Method for generating plurality of projection records in plurality of successive exposure periods

Abstract

The invention relates to a method for generating a plurality of projection records. The method comprises the steps of: simultaneously activating a plurality of X-ray sources multiple times at a start time for each clocked exposure time period to generate an X-ray beam having a modulated emission intensity; and during the exposure time period, detecting an X-ray beam of the X-ray source by means of the X-ray detector at a start time, thereby producing a plurality of projection records. The method is characterized in that during the period of the exposure time period, the emission intensity of the X-ray sources is amplitude-modulated about a constant offset emission intensity greater than zero, such that the emission intensity of at least one of the X-ray sources differs at two successive starting times, the emission intensity of the X-ray sources being not equal to zero during the exposure time period.

Description

Technical Field

[0001] The present invention relates to a method for generating multiple projection records, an imaging modality, and a computer program product. Background Technology

[0002] In virtually all X-ray imaging methods, an image of the object being fluoroscopic is produced by the absorption of an X-ray beam within the object. Traditionally, this is done using an X-ray source that irradiates an X-ray detector with the X-ray beam, with the object positioned between the X-ray source and the detector. In the case of distributed X-ray sources, such as dual-source computed tomography (CT) devices, typically, the X-ray source irradiates the X-ray detector separately, where the X-ray detectors used for X-ray images that follow each other can be identical.

[0003] For this type of imaging method, an exposure period is typically provided, during which the X-ray source must provide the dose required to produce the projection record. Therefore, in tomographic fusion imaging, each X-ray source can advantageously produce an X-ray beam with maximum emission intensity during the exposure period. If, for example, N projection records are needed to generate a tomographic fusion 3D image dataset, then the conventional tomographic fusion imaging modality must therefore have N X-ray sources, all of which can provide maximum emission intensity for the exposure period. Typically, each of the N projection records images the object from a different angle. Conventionally, multiple X-ray sources are activated sequentially and individually, or the X-ray sources move across the object. It is noteworthy that the requirement for the maximum emission intensity of the X-ray sources used in the tomographic fusion imaging modality to date is relatively high.

[0004] In principle, 3D image datasets can be generated using tomographic fusion imaging. Traditional tomographic imaging forms an alternative to this, in which it produces a projection record around the object of more than 180°.

[0005] The modulation of emission intensity is known in principle from existing technologies. Here, typically, modulation is applied to an electron beam generated by an electron emitter, thereby similarly modulating an X-ray beam.

[0006] DE 10 2012 208 531 A1 applies labeled frequencies to different directions of radiation emitted by an X-ray source in order to separate scattered radiation from the absorption image. The X-ray detector used here is irradiated by only one X-ray source.

[0007] DE 10 2015 217 996 A1 describes time modulation of X-ray sources. Here, the emission intensity of a single X-ray source is modulated during recording by means of laser radiation, thereby one-to-one marking frequencies reaching all groups of X-ray detectors.

[0008] For example, US10 238 352 B2 describes a method in which an image of an antiscattering grid from an image sequence is removed by means of unfolding in Fourier space. The X-ray detector used here is irradiated only by an X-ray source.

[0009] J. Zhang et al., in “Multiplexing radiography using a carbon nanotube based x-ray source”, Appl. Phys. Lett. 89, 1 (2006), DOI: 10.1063 / 1.2234744, described the spatial and temporal modulation of an X-ray beam. The X-ray beam was generated by multiple X-ray sources, which were switched on and off at individualized frequencies. Each X-ray source had a 50% clock duty cycle, meaning the average power was limited to 50% of the maximum power that a single X-ray source could provide. Due to this limitation, a correlation was generated between the switching frequency of the individual X-ray sources and the readout frequency of the X-ray detector.

[0010] In principle, it is conceivable to distribute the dose typically required for low-noise X-ray images across multiple short exposure time periods X Δt, rather than onto a single long exposure time period. This can be advantageous in principle because, while adhering to the same maximum temperature specification, the applicable emission intensity of such an X-ray source configured with a fixed anode over the exposure time period is typically comparable to that over Δt > 1 μs. The advantages are particularly applicable if the required dose can be generated within a single, short exposure time, such as at maximum emission intensity, thereby shortening the imaging method. This maximum emission intensity can be limited, for example, by the design limits of a high-voltage generator configured to provide high voltages suitable for electron acceleration and / or to achieve a high lifetime for the accelerated electrons emitted from the anode surface to generate an X-ray beam. If the dose within the exposure time of maximum emission intensity is insufficient, multiple records can instead be generated within successive exposure times.

[0011] If the emission intensity P (where must be ) is the scan duration Δt, then... If the required dose during a long exposure period is distributed across X exposure periods, then each exposure period can advantageously achieve a higher emission intensity. Passing through. (The time t is used for reading from the detector.)a The regular intervals between the various exposure time periods make the total duration from the beginning of the first exposure time period to the end of the last exposure time period longer than the pure sum of the exposure time periods of the X-ray source. This results in an increase in the time required to obtain an image of the object being detected.

[0012] If the following three conditions are met:

[0013]

[0014] Therefore, in principle, it is possible to shorten the total duration of X-ray sources that are sequentially switched on. This is particularly relevant in cases where the exposure time has been set very high relative to the readout time of the X-ray detector. Summary of the Invention

[0015] The purpose of this invention is to provide a method for generating multiple projection records, an imaging modality, and a computer program product, wherein the X-ray source used for this purpose must have low power requirements.

[0016] The objective is achieved through the features of the invention. Advantageous designs are described in the following description.

[0017] The following describes the solution according to the invention for the claimed purpose, not only with respect to the claimed device but also to the claimed method. The features, advantages, or alternative embodiments mentioned herein can also be adapted to other claimed subjects, and vice versa. In other words, physical embodiments (such as those for devices) can also be improved by incorporating the features described or claimed in conjunction with the method. The corresponding functional features of the method are here constituted by corresponding physical modules.

[0018] Regardless of the grammatical part of speech of a particular term, people with male or female gender identities are included.

