Methods for providing adapted 4D CT data

Abstract

A method for providing adapted 4D CT data is provided. The invention relates to a computer-implemented method for providing adapted 4D CT data, the method comprising: - receiving initial 4D CT data, the initial 4D CT data corresponding to a first 4D CT scan, the first 4D CT scan relating to an anatomical structure at a first examination date, - receiving supplementary 4D CT data, the supplementary 4D CT data corresponding to a partial 4D CT scan, the partial 4D CT scan relating to the anatomical structure at a second examination date, - computing adapted 4D CT data based on the initial 4D CT data and the supplementary 4D CT data, the adapted 4D CT data corresponding to a second 4D CT scan, the second 4D CT scan relating to the anatomical structure at the second examination date, - providing the adapted 4D CT data.

Description

Technical Field

[0001] In one aspect, the invention relates to a computer-implemented method for providing adapted 4DCT data. In other aspects, the invention relates to a data processing system, a computer program product, a computer-readable storage medium, a medical imaging device, and a radiation treatment planning system. Background Technology

[0002] Cancer management, particularly lung cancer management, is constantly evolving due to technological advancements in radiation therapy delivery. Adaptive radiation therapy (ART) allows for modifications to management plans aimed at improving the dose distribution to the patient due to anatomical and / or physiological deviations from initial simulations. Cancer radiation management planning can be based on 4D CT data (four-dimensional computed tomography). 4D CT simulations can be applied to 4D CT data to generate snapshots of tumor size, shape, and position relative to normal tissue, which are used to create the internal total tumor volume (IGTV) or internal target volume (ITV). While techniques for managing these tumors allow for highly conformal dose distributions, the complex geometric uncertainties involved in lung cancer management planning necessitate large safety margins to create the planned target volume (PTV), which can hinder dose escalation.

[0003] Furthermore, because treatment cycles and the total duration of treatment in radiation therapy are typically quite long, there can be weeks between the acquisition of planned images and the actual treatment. This poses a risk of poor tumor coverage and more severe off-target effects. ART addresses these weaknesses by enabling the periodic modification of treatment plans. However, 4D CT image acquisition can impose a non-negligible dose burden on patients, for example, in the range of 30 mGy to 60 mGy. Therefore, adaptive planning for moving tumors in the liver and lungs presents the challenge of additional dose burden. This limits clinicians to following a “plan-of-the-day” approach, where an initial treatment plan is adapted the eve of each treatment to improve accuracy. Summary of the Invention

[0004] The underlying technical problem of this invention is to facilitate adaptive treatment planning in medical radiology, particularly in terms of improved radiation dose and image quality. This problem is solved by the technical solutions of the independent claims. Dependent claims relate to other aspects of the invention. Regardless of grammatical usage, individuals with male, female, or other gender identities are included within the terminology.

[0005] This invention relates to a computer-implemented method for providing adapted 4D CT data, the method comprising:

[0006] - Receive initial 4D CT data corresponding to a first 4D CT scan relating to anatomical structures on a first examination date.

[0007] - Receive supplemental 4D CT data corresponding to a partial 4D CT scan relating to anatomical structures on the second examination date.

[0008] - Adapted 4D CT data is calculated based on initial and supplementary 4D CT data, which corresponds to a second 4D CT scan relating to the anatomical structures on the second examination date.

[0009] - Provides adapted 4D CT data.

[0010] Specifically, anatomical structures can refer to the patient's anatomical structures. Anatomical structures can be, for example, organs, particularly the lungs or liver. Anatomical structures can include lesions, such as tumors.

[0011] 4D CT data can be associated with three spatial dimensions and one temporal dimension. The temporal dimension can be specifically associated with sequences of respiratory signals and / or respiratory phases. The first 4D CT scan can be a first full-quality 4D CT scan. Compared to the first 4D CT scan, a partial 4D CT scan exposes anatomical structures to a smaller radiation dose, thereby impairing image quality, image resolution, temporal resolution, and / or scan range. In particular, the initial 4D CT data can cover at least one 4D sampling point not covered by supplementary 4D CT data.

[0012] An initial treatment plan can be calculated based on initial 4D CT data. For example, a first representation of the anatomical structures can be calculated based on the initial 4D CT data, relating to the anatomical structures at the first examination date. Specifically, based on the initial 4D CT data, first information relating to the size and / or movement of the tumor and / or to the anatomical and / or morphological condition of the patient can be calculated. For example, an initial treatment plan can be calculated based on the first representation and / or based on the first information.

