulting from the further PET examination are obtained, and based on this further PET data, further attenuation-corrected PET image data are generated using this additional common attenuation map.

[0027] In particular, the steps mentioned above take place after the PET scan has been performed or after the attenuation-corrected image data has been generated.

[0028] This further clarifies that only the common vulnerability map needs to be individually determined for each use case, while the mainly time- and computationally intensive steps of generating and transforming the individual vulnerability maps for the individual hardware components only need to be performed once.

[0029] According to at least one embodiment, the transformation rule includes nonlinear data interpolation.

[0030] In this case, the transformation rule therefore includes both the coordinate transformation and the non-linear data interpolation.

[0031] The imaging system used to generate three-dimensional image data generally differs from the PET system used for the PET scan. Consequently, the resolution of the PET data, i.e., the spatial resolution of the PET data, also generally differs from the spatial resolution of the three-dimensional image data. In particular, when the three-dimensional image data is generated using a CT system, its spatial resolution is sometimes much higher than that of the PET data. While the latter is on the order of one millimeter or less, CT scans achieve a spatial resolution in the range of one-tenth of a millimeter or similar. Therefore, in such cases, it is necessary to interpolate the three-dimensional image data to match the resolution of the PET data. This is also known as downsampling.

[0032] In the described embodiments, the data interpolation, particularly the interpolation of the three-dimensional image data, is nonlinear. This offers the advantage of more accurate data interpolation but is not used in conventional attenuation correction methods because it increases computation time. However, since, according to the invention, the generation of the individual attenuation maps for the individual hardware components, as well as the transformation of the attenuation maps, precede the actual PET scan, the increased time required for nonlinear data interpolation is less significant. Thus, the advantages of nonlinear data interpolation can be utilized without delaying the PET scan.

[0033] For example, nonlinear data interpolation can be, or include, bicubic data interpolation.

[0034] According to at least one embodiment, prior to performing the PET examination, wherein the performance of the PET examination, as mentioned above, is not necessarily part of the method according to the invention, it is checked, depending on identification data which identify the transformation instructions and, for example, depending on the examination configuration, whether the transformation instructions correspond to an actual configuration for performing the PET examination, and the performance of the PET examination is only initiated if the transformation instruction corresponds to the actual configuration for performing the PET examination.

[0035] In other words, different transformation rules can be stored, corresponding to the different positions, orientations, or positions of the relevant hardware components in space or relative to the PET detector or other reference point of the PET system. Each transformation rule can be assigned corresponding identification data that clearly indicates which configuration was assumed for conducting the PET scan when the transformation rule was generated. In the aforementioned embodiments, before the actual PET scan is performed, it is checked whether the intended transformation rule corresponds to the actual configuration, and only then is the PET scan carried out. Otherwise, the transformation is performed again, and the PET scan is then carried out.

[0036] This avoids errors in weakening correction caused by incorrect or suboptimal transformation rules. This is particularly advantageous due to the earlier timing of the transformation, as this increases the likelihood of potential configuration changes.

[0037] According to at least one embodiment, the identification data is determined using a scatter function, depending on the transformation rules.

[0038] A scatter function is also called a hash function.

[0039] In other words, data that clearly define the specific transformation rules are processed using the scatter function, or the scatter function is applied to the aforementioned data to determine the identification data, namely, in particular, a hash value.

[0040] According to at least one embodiment, the common vulnerability map is generated by averaging corresponding entries of the transformed vulnerability maps of the subset of hardware components.

[0041] In particular, the common vulnerability map is generated solely by averaging the corresponding entries of the transformed vulnerability maps.

[0042] This represents a very efficient and cost-effective calculation. Consequently, time can be saved during the PET scan itself.

[0043] As an alternative to averaging, a maximum value of the corresponding entries from the transformed attenuation maps can also be determined as the associated entry for the combined attenuation map. Determining the maximum value is particularly advantageous in the case of multiple hardware components overlapping in three-dimensional space.

[0044] According to at least one embodiment, the PET system is an MR-PET system and the plurality of hardware components include at least one MR coil, in particular an MR local coil.

[0045] In particular, even the subset of the multitude of hardware components includes at least one MR coil.

[0046] The MR coil can, in particular, be a high-frequency receiving coil that is attached or placed locally on the area of ​​the patient being examined, for example, on the knee, head, arm, or the like. An MR local coil is therefore a coil that is not permanently installed, and its position and orientation can thus change accordingly. In this case, the invention is particularly advantageous because, depending on the objective of the PET examination, certain MR coils may or may not be used, and may be used in different positions. Alternatively or in addition to the at least one MR coil, in particular the at least one MR local coil, the plurality of hardware components, in particular a subset of the plurality of hardware components, can include a patient table.