[0019] This invention relates to a method for generating multiple projection records over multiple successive exposure time periods, particularly for tomographic fusion imaging. The method includes the steps of simultaneously activating multiple X-ray sources multiple times at the start time for each clock-controlled exposure time period to generate X-ray beams with modulated emission intensities. The method further includes the step of simultaneously detecting the X-ray beams of the multiple X-ray sources multiple times at the start time during the exposure time period using an X-ray detector, thereby generating multiple projection records. The method is characterized in that, during the clock cycle of the exposure time period, the emission intensities of the multiple X-ray sources are amplitude modulated with a constant offset emission intensity greater than zero, such that the emission intensity of at least one of the multiple X-ray sources differs at two successive start times, and thus, the emission intensities of the multiple X-ray sources are not equal to zero during the exposure time period.

[0020] According to the invention, the term X-ray source particularly includes a single X-ray source point as the origin of a single X-ray beam. A single X-ray source point may be associated with one or more pixels of an unpartitioned electron emitter, such as a thermionic emitter, and / or a partitioned electron emitter, such as a field-effect based emitter. According to the invention, N X-ray sources are activated simultaneously, particularly during the exposure time period. Here, N X-ray beams are generated and emitted.

[0021] During the activation of the X-ray source, the X-ray source generates an X-ray beam. In other words, when the X-ray source is activated, the X-ray source emits an X-ray beam.

[0022] The X-ray beams are emitted separately by X-ray sources and detected by X-ray detectors. The X-ray detectors detect the sum of the X-ray beams in the form of projection records within the exposure time period. Specifically, the X-ray detectors detect the clock-controlled X-ray beams emitted by multiple X-ray sources sequentially within the exposure time period. The X-ray detectors thus detect projection records for each exposure time period. The total exposure time is derived from the sum of the exposure time periods and the optional "intervals" between them, during which the X-ray detectors can be read, for example. During the exposure time period, the X-ray detectors can detect not only radiation directly incident on them, such as radiation caused by the X-ray beams, but also indirect radiation, such as scattered radiation. Therefore, projection records are detected by the X-ray detectors during each exposure time period. Thus, the projection records are derived from the superposition of multiple X-ray beams and scattered radiation during the corresponding exposure time periods.

[0023] In particular, the X-ray source and X-ray detector are configured such that the X-ray beam emitted by the X-ray source passes through the object or at least a portion of the object before being detected by the X-ray detector. In this manner, the object or a portion of the object is projected onto the X-ray detector by the respective X-ray beams. Here, the object can be, in particular, a patient (especially a person or animal) or an object.

[0024] Specifically, N projection records are detected using an X-ray detector over N exposure time periods. In other words, projection records are detected within each exposure time period.

[0025] In this context, clock-controlled exposure time periods mean that each exposure time period is used to generate its own projection record. Furthermore, clock-controlled exposure time periods can mean that the emission intensity of at least one of a plurality of X-ray sources changes between two exposure time periods. Alternatively, clock-controlled exposure time periods can mean that X-ray sources are not activated between exposure time periods, i.e., no X-ray beam is generated or emitted.

[0026] Exposure time periods, in particular, include fixed time intervals. Advantageously, all exposure time periods are of the same length.

[0027] The exposure periods begin at a specific start time. Therefore, at each start time, preferably all X-ray radiation sources are activated for at least the duration of the exposure period. Thus, the time interval between two successive start times is at least as long as the exposure period. Alternatively, the time interval between two successive start times may be as long as the exposure period plus the time required to read the X-ray detector.

[0028] In tomographic fusion imaging, multiple X-ray sources are positioned in an arc surrounding the object.

[0029] The term "modulated emission intensity" means modulating the intensity of the individual X-ray beams independently of each other between exposure time periods. Specifically, the emission intensity of at least one X-ray source, or the intensity of an X-ray beam, is different at two successive start times. Consequently, the average emission intensity of the two X-ray beams from at least one X-ray source is different during the two successive exposure time periods. Here, the emission intensity of the two X-ray beams changes with a positive-zero offset. This is called amplitude modulation.

[0030] In particular, the emission intensity of the X-ray beam generated by the X-ray source changes around the offset emission intensity, or all X-ray beams of the X-ray source have an emission intensity equal to the offset emission intensity. In other words, during the exposure time, no single X-ray source fails to emit an X-ray beam. In other words, the emission intensity of multiple X-ray sources is not zero during the exposure time. In other words, all X-ray sources are active and emit X-ray beams throughout the entire exposure time.

[0031] Optionally, except for the emission intensity of the X-ray beam from one X-ray source, the emission intensity of the X-ray beam from all X-ray sources varies around the offset emission intensity. Here, the frequency of the variation advantageously differs between the X-ray sources. An X-ray source whose emission intensity does not change constantly emits an X-ray beam with a non-zero emission intensity, advantageously having an emission intensity equal to the offset emission intensity.

[0032] This invention is based on the aforementioned optimizations made with respect to three applicable conditions. Furthermore, by employing amplitude modulation with a non-zero offset emission intensity according to the invention, the total exposure time can be further reduced, since all X-ray sources are active during each exposure period. Therefore, significantly less than N*(Δt+t) can be achieved by means of the claimed method. a The total exposure time. In particular, each individual X-ray source must therefore only provide an average power of Pmax / N, where Pmax describes the maximum emission intensity that the X-ray source can emit. Because a fixed anode is used in all currently known tomofusion facilities, and thus the maximum emission intensity is limited for a fixed focal spot size and time interval Δt, the requirements for X-ray sources are reduced, or applications that have been difficult to achieve for tomofusion to date can be realized. As applicable, the higher the number N of multiple X-ray sources, the lower the emission intensity with respect to the maximum emission intensity of each of the multiple X-ray sources.

[0033] Furthermore, advantageously, a higher degree of monochromaticity can be achieved by reducing the power of each X-ray source. This can result in improved image quality on the one hand, and on the other hand, reduce the amount of material applied to the object on the other.

[0034] According to one aspect of the invention, the average emission intensity of at least two of the plurality of X-ray sources, relative to the exposure time period, is different at at least one start time.

