CT imaging dependent on the patient's intrinsic respiratory substitutes

Abstract

Provides CT imaging dependent on the patient's intrinsic respiratory substitute. A method is described for performing a CT imaging procedure dependent on the individual respiratory behavior of a patient (P). The method includes the step of recording the respiratory movement of the patient (P) by monitoring the intrinsic respiratory substitute (IRS). In the context of recording the intrinsic respiratory substitute (IRS), raw CT data (RD) is acquired from the examination volume (V) of the patient (P). Subsequent stacks (ST) of the examination volume (V) at different z-positions are then reconstructed. i 3D-CT images based on subsequent stacking (ST). i The method uses reconstructed 3D-CT images to perform automated organ segmentation, wherein at least one portion of the examination volume (V) is segmented. Furthermore, respiratory movement of the segmented portion is detected and identified as an intrinsic respiratory substitute (IRS). The method also includes a step of adapting the CT imaging process based on the patient's (P) intrinsic respiratory substitute (IRS). An adaptation device (70) is also described. A CT system (1) is also described.

Description

Technical Field

[0001] This invention relates to a method for performing a CT imaging procedure that depends on the individual respiratory behavior of a patient. The invention also relates to an adapter. Furthermore, the invention relates to a CT system. Background Technology

[0002] In radiation therapy planning, CT images (CT stands for computed tomography) are used to calculate and optimize dose distribution maps and radiation therapy plans. Depending on the location of the tumor, if the tumor is easily movable, respiratory-phase-related reconstruction may be necessary to avoid radiation damage to at-risk healthy tissues and organs.

[0003] By using information about a patient's respiratory movements, time-resolved reconstructions related to the patient's respiratory movements can be performed, thereby optimizing radiation therapy plans for respiratory-induced movements of the target tumor (e.g., lung tumor).

[0004] In order to perform high-quality stage-related reconstruction, accurate measurements of the patient's respiratory movements (so-called respiratory surrogate) are essential.

[0005] Currently, information about respiratory movements (i.e., so-called respiratory substitutes) is collected by external devices. Such external devices can be: optical systems that track respiratory movements via camera systems; or tension-based systems in which an elastic band is fitted around the patient's chest, and the tension-based system directly measures respiratory movements via a built-in tension sensor.

[0006] To date, respiratory information collected through so-called "breathing substitutes" has only been used in dedicated 4D (4D = 4-dimensional) respiratory scanning modes and protocols for CT scanning systems. Here, breathing substitutes have been used to: determine the patient's respiratory stage during scanning to enable stage-related scanning, or to determine the patient's respiratory stage after scanning to perform stage-related reconstruction of image data based on the raw scan data.

[0007] In standard and non-breathing scans and reconstructions, respiratory substitutes are not recorded at all. This is because, until now, respiratory substitutes have been recorded by external measurement systems, which are very complex and difficult to attach to patients.

[0008] Breathing commands are included in almost any CT protocol. Typically, these commands are given just before or during the scan to advise the patient on how to control their breathing and avoid artifacts in the reconstructed images caused by respiratory movement. Currently, commands are usually pre-recorded voice commands, which can be recorded and stored by the clinical user of the CT scanning unit. Generally, each clinical imaging task (e.g., cardiac, dual-energy, standard contrast and non-contrast examinations) has its own dedicated commands, which are pre-recorded and stored in a specific protocol by the clinical user according to their needs and clinical practice. The disadvantage of these pre-recorded commands is that they do not take into account the current respiratory characteristics of the patient and they cannot be adapted to the patient's current respiratory status. For example, it is impossible to detect whether the patient is following the commands, which in the worst case can result in non-diagnostic images and require a rescan. Summary of the Invention

[0009] Therefore, the underlying problem of this invention is to improve the CT scanning process that is affected by the patient's breathing movements.

[0010] The problem is solved by the following: the method for performing a CT imaging procedure that depends on the individual respiratory behavior of the patient according to claim 1, the adapter according to claim 12, and the CT system according to claim 13.

[0011] According to methods used to perform CT imaging procedures dependent on the individual respiratory behavior of a patient, respiratory movement is recorded by monitoring intrinsic respiratory substitutes. In contrast to extrinsic substitutes, intrinsic respiratory substitutes are defined as substitutes not created through additional measurements (such as the use of markers or external imaging equipment). Intrinsic respiratory substitutes are determined directly based on CT imaging data, which is based on raw CT data and can also be used to reconstruct 4D-CT image data. 4D-CT image data includes a sequence of subsequently recorded 3D-CT images.

