System for x-ray dark-field, phase-contrast and attenuation image acquisition

Abstract

The invention relates to a system (10) for X-ray dark-field, phase-contrast and attenuation image acquisition. The system comprises an X-ray source (20), an interferometer arrangement (30), an X-ray detector (40), a control unit (50) and an output unit (60). An axis extending from a center of the X-ray source to a center of the X-ray detector is defined; an examination region is located between the X-ray source and the X-ray detector. The axis extends through the examination region and the examination region is configured to enable positioning of an object to be examined. The interferometer arrangement is located between the X-ray source and the X-ray detector. The interferometer arrangement comprises a first grating (32) and a second grating (34). For a first operating mode: the control unit is configured to control at least one laterally moving transducer (70) to move the first grating or to move the second grating in a lateral position direction perpendicular to the axis. The control unit is configured to control the X-ray detector to acquire image data while the first grating and / or the second grating is moved. During an exposure time of the X-ray detector, the first grating and / or the second grating has moved a distance which is less than a period of the first grating and / or the second grating. The control unit is configured to control the movement of the first grating and / or the second grating such that image data is acquired while the first grating and / or the second grating is moving. For the first operating mode, the output unit is configured to output one or more of the following: dark-field image data, phase-contrast image data and attenuation image data.

Description

Technical Field

[0001] This invention relates to a system for acquiring X-ray dark-field, phase-contrast, and attenuation images, a method for acquiring X-ray dark-field, phase-contrast, and attenuation images, a method for acquiring attenuation images and / or calibration data, as well as a computer program unit and a computer-readable medium. Background Technology

[0002] Conventional linear attenuation X-ray systems and conventional computed tomography (CT) measures the linear attenuation coefficient of an object. One of the main drawbacks of this traditional technique is the low contrast between different tissue types, which requires the use of very high X-ray doses and / or additional contrast agents.

[0003] Grating-based phase contrast (gbPC) X-ray imaging (both radiography and computed tomography) is a method that provides new X-ray imaging modalities, simultaneously providing images of linear attenuation coefficients, electron density, and small-angle scattering (i.e., images obtained from dark-field signals).

[0004] X-ray phase contrast and dark-field imaging are two novel imaging modalities that have demonstrated the potential to significantly improve the diagnostic accuracy of soft tissue imaging. One of the areas identified as potentially most likely to benefit from these two new imaging modalities is chest X-ray radiography. For example, it has been shown that dark-field X-ray information can significantly aid in the diagnosis of lung diseases such as chronic obstructive pulmonary disease (COPD) or fibrotic lung disease.

[0005] To obtain these new imaging modes, two or three grating interferometers are introduced into the X-ray beam, commonly referred to as G0, G1, and G2 gratings. The source grating G0 can be used to make the radiation from the source more coherent, but is not always necessary; gratings G1 and G2 are often referred to as phase and analysis gratings. Subsequently, one of the two gratings G1 or G2 is moved relative to the other gratings perpendicular to the grating sheet by several steps (so-called stepping), and if the source grating G0 is used, it can be stepped laterally (where laterally means perpendicular to the grating direction). Thus, for each new grating position, an image is recorded. By comparing the image sequences obtained with and without samples in the beam, three imaging signals can be calculated: transmission or attenuation (conventional X-ray image), phase-contrast image, and dark-field image. At least three images in the sequence (stepping curves) are required to calculate the three imaging signals. However, in practice, more images are recorded to achieve stable signal extraction.

[0006] Therefore, the GBPC system uses a step acquisition method. This means that for a multimodal image, several projections are combined. Between each projection, a grating moves to another position to retrieve the step curve. These settings focus on minimizing grating movement during acquisition, such as from vibration, to ensure good results. Repeatability and speed of repositioning can be challenging and will always result in a time interval between measurements, during which the device is moving and no acquisition is active.

[0007] The reason is that the fringe patterns analyzed in GBPC imaging are fine structures within the micrometer range. Using an analyzer grating with the same period, the moiré pattern can be measured using a detector. Any movement of one or more interferometer components within this length range will alter the phase of the moiré pattern. During exposure, this movement causes signal blurring, resulting in signal degradation. Here, exposure refers to the time it takes for the X-rays transmitted through the object to be integrated to generate the original image. This is also known as the integration period.

[0008] State-of-the-art X-ray imaging systems are designed for structures several orders of magnitude larger than this fringe pattern; therefore, standard X-ray systems can withstand greater vibrations than GBPC setups. To be able to combine GBPC and traditional CT infrastructure, the implementation must be vibration-resistant. Because laboratory GBPC imaging systems are developed in a virtually vibration-free environment, common acquisition protocols involve 5 to 30 exposures with exposure times of several seconds. Repositioning time between exposures is not used, and the system must stop and become silent before acquiring the next image in the step-pattern image set. Both of these points present challenges when converting the step-pattern approach from the laboratory to traditional CT. On the one hand, the repositioning interval must be shortened to minimize acquisition time. US2010 / 0074395A1 provides a method for measuring intensity curves at detector pixels relative to upstream grating displacement in a Talbot interferometer, which provides the required information (e.g., phase, amplitude, or median intensity) in a simplified manner, allowing uninterrupted exposures because there is virtually no downtime during the measurement. On the other hand, the system can no longer be considered vibration-free. This degrades images with longer exposure times because the fringe pattern moves during the measurement.

[0009] Another issue arises during calibration protocols, such as detector calibration measurements. For these measurements, it is best to remove all gratings from the system; however, this is not always feasible, and doing so would alter the filtering of X-rays, leading to calibration errors.

[0010] These problems need to be addressed. Summary of the Invention

[0011] An improved system for acquiring dark-field, phase-contrast, and attenuated X-ray image data, as well as for determining calibration data for such a system, would be advantageous.