[0035] The average emission intensity over the exposure time period or the average emission intensity within the exposure time period describes the average intensity of the X-ray beam during the exposure time period.

[0036] In other words, at at least one initial moment, the average emission intensities of at least two X-ray beams are different or dissimilar. In other words, the deviations between the average emission intensity and the offset emission intensity during the exposure time of at least two X-ray beams are different. Specifically, at least two X-ray beams are differently altered or modulated around the offset emission intensity.

[0037] Information about the X-ray beam in the projection record can be separated in the manner described above, or by different amplitude modulations around the offset emission intensity. In other words, a fluoroscopic projection record is determined for each of the two differently modulated X-ray sources based on N projection records by different amplitude modulations of the two X-ray sources. Each projection record in the fluoroscopic projection record images the object from the direction in which the corresponding X-ray source illuminates, spews, or transmits light through the object.

[0038] According to one aspect of the invention, the emission intensities of all the multiple X-ray sources are constant during the exposure time period.

[0039] In other words, the amplitude modulation or alteration of the emission intensity of each X-ray source occurs between or about the exposure time period. Within the exposure time period, the emission intensity emitted by each X-ray source or the emission intensity of each X-ray beam is constant. In other words, the emission intensity of the X-ray sources is constant during each individual exposure time period, while the emission intensity can be varied between exposure time periods according to amplitude modulation.

[0040] In this manner, it can be ensured that information about each X-ray beam can be separated from the projection record regardless of the duration of the exposure time. In other words, the emission intensity for each X-ray beam or for each X-ray source is known in each projection image, thereby ensuring stable reconstruction of the projection images for each X-ray source. Furthermore, in this manner, it can be achieved that changing the length of the exposure time only alters the statistical characteristics, i.e., the noise in the projection record, and thus the transparent projection record, but does not change the image detection itself, because even if the duration of the exposure time changes, the emission intensity of each X-ray source remains constant within each exposure time.

[0041] According to one aspect of the invention, the emission intensity is derived from the product of a non-zero modulation factor individualized for each of a plurality of X-ray sources and a constant offset emission intensity.

[0042] Here, the modulation factor can change over time. In other words, the modulation factor can be different for different start times. In particular, the emission intensity of the X-ray source can be constant over the exposure time period, depending on the value of the modulation factor at the corresponding start time. In other words, during the exposure time period, the emission intensity can remain constant, taking the value corresponding to the time-varying modulation factor at the start time of the corresponding exposure time period.

[0043] The timing and / or amplitude of the modulation factor can be individualized or different for different X-ray sources. In this manner, individualized amplitude modulation can be ensured for each of a plurality of X-ray sources by means of the modulation factor.

[0044] Amplitude modulation around the offset emission intensity can be achieved in this manner. In particular, it can be ensured that no X-ray source emits zero emission intensity during any exposure period within the exposure time. Specifically, individualizable modulation factors ensure that different X-ray sources are modulated around the same offset emission intensity at different frequencies. In this manner, a fluoroscopic projection record can be determined from N projection records for each of the N thus modulated X-ray sources. In other words, information about each individual X-ray source can be extracted from the N projection records through characteristic amplitude modulation for each X-ray source, thereby determining the N fluoroscopic projection records.

[0045] According to another aspect of the invention, the modulation factor is derived from the following:

[0046]

[0047] Where N represents the number of X-ray sources.

[0048] Where k = 0, 1, ..., N-1, serves as the number for each individual X-ray source among a plurality of N X-ray sources.

[0049] Where POff represents the offset emission intensity.

[0050] Where t = t0, t1, ..., tN-1 are the corresponding start times.

[0051] Where M≤1 is the modulation amplitude.

[0052] In particular, the following should be followed:

[0053] P max (1+M)<P max设计 ,

[0054] Where Pmax is the offset emission intensity of the corresponding X-ray source at its maximum operating speed, and Pmax design is the maximum emission intensity that the X-ray source can operate at during continuous operation. These limits ensure reliable operation in a simple way. Because for each X-ray source, the maximum power P... max (1+M) only occurs in a short time Δt, so if anode wear can be tolerated,

[0055] A slightly higher power would also be reasonable.

[0056] Importantly, according to the invention, the modulation amplitude is... The following is given in Chinese:

[0057]

[0058] The sampling frequency is given by reading the frequency from the detector:

[0059]

[0060] This automatically satisfies the sampling limit according to the Nyquist theorem:

[0061] f 采样 =f 探测器 >2f 信号 .

[0062] Therefore, even at frequencies smaller than those given above, the objective according to the invention is still satisfied when L > 1:

[0063]

[0064] For example, where L = 5.

[0065] According to another aspect of the invention, the modulation amplitude is in the range between 0.1 and 0.3.

[0066] Within this range, the modulation amplitude is clearly measurable, and the X-ray source is designed to operate relatively close to the design limit Pmax.

[0067] According to another aspect of the invention, multiple X-ray sources are activated such that the sum of the emission intensities of all X-ray sources is the same after all projection records have been generated.

[0068] In other words, the total power of all X-ray sources is the same in all N projections:

[0069]

[0070] Where j is the number of the exposure time period.

[0071] In this manner, it can be ensured that each X-ray source is considered by means of the same statistical properties. In other words, it ensures that the reconstructed fluoroscopic projection records of each X-ray source have the same statistical properties. In particular, it can be ensured that all X-ray sources are loaded equally on an average basis.

[0072] Furthermore, the present invention relates to an imaging modality The imaging modality includes multiple X-ray sources, X-ray detectors, and a computing unit. Here, the computing unit is configured to control the imaging modality according to any of the above embodiments.

[0073] Imaging modalities specifically constitute the means for performing tomographic fusion or tomographic scanning of an object. For this purpose, multiple X-ray sources are used to transmit light through the object from different directions.

[0074] Imaging modalities therefore have the advantage of describing the method.

[0075] According to one aspect of the invention, the plurality of X-ray sources each have a maximum emission intensity of less than or equal to 10 kW.