[0012] According to the method of the present invention, raw CT data is acquired from the patient's examination volume. Then, preferably, 3D-CT images (3D-CT images = three-dimensional computed tomography images) of subsequent stacks of the examination volume at different z-positions are reconstructed in real time and timely, in parallel with the acquisition of the raw data, with time increments. The z-position is the z-coordinate value within the CT system, where the z-coordinate is the coordinate value of the z-axis. The z-axis is the rotation axis of the rotating part of the CT system and / or the system axis. A single stack may include a single layer, i.e., a layer with a thickness of a single voxel. A single stack may also include multiple layers. Because the 3D-CT images are reconstructed in real time and timely, in parallel with the acquisition of the raw data, the reconstructed images are realized as quasi-fixed images, wherein subsequent images are assigned to subsequent different stages of the patient's respiratory movement.

[0013] Real-time reconstruction is possible because the duration of a respiratory cycle is typically in the range of 3 to 12 seconds (s is an abbreviation for seconds), which is at least an order of magnitude longer than the typical time for acquiring and reconstructing the minimum amount of raw data required for reconstructing 3D-CT images (i.e., the time for acquiring raw data within a 180° plus the fan angle of the X-ray beam).

[0014] Furthermore, automatic segmentation is performed based on 3D-CT images, preferably organ segmentation, wherein at least one portion of the examined volume is segmented, and the at least one portion is preferably an organ.

[0015] It's also possible to segment something other than an organ to calculate respiratory substitutes. Segmentation means generating content-related regions by combining adjacent pixels or voxels according to some homogeneity criterion. For example, different parts of the body (e.g., organs) are distinguished from each other. Therefore, respiratory substitutes can be determined based on the segmented organs. However, it's also conceivable, for example, that the abdominal wall or the entire chest is segmented to draw conclusions about a patient's respiratory behavior. The level of detail in the reconstruction must be appropriate for the task. The reconstruction must be detailed enough that relevant structures remain identifiable.

[0016] As described above, segmentation is preferably achieved automatically based on AI algorithms (AI is an abbreviation for Artificial Intelligence). Such automatic segmentation is described in “Automatic Liver Segmentation Using an Adversarial Image-to-Image Network” (Medical Image Computing and Computer-Assisted intervention - MICCAI 2017: 20th International Conference, Quebec City, QC, Canada, September 11-13, Conference Proceedings) by Yang D, Daguang X, Kevin Zhou S, Georgescu B, Chen M, Grbic S, Metaxas D, and Comaniciu D.

[0017] By performing segmentation, the foundation for detecting respiratory movement has been laid. This is because by comparing time samples of the automatic segmentation results, respiratory parameters can be determined using information about which organ was segmented and in which direction it moved. These parameters include the direction and displacement of organ movement, and especially whether a complete respiratory cycle has been captured. This method is more robust to larger detector z-coverage (i.e., stacks with higher layers) because the larger the z-coverage of a z-stack (where the z-direction is the stacking direction of the z-stack), the easier the automatic segmentation becomes, as more extended image segments can be used for detection segmentation.

[0018] Then, the respiratory movement of the segmented portion (preferably an organ or part of an organ) is detected and identified as an intrinsic respiratory substitute. Specifically, the segmentation allows for the determination of the time-dependent location or extension of the segmented portion. Based on this time-dependent location or extension, the respiratory phase at the time interval of the raw data acquisition for each stack can be determined.

[0019] Therefore, the time dependence of the respiratory phase and the acquired raw data is achieved, which is a function of the respiratory substitute. All these steps are performed in real time: reconstruction of quasi-fixed images, automatic segmentation, and determination of the intrinsic respiratory substitute, so that the results can be used to adapt the CT imaging process based on the patient's intrinsic respiratory substitute. For example, as an adaptation, X-ray on / off control of respiratory-related scan patterns can be implemented based on the determined intrinsic respiratory substitute. As described later, consistent with the determined intrinsic respiratory substitute, phase-related reconstruction for generating 4D-CT images of organs readily capable of respiratory movement can also be achieved. Advantageously, the external (i.e., conventional) respiratory substitute can be omitted, simplifying the imaging process. In contrast to conventional methods, the method according to the invention does not require an external measurement system, but allows the respiratory substitute to be simply derived from the measured raw CT data, and thus can be fully integrated into conventional CT scanning workflows. Furthermore, the ability to adapt CT imaging in real time provides the advantage of flexibility and real-time responsiveness during the CT imaging process. For example, in the case of X-ray therapy used in CT imaging to monitor tumors, real-time response is necessary when a patient's healthy tissue is inadvertently penetrated by X-rays to prevent unnecessary health burden on the patient.