[0013] An adapted treatment plan can be calculated based on adapted 4D CT data. For example, a second representation of the anatomical structure can be calculated based on the adapted 4D CT data, relating to the anatomical structure on a second examination date. Specifically, based on the adapted 4D CT data, second information relating to the size and / or movement of the tumor and / or to the anatomical and / or morphological condition of the patient can be calculated. For example, an adapted treatment plan can be calculated based on the second representation and / or based on the second information.

[0014] To reduce the dose burden of adaptive replanning, particularly for updating treatment plans at specific points in time, either immediately before actual treatment (to create a "day plan") or during treatment, initial 4D CT data can be used as prior information and modified based on the latest information from supplementary 4D CT data. The use of prior information from initial 4D CT data can help reduce the dose burden of adaptively updating the 4D CT planning dataset during radiation treatment planning, especially in the form of incremental replanning.

[0015] For example, a second 4D CT scan can be substantially equivalent to a repeat of the first 4D CT scan on a second examination date. Specifically, the second examination date can be later than the first examination date. For example, the second examination date can occur at least two days after the first examination date, at least one week after the first examination date, and / or at least one month after the first examination date.

[0016] The proposed method enables a dose-reduced workflow for 4D CT imaging, allowing for adaptive recalculation of the treatment plan during different fractions of treatment to adapt the radiation plan to changes during treatment. These changes may be related to, for example, tumor size, tumor motion, and the condition and / or morphology of the tissue surrounding the tumor.

[0017] Since there can be several weeks between the acquisition of initial 4D CT data and the actual treatment, this approach can help significantly improve the quality, effectiveness, and accuracy of radiation treatment planning while maintaining a low additional dose burden.

[0018] Compared to the first 4D CT scan, the radiation dose of a partial 4D CT scan can be reduced, particularly significantly. Specifically, the dose of a partial 4D CT scan can be reduced by orders of magnitude relative to the first 4D CT scan, for example, to achieve methods such as performing 4D CT-based adaptive replanning or even moving towards a "day-to-day" schedule. The radiation dose of the second 4D CT scan can be comparable to, and particularly substantially equal to, the radiation dose of the first 4D CT scan.

[0019] The radiation dose of the first 4D CT scan can be higher than 10 mGy, particularly higher than 30 mGy, and / or less than 100 mGy, particularly less than 60 mGy. The radiation dose of a partial 4D CT scan can be less than 50% of the radiation dose of the first 4D CT scan, particularly less than 25% of the radiation dose of the first 4D CT scan, particularly less than 10% of the radiation dose of the first 4D CT scan. The radiation dose of the second 4D CT scan can be higher than 50% of the radiation dose of the first 4D CT scan, particularly higher than 75% of the radiation dose of the first 4D CT scan, particularly equal to the radiation dose of the first 4D CT scan.

[0020] Since the adapted 4D CT data corresponds to the second 4D CT scan, this method does not require explicit or implicit application of the second 4D CT scan to the anatomical region. The second 4D CT scan can be understood as a fictitious object used to characterize the adapted 4D CT data.

[0021] Compared to the first 4D CT scan, the fractional volume of anatomical structures scanned in a partial 4D CT scan can be reduced, particularly significantly. Throughout this specification, "significantly reduced" can be understood as a reduction to at least one-half, particularly at least one-quarter, for example, at least one-tenth. The fractional volume of the second 4D CT scan can be comparable to, particularly substantially equal to, the fractional volume of the first 4D CT scan. To generate supplementary 4D CT data, partial 4D CT scans can be performed only on the most relevant regions, such as those containing tumors.

[0022] The scan range of a partial 4D CT scan can be selected based on the initial 4D CT data. Compared to the scan range of the first 4D CT scan, the scan range of the partial 4D CT scan is reduced, particularly significantly reduced. The scan range of the second 4D CT scan can be comparable to, or substantially equal to, the scan range of the first 4D CT scan. To reduce the volume fraction scanned and thus irradiated during the partial 4D CT scan, one possible approach would be to reduce and adjust the scan range of the 4D CT scan so that only areas of tumor motion are irradiated during the scan.

[0023] Compared to the first 4D CT scan, the extension of the radiation field along the X-ray fan-shaped direction in a partial 4D CT scan can be reduced, particularly significantly. The extension of the radiation field along the X-ray fan-shaped direction in a second 4D CT scan can be comparable to, and particularly substantially equal to, the extension of the radiation field along the X-ray fan-shaped direction in a first 4D CT scan. If the CT scanner used is also capable of adjusting its radiation field along the fan-shaped direction, this would be another potential source of radiation reduction. In this case, the first 4D CT scan can be used to perform a partial 4D CT scan cutoff.