[0076] Advantageously, due to the above-described method, the maximum power requirement of the X-ray source is reduced compared to conventional imaging systems designed for tomographic fusion and / or computed tomography. Therefore, X-ray sources with lower maximum emission intensities can be used without requiring longer recording times. Such X-ray sources are typically cheaper and have longer lifespans. In particular, fixed-anode X-ray tubes can therefore be used instead of rotating-anode X-ray tubes.

[0077] According to another aspect of the invention, a plurality of X-ray sources are fixedly positioned relative to the X-ray detector and with respect to the environmental position of the imaging mode.

[0078] In particular, multiple X-ray sources do not move during tomographic fusion and / or tomographic scanning.

[0079] In this manner, the requirements for the mechanical components of the imaging system are reduced compared to conventional tomographic fusion or tomographic scanning systems. In particular, there is no need for mechanical devices to rotate multiple X-ray sources. Therefore, the imaging system requires significantly less maintenance. Furthermore, motion artifacts caused by rotation of parts of the imaging system do not occur during image inspection.

[0080] According to another aspect of the invention, the anodes of the plurality of X-ray sources are made of a material having a lower melting temperature than tungsten.

[0081] In particular, the anode material may include copper and / or tin and / or tantalum and / or steel and / or ceramics and / or silver and / or gold. Ceramics may in particular include rare earth elements.

[0082] Due to the lower power requirements of each X-ray tube and thus less temperature input to the anode, materials with a lower melting temperature than conventionally used tungsten can be used. Therefore, cheaper materials can be used in particular. Especially, materials whose characteristic spectra are particularly suitable for imaging can be used.

[0083] Furthermore, the present invention relates to a mammography system comprising a compression unit for immobilizing a subject and the aforementioned imaging modality. Here, a plurality of X-ray sources are arranged in an arc surrounding the compression unit.

[0084] In particular, multiple X-ray sources are arranged around the compression unit and thus around the object fixed in the compression unit, so that multiple perspective projection records of the object can be detected from different directions by means of each X-ray source. In particular, the multiple X-ray sources are arranged here to enable tomographic fusion recording to be performed from the multiple perspective projection records.

[0085] In particular, the fluoroscopic projection record can be determined for each of the N X-ray sources from the N projection records detected over N exposure time periods as described above. The fluoroscopic projection record is determined here by means of the discrete Fourier transform of the N projection records:

[0086]

[0087] Here, the detector dataset is typically two-dimensional in a planar detector, i.e., a_k = a_k(x,y), and the equations for I_k must be computed separately for each pair (x,y). Each detector dataset here corresponds to a projection record.

[0088] Then, a three-dimensional image of the object can be determined from the projection records of N perspectives using the traditional tomographic fusion reconstruction method.

[0089] Therefore, motion artifacts that may arise from the movement of the X-ray source around the subject can be avoided, especially in mammography, while allowing the use of X-ray sources with lower power requirements. In particular, this mammography system combines the advantages described above regarding the method. Furthermore, the total recording time for tomographic fusion imaging can be reduced because a single X-ray source does not need to move around the subject and be activated and deactivated; instead, all N X-ray sources are activated simultaneously.

[0090] Furthermore, the present invention relates to a computed tomography (CT) scanner having a gantry with a patient tunnel and the aforementioned imaging modality. Here, the imaging modality is arranged around the patient tunnel.

[0091] In this context, the patient tunnel can be cylindrical. The object is positioned within the patient tunnel for imaging.

[0092] N X-ray sources are arranged around the patient tunnel, such that the X-ray sources cover at least 180° or in a semi-circular manner.

[0093] As described regarding mammography systems, N fluoroscopic projection records can be determined from N projection records, which can be used to determine three-dimensional computed tomography records.

[0094] In this way, computed tomography (CT) scans can be performed using N less powerful X-ray sources. The mechanical requirements of this CT scanner are less than those of a conventional CT scanner because there is no rotating X-ray source, thus avoiding both the load caused by rotation and the need for complex cabling for rotating X-ray sources. Furthermore, the use of a fixed-position X-ray source avoids motion artifacts that may occur due to rotation, eliminating the need for N extremely powerful X-ray sources. With the CT scanner described using the described method, it is feasible to use a fixed anode tube with a corresponding power of only 100W.

[0095] According to one aspect of the invention, a plurality of X-ray sources of a computed tomography (CT) apparatus are arranged in an arc comprising at least 180° surrounding a patient tunnel.

[0096] In other words, in this manner, N perspective projection records can be determined from each direction using N X-ray sources at discrete angular intervals.

[0097] According to one aspect of the invention, a plurality of X-ray sources of a computed tomography (CT) apparatus are arranged in a complete circle surrounding a patient tunnel.

[0098] In other words, multiple X-ray sources are arranged around the object along the patient tunnel, so that X-ray records of the object's perspective can be determined from all possible directions at discrete angular intervals within the patient tunnel.

[0099] In this manner, as in conventional computed tomography, perspective projection records are detected or determined from all possible directions (at discrete intervals) surrounding the object. Therefore, image quality is not reduced compared to conventional computed tomography, while offering the advantage of reduced motion artifacts without relying on N very powerful X-ray sources.

[0100] According to one aspect of the invention, a plurality of X-ray sources of a computed tomography (CT) device are arranged in a matrix at least in a 2×2 configuration along the patient tunnel.

[0101] Here, multiple X-ray sources can be configured to cover not only the entire circle but also the column surrounding the object. In this manner, images of the object within the patient tunnel can be recorded along an extension of the central axis of the patient tunnel without requiring the object to move or be moved along the central axis.

[0102] As is known in conventional computed tomography (CT) scans, image recording is performed in a spiral pattern. Here, the object moves along a central axis while the X-ray source rotates around it. Because of the matrix-like arrangement, this movement is unnecessary to achieve image recording with an extension along the central axis. Motion artifacts can be further reduced in this manner. Furthermore, the requirements for the mechanical devices of the examination table (on which the object is supported within the patient tunnel) are reduced, as the examination table does not need to be precisely and movable.