[0012] It should be noted that the aspects and embodiments described below in this invention are also applicable to X-ray dark field, phase contrast and attenuation image acquisition systems, methods for X-ray dark field, phase contrast and attenuation image acquisition, systems for attenuation image and / or calibration data acquisition, methods for attenuation image and / or calibration data acquisition, as well as computer program units and computer-readable media.

[0013] In a first aspect, a system for acquiring X-ray dark-field, phase-contrast, and attenuation images is provided. The system includes an X-ray source, an interferometer assembly, an X-ray detector, a control unit, and an output unit. An axis is defined extending from the center of the X-ray source to the center of the X-ray detector; an inspection area is positioned between the X-ray source and the X-ray detector. The axis extends through the inspection area, and the inspection area is configured to allow positioning of an object to be inspected. The interferometer assembly is positioned between the X-ray source and the X-ray detector. The interferometer assembly includes a first grating and a second grating. For a first operating mode: the control unit is configured to control at least one laterally movable transducer to move the first grating or the second grating in a lateral position direction perpendicular to the axis. For the first operating mode, the control unit is configured to control the X-ray detector to acquire image data as the first grating and / or the second grating moves. For the first operating mode, during the exposure time of the X-ray detector, the first grating and / or the second grating have moved a distance less than the period of the first grating and / or the second grating. In the first operating mode, the control unit is configured to control the movement of the first grating and / or the second grating, such that image data is acquired while the first grating and / or the second grating is moving. In the first operating mode, the output unit is configured to output one or more of the following: dark-field image data, phase-contrast image data, and attenuation image data.

[0014] In other words, the X-ray imaging system is provided with an interferometer device in which a first or second grating is laterally moved to generate the desired step curve, from which dark field, phase contrast, and attenuation image data can be reconstructed. However, one or both of these gratings are intentionally moved during image acquisition, which is achieved by making the exposure time short enough so that the moiré fringes on the detector are not washed away by the movement.

[0015] In this way, “stepped” curve image data, which may require 5-30 individual images, can be acquired more quickly and with reduced X-ray exposure to the patient at different lateral positions of the first and / or second gratings. This is because the gratings can always be moved, and the image data can be acquired, for example, as part of moving to the next position out of 5-30 different positions. Therefore, the gratings themselves are not stepped, meaning they are not stationary during image data acquisition but are intentionally moved during acquisition and can indeed be continuously moved.

[0016] In other words, the system allows for continuous data acquisition in grating-based phase contrast and dark-field measurements.

[0017] In the example, for the first operating mode, the control unit is configured to control the X-ray detector such that the exposure time is less than the time period of the resonant frequency of the vibration of the first grating and / or the second grating.

[0018] In this way, in addition to having a short exposure time that prevents the intentional movement of (one or more) gratings from washing away the stripe pattern, the vibration and repositioning time gaps of the device are also mitigated due to the reduced acquisition time (which is a fraction of the system's vibration cycle). The vibration source can be inherent to the system or added via external equipment (e.g., a vibration transducer).

[0019] Therefore, in the first operating mode, a continuously moving grating(s) is used to reduce the blurring effect by shortening the exposure time, which is short enough that the grating movement during a single exposure can be effectively ignored. This can be achieved when the exposure time is significantly shorter than the period of the grating's dominant vibration frequency. Here, the continuously moving grating(s) can refer to one or more gratings moving in a continuous linear motion in one direction, or it can refer to one or more gratings or both performing periodic motion.

[0020] In other words, the system allows for continuous data acquisition in grating-based phase contrast and dark-field measurements, and additionally tolerates external vibrations.

[0021] In the example, for the first operating mode, the movement of the first grating and / or the second grating during the exposure time includes movement caused by at least one lateral movement transducer.

[0022] Therefore, at least one lateral moving transducer can continuously move one or more gratings to a position for image data acquisition, specifically for dark-field and phase-contrast image data acquisition. Previously, grating movement needed to stop during image acquisition, but now image acquisition occurs as the gratings move between the desired positions, reducing the overall image acquisition timescale and patient dose.

[0023] In the example, the movement of the first grating and / or the second grating during the exposure time includes movement caused by at least one lateral movement transducer during the movement in the lateral position direction, which is part of the image acquisition protocol.

[0024] In the example, for the second operating mode, the control unit is configured to control the X-ray detector to acquire image data as the first grating and / or the second grating moves. For the second operating mode, during the exposure time of the X-ray detector, the first grating and / or the second grating has moved a distance greater than or equal to the period of the first grating and / or the second grating. For the second operating mode, the output unit is configured to output attenuated image data and / or calibration data.

[0025] In other words, the system operates as a DAX system in the first mode, where moiré fringes on the detector are used to generate dark fields, phase contrast, and actual attenuation data. But now in the second mode, the grating is still in the beam, the fringe pattern is washed out, and the system operates in a "normal" attenuation mode, thus providing calibration functionality.

[0026] In other words, moving one or both of these gratings by at least this distance results in the stripes being washed away from the detector required for the DAX system. Thus, in one operating mode, the system operates continuously to acquire data in a grating-based phase contrast and dark field measurement system with one or more moving gratings, and in a second mode, the system operates as a conventional attenuated imaging X-ray system, which provides system characterization and calibration without removing the gratings from the beam path.

[0027] The movement of the grating in the second mode can be inherent, for example, through vibration of the grating’s dominant frequency or resonant frequency, or intentionally provided via a moving or vibrating transducer.

[0028] In the example, for the second operating mode, the control unit controls the movement of the first grating and / or the second grating so that image data is acquired when the first grating and / or the second grating moves.

[0029] In the example, the movement of the first grating and / or the second grating during the exposure time includes movement caused by at least one vibrating transducer controlled by the control unit. The at least one vibrating transducer is configured to vibrate the first grating and / or the second grating.