[0020] The adapter according to the invention includes an acquisition unit for acquiring raw CT data from a patient's examination volume. Furthermore, the adapter includes a reconstruction unit for reconstructing subsequent stacked 3D-CT images of the examination volume at different z-positions (preferably in parallel, in real-time, and timely with the acquisition of the raw data, using time increments). The adapter also includes a segmentation unit for performing automatic segmentation (preferably organ segmentation) of at least one portion of the examination volume based on the subsequently reconstructed stacked 3D-CT images. A portion of the adapter also includes a substitute determination unit for determining respiratory movement of the segmented portion as an intrinsic respiratory substitute. The adapter further includes an adapter unit for adapting the CT imaging process based on the patient's intrinsic respiratory substitute. The adapter unit may include a reconstruction unit for reconstructing image data in accordance with the patient's respiratory movement. The adapter unit may also include a control function for controlling the X-ray source in a respiratory-related scanning mode. The adapter shares the advantages of the method according to the invention.

[0021] The CT system according to the invention includes: a scanning unit for performing CT imaging from a patient; and an adapter according to the invention for adapting the CT imaging process of the scanning unit to the patient's recorded respiratory movements. The CT system shares the advantages of the method according to the invention.

[0022] The basic components of the adapter device according to the invention can largely be designed as software components. This is particularly applicable to the reconstruction unit, segmentation unit, substitute determination unit, and adaptation unit of the adapter device, and also to the input interface portion. However, in principle, some of these components can also be implemented as software-supported hardware (e.g., FPGA, etc.), especially when particularly fast computation is involved; or implemented using a computer processor. Similarly, the required interfaces (e.g., if it is simply a matter of transmitting data from other software components) can be designed as software interfaces. However, they can also be designed as hardware-based interfaces controlled by appropriate software. Furthermore, some parts of the aforementioned components can be distributed and stored in a local, regional, or global network or a combination of network and software (especially cloud systems).

[0023] The software-based implementation has the advantage that existing CT systems can be easily modified through software updates to operate according to the invention. In this respect, this objective is also achieved by a corresponding computer program product having a computer program that can be directly loaded into the memory device of, for example, the control device of the CT system. This computer program has program segments that, if executed in the CT system (particularly the control device), perform all the steps of the method according to the invention. In addition to the computer program, such a computer program product may include: additional components such as documentation; and / or additional components including hardware components, such as hardware keys (dongles, etc.) for using the software.

[0024] For transport to and / or storage on or within a CT system, program segments of a computer program that can be read and executed by a computer unit of the medical imaging system are stored on a computer-readable medium, such as a memory stick, hard disk, or some other transportable or permanently mountable data carrier. The computer unit may include, for example, one or more cooperating microprocessors for this purpose.

[0025] The dependent claims and the following description each contain particularly advantageous embodiments and developments of the invention. In particular, a claim of one claim class can be further developed similarly to a dependent claim of another claim class. Furthermore, within the scope of the invention, various exemplary embodiments and features of the claims can be combined to form new exemplary embodiments.

[0026] In a variation of the method according to the invention, the adaptation of the CT imaging process includes: performing post-operative respiratory phase-related 4D-CT reconstruction of the 4D-CT images of the examination volume based on the determined intrinsic respiratory substitute. As described above, the 4D-CT images are defined as, for example, a sequence of multiple 3D-CT images assigned to different respiratory phases. Advantageously, information about the patient's individual respiratory behavior can be used not only as real-time information for dynamic adaptation of the scanning process during the actual scanning procedure, but also as information for steps after the scanning procedure has been completed (such as reconstruction of image data). Therefore, the image quality of the 4D-CT images is improved compared to reconstruction without a respiratory substitute.

[0027] In another variation of the method according to the invention, reconstruction of the subsequently stacked 3D-CT images is performed non-stage-dependently. Advantageously, since the subsequent stacks remain almost stationary during the acquisition of raw data, stage-dependent information at the time of raw data acquisition is unnecessary.

[0028] In another variation of the method according to the invention, the determination of the intrinsic respiratory substitute based on the respiratory movement of the segmented portion (preferably the segmented organ) includes determining at least one of the following:

[0029] Which organ was divided?

[0030] - In which direction does the organ move?

[0031] - Organ displacement,

[0032] - Has raw data for the entire respiratory cycle been collected?

[0033] The above information can be used to determine intrinsic respiratory alternatives based on the segmented portion.