[0103] Therefore, due to the arbitrary arrangement of multiple X-ray sources, arbitrary geometries can be covered during image detection. The content mentioned herein should be understood as exemplary only. By applying the method described, it is not necessary for each individual X-ray source to be of the same power as those used to date. Therefore, significantly cheaper X-ray sources and / or those with characteristic spectral matching can be used. Furthermore, compared to existing techniques, excessively long recording periods can be avoided by ensuring all X-ray sources are active during each exposure period.

[0104] This invention also relates to a computer program product having a computer program and a computer-readable medium. The largely software-based implementation has the advantage that existing imaging modalities can be easily modified via software upgrades to operate in the described manner. In addition to the computer program, such a computer program product may, if necessary, include additional components and / or additional parts such as documentation, and hardware components, such as hardware keys (software dongles, etc.), to use the software.

[0105] In particular, the present invention also relates to a computer program product having a computer program that can be directly loaded into the memory of an imaging modality, the computer program having program segments so that, when executed by the imaging modality, all steps and aspects of the method described above for generating multiple projection records in multiple successive exposure time periods are performed.

[0106] In particular, the present invention relates to a computer-readable storage medium storing program segments readable and executable by an imaging mode, such that when the program segments are executed by the imaging mode, all steps and aspects of the method described above for generating multiple projection records in multiple successive exposure time periods are performed.

[0107] One implementation method is proposed,

[0108] A computer program product may be a computer program or may include a computer program. In particular, the computer program product has a program code structure that describes the method steps according to the invention. This allows the method according to the invention to be performed in a defined and repeatable manner, and allows for control over the forwarding of information regarding the method according to the invention. The computer program product is preferably configured such that a computing unit can perform the method steps according to the invention by means of the computer program product. Program segments may be loaded into the memory of the computing unit and typically executed by means of the processor of the computing unit via memory access. If the computer program product, especially program segments, is run in the computing unit, then all embodiments of the described method according to the invention can typically be performed. The computer program product is stored, for example, on a physical, computer-readable medium and / or stored digitally as data packets in a computer network. The computer program product may be a physical, computer-readable medium and / or a data packet in a computer network. Therefore, the invention can also be based on a physical, computer-readable medium and / or a data packet in a computer network. Physical, computer-readable media can typically be directly connected to the computing unit, for example, by placing the physical, computer-readable media in a DVD disk drive or inserting it into a USB port, thereby allowing the computing unit to access the physical, computer-readable media in a read-only manner. Data packets can preferably be retrieved from a computer network. The computer network can have the computing unit or be indirectly connected to the computing unit via a wide area network (WAN) or (wireless) local area network (WLAN or LAN) connection. For example, a computer program product can be digitally stored on a cloud server at a storage location on the computer network and transmitted to the computing unit via the Internet via a WAN and / or via a WLAN or LAN, particularly by accessing a download link pointing to the storage location of the computer program product.

[0109] The above-described features, characteristics, and advantages of the present invention become clear and readily understood in conjunction with the following drawings and description. Hereinafter, the drawings and description should not be construed as limiting the invention or its embodiments in any way. Attached Figure Description

[0110] The invention is described and illustrated below with reference to the embodiments shown in the accompanying drawings. In principle, the same structures and units are maintained in the following description of the drawings, named with the same reference numerals as when the corresponding structure or unit first appears. The drawings are generally not to scale.

[0111] The attached diagram shows:

[0112] Figure 1 An embodiment of an imaging modality for performing a method for generating multiple projection records over multiple successive exposure time periods is shown, wherein the imaging element is focused.

[0113] Figure 2 An example of a graph showing the amplitude modulation of the emission intensity of an X-ray source is shown.

[0114] Figure 3 An embodiment of a mammography system is shown.

[0115] Figure 4 An embodiment of a computed tomography (CT) scanner is shown.

[0116] Figure 5 An embodiment of an imaging modality for performing a method for generating multiple projection records over multiple successive exposure time periods is shown, wherein a focus is on a control unit. Detailed Implementation

[0117] Figure 1 An embodiment of an imaging modality SYS is shown for performing a method for generating multiple projection records over multiple successive exposure time periods, wherein an imaging element is focused.

[0118] The imaging system SYS comprises N X-ray sources Q0, Q1, ..., QN-1 and an X-ray detector D. The X-ray sources Q0, Q1, ..., QN-1 are configured to emit at least one X-ray beam when activated. The X-ray detector D is configured to detect the X-ray beams when they strike its surface. The X-ray detector D thus detects a projection record derived from the superposition of the X-ray beams emitted by the X-ray sources Q0, Q1, ..., QN-1 and the scattered radiation.

[0119] Therefore, the object from which imaging should be performed is typically positioned between the X-ray source Q0, Q1, ..., QN-1 and the X-ray detector for imaging purposes, such that the X-ray beam emitted by the X-ray source Q0, Q1, ..., QN-1 penetrates the object or at least a portion of the object before it is detected by the X-ray detector D.

[0120] According to the method, particularly for tomographic fusion imaging, multiple projection records are generated over several successive exposure time periods Δt. Specifically, N projection records are generated using N X-ray sources Q0, Q1, ..., QN-1 or detected using an X-ray detector D.

[0121] Therefore, X-ray sources Q0, Q1, ..., QN-1 are activated simultaneously and multiple times in successive, clock-controlled exposure time periods Δt to emit X-ray beams. Each exposure time period Δt begins at start times t0, t1, tN-1 and has a specific duration Δt. Here, each X-ray beam is characterized by its emission intensity P00, P10, P01, P11, ..., P0N-1, P1N-1. The emission intensities P00, P10, P01, P11, ..., P0N-1, P1N-1 of the X-ray beams within different exposure time periods Δt are modulated.

[0122] Here, the emission intensities P00, P10, P01, P11, ..., P0N-1, P1N-1 are amplitude modulated around an offset emission intensity POff that is greater than zero.

[0123] Here, amplitude modulation is performed such that at least one of the plurality of X-ray sources Q0, Q1, ..., QN-1 emits an X-ray beam, the emission intensities P00, P10, P01, P11, ..., P0N-1, P1N-1 of which are different in at least two successive exposure time periods Δt. In other words, the emission intensity of the X-ray beam from at least one X-ray source Q0, Q1, ..., QN-1 is different at at least two successive start times t0, t1, tN-1.