[0024] Once a partial 4D CT scan with a reduced irradiation range has been completed, it is proposed to combine supplementary 4D CT data with the initial 4D CT data. Thus, the tumor region in the initial 4D CT data can be replaced and / or updated by the supplementary 4D CT data. To adjust the initial and supplementary 4D CT data in the transition region, non-rigid registration or any other suitable image registration algorithm can be used.

[0025] Compared to the first 4D CT scan, the fractional portion of the respiratory cycle in a partial 4D CT scan can be reduced, particularly significantly reduced. The fractional portion of the respiratory cycle in a second 4D CT scan can be comparable to, and particularly substantially equal to, the fractional portion of the respiratory cycle in the first 4D CT scan. Specifically, the respiratory cycle can be the patient's respiratory cycle. For example, the fractional portion of the respiratory cycle can be applied to a partial 4D CT scan, particularly only to the expiratory or inspiratory phases, rather than to the entire scanning range of a partial 4D CT scan equal to that of the first 4D CT scan.

[0026] Adapted 4D CT data can be calculated based on initial and supplementary 4D CT data by applying image registration, particularly a non-rigid transformation, from a given phase of the respiratory cycle scanned during the first 4D CT scan to its corresponding phase in a portion of the respiratory cycle skipped during a partial 4D CT scan. This fills in the missing portions of the respiratory cycle in the partial 4D CT scan, resulting in adapted 4D CT data covering the entire respiratory cycle. Image information about the missing phases is thus obtained from the original full-quality 4D CT. The respiratory signals used for the adapted 4D CT data can be acquired entirely during, before, and / or after the partial 4D CT scan. Alternatively, a partial respiratory signal covering only the scanned fraction of the respiratory cycle covering the partial scan can be acquired and used to calculate the missing portions of the respiratory signal, for example, based on the assumption that inspiratory and expiratory movements are substantially opposite.

[0027] Some 4D CT scans can be prospective, phase-selective 4D CT scans of a single phase of the respiratory cycle. Specifically, a prospective, phase-selective 4D CT scan can be a prospectively triggered, phase-selective 4D CT scan. In this case, 3D volumetric information is acquired from supplementary 4D CT data, while respiratory motion information is acquired from the initial 4D CT data.

[0028] The motion vector field of respiratory motion of anatomical structures can be calculated based on initial 4D CT data, with adapted 4D CT data calculated based on the motion vector field and supplementary 4D CT data, particularly supplementary 4D CT data for a single phase of the respiratory cycle. The motion vector field of respiratory motion can be calculated based on the initial 4D CT data and used to calculate adapted 4D CT data based on supplementary 4D CT data obtained from partial 4D CT scans of a single phase. By using information from the initial 4D CT data, the entire motion vector field of respiratory motion can be calculated, allowing each phase to be transformed into each other phase of the cycle.

[0029] Initial radiation treatment planning data for anatomical structures can be calculated based on initial 4D CT data, and / or adapted radiation treatment planning data for anatomical structures can be calculated based on adapted 4D CT data.

[0030] The present invention also relates to a computer program product or computer-readable storage medium comprising instructions that, when executed by a computer, cause the computer to perform a method according to one aspect of the invention.

[0031] The present invention also relates to a data processing system comprising a data interface and a processor, the data processing system being configured to perform a method according to one aspect of the present invention.

[0032] The present invention also relates to a medical imaging apparatus comprising a data processing system according to one aspect of the present invention, and configured to perform a first 4D CT scan relating to anatomical structures to obtain initial 4D CT data, and / or to perform a partial 4D CT scan relating to anatomical structures to obtain supplementary 4D CT data.

[0033] Medical imaging equipment can be, for example, computed tomography (CT) equipment and / or cone-beam CT equipment.

[0034] The present invention also relates to a radiation treatment planning system comprising a data processing system according to one aspect of the present invention, and configured to provide initial radiation treatment planning data on anatomical structures, and / or to provide adapted radiation treatment planning data on anatomical structures.

[0035] Any algorithms and / or models mentioned in this article may be based on one or more of the following architectures: deep convolutional neural networks, deep belief networks, random forests, deep residual learning, deep reinforcement learning, recurrent neural networks, Siamese networks, generative adversarial networks, or autoencoders.

[0036] A computer program product can be, for example, a computer program, or include another element besides a computer program. This other element can be: hardware, such as a memory device on which the computer program is stored, a hardware key for using the computer program, etc.; and / or software, such as a software key or documentation for using the computer program. A computer-readable storage medium can be embodied as non-persistent main memory (e.g., random access memory) or permanent mass storage devices (e.g., hard disks, USB sticks, SD