[0034] To achieve real-time reconstruction of fixed image data for intrinsic respiratory substitutes, the time for determining the respiratory phase of a 3D-CT volume (the time for determining the intrinsic respiratory substitute in a single stack of the examination volume) must be less than the time interval of respiratory cycles. Preferably, the time for determining the respiratory phase of a 3D-CT volume is at least an order of magnitude smaller than the time interval of the corresponding respiratory cycle (i.e., one-tenth of the time interval of the corresponding respiratory cycle). Advantageously, reconstructed partial 3D-CT images of subsequent stacks are reconstructed as quasi-fixed images, so that precise reconstruction of subsequent stacks does not require observation of respiratory movement.

[0035] Preferably, by reducing the reconstruction time T of a single stack of 3D-CT images used to reconstruct the examination volume. reconThis reduces the time spent on the respiratory phase for determining 3D-CT volume. The time spent on the respiratory phase for determining 3D-CT volume, T... ph as follows:

[0036] T ph =T rot / 2+T recon +T autoseg (1)

[0037] Where T rot It is the rotation time of the detector and X-ray source in the CT system.

[0038] To reduce reconstruction time T recon Reconstruction can be achieved using a coarser pattern. For example, the reconstruction matrix can be reduced.

[0039] Furthermore, preferably, the reconstruction time T recon The reduction includes measures to reduce the time-consuming optimization algorithms used for reconstruction. For example, time-consuming processes include iterative reconstruction or bundle hardening correction. Since the reconstruction of images of intrinsic respiratory movement can be coarse, fine reconstruction at the first stage is not truly necessary. Reducing reconstruction time allows for increased stage resolution of the reconstruction and reduces artifacts caused by the patient's respiratory movement.

[0040] To achieve more accurate results, after 4D-CT reconstruction of the 4D-CT image of the examination volume, the final calculation of the intrinsic respiratory substitute can be performed additionally based on the reconstructed examination volume and the segmented parts (e.g., segmented organs).

[0041] To obtain a complete raw dataset for each respiratory phase at each z-position, raw data for the entire respiratory cycle are recorded for each z-position. As described above, knowledge of the patient's respiratory movement throughout the entire respiratory cycle can be used to assign the raw data to the correct phase for subsequent 4D-CT phase-related reconstruction.

[0042] In one alternative variation, during raw data collection, the patient's proper breath-holding is assessed based on detected intrinsic respiratory substitutes, and in cases where the patient is not properly holding their breath...

[0043] - Play commands to remind and encourage the patient to hold their breath further, and / or

[0044] The scanning process is dynamically reparameterized.

[0045] Advantageously, patient behavior or control of the scanning process can be adapted in real time during the scanning procedure.

[0046] Preferably, respiratory phase-related 4D-CT reconstruction of the examination volume is performed by classifying the reconstructed subsequent stacks of 3D-CT images of the examination volume according to the calculated intrinsic respiratory substitutes. If the resolution of the very coarsely reconstructed 3D-CT images is high enough for current medical applications, the 3D-CT images can be used as a sequence of 3D-CT images, i.e., as 4D-CT images. Advantageously, additional reconstruction is not necessary to achieve respiratory phase-related 4D-CT reconstruction. Only the step of classifying the reconstructed 3D-CT images generated for determining intrinsic respiratory substitutes must be performed, thus minimizing the scope used to generate 4D-CT images.

[0047] Alternatively, respiratory phase-related 4D-CT reconstruction of the examined volume can be performed by using the segmentation results as 4D-CT image results. This means that 4D-CT images (i.e., a sequence of 3D-CT images) are generated by classifying the segmented portions (e.g., organs) based on calculated respiratory substitutes. Furthermore, for this variant, post-construction of the 4D-CT images can be cancelled. In other words, in this variant, real-time automatic segmentation results can be reused in the same way that real-time 3D-CT images can be reused for final reconstruction. This alternative is also suitable when the resolution requirement for the 4D image sequence is not so high.

[0048] In another variation, during the pre-scanning phase, adaptation can be achieved by training the patient to breathe optimally for a given scan pattern or task, based on identified intrinsic breathing substitutes and considering the patient's individual breathing behavior for that particular scan pattern or task. Advantageously, the patient's recorded breathing behavior can be used as feedback information in a feedback loop to train the patient for the individual scan pattern or task.

[0049] Then, after completing the training phase, during the scanning phase, it is determined whether the patient is holding their breath appropriately based on intrinsic breathing substitutes. If the patient is not holding their breath appropriately, commands are played to remind and encourage the patient to hold their breath further. Advantageously, feedback from the patient's behavior can be used to attempt to influence the patient's breathing behavior in real time, saving current scanning operations if the patient does not follow breathing commands precisely. Furthermore, if the patient appears unable to hold their breath appropriately, the scanning procedure can also be dynamically reparameterized (e.g., by increasing the interval based on the determined intrinsic breathing substitutes). In that case, especially if the patient does not improve their breathing behavior (even though they have been advised to do so), the scanning procedure can be modified to increase the recording speed of raw data, making it tolerable for the patient's shortened breath-holding time.