[0124] Furthermore, each of the X-ray sources Q0, Q1, ..., QN-1 emits an X-ray beam with non-zero emission intensities P00, P10, P01, P11, ..., P0N-1, P1N-1 during each exposure time period. In other words, none of the X-ray sources Q0, Q1, ..., QN-1 is turned off or deactivated during the exposure time period Δt.

[0125] According to one embodiment, the average emission intensities P00, P10, P01, P11, ..., P0N-1, P1N-1 of at least two of the plurality of X-ray sources Q0, Q1, ..., QN-1, related to the exposure time period Δt, are different at at least one start time t0, t1, ..., tN-1.

[0126] The average values ​​associated with the exposure time period Δt describe the average emission intensities P00, P10, P01, P11, ..., P0N-1, P1N-1 of X-ray sources Q0, Q1, ..., QN-1 during the exposure time period Δt.

[0127] According to one embodiment, the emission intensities P00, P10, P01, P11, ..., P0N-1, P1N-1 of each individual X-ray source Q0, Q1, ..., QN-1 are different at each start time t0, t1, ..., tN-1, except for at most one X-ray source Q0, Q1, ..., QN-1, and thus different for each exposure time period Δt. In other words, all X-ray sources Q0, Q1, ..., QN-1 except for at most one X-ray source Q0, Q1, ..., QN-1 are amplitude modulated and have different emission intensities P00, P10, P01, P11, ..., P0N-1, P1N-1 for each exposure time period Δt. Here, the at most one X-ray source Q0, Q1, ..., QN-1 that is not amplitude modulated can have constant emission intensities P00, P10, P01, P11, ..., P0N-1, P1N-1 equal to the offset emission intensity POff. In particular, the emission intensities P00, P10, P01, P11, ..., P0N-1, P1N-1 of each X-ray source Q0, Q1, ..., QN-1 vary or change from one another.

[0128] Optionally, all emission intensities P00, P10, P01, P11, ..., P0N-1, P1N-1 of each X-ray source Q0, Q1, ..., QN-1 are constant during the exposure time period Δt. In other words, the emission intensities P00, P10, P01, P11, ..., P0N-1, P1N-1 of the X-ray beams of X-ray sources Q0, Q1, ..., QN-1 are constant during the exposure time period Δt. In particular, therefore, the emission intensities P00, P10, P01, P11, ..., P0N-1, P1N-1 throughout the exposure time period correspond to the average values ​​of the emission intensities P00, P10, P01, P11, ..., P0N-1, P1N-1 associated with the exposure time period Δt.

[0129] Optionally, the emission intensities P00, P10, P01, P11, ..., P0N-1, P1N-1 of each X-ray source Q0, Q1, ..., QN-1 are derived from the product of a non-zero modulation factor F individualized for each of the multiple X-ray sources Q0, Q1, ..., QN-1 and a constant offset emission intensity POff.

[0130] For example, the individualized modulation factor F for each X-ray source in X-ray sources Q0, Q1, ..., QN-1 can be derived as follows:

[0131]

[0132] Where N represents the number of multiple X-ray sources Q0, Q1, ..., QN-1.

[0133] Where k = 0, 1, ..., N-1, is the number of each individual X-ray source among multiple N X-ray sources Q0, Q1, ..., QN-1.

[0134] Where POff is the offset emission intensity POff.

[0135] Where t = t0, t1, ..., tN-1 are the corresponding start times.

[0136] Where M < 1 is the modulation amplitude.

[0137] In particular, the modulation amplitude can be in the range between 0.1 and 0.3.

[0138] Optionally, multiple X-ray sources Q0, Q1, ..., QN-1 can be activated such that, after all projection records are generated, the sum of all emission intensities P00, P10, P01, P11, ..., P0N-1, P1N-1 for each individual X-ray source Q0, Q1, ..., QN-1 is identical. The sum of all emission intensities P00, P10, P01, P11, ..., P0N-1, P1N-1 of X-ray sources Q0, Q1, ..., QN-1 is derived from the sum or integral of the emission intensities P00, P10, P01, P11, ..., P0N-1, P1N-1 emitted by X-ray sources Q0, Q1, ..., QN-1 over all exposure time periods Δt. In this manner, the sum can be calculated for each of the multiple X-ray sources Q0, Q1, ..., QN-1. The accumulated totals can then all be identical to ensure that the contribution of each X-ray source Q0, Q1, ..., QN-1 is the same in all projection records. In particular, in this manner, it can be ensured that the fluoroscopic X-ray records of each X-ray source Q0, Q1, ..., QN-1, as described in the more detailed description below, are based on the same statistical properties.

[0139] Then, from the N projection records, the fluoroscopic projection record can be determined separately for each of the multiple X-ray sources Q0, Q1, ..., QN-1 using the discrete Fourier transform:

[0140]

[0141] Here, the detector dataset is typically two-dimensional in a planar detector, i.e., a_k = a_k(x,y), and the equations for I_k must be computed separately for each pair of (x,y). Each detector dataset here corresponds to a projection record.

[0142] Here, the perspective projection records of X-ray sources Q0, Q1, ..., QN-1 are used to image the object from the viewpoint of the corresponding X-ray source Q0, Q1, ..., QN-1.

[0143] Regarding the imaging mode SYS, in addition to multiple X-ray sources Q0, Q1, ..., QN-1 and X-ray detector D, the imaging mode also includes a computing unit SYS.CU, which constitutes the basis for controlling the aforementioned methods. Figure 5 The calculation unit is described in detail.

[0144] Optionally, multiple X-ray sources Q0, Q1, ..., QN-1 can each have a maximum emission intensity Pmax0, Pmax1, ..., PmaxN-1 less than or equal to 10 kW. The maximum emission intensities Pmax0, Pmax1, ..., PmaxN-1 here refer to the maximum possible values ​​of the emission intensities P00, P10, P01, P11, ..., P0N-1, P1N-1 emitted by the X-ray sources Q0, Q1, ..., QN-1.