[0030] In the example, for the second operating mode, the movement of the first grating and / or the second grating during the exposure time includes movement caused by at least one lateral movement transducer.

[0031] Therefore, for example, a transducer that operates in a first mode to enable the acquisition of dark field and phase difference data can operate in a second mode, wherein, for example, movement at a certain speed in the first mode is acceptable due to the short exposure time, but now results in the stripes being washed away due to the longer exposure time. Alternatively, the transducer can operate in the second mode in a different manner than in the first mode, wherein, relative to the first mode, it imparts faster movement and / or vibration to the grating in the second mode, such that for a constant exposure time between the two modes, stripes visible in the first mode are washed away or eliminated in the second mode.

[0032] In the example, the exposure time of the first operating mode is equal to the exposure time of the second operating mode.

[0033] In the example, for the second operating mode, the control unit is configured to control the X-ray detector such that the exposure time is greater than the resonant frequency of the first grating and / or the second grating for a period of time.

[0034] In a second aspect, a method for acquiring X-ray dark-field, phase-contrast, and attenuation images is provided, the method comprising:

[0035] a) Orient the X-ray source relative to the X-ray detector to define an axis extending from the center of the X-ray source to the center of the X-ray detector;

[0036] b) Locating an inspection area between an X-ray source and an X-ray detector, wherein a first axis extends through the inspection area, and wherein the inspection area is configured to enable the location of the object to be inspected.

[0037] c) Positioning an interferometer device between an X-ray source and an X-ray detector, wherein the interferometer device includes a first grating and a second grating;

[0038] d) In the first operating mode, the control unit controls at least one lateral movement transducer to move the first grating or the second grating in a lateral position direction perpendicular to the axis;

[0039] e) In a first operating mode, the control unit controls the X-ray detector to acquire image data while the first grating and / or the second grating are moving, wherein during the exposure time of the X-ray detector, the first grating and / or the second grating have moved a distance less than the period of the first grating and / or the second grating, and wherein the control unit controls the movement of the first grating and / or the second grating such that image data is acquired while the first grating and / or the second grating are moving; and

[0040] g) The output unit outputs one or more of the following: dark field image data, phase contrast image data, and attenuation image data.

[0041] In one example, the method includes:

[0042] f) In the second operating mode: the control unit controls the X-ray detector to acquire image data while the first grating and / or the second grating are moving, wherein, during the exposure time of the X-ray detector, the first grating and / or the second grating has moved a distance greater than or equal to the period of the first grating and / or the second grating; and

[0043] h) In the second operating mode, the output unit outputs attenuated image data and / or calibration data.

[0044] In a third aspect, a system for acquiring attenuated image and / or calibration data is provided. The system includes an X-ray source, an interferometer device, an X-ray detector, a control unit, and an output unit. An axis is defined extending from the center of the X-ray source to the center of the X-ray detector; an inspection area is positioned between the X-ray source and the X-ray detector. The axis extends through the inspection area. The inspection area is configured to allow positioning of an object to be inspected. The interferometer device is positioned between the X-ray source and the X-ray detector. The interferometer device includes at least a first grating and a second grating. The control unit is configured to control the X-ray detector to acquire image data as the first grating and / or the second grating moves. During the exposure time of the X-ray detector, the first grating and / or the second grating has moved a distance greater than or equal to the period of the first grating and / or the second grating. The output unit is configured to output attenuated image data and / or calibration data.

[0045] In a fourth aspect, a method for acquiring attenuation images and / or calibration data is provided, the method comprising:

[0046] a) Orient the X-ray source relative to the X-ray detector to define an axis extending from the center of the X-ray source to the center of the X-ray detector;

[0047] b) Locating an inspection area between an X-ray source and an X-ray detector, wherein a first axis extends through the inspection area, and wherein the inspection area is configured to enable the location of the object to be inspected.

[0048] c) Positioning an interferometer device between an X-ray source and an X-ray detector, wherein the interferometer device includes a first grating and a second grating;

[0049] f) The control unit controls the X-ray detector to acquire image data while the first grating and / or the second grating are moving, wherein during the exposure time of the X-ray detector, the first grating and / or the second grating have moved a distance greater than or equal to the period of the first grating and / or the second grating; and

[0050] h) The output unit outputs attenuated image data and / or calibration data.

[0051] According to another aspect, a computer program unit is provided for controlling the system as described above, the computer program unit being adapted, when executed by a processing unit, to perform the steps of the method as described above.

[0052] According to another aspect, a computer-readable medium storing the computer units as described above is provided.

[0053] The computer program unit may be, for example, a software program, but may also be an FPGA, PLD, or any other suitable digital device.

[0054] The advantage is that the benefits provided by any of the above aspects also apply to all other aspects, and vice versa.

[0055] The above aspects and examples will become apparent and will be illustrated with reference to the embodiments described below. Attached Figure Description

[0056] Exemplary embodiments will now be described with reference to the accompanying drawings:

[0057] Figure 1 A schematic diagram of an example system for acquiring X-ray dark-field, phase-contrast, and attenuated images is shown.

[0058] Figure 2 Methods for acquiring X-ray dark-field, phase-contrast, and attenuation images are illustrated.