[0050] In another variation of the method according to the invention, during the scanning phase, if it is detected that the scan results may be insufficient and a rescan cannot be avoided based on respiratory behavior recorded from an intrinsic respiratory substitute, the scanning process is terminated early. Advantageously, if the current scanning process is likely to result in inadequate image quality for the medical images, scanning and time resources can be saved.

[0051] Furthermore, during the scanning phase, whether the patient is properly holding their breath can be detected based on intrinsic breathing substitutes. If the patient is not properly holding their breath, the scanning process can be stopped, and the scanning process can be paused at the relevant z-position that allows the patient to stop holding their breath. In that case, after the pause, the patient is instructed to hold their breath again, and the scanning process resumes at the z-position where the scanning process was stopped, or at the position where the patient is still properly holding their breath. Advantageously, even though the patient cannot properly follow the breathing commands of the medical imaging system temporarily, the current scanning process can be saved.

[0052] In another variation of the method according to the invention, in the post-scan phase, individual respiratory behavior is analyzed based on recorded respiratory curves derived from an intrinsic respiratory substitute. If a patient is detected not properly following breathing commands during the scan phase, and if severe artifacts are expected, a rescan is recommended. Advantageously, the decision on whether a rescan is necessary can be made automatically based on feedback information regarding the patient's respiratory behavior. In that case, reconstruction based on deteriorated raw data can be cancelled, thus saving time, resources, and medical examination capacity.

[0053] Furthermore, in a variation of the method according to the invention, the adaptation of the medical imaging process is automatically determined based on recorded respiratory behavior. This means that, based on information about intrinsic respiratory substitutes, a decision is made on which measure or combination of such measures to perform to improve the scanning process. Analysis of this decision can be performed using classical signal processing methods or by means of deep learning-based algorithms. For example, analysis of respiratory curves can be accomplished using some form of artificial neural network. Attached Figure Description

[0054] The invention will now be explained again with reference to the accompanying drawings. In the various drawings, the same components are provided with the same reference numerals.

[0055] The accompanying diagrams are usually not to scale.

[0056] Figure 1 A flowchart is shown illustrating a method for performing a CT imaging procedure that depends on the individual respiratory behavior of a patient, according to an embodiment of the present invention.

[0057] Figure 2A schematic view of the patient is shown, in which the internal organs move due to the patient's breathing.

[0058] Figure 3 A schematic view is shown regarding multiple stacks containing internal organs, comprised of an imaging volume.

[0059] Figure 4 A flowchart illustrating a method for performing a CT imaging procedure dependent on the individual respiratory behavior of a patient, according to a second embodiment of the present invention, is shown.

[0060] Figure 5 A flowchart is shown illustrating a method for performing a CT imaging procedure dependent on the individual respiratory behavior of a patient, according to a third embodiment of the present invention.

[0061] Figure 6 A flowchart is shown illustrating a method for performing a CT imaging procedure dependent on the individual respiratory behavior of a patient, according to a fourth embodiment of the present invention.

[0062] Figure 7 A schematic view of an adapter device according to an embodiment of the present invention is shown.

[0063] Figure 8 An embodiment of the present invention is shown, including Figure 7 The CT system with compatible equipment is shown in the image. Detailed Implementation

[0064] Figure 1 A flowchart 100 is shown, illustrating a method for performing a CT imaging procedure dependent on the individual respiratory behavior of a patient P. In step 1.I, raw CT data RD is acquired from the patient's examination volume. When the computed tomography system is in operation, an X-ray source emits X-rays in the direction of an X-ray detector, which penetrates the patient and is transmitted by the X-ray detector as recorded raw data RD or a measurement signal. During acquisition, the combination of the X-ray source and the X-ray detector moves in a helical manner about the z-axis of the CT system (e.g., ...). Figure 8 (as shown), and raw data is collected from all radial directions.

[0065] In step 1.II, with time increment T ph In parallel with the acquisition of the original data RD, the subsequent stacked ST of the inspection volume V located at different z positions is reconstructed in real time and in a timely manner. i Therefore, during the acquisition of the raw data RD, a subsequent stacking ST of the check volume V is performed. i A rough reconstruction. These stacked STs iIt can be a portion of the volume V to be examined, and can include the organ L or an accessory organ to be examined, which moves in relation to the respiratory movement of the patient P. This is related to the respiratory cycle T of the patient P. br Compared to the time interval, the time increment T ph Very small, making a single stacked ST i The image can be considered a fixed image and assigned to a specific phase of the patient P's respiratory movement.