[0145] Optionally, multiple X-ray sources Q0, Q1, ..., QN-1 are fixedly positioned relative to the X-ray detector and in relation to the environmental position of the imaging mode. In particular, the imaging of multiple projection records is thus performed statically without the multiple X-ray sources Q0, Q1, ..., QN-1 moving.

[0146] Optionally, the anodes of the multiple X-ray sources Q0, Q1, ..., QN-1 are made of a material with a lower melting temperature than tungsten. In particular, the anode material can be, for example, copper and / or tin and / or tantalum and / or steel and / or ceramics, especially ceramics that also contain rare earth elements, and / or include silver and / or gold. In particular, anode substrates different from expensive copper or molybdenum can be used, such as graphite or steel.

[0147] Figure 2 An example of an amplitude modulation graph showing the emission intensity of X-ray sources Q0, Q1, ..., QN-1 is shown.

[0148] exist Figure 2 The text uses graphics to illustrate how this can be achieved, as shown in the image. Figure 1 The modulation of the emission intensities P00, P10, P01, P11, ... P0N-1, P1N-1 is described.

[0149] The diagram illustrates modulation using two X-ray sources Q0, Q1, ..., QN-1 as an example.

[0150] Here, the emission intensities P00, P10, P01, P11, ..., P0N-1, P1N-1 of the X-ray sources Q0, Q1, ..., QN-1 are all less than the maximum emission intensities Pmax0 and Pmax1.

[0151] Figure 3 An embodiment of a mammography system MS is shown.

[0152] The mammography system MS includes a compression unit COMP for fixing the object during imaging. The mammography system MS also includes, according to... Figure 1 and Figure 5 The imaging mode SYS is described. Multiple X-ray sources Q0, Q1, ..., QN-1 are arranged in an arc surrounding the compression unit COMP. Specifically, the multiple X-ray sources Q0, Q1, ..., QN-1 are arranged around the compression unit COMP such that the fluoroscopic projection record determined as described above is suitable for tomographic fusion.

[0153] Figure 4 An embodiment of a computed tomography (CT) scanner is shown.

[0154] Computed tomography (CT) devices include a gantry with a patient tunneling device (PT). CT devices also include components according to... Figure 1 and Figure 5 The imaging modality SYS is described here. The imaging modality SYS is set around the patient tunnel PT.

[0155] The patient tunnel PT is configured to position or support the object within the patient tunnel PT during imaging.

[0156] The patient tunnel PT can be particularly cylindrical in this case.

[0157] In particular, the imaging modality SYS included in a computed tomography (CT) device may include more than one X-ray detector D1, D2, D3, D4. Specifically, the imaging modality may include two, three, or four X-ray detectors D1, D2, D3, D4. The X-ray detectors D1, D2, D3, D4 are configured such that an X-ray beam emitted from each of the X-ray sources Q0, Q1, ..., QN-1 is detected by at least one X-ray detector D1, D2, D3, D4. In particular, at least one of the X-ray detectors D1, D2, D3, D4 may be curved along the shape of the patient tunnel PT.

[0158] Specifically, multiple X-ray sources Q0, Q12, ..., QN-1 are arranged in an arc encompassing at least 180° surrounding the patient tunnel PT. More specifically, the multiple X-ray sources Q0, Q1, ..., QN-1 can be arranged in a complete circle surrounding the patient tunnel PT. The number of X-ray detectors D1, D2, D3, D4 is also related to the angular range covered by the X-ray sources Q0, Q1, ..., QN-1 within the patient tunnel PT. Figure 4 In the embodiment shown, multiple X-ray sources Q0, Q1, ..., QN-1 are arranged in a complete circle surrounding the patient tunnel PT.

[0159] In another embodiment, multiple X-ray sources Q0, Q1, ..., QN-1 can be arranged in a matrix at least in a 2×2 configuration along the patient tunnel PT. In other words, the X-ray sources Q0, Q1, ..., QN-1 further extend in a direction along the central axis of the patient tunnel PT, eliminating the need to move the object along the central axis within the patient tunnel PT for extended image recording, as is required in conventional computed tomography (CT) devices. Specifically, the modulation period T can be selected to be the same as or shorter than the rotation period of the X-ray sources in a conventional CT device. A complete sine wave is then depicted by combining the projection records from the fluoroscopy. It is particularly advantageous to choose a modulation period T that is shorter than the rotation period of the X-ray sources in a conventional CT device. This is feasible because the X-ray sources do not rotate, thus avoiding the centrifugal force that limits the rotation period, as is the case in conventional CT devices.

[0160] Figure 5 An embodiment of an imaging modality SYS is shown for performing a method for generating multiple projection records in multiple successive exposure time periods t0, t1, ..., tN-1, wherein a focus is on a control unit.

[0161] An imaging mode SYS, as shown, is configured to execute a method for generating multiple projection records within multiple successive exposure time periods t0, t1, ..., tN-1, according to the present invention. The imaging mode SYS includes an interface SYS.IF, a computing unit SYS.CU, and a storage unit SYS.MU.

[0162] An imaging modality SYS can be, in particular, a computer, a microcontroller, or an integrated circuit (IC). Alternatively, an imaging modality SYS can be a real or virtual computer network (the technical term for a real computer network is "cluster," and the technical term for a virtual computer network is "cloud"). An imaging modality SYS can be configured as a virtual system that runs on a computer or a real or virtual computer network (the technical term is "virtualization").

[0163] The interface SYS.IF can be a hardware interface or a software interface (such as a PCI bus, USB, or FireWire). The computing unit SYS.CU can include hardware and / or software components, such as a microprocessor or a so-called FPGA (Field Programmable Gate Array). The storage unit SYS.MU can be configured as non-persistent working memory (Random Access Memory, RAM) or persistent mass storage (hard drive, USB stick, SD card, solid-state drive (SSD)).