[0059] Figure 3 A schematic setup of an example phase-contrast, dark-field, and attenuation imaging system is shown; and

[0060] Figure 4 It shows the result of Figure 3 The step curve data obtained by the imaging system. Detailed Implementation

[0061] Figure 1An example of a system 10 for acquiring X-ray dark-field, phase-contrast, and attenuation images is shown, wherein not all features shown are necessary, as will be discussed in more detail now. In one example, the system includes an X-ray source 20, an interferometer device 30, an X-ray detector 40, a control unit 50, and an output unit 60. An axis is defined extending from the center of the X-ray source to the center of the X-ray detector; an inspection area is positioned between the X-ray source and the X-ray detector. The axis extends through the inspection area, and the inspection area is configured to allow positioning of the object to be inspected. The interferometer device is positioned between the X-ray source and the X-ray detector. The interferometer device includes a first grating 32 and a second grating 34. For a first operating mode, the control unit is configured to control at least one laterally movable transducer to move the first grating or the second grating in a lateral position direction perpendicular to the axis. For the first operating mode, the control unit is configured to control the X-ray detector to acquire image data as the first grating and / or the second grating move. For the first operating mode, during the exposure time of the X-ray detector, the control unit is configured to move the first grating and / or the second grating by a distance less than the period of the first grating and / or the second grating. The control unit is configured to control the movement of the first grating and / or the second grating such that image data is acquired while the first grating and / or the second grating is moving. For the first operating mode, the output unit is configured to output one or more of the following: dark-field image data, phase-contrast image data, and attenuation image data.

[0062] In one example, the movement of the first grating or the second grating in a lateral position direction perpendicular to the axis is also perpendicular to the grating lines in the grating.

[0063] In one example, the first grating is located between the second grating and the X-ray source.

[0064] In one example, the inspection area is located between the first grating and the X-ray detector.

[0065] In the example, the interferometer apparatus includes three gratings, wherein a source grating is positioned to interact with X-rays emitted from the source, and the source grating is used to increase the coherence of the X-rays propagating through the interferometer apparatus. Therefore, without a source grating, there can be two gratings, where the first grating is closest to the source and is an absorption grating or a phase grating, and the second grating is closest to the detector and is an absorption grating. However, with three gratings, the source grating closest to the source can be the first grating, and either of the other two gratings can be the second grating, or the grating above which could be an absorption grating or a phase grating can be the first grating, and so on.

[0066] In one example, the first grating is an absorption grating and the second grating is an absorption grating. In another example, the first grating is a phase grating and the second grating is an absorption grating.

[0067] According to the example, for the first operating mode, the control unit is configured to control the X-ray detector such that the exposure time is less than the time period of the resonant frequency of the vibration of the first grating and / or the second grating.

[0068] According to the example, for a first operating mode, the movement of the first grating and / or the second grating during the exposure time includes movement caused by at least one lateral movement transducer.

[0069] According to the example, the movement of the first grating and / or the second grating during the exposure time includes movement caused by at least one lateral movement transducer during the movement process in the lateral position direction, which is part of the image acquisition protocol.

[0070] According to the example, for the second operating mode, the control unit is configured to control the X-ray detector to acquire image data as the first grating and / or the second grating moves. In the second operating mode, during the exposure time of the X-ray detector, the first grating and / or the second grating has moved a distance greater than or equal to the period of the first grating and / or the second grating. In the second operating mode, image data is acquired as the first grating and / or the second grating moves. In the second operating mode, the output unit is configured to output attenuated image data and / or calibration data.

[0071] In the example, the vibration transducer can operate continuously in both a first mode and a second mode, wherein the detector exposure time in the first mode is shorter than the detector exposure time in the second mode.

[0072] According to the example, for the second operating mode, the control unit controls the movement of the first grating and / or the second grating so that the image data is acquired when the first grating and / or the second grating moves.

[0073] According to the example, the movement of the first grating and / or the second grating during the exposure time includes movement caused by at least one vibrating transducer controlled by the control unit. The at least one vibrating transducer is configured to vibrate the first grating and / or the second grating.

[0074] In the example, the at least one vibration transducer is configured to vibrate the first grating and / or the second grating with a vibration having an amplitude greater than 10 μm.

[0075] Therefore, in order to perform calibration measurements without a moiré pattern but with all gratings in the beam path, a transducer is used to add high-frequency and “large” (i.e., several 10 μm) amplitude vibrations to one or more gratings. This eliminates all moiré fringes in the measurement because, even if the exposure time is very short, the fringe movement would cause the fringe pattern to become blurred due to the additional vibration frequency and amplitude.

[0076] Therefore, in the second mode, the detector exposure time can be greater than that in the first mode, where in the first mode, one or more gratings move at a specific speed that allows the detection of the moiré pattern. Now, in the second mode, with a longer exposure time, as the gratings move further, the fringes are washed away, making it possible to acquire attenuation data and / or calibration data. However, by introducing vibrations into the gratings in the second mode, the gratings move more in the second mode than in the first mode, and the detector can have the same exposure time in both modes, thus providing simplified detector electronics and processing. However, in both cases now in the second mode, the fringe pattern visible in the first mode is now eliminated, leaving a normal attenuation image that can be used for calibration purposes or is itself provided as a useful attenuation image.

[0077] According to the example, for the second operating mode, the movement of the first grating and / or the second grating during the exposure time includes movement caused by at least one lateral movement transducer.

[0078] According to the example, the exposure time for the first operating mode is equal to the exposure time for the second operating mode.

[0079] According to the example, for the second operating mode, the control unit is configured to control the X-ray detector such that the exposure time is greater than the resonant frequency of the first grating and / or the second grating for a period of time.

[0080] Referring to the system described above for obtaining dark-field and phase contrast data and associated attenuation data, the system can be operated to acquire attenuation data and / or calibration data by simply washing away the moiré pattern. Therefore, an example of a system for acquiring attenuation image and / or calibration data includes an X-ray source 20, an interferometer device 30, an X-ray detector 40, a control unit 50, and an output unit 60. An axis is defined extending from the center of the X-ray source to the center of the X-ray detector; an inspection area is positioned between the X-ray source and the X-ray detector. The axis extends through the inspection area, and the inspection area is configured to allow positioning of the object to be inspected. The interferometer device is positioned between the X-ray source and the X-ray detector. The interferometer device includes a first grating 32 and a second grating 34. The control unit is configured to control the X-ray detector to acquire image data as the first grating and / or the second grating moves. During the exposure time of the X-ray detector, the first grating and / or the second grating has moved a distance greater than or equal to the period of the first grating and / or the second grating. The output unit is configured to output attenuation image data and / or calibration data.