[0066] In step 1.III, based on the reconstructed subsequent stacked ST i To perform automatic organ segmentation. For example, the region of organ L is segmented, where organ L moves with the patient's breathing.

[0067] Therefore, in step 1.IV, based on the detected and segmented movement of organ L, the respiratory movement of the segmented organ L is detected and identified as the intrinsic respiratory substitute IRS.

[0068] In step 1.V, the entire examination volume V is reconstructed, wherein the reconstructed stack ST of the examination volume V is calculated based on the respiratory substitute IRS. i To classify and perform 4D-CT reconstruction (4D-CT-R) of the respiratory phase related to the examination volume V, that means: stacked STs belonging to the same respiratory phase. i Partial images are combined to form the final 3D-CT image, and a sequence of stage-related 3D-CT images is realized, which forms a 4D-CT image, i.e., a 3D-CT image sequence.

[0069] Figure 2 A schematic top view 20 is shown with respect to patient P, in which the internal organ L moves due to the patient P's breathing. Figure 2 The image shows the liver L in the abdominal portion of patient P. The liver L is shown for two different respiratory stages, one with a solid line and the other with a dashed line. From... Figure 2 It can be seen that the liver L moves in the direction of movement D between these two respiratory phases, and the diagram shows the movement from the center point P. L The displacement represents the displacement of the liver L.

[0070] exist Figure 3 The diagram illustrates multiple stacked STs comprising an examination volume V containing internal organs L. i A schematic view of (i = 1, 2, 3). Each individual stack includes a portion of a moving internal organ L. Since the internal organ L moves slowly, its role in acquiring, reconstructing, and segmenting individual stacks ST can be ignored. i Required short time T ph Movement during the period. Figure 3In the process, the examination volume V is divided into 5 stacks, each stack containing 5 fixed 3D-CT images of a portion of the examination volume V. Each individual stack ST i The internal organs L can be segmented through an automatic segmentation process, so that the internal organs L are located in the corresponding stack ST. i The portion within was located and detected. Based on five 3D-CT images of the portion volume at different respiratory stages, the location of the portion during the respiratory cycle T was determined. br Different time intervals T ph The movement and position of the internal organ L at different time points in the study.

[0071] exist Figure 4 The diagram shows flowchart 400, which illustrates a method for performing a CT imaging procedure dependent on the individual respiratory behavior of a patient according to a second embodiment of the present invention. Steps 4.1 to 4.V correspond to... Figure 1 Steps 1.I to 1.V in the previous section are therefore not described again. In step 4.VI, based on the different stacks ST assigned to the inspection volume V... i Knowledge of the relationship between raw data RD and different stages of the respiratory cycle is used to perform examinations of the stacked volume V of the intrinsic respiratory substitute IRS. i More precise reconstruction of the 3D-CT volume allows for the realization of enhanced intrinsic respiratory substitutes (IRS-E). For example, partial or complete 4D-CT images (4D-CT-R) can be used to determine the enhanced intrinsic respiratory substitutes (IRS-E). Subsequently, in step 4.VII, an enhanced 4D-CT image (4D-CT-RE) is reconstructed based on the acquired raw data (RD) and the enhanced intrinsic respiratory substitutes (IRS-E). The enhanced 4D-CT image (4D-CT-RE) has higher image quality compared to the image sequence (4D-CT-R) reconstructed in step 4.V.

[0072] exist Figure 5 In the figure, flowchart 500 is depicted, which illustrates a method for performing a CT imaging procedure that depends on the individual respiratory behavior of a patient according to a third embodiment of the present invention.

[0073] Steps 5.I to 5.IV correspond to steps 1.I to 1.IV and are not repeated herein. In step 5.V, based on the detection of the intrinsic breathing substitute (IRS), it is determined whether the patient P has properly held their breath HBP. This is provided that the patient has correctly followed some predetermined instructions (which in...). Figure 5 If "y" is used to represent the position of the patient (in this case), the process continues to step 5.VI, where a 4D-CT reconstruction of the respiratory phase of the examination volume V is performed based on the determined intrinsic respiratory substitute IRS. This is in the case where the patient P did not properly hold their breath (which is in...). Figure 5If "n" is used to represent the number of breaths, then in step 5.VII, the command RI is played to remind and encourage patient P to hold their breath further. Alternatively or additionally, the scanning process is dynamically reparameterized to suit the patient's detected respiratory movements. Therefore, in the third embodiment, the intrinsic respiratory substitute IRS is additionally used to control the predetermined respiratory behavior of patient P.