[0164] The interface SYS.IF may in particular include multiple sub-interfaces, which perform different method steps according to the method according to the invention. In other words, the interface SYS.IF may be configured as multiple interfaces SYS.IF. The computing unit SYS.CU may in particular include multiple sub-computing units, which perform different method steps according to the method according to the invention. In other words, the computing unit SYS.CU may be configured as multiple computing units SYS.CU.

[0165] Although the details of the present invention have been described and illustrated in detail through preferred embodiments, the present invention is not limited to the disclosed examples and other variations can be derived by those skilled in the art without departing from the scope of protection of the present invention.

[0166] Where not explicitly stated but meaningful and within the scope of the invention, various embodiments, their sub-aspects, or features can be combined or interchanged with each other without departing from the scope of the invention. Where applicable, the advantages of the invention described with reference to one embodiment also apply to other embodiments without explicit mention.

Claims

1. A method for generating multiple projection records over multiple successive exposure time periods (Δt), particularly for tomographic fusion imaging. The method includes the following steps: - For each clock-controlled exposure time period (Δt), multiple X-ray sources (Q0, Q1, ..., QN-1) are simultaneously activated multiple times at the start time (t0, t1, ..., tN-1) to generate X-ray beams with modulated emission intensities (P00, P10, P01, P11, ..., P0N-1, P1N-1). - During the exposure time period (Δt), at the start time (t0, t1, ..., tN-1), the X-ray beams of the plurality of X-ray sources (Q0, Q1, ..., QN-1) are simultaneously detected multiple times simultaneously by means of X-ray detectors (D, D1, D2, D3, D4), thereby generating multiple projection records. Its features are, - During the clock cycle of the exposure time period (Δt), the emission intensities (P00, P10, P01, P11, ..., P0N-1, P1N-1) of the plurality of X-ray sources (Q0, Q1, ..., QN-1) are amplitude modulated around a constant offset emission intensity (POff) greater than zero, such that the emission intensity (P00, P10, P01, P11, ..., P0N-1, P1N-1) of at least one of the plurality of X-ray sources (Q0, Q1, ..., QN-1) is different at two successive start times (t0, t1, ..., tN-1). - wherein, during the exposure time period (Δt), the emission intensities (P00, P10, P01, P11, ..., P0N-1, P1N-1) of the plurality of X-ray sources (Q0, Q1, ..., QN-1) are not equal to zero.

2. The method according to claim 1, The average emission intensity (P0, P1, ..., PN-1) of at least two of the plurality of X-ray sources (Q0, Q1, ..., QN-1) is different at at least one start time (t0, t1, ..., tN-1) relative to the exposure time period (Δt).

3. The method according to claim 2, The emission intensities (P00, P10, P01, P11, ..., P0N-1, P1N-1) of the plurality of X-ray sources (Q0, Q1, ..., QN-1) are constant during the exposure time period (Δt).

4. The method according to any one of the preceding claims, The emission intensities (P00, P10, P01, P11, ..., P0N-1, P1N-1) are derived from the product of the non-zero modulation factor F, which is individualized for each of the plurality of X-ray sources (Q0, Q1, ..., QN-1), and the constant offset emission intensity (Poff).

5. The method according to claim 4, The modulation factor F is derived from the following: Where N represents the number of the plurality of X-ray sources (Q0, Q1, ..., QN-1). Where k = 0, 1, ..., N-1, serves as the numbering for each individual X-ray source among multiple N X-ray sources (Q0, Q1, ..., QN-1). Where POff represents the offset emission intensity (POff), Where t = t0, t1, ..., tN-1 are the corresponding start times. Where M < 1 is the modulation amplitude.

6. The method according to claim 5, The modulation amplitude M is in the range between 0.1 and 0.

3.

7. The method according to any one of the preceding claims, The plurality of X-ray sources (Q0, Q1, ..., QN-1) are activated such that after all projection records are generated, the sum of all emission intensities (P00, P10, P01, P11, ..., P0N-1, P1N-1) of each X-ray source (Q0, Q1, ..., QN-1) is the same.

8. An imaging mode (SYS) having: - Multiple X-ray sources (Q0, Q1, ..., QN-1), -X-ray detector (D), and - A computing unit (SYS, CU) configured to control the imaging modality according to any one of the preceding claims.

9. The imaging modality (SYS) according to claim 8, The plurality of X-ray sources (Q0, Q1, ..., QN-1) each have a maximum emission intensity (Pmax0, Pmax1, ..., PmaxN-1) of less than or equal to 10 kW.

10. The imaging modality (SYS) according to claim 8 or 9, The plurality of X-ray sources (Q0, Q1, ..., QN-1) are positioned in a fixed manner relative to the X-ray detector (D) and to the environment of the imaging mode.

11. The imaging mode (SYS) according to any one of claims 8 to 10, The anodes of the plurality of X-ray sources (Q0, Q1, ..., QN-1) are made of a material having a lower melting temperature than tungsten.

12. A mammography system (MS), comprising: -Compression unit for fixing objects, and - The imaging mode (SYS) according to any one of claims 8 to 11, wherein the plurality of X-ray sources (Q0, Q1, ..., QN-1) are arranged in an arc surrounding the compression unit COMP.

13. A computed tomography (CT) scanner, comprising: - A gantry with a patient tunnel (PT), and - The imaging modality (SYS) according to any one of claims 8 to 11, The imaging modality (SYS) is positioned around the patient tunnel (PT).

14. The computed tomography (CT) apparatus according to claim 13, The plurality of X-ray sources (Q0, Q1, ..., QN-1) are arranged in an arc comprising at least 180° around the patient tunnel (PT).

15. The computed tomography (CT) apparatus according to claim 13, The plurality of X-ray sources (Q0, Q1, ..., QN-1) are arranged in a complete circle surrounding the patient tunnel (PT).

16. The computed tomography (CT) apparatus according to claim 13, The plurality of X-ray sources (Q0, Q1, ..., QN-1) are arranged in a matrix at least in a 2×2 configuration along the patient tunnel (PT).

17. A computer program product having a computer program that can be directly loaded into the memory (SYS.MU) of an imaging modality (SYS), the computer program having program segments that, when executed by the imaging modality (SYS), perform all steps of the method according to any one of claims 1 to 7.

Images