[0081] In an example of a system for acquiring attenuated images and / or calibration data, a control unit controls the movement of a first grating and / or a second grating such that image data is acquired while the first grating and / or the second grating are moving.

[0082] In an example of a system for attenuating image and / or calibrating data acquisition, the movement of the first grating and / or the second grating during the exposure time includes movement caused by at least one vibrating transducer 80 controlled by a control unit, wherein the at least one vibrating transducer is configured to vibrate the first grating and / or the second grating.

[0083] In an example of a system for attenuating image and / or calibrating data acquisition, at least one vibration transducer is configured to vibrate a first grating and / or a second grating with an amplitude greater than 10 μm.

[0084] In an example of a system used for attenuating image and / or calibration data acquisition, the movement of the first grating and / or the second grating during exposure time includes movement caused by at least one lateral movement transducer 70. The control unit is configured to control at least one lateral movement transducer to move the first grating or the second grating in a lateral position direction perpendicular to the axis.

[0085] In an example of a system used for attenuating image and / or calibrating data acquisition, the control unit is configured to control the X-ray detector such that the exposure time is greater than the resonant frequency of the first grating and / or the second grating for a period of time.

[0086] Figure 2An example of a method 100 for acquiring X-ray dark-field, phase-contrast, and attenuation images is shown in its basic steps. Method 100 includes:

[0087] In orientation step 110, also known as step a), the X-ray source 20 is oriented relative to the X-ray detector 40 to define an axis extending from the center of the X-ray source to the center of the X-ray detector.

[0088] In positioning step 120, also known as step b), the inspection area between the X-ray source and the X-ray detector is positioned, wherein a first axis extends through the inspection area, and wherein the inspection area is configured to enable the positioning of the object to be inspected.

[0089] In positioning step 130, also known as step c), an interferometer device 30 is positioned between the X-ray source and the X-ray detector, wherein the interferometer device includes a first grating 32 and a second grating 34.

[0090] In the first operating mode:

[0091] In control step 140, also known as step d), the control unit 50 controls at least one lateral movement sensor 70 to move the first grating or the second grating in a lateral position direction perpendicular to the axis.

[0092] In control step 150, also referred to as step e), the control unit controls the X-ray detector to acquire image data while the first grating and / or the second grating are moving, wherein, during the exposure time of the X-ray detector, the first grating and / or the second grating have moved a distance less than the period of the first grating and / or the second grating, and wherein the control unit controls the movement of the first grating and / or the second grating such that image data is acquired while the first grating and / or the second grating are moving; and

[0093] In output step 160, also known as step g), output unit 60 outputs one or more of the following: dark field image data, phase contrast image data, and attenuation image data.

[0094] In the example, for the first operating mode, the method includes controlling the X-ray detector by the control unit such that the exposure time is less than the time period of the resonant frequency of the vibration of the first grating and / or the second grating.

[0095] In the example, in step e), the movement of the first grating and / or the second grating during the exposure time includes movement caused by at least one lateral movement transducer.

[0096] In the example, in step e), the movement of the first grating and / or the second grating during the exposure time includes movement caused by at least one lateral movement transducer during the movement in the lateral position direction, which is part of the image acquisition protocol.

[0097] Therefore, in the example, steps d) and e) can occur simultaneously.

[0098] According to one example, the method in a second operating mode includes step f): the control unit controls the X-ray detector 170 to acquire image data while the first grating and / or the second grating is moving, wherein, during the exposure time of the X-ray detector, the first grating and / or the second grating has moved a distance greater than or equal to the period of the first grating and / or the second grating. The method in the second operating mode also includes step h), where the output unit outputs attenuated image data and / or calibration data 180.

[0099] In one example, step f) includes controlling the movement of the first grating and / or the second grating by the control unit, such that image data is acquired as the first grating and / or the second grating moves.

[0100] In the example, in step f), controlling the movement of the first grating and / or the second grating during the exposure time includes controlling at least one vibrating transducer (80) by the control unit to vibrate the first grating and / or the second grating.

[0101] In the example, step f) includes causing the first grating and / or the second grating to vibrate with an amplitude greater than 10 μm by the at least one vibration transducer.

[0102] In the example, step f) includes moving the first grating and / or the second grating by at least one lateral moving transducer during the exposure time.

[0103] In one example, the exposure time in step e) is equal to the exposure time in step f).

[0104] In one example, step f) includes controlling the X-ray detector by the control unit such that the exposure time is greater than the resonant frequency of the first grating and / or the second grating for a period of time.

[0105] Referring to the methods described above for obtaining dark field and phase contrast data and associated attenuation data, these methods can be operated to acquire attenuation data and / or calibration data by simply washing away the moiré pattern. Therefore, examples of methods for acquiring attenuated image and / or calibration data include:

[0106] In orientation step 110, also known as step a), the X-ray source 20 is oriented relative to the X-ray detector 40 to define an axis extending from the center of the X-ray source to the center of the X-ray detector.

[0107] In positioning step 120, also known as step b), the inspection area between the X-ray source and the X-ray detector is positioned, wherein a first axis extends through the inspection area, and wherein the inspection area is configured to enable the positioning of the object to be inspected.

[0108] In positioning step 130, also known as step c), an interferometer device 30 is positioned between the X-ray source and the X-ray detector, wherein the interferometer device includes a first grating 32 and a second grating 34.