[0074] exist Figure 6 In this document, flowchart 600 is depicted, illustrating a method according to a fourth embodiment of the invention for performing a CT imaging process dependent on the individual respiratory behavior of a patient. Steps 6.1 to 6.4 correspond to steps 1.1 to 1.4 and are not described again herein. In step 6.5, a respiratory phase-related 4D-CT reconstruction 4D-CT-R(L) of the examination volume V is performed by classifying the volume of the segmented organ L according to the calculated respiratory substitute IRS. That means that additional reconstruction of the 4D-CT image directly based on the acquired raw data RD is omitted. Instead, the final image sequence (i.e., 4D-CT images) is achieved by classifying and combining volumes that are stacked ST. i (i.e., the segmented organ L) segmented 3D-CT images, where classification and combination are performed based on knowledge of the intrinsic respiratory substitute IRS.

[0075] exist Figure 7 The diagram schematically illustrates an adapter device in the form of a reconstruction device 70 according to an embodiment of the present invention. The reconstruction device 70 includes an acquisition unit 71 for acquiring raw CT data RD from an examination volume V of a patient P. The acquired raw data RD is transmitted to a first reconstruction unit 72, which is used to reconstruct subsequent stacks ST of the examination volume V at different z-positions in real-time and with time increments, in parallel with the acquisition of the raw data. i Subsequent stacking of ST i The reconstructed coarse image data is transmitted to segmentation unit 73, which is used for subsequent stacking of ST based on the reconstructed data. i Automatic organ segmentation is performed using reconstructed coarse image data. The segmented organ L is then transmitted to a substitute determination unit 74, which is configured to determine the respiratory movement of the segmented organ L as an intrinsic respiratory substitute (IRS). After acquisition, the determined IRS is transmitted to an adaptation unit, which in this embodiment is implemented as a second reconstruction unit 75. The second reconstruction unit 75 is configured to reconstruct a sequence of so-called 4D-CT image data (4D-CT-R) consistent with the determined IRS.

[0076] Figure 8A schematic representation of a computed tomography (CT) system 1 is shown, which includes, as in... Figure 7 The reconstruction apparatus 70 according to an embodiment of the present invention is discussed in detail in the context of [the previous section]. The apparatus includes a gantry, also referred to as a scanning unit 2, having a stationary portion 3, also referred to as a gantry frame, and a portion 4, also referred to as a rotor or drum, which is rotatable about a system axis. The rotating portion 4 has an imaging system (X-ray system) including an X-ray source 6 and an X-ray detector 7 arranged opposite to each other on the rotating portion 4. When the computed tomography system 1 is in operation, the X-ray source 6 emits X-rays 8 in the direction of the X-ray detector 7, penetrating the object being measured (e.g., patient P), and the result is transmitted by the X-ray detector 7 in the form of recorded measurement data or measurement signals.

[0077] exist Figure 8 In the image, a patient table 9 for positioning patient P can also be seen. The patient table 9 includes a bed base 10 on which a patient support plate 11 is arranged, the patient support plate 11 being provided for actual positioning of patient P. The patient support plate 11 can be adjusted relative to the bed base 10 in the direction of the system axis z (i.e., in the z-direction) such that it enters the opening 12, allowing patient P to be introduced into the opening 12 of the scanning unit 2 for recording X-ray projections from patient P. The computational processing of the X-ray projections recorded by the imaging system, or the reconstruction of cross-sectional images, 3D images, or 3D datasets based on measurement data or signals from the X-ray projections, is performed in the image computer 13 of the computed tomography apparatus 1, wherein the cross-sectional images or 3D images can be displayed on a display device 14. The image computer 13 can also be designed as a control unit for controlling the imaging process, for controlling the scanning unit 2 and, in particular, the imaging system of the scanning unit 2. The image computer 13 also includes, as in... Figure 7 The reconstruction device 70 is described in the context of the above.

[0078] The above description is merely a preferred embodiment of this disclosure and is not intended to limit this disclosure. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the scope of protection of this disclosure.

[0079] Furthermore, the use of the indefinite article "a" or "one" does not preclude the possibility that the mentioned feature may exist several times. Similarly, the terms "unit" or "device" do not preclude that it consists of several components, which may also be spatially distributed.