[0047] According to a further aspect of the invention, a method for attenuation correction in a PET examination is specified, wherein a computer-implemented method according to the invention is carried out and wherein the three-dimensional image data are generated using a CT system or using the PET system.

[0048] The three-dimensional image data is generated particularly before the PET scan.

[0049] According to a further aspect of the invention, a method for PET is described, wherein three-dimensional image data of a plurality of hardware components are obtained by means of a data processing system for use in a PET examination using a PET system, and depending on the three-dimensional image data, an associated attenuation map is generated for each hardware component of the plurality of hardware components by means of the data processing system. A subset of the plurality of hardware components is selected by means of the data processing system, which are arranged in a predetermined field of view of the PET system during a PET examination. The PET examination is carried out using the PET system.Depending on the attenuation maps, a common attenuation map is generated using the data processing system of the subset of hardware components, PET data resulting from the PET examination are obtained, and attenuation-corrected PET image data are generated based on the PET data using the common attenuation map.

[0050] The PET scan is performed after at least the attenuation maps have been generated. The selection of the subset of hardware components and / or the generation of the common attenuation map can take place before, after, or during the PET scan.

[0051] Further embodiments of the PET method according to the invention follow directly from the various configurations of the computer-implemented attenuation correction method according to the invention, and vice versa. In particular, individual features and corresponding explanations as well as advantages relating to the various configurations of the computer-implemented attenuation correction method according to the invention can be transferred analogously to corresponding configurations of the PET method according to the invention.

[0052] According to another aspect of the invention, a data processing system is provided which is configured to carry out a computer-implemented method according to the invention.

[0053] In the present disclosure, the terms "data processing system" and "at least one data processing device" can be used interchangeably. A data processing device can be understood to be, in particular, a data processing device that contains a processing circuit. The data processing device can thus, in particular, process data to perform arithmetic operations. This may also include operations to perform indexed accesses to a data structure, for example, a lookup table (LUT), as well as a data processing process implemented in hardware.

[0054] The data processing device may, in particular, contain one or more computers, one or more microcontrollers, and / or one or more integrated circuits, for example, one or more application-specific integrated circuits (ASICs), one or more field-programmable gate arrays (FPGAs), and / or one or more systems on a chip (SoCs). The data processing device may also contain one or more processors, for example, one or more microprocessors, one or more central processing units (CPUs), one or more graphics processing units (GPUs), and / or one or more signal processors, in particular one or more digital signal processors (DSPs).The data processing device may also include a physical or virtual network of computers or other units of the aforementioned type.

[0055] In various embodiments, the data processing device includes one or more hardware and / or software interfaces and / or one or more storage units.

[0056] A storage unit can be volatile data storage, for example as dynamic random access memory (DRAM) or static random access memory (SRAM), or as non-volatile data storage, for example as read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), flash memory or flash EEPROM, ferroelectric random access memory (FRAM), or magnetoresistive random access memory.It can be designed as MRAM (magnetoresistive random access memory) or as phase-change random access memory, PCRAM (phase-change random access memory).

[0057] According to a further aspect of the invention, a PET system is specified which has a data processing system according to the invention and wherein the PET system is set up to carry out the PET examination.

[0058] According to at least one embodiment of the PET system, it is designed as an MR-PET system.

[0059] Further embodiments of the PET system according to the invention follow directly from the various configurations of the methods according to the invention, and vice versa. In particular, individual features and corresponding explanations as well as advantages relating to the various embodiments of the methods according to the invention can be transferred analogously to corresponding embodiments of the PET system according to the invention. In particular, the PET system according to the invention is configured or programmed to carry out a method according to the invention. In particular, the PET system according to the invention carries out a method according to the invention.

[0060] According to a further aspect of the invention, an arrangement is specified which comprises a PET system according to the invention, as well as a further imaging system which is configured to generate the three-dimensional image data of the plurality of hardware components.

[0061] The additional imaging system is designed, for example, as a CT system.

[0062] Further embodiments of the arrangement according to the invention follow directly from the various configurations of the methods according to the invention, and vice versa. In particular, individual features and corresponding explanations as well as advantages relating to the various embodiments of the methods according to the invention can be transferred analogously to corresponding embodiments of the arrangement according to the invention. In particular, the arrangement according to the invention is configured or programmed to carry out a method according to the invention. In particular, the arrangement according to the invention carries out a method according to the invention.

[0063] According to another aspect of the invention, a first computer program with first instructions is specified. When the first instructions are executed by a data processing system, the instructions cause the data processing system to carry out a computer-implemented method according to the invention.