[0109] In control step 170, also referred to as step f), the control unit controls the X-ray detector to acquire image data while the first grating and / or the second grating are moving, wherein, during the exposure time of the X-ray detector, the first grating and / or the second grating have moved a distance greater than or equal to the period of the first grating and / or the second grating; and

[0110] In output step 180, also known as step h), the output unit outputs attenuated image data and / or calibration data.

[0111] In the example, step f) includes the control unit controlling the movement of the first grating and / or the second grating, such that image data is acquired as the first grating and / or the second grating moves.

[0112] In the example, in step f), controlling the movement of the first grating and / or the second grating during the exposure time includes controlling at least one vibrating transducer 80 by the control unit to vibrate the first grating and / or the second grating.

[0113] In the example, step f) includes causing the first grating and / or the second grating to vibrate with an amplitude greater than 10 μm by the at least one vibration transducer.

[0114] In the example, step f) includes moving the first grating and / or the second grating by at least one lateral moving transducer during the exposure time, wherein the control unit is configured to control at least one lateral moving transducer to move the first grating or move the second grating in a lateral position direction perpendicular to the axis.

[0115] In the example, step f) includes the control unit controlling the X-ray detector such that the exposure time is greater than the resonant frequency of the first grating and / or the second grating for a period of time.

[0116] Systems and methods for acquiring X-ray dark-field, phase-contrast, and attenuation images, as well as systems and methods for acquiring attenuation images and / or calibration data, are now described in more detail below, with reference to... Figure 3-4 .

[0117] As described above, in the new imaging modality, the inter-grating movement required for the step curve allows for the determination of X-ray dark field and phase contrast information (as well as normal attenuation information) while one or more gratings are being moved. Therefore, this refers to a step curve, but the gratings do not necessarily need to be stepped, as they never need to be intentionally stopped. This is achieved by moving the gratings and reducing the blurring effect by decreasing the exposure time. The exposure time must be short enough that the grating movement during a single exposure is practically negligible, or at least does not wash away the fringes. This can be ensured when the exposure time is significantly shorter than the period of the grating's dominant vibration frequency. The grating vibration can be inherent to the system or, for example, externally caused by a vibrating transducer. However, the system can operate to obtain X-ray attenuation data and / or normal X-ray attenuation data without having to move the interferometer apparatus out of the beamline. This is done when the grating movement or vibration is large enough to wash away the moiré pattern. The movement can be part of an image acquisition run to acquire dark field data, phase contrast, and associated attenuation data. And / or the movement can be due to vibration. The vibration of the grating can be inherent to the system or caused externally, for example, by a vibrating transducer. To enable calibrated measurements with all gratings in the beam path but without a moiré pattern, high-frequency and “large” (i.e., several 10 μm) amplitude vibrations are added to the grating using a transducer. This eliminates all moiré fringes in the measurement because even with very short exposure times, the fringe movement due to the additional vibration frequency and amplitude would cause extreme blurring of the fringes.

[0118] refer to Figure 3-4 Explain the new imaging modality.

[0119] Figure 3 An example of the interferometer section of a system is shown, which can acquire X-ray phase contrast, dark field, and attenuation image data. Referring to the interferometer arrangement above, only the grating of the interferometer section of the system is considered. This system is capable of imaging the spatial distribution of attenuation in a sample, or the spatial distribution of attenuation within a sample, and simultaneously imaging the spatial distribution of refraction (phase contrast imaging) and the spatial distribution of small-angle scattering (dark field imaging). The system features a grating-based interferometer. In this example, the interferometer comprises two grating structures G1 and G2, but in other examples a three-grating interferometer (with gratings G0, G1, and G2) is used, where the source grating G0, located near the source, is used to increase the coherence of radiation propagating through the sample and gratings G1 and G2.

[0120] exist Figure 3 In the diagram, the source grating G0 is not shown, and the following discussion considers two grating structures G1 and G2, but G0, G1, and G2 can all exist, and G0 can be a laterally shifted grating. Figure 3 In this system, grating G1 is a phase grating (but could also be an absorption grating), and G2 is the absorbing light. The system includes an X-ray source and an X-ray detector. The X-ray detector, shown herein as a CCD detector, can be a planar or curved 2D full-view X-ray detector. Multiple detector pixels are arranged in rows and columns in an array to form a 2D X-ray radiation-sensitive surface capable of recording X-ray radiation emitted by the X-ray source. The X-ray detector and the X-ray source are spaced apart to form an examination area. The examination area is appropriately spaced to receive a sample to be imaged. The sample can be, for example, a patient's breast, or a patient's chest to examine the lungs. Either G1 or G2 can be curved or flat, but even if curved, a plane parallel to the center of the grating can be defined. The system has a transducer for laterally moving the grating and may also have a vibrating transducer for vibrating one of the gratings.

[0121] The sample then modulates attenuation, refraction, and small-angle scattering information onto the radiation, which can then be extracted by operating gratings G1 and G2 in series. Gratings G1 and G2 induce an interference pattern, which can be detected as fringes of a moiré pattern on an X-ray detector. If there is no object in the area being examined, an observable interference pattern still exists on the X-ray detector, called the reference pattern, which is typically captured during calibration. This is achieved by specifically adjusting or “detuning” the mutual spatial relationship between the two gratings G1 and G2, for example, by inducing a slight bend so that the two gratings are not perfectly parallel. Now, if the sample is located in the area being examined and interacts with the radiation described above, the moiré pattern (now more appropriately called the sample pattern) can be understood as a disturbed version of the reference pattern.