Claims

1. A method for performing a CT imaging procedure dependent on the individual respiratory behavior of a patient (P), comprising the following steps: - The patient's (P) respiratory movement is recorded by monitoring the intrinsic respiratory substitute (IRS), in which - Acquire raw CT data (RD) from the examination volume (V) of the patient (P). - Reconstruct the subsequent stacking (ST) of the inspected volume (V) at different z-positions. i 3D-CT images, -Based on the subsequent stacking (ST) i Automatic segmentation is performed using the reconstructed 3D-CT image, wherein at least one portion of the examination volume (V) is segmented. - The respiratory movement (RM) of the at least one segmented portion is detected and identified as the intrinsic respiratory substitute (IRS). - Adapting the CT imaging process based on the patient's (P) intrinsic respiratory substitute (IRS). -During the acquisition of raw data, the system detects whether the patient is properly holding their breath based on the detected intrinsic breathing substitutes, and in cases where the patient is not properly holding their breath, - Play commands to remind and encourage the patient to hold their breath further, and / or The scanning process is dynamically reparameterized.

2. The method of claim 1, wherein the time increment (T) ph The reconstruction of the 3D-CT images is performed in real time and in a timely manner, in parallel with the acquisition of raw CT data (RD).

3. The method according to claim 1 or 2, wherein the at least one portion of the examined volume (V) comprises an organ (L) that is segmented.

4. The method according to claim 1 or 2, wherein the adaptation of the CT imaging process includes: Post-exposure phase-related 4D-CT reconstruction (4D-CT-R) of the 4D-CT images of the examination volume (V) based on the determined intrinsic respiratory substitute (IRS).

5. The method of claim 3, wherein the determination of the intrinsic respiratory substitute (IRS) based on the respiratory movement of the segmented portion includes determining at least one of the following: -Which organ (L) is divided? - In which direction (D) does the organ (L) move? - The displacement of the segmented organ (L). - Has raw data (RD) for the entire respiratory cycle been collected? 6. The method according to any one of claims 2 and 5, wherein a single time increment (T0) is used as the time interval for determining the respiratory phase of a 3D-CT image. ph The time interval of the respiratory cycle (T) is less than the time interval of the respiratory cycle. br ).

7. The method according to any one of claims 1, 2, and 5, wherein by reducing the number of individual stacks (ST) used to reconstruct the inspection volume (V). i Reconstruction time (T) of 3D-CT images recon This reduces the time interval used to determine the respiratory phase in 3D-CT images.

8. The method of claim 7, wherein the reconstruction time (T) recon The reduction mentioned above includes at least one of the following reduction measures: - Reduce the size of the reconstructed matrix. - Turn off the time-consuming optimization algorithm used for the reconstruction.

9. The method of claim 4, wherein after the 4D-CT reconstruction (4D-CT-R) of the 4D-CT image of the examination volume (V), the final calculation of the intrinsic respiratory substitute (IRS) is performed based on the reconstructed 4D-CT image of the examination volume (V) and the segmented portion.

10. The method according to any one of claims 1, 2, 5, 8, and 9, wherein for each z-position, i.e. for each individual stack (ST) i Record raw CT data (RD) for the complete respiratory cycle (BC).

11. The method of claim 4, wherein the reconstructed subsequent stack (ST) of the examination volume (V) is performed based on the calculated respiratory alternative (IRS). i The 4D-CT reconstruction (4D-CT-R) is performed by classifying the volume (V) of the examination for the respiratory phase.

12. An adapter device (70), comprising: - Acquisition unit (71), which is used to acquire raw CT data (RD) from the examination volume (V) of the patient (P), - Reconstruction unit (72), which is used to reconstruct the subsequent stack (ST) of the inspection volume (V) at different z positions. i 3D-CT images, - Segmentation unit (73), which is used for the subsequent stack (ST) i The reconstructed 3D-CT image is used to perform automatic segmentation, wherein at least a portion of the examination volume (V) is segmented. - Substitute determination unit (74), which is used to determine the respiratory movement of the segmented at least one portion as an intrinsic respiratory substitute (IRS), - An adapter unit (75) for adapting the CT imaging process based on the patient's (P) intrinsic respiratory substitute (IRS). -During the acquisition of raw data, the system detects whether the patient is properly holding their breath based on the detected intrinsic breathing substitutes, and in cases where the patient is not properly holding their breath, - Play commands to remind and encourage the patient to hold their breath further, and / or The scanning process is dynamically reparameterized.

13. A CT system (1), comprising: - Scanning unit (2), which is used to perform CT imaging from the patient (P), - The adapter (70) according to claim 12 is used to adapt the CT imaging of the scanning unit (2) to the recorded respiratory movements of the patient (P).

14. A computer program product having a computer program that can be directly loaded into a memory device (13) of a CT system (1), the computer program having program segments that, when executed in the CT system (1), perform all the steps of the method according to any one of claims 1 to 11.

15. A computer-readable medium having stored thereon a program segment that can be read and executed by a computer unit so as to perform all the steps of the method according to any one of claims 1 to 11 when the program segment is executed by the computer unit.

Images