[0064] The initial instructions can be provided as program code. This program code can be, for example, binary code or assembly language, and / or source code in a programming language such as C, and / or a program script such as Python.

[0065] According to a further aspect of the invention, a second computer program with second instructions is provided. When the second instructions are executed by a PET system according to the invention, in particular by the data processing system of the PET system, the second instructions cause the PET system to carry out a PET method according to the invention.

[0066] The second set of instructions can be provided as program code. This program code can be, for example, binary code or assembly language, and / or source code in a programming language such as C, and / or a program script such as Python.

[0067] According to a further aspect of the invention, a third computer program with third commands is specified. When the third commands are executed by an arrangement according to the invention, in particular by the data processing system of the arrangement, the third commands cause the arrangement to perform an attenuation correction method according to the invention in a PET scan.

[0068] The third set of instructions can be provided as program code. This program code can be, for example, binary code or assembly language, and / or source code in a programming language such as C, and / or a program script such as Python.

[0069] According to a further aspect of the invention, a computer-readable storage medium is specified, in particular a physical and / or non-volatile computer-readable storage medium that stores a first computer program and / or a second computer program and / or a third computer program according to the invention.

[0070] The first computer program, the second computer program, the third computer program and the computer-readable storage medium are each computer program products containing the first instructions, the second instructions and / or the third instructions.

[0071] Further features and combinations of features of the invention will become apparent from the figures and their description, as well as from the claims. In particular, further embodiments of the invention need not necessarily include all features of any one of the claims. Further embodiments of the invention may have features or combinations of features that are not mentioned in the claims.

[0072] The invention is explained in more detail below with reference to specific embodiments and associated schematic drawings. In the figures, identical or functionally equivalent elements may be designated with the same reference numerals. The description of identical or functionally equivalent elements is not necessarily repeated with respect to different figures.

[0073] The figures show Fig. 1 a schematic representation of an exemplary embodiment of a PET system according to the invention; and Fig. 2 a schematic flowchart of an exemplary embodiment of a computer-implemented method according to the invention for attenuation correction in a PET.

[0074] Fig. Figure 1 shows a schematic representation of an exemplary embodiment of a PET system 1 according to the invention, comprising a PET scanner 2, for example an MR-PET scanner, a patient table 3, and a data processing system 4 according to the invention, which is configured to perform a computer-implemented method according to the invention for attenuation correction in a PET scan. The PET system 1, in particular the PET scanner 2, is configured to perform a PET scan according to a predetermined scan configuration 6 (see Figure 1). Fig. 2) to carry out.

[0075] Fig.Figure 2 shows a schematic flowchart of an exemplary embodiment of a computer-implemented method according to the invention for attenuation correction in a PET scan.

[0076] In step 200, three-dimensional image data 5 of a variety of hardware components, such as the patient table 3 and / or MR local coils, are obtained for use in a PET scan using a PET system 1. The three-dimensional image data 5 may, for example, have been acquired beforehand with a CT system.

[0077] In step 210, a corresponding attenuation map is generated for each hardware component of the plurality of hardware components, depending on the three-dimensional image data 5. In step 220, a transformation rule is determined for each hardware component of the plurality of hardware components, which includes a coordinate transformation between a coordinate system corresponding to the generation of the respective three-dimensional image data 5 and a reference coordinate system of the PET system 1. In step 230, a plurality of transformed attenuation maps is generated by transforming the attenuation maps of the plurality of attenuation maps using the respective transformation rule, and the transformed attenuation maps of the plurality of hardware components are stored on a data carrier, in particular the data processing system 4.

[0078] After the transformed attenuation maps have been stored on the data carrier, in step 240 an examination configuration for the PET examination is obtained and, depending on the examination configuration, a subset of the multitude of hardware components is selected which are or will be arranged in a given field of view of the PET system 1 during the PET examination.

[0079] In step 250, a common attenuation map is generated based on the attenuation maps of the subset of hardware components. In step 260, PET data resulting from the PET scan are obtained, and in step 270, attenuation-corrected PET image data are generated based on the PET data using the common attenuation map.

[0080] Optionally, in step 250, depending on identification data that identifies the transformation rules, a check is performed to determine whether the transformation rules correspond to an actual configuration for performing the PET scan. The PET scan is only initiated if the transformation rules correspond to the actual configuration. Otherwise, the transformation rules are adjusted, for example, according to the actual configuration.

[0081] It may also be possible to provide that the common attenuation map is only generated, depending on the transformed attenuation maps of the subset of hardware components, if the transformation rule corresponds to the actual configuration for carrying out the PET study.