[0122] To separate this phase information from other contributions to the signal (such as sample attenuation, uneven illumination, or grating defects), an improved phase "stepping" method was used. This stepping occurs along the transverse x-axis within at least one period of the grating. g (like Figure 3 The scanning grating (shown) scans a grating (G1 or G2—or G0, if present), and for each point scanned, an image is captured at the detector exposure time, and this image data is acquired as the grating moves, ensuring the moiré pattern is not washed away. If a source grating G0 is present, it can be scanned in the lateral direction. The resulting phase contrast, dark field, and attenuation data then oscillate sinusoidally with and without samples, as shown. Figure 4The phase contrast (A), dark field (B), and attenuation (C) are shown in the figure. More details about the standard phase stepping method can be found in the following paper by Weitkamp et al.: Optics Express, Vol. 13, No. 16, (2005) 6296-6304.

[0123] However, for the system described herein, an alternative operating mode is used to obtain X-ray calibration data or normal attenuation data. The grating, as described above, can be moved in the same manner by laterally moving the transducer, but the detector exposure time can be increased to wash away the fringes. Furthermore, for a constant detector exposure time, the moving speed can be increased. As readily apparent, there are combinations of moving speed and exposure time that result in edge washing away. However, due to the inherent vibrations of the system, another method to wash away the fringes is simply to increase the exposure time to the duration for which the fringes disappear, as a result of the system's inherent vibrations. These vibrations can be amplified by using a vibrating transducer to enhance the lateral vibrations of the grating, thereby washing away the moiré pattern when using the detector exposure time.

[0124] In another exemplary embodiment, a computer program or computer program unit is provided, characterized in that it is configured to perform method steps of a method according to one of the foregoing embodiments on a suitable system.

[0125] The computer program unit can therefore be stored on the computing unit, which may also be part of the embodiments. The computing unit can be configured to perform the steps of the described method or cause the execution of the steps of the described method. Furthermore, it can be configured to operate components of the described apparatus and / or system. The computing unit can be configured to automatically operate and / or execute user commands. The computer program can be loaded into the working memory of the data processor. The data processor can therefore be equipped to perform the method according to one of the foregoing embodiments.

[0126] This exemplary embodiment of the invention covers both computer programs that use the invention from the outset and computer programs that have been updated to use the invention.

[0127] In addition, the computer program unit may be able to provide all the necessary steps to complete the process of an exemplary embodiment of the method as described above.

[0128] According to another exemplary embodiment of the present invention, a computer-readable medium, such as a CD-ROM, a USB memory stick, etc., is provided, wherein the computer-readable medium has computer program units stored thereon, the computer program units being described in the preceding part.

[0129] Computer programs can be stored and / or distributed on suitable media, such as optical storage media or solid-state media that are provided together with or as part of other hardware, but computer programs can also be distributed in other forms, such as via the Internet or other wired or wireless telecommunications systems.

[0130] However, computer programs can also be provided via networks such as the World Wide Web and can be downloaded from such networks into the working memory of a data processor. According to another exemplary embodiment of the invention, a medium is provided for making computer program units available for download, said computer program units being arranged to perform one of the embodiments previously described in the invention.

[0131] It must be noted that embodiments of the present invention are described with reference to different subjects. In particular, some embodiments are described with reference to method claims, while others are described with reference to device claims. However, those skilled in the art will understand from the above and the following description that, unless otherwise indicated, any combination of features relating to different subjects, except for any combination of features belonging to the same type of subject matter, is also considered to be disclosed in this application. However, all features can be combined to provide synergistic effects beyond the simple sum of the features.

[0132] Although the invention has been illustrated and described in detail in the accompanying drawings and the foregoing description, such illustrations and descriptions should be considered illustrative or exemplary, not restrictive. The invention is not limited to the disclosed embodiments. Those skilled in the art, through studying the drawings, the disclosure, and the dependent claims, will understand and implement other variations of the disclosed embodiments in practicing the claimed invention.

[0133] In the claims, the word "comprising" does not exclude other elements or steps, and the words "a" or "an" do not exclude multiple. A single processor or other unit can perform the functions of several items recited in the claims. Although specific measures are listed in mutually different dependent claims, this does not indicate that combinations of these measures cannot be advantageously used. Any reference numerals in the claims should not be construed as limiting the scope.

Claims

1. A system (10) for acquiring X-ray dark-field, phase-contrast, and attenuation images, the system comprising: X-ray source (20); Interferometer device (30); X-ray detector (40); Control unit (50); as well as Output unit (60); Here, an axis is defined extending from the center of the X-ray source to the center of the X-ray detector; The inspection area is located between the X-ray source and the X-ray detector, and the axis extends through the inspection area, and the inspection area is configured to enable the positioning of the object to be inspected. The interferometer device is positioned between the X-ray source and the X-ray detector, and the interferometer device includes a first grating (32) and a second grating (34). Specifically, for the first operating mode: The control unit is configured to control at least one lateral movement transducer (70) to move either the first grating or the second grating in a lateral position direction perpendicular to the axis; and The control unit is configured to control the X-ray detector to acquire image data while the first grating and / or the second grating are moving, wherein during the exposure time of the X-ray detector, the first grating and / or the second grating have moved a distance less than the period of the first grating and / or the second grating, and wherein the control unit is configured to control the movement of the first grating and / or the second grating such that the image data is acquired while the first grating and / or the second grating are moving; and In the first operating mode, the output unit is configured to output one or more of the following: dark field image data, phase contrast image data, and attenuation image data; Specifically, regarding the second operating mode: The control unit is configured to control the X-ray detector to acquire image data while the first grating and / or the second grating are moving, wherein, during the exposure time of the X-ray detector, the first grating and / or the second grating have moved a distance greater than or equal to the period of the first grating and / or the second grating; and In the second operating mode, the output unit is configured to output attenuated image data and / or calibration data.

2. The system according to claim 1, wherein, For the first operating mode, the control unit is configured to control the X-ray detector such that the exposure time is less than the time period of the resonant frequency of the vibration of the first grating and / or the second grating.