[0082] In some embodiments, the attenuation maps of the hardware components are calculated from CT scans. A transformation matrix is ​​calculated to convert the attenuation maps into the target coordinate system of the PET scanner 2 detector. The transformation matrix is ​​used to convert the attenuation maps into the target coordinate system. During this process, the resolution is also adjusted by resampling to achieve the ideal resolution for the subsequent attenuation correction. This results in correspondingly transformed attenuation maps of the hardware components. These can be stored in a separate file for each hardware component. The transformation matrix used can be stored along with the transformed attenuation maps, for example, in the headers of the respective files. When attenuation correction is to be performed, the attenuation maps do not need to be calculated again, but only read in.The system checks whether the stored transformation matrix matches the current configuration. If it does not, a warning is issued, and the transformation is performed using the correct transformation matrix. The system then determines which hardware components are currently in use and, based on the position of patient table 3, selects those whose bounding boxes intersect or lie entirely within the PET detector's field of view. The corresponding areas are copied from the transformed attenuation maps and added together, or maximum values ​​of the overlapping voxels are taken, resulting in the combined attenuation map. No computationally intensive operations such as resampling or coordinate transformations are required, making the procedure very fast. The attenuation correction is then performed using this combined attenuation map.

[0083] Regardless of the grammatical gender of a particular term, persons with male, female or other gender identities are included.

Claims

[1] Computer-implemented method for attenuation correction in positron emission tomography, PET, wherein - three-dimensional image data (5) of a variety of hardware components for use in a PET examination using a PET system (1) are obtained; - depending on the three-dimensional image data (5) for each hardware component of the multitude of hardware components, an associated attenuation map is generated; - for each hardware component of the multitude of hardware components, a transformation rule is determined which includes a coordinate transformation between a coordinate system corresponding to the generation of the respective three-dimensional image data (5) and a reference coordinate system of the PET system (1); - a large number of transformed weakening maps are generated by transforming the weakening maps of the large number of weakening maps using the respective transformation rule; - the transformed vulnerability maps of the multitude of hardware components are stored on a data carrier; - after the transformed attenuation maps have been stored on the data carrier, an examination configuration for the PET examination is obtained, depending on the examination configuration a subset of the multitude of hardware components is selected which are arranged in a predefined field of view of the PET system (1) during the PET examination, depending on the transformed attenuation maps of the subset of hardware components a common attenuation map is generated, PET data resulting from the PET examination are obtained and attenuation-corrected PET image data are generated based on the PET data using the common attenuation map. [2] Computer-implemented method according to claim 1, wherein the transformed attenuation maps are generated and stored on the data carrier prior to the PET examination and are thus available for the PET examination and one or more further PET examinations. [3] Computer-implemented method according to any of the preceding claims, wherein the transformation rules include non-linear data interpolation. [4] Computer-implemented method according to claim 3, wherein the non-linear data interpolation includes bicubic data interpolation. [5] Computer-implemented method according to one of claims 2 to 4, wherein, prior to performing the PET examination, it is checked, depending on identification data which identify the transformation instructions, whether the transformation instructions correspond to an actual configuration for performing the PET examination and the PET examination is only initiated if the transformation instructions correspond to the actual configuration for performing the PET examination. [6] Computer-implemented method according to claim 5, wherein the identification data are determined using a scatter function depending on the transformation rules. [7] Computer-implemented method according to any one of claims 2 to 6, wherein the common weakening map is generated by averaging corresponding entries of the transformed weakening maps of the subset of hardware components. [8] Computer-implemented method according to one of the preceding claims, wherein the PET system (1) is an MR-PET system and the plurality of hardware components includes at least one MR coil. [9] Computer-implemented method according to claim 8, wherein the at least one MR coil includes an MR local coil. [10] Computer-implemented method according to one of the preceding claims, wherein the plurality of hardware components includes a patient couch (3). [11] Computer-implemented method according to one of the preceding claims, wherein, after the transformed attenuation maps have been stored on the data carrier, a further examination configuration for a further PET examination is obtained, depending on the further examination configuration, a further subset of the plurality of hardware components is selected which are arranged in the field of view of the PET system (1) during the further PET examination, depending on the transformed attenuation maps of the further subset of hardware components, a further common attenuation map is generated, further PET data resulting from the further PET examination are obtained, and further attenuation-corrected PET image data are generated based on the further PET data using the further common attenuation map. [12] Data processing system (4) configured to carry out a computer-implemented method according to any one of claims 1 to 11. [13] PET system (1) comprising a data processing system (4) according to claim 12, wherein the PET system (1) is set up to perform the PET examination. [14] PET system (1) according to claim 13, wherein the PET system (1) is configured as an MR-PET system. [15] Computer program product comprising instructions which, when executed by a data processing system (4), cause the data processing system (4) to perform a method according to any one of claims 1 to 11.

Images