3. The system according to any one of claims 1-2, wherein, For the first operating mode, the movement of the first grating and / or the second grating during the exposure time includes movement caused by the at least one lateral movement transducer.

4. The system according to claim 3, wherein, The movement of the first grating and / or the second grating during the exposure time includes movement caused by at least one lateral movement transducer during the movement in the lateral position direction, which is part of the image acquisition protocol.

5. The system according to claim 1, wherein, In the second operating mode, the control unit controls the movement of the first grating and / or the second grating so that image data is acquired while the first grating and / or the second grating is moving.

6. The system according to claim 5, wherein, The movement of the first grating and / or the second grating during the exposure time includes movement caused by at least one vibrating transducer (80) controlled by the control unit, wherein the at least one vibrating transducer is configured to vibrate the first grating and / or the second grating.

7. The system according to any one of claims 1-2, wherein, For the second operating mode, the movement of the first grating and / or the second grating during the exposure time includes movement caused by the at least one lateral movement transducer.

8. The system according to any one of claims 1-2, wherein, The exposure time for the first operating mode is equal to the exposure time for the second operating mode.

9. The system according to any one of claims 1-2, wherein, For the second operating mode, the control unit is configured to control the X-ray detector such that the exposure time is greater than the resonant frequency of the first grating and / or the second grating for a period of time.

10. A method (100) for acquiring X-ray dark-field, phase-contrast, and attenuation images, the method comprising: a) Orienting (110) the X-ray source (20) relative to the X-ray detector (40) to define an axis extending from the center of the X-ray source to the center of the X-ray detector; b) Locate an inspection area between the X-ray source and the X-ray detector, wherein a first axis extends through the inspection area, and wherein the inspection area is configured to enable the location of the object to be inspected; c) Positioning an interferometer device (30) between the X-ray source and the X-ray detector, wherein the interferometer device includes a first grating (32) and a second grating (34); d) In the first operating mode, the control unit (50) controls (140) at least one lateral movement transducer (70) to move the first grating or the second grating in a lateral position direction perpendicular to the axis; e) In the first operating mode, the control unit controls the X-ray detector to acquire image data while the first grating and / or the second grating are moving, wherein during the exposure time of the X-ray detector, the first grating and / or the second grating have moved a distance less than the period of the first grating and / or the second grating, and wherein the control unit controls the movement of the first grating and / or the second grating such that the image data is acquired while the first grating and / or the second grating are moving; g) Output (160) one or more of the following from the output unit (60): dark field image data, phase contrast image data, and attenuation image data; and In the second operating mode, the X-ray detector is controlled to acquire image data while the first grating and / or the second grating are moving, wherein, during the exposure time of the X-ray detector, the first grating and / or the second grating have moved a distance greater than or equal to the period of the first grating and / or the second grating; and In the second operating mode, attenuated image data and / or calibration data are output.

11. The method of claim 10, wherein the second operating mode includes step f): the control unit controls the X-ray detector to acquire image data while the first grating and / or the second grating are moving, wherein, During the exposure time of the X-ray detector, the first grating and / or the second grating has moved a distance greater than or equal to the period of the first grating and / or the second grating; and wherein the method includes step h): outputting attenuated image data and / or calibration data by the output unit in the second operating mode.

12. A system for attenuating image and / or calibrating data acquisition, the system comprising: X-ray source (20); Interferometer device (30); X-ray detector (40); Control unit (50); as well as Output unit (60); Here, an axis is defined extending from the center of the X-ray source to the center of the X-ray detector; The inspection area is located between the X-ray source and the X-ray detector, and the axis extends through the inspection area, and the inspection area is configured to enable the positioning of the object to be inspected. The interferometer device is positioned between the X-ray source and the X-ray detector, and the interferometer device includes a first grating (32) and a second grating (34). The control unit is configured to control the X-ray detector to acquire image data while the first grating and / or the second grating are moving, wherein during the exposure time of the X-ray detector, the first grating and / or the second grating have moved a distance greater than or equal to the period of the first grating and / or the second grating; The control unit controls the movement of the first grating and / or the second grating such that image data is acquired while the first grating and / or the second grating are moving. The movement of the first grating and / or the second grating during the exposure time includes movement caused by at least one vibrating transducer (80) controlled by the control unit, and the at least one vibrating transducer is configured to vibrate the first grating and / or the second grating. The output unit is configured to output attenuated image data and / or calibration data.

13. A method for attenuating image and / or calibrating data acquisition, the method comprising: a) Orienting (110) the X-ray source (20) relative to the X-ray detector (40) to define an axis extending from the center of the X-ray source to the center of the X-ray detector; b) Locate an inspection area between the X-ray source and the X-ray detector, wherein a first axis extends through the inspection area, and wherein the inspection area is configured to enable the location of the object to be inspected; c) Positioning an interferometer device (30) between the X-ray source and the X-ray detector, wherein the interferometer device includes a first grating (32) and a second grating (34); f) The control unit controls the X-ray detector to acquire image data while the first grating and / or the second grating is moving, wherein, during the exposure time of the X-ray detector, the first grating and / or the second grating has moved a distance greater than or equal to the period of the first grating and / or the second grating, wherein step f) includes controlling the movement of the first grating and / or the second grating by the control unit such that the image data is acquired while the first grating and / or the second grating is moving, and wherein controlling the movement of the first grating and / or the second grating during the exposure time in step f) includes at least one vibrating transducer (80) controlled by the control unit to vibrate the first grating and / or the second grating; and h) The output unit outputs (180) attenuated image data and / or calibration data.

14. A computer program unit for controlling a system according to any one of claims 1-9, the computer program unit being configured, when executed by a processor, to perform the method according to any one of claims 10-11 and / or the computer program unit being configured, when executed by a processor, to perform the method according to claim 13 for controlling a system according to claim 12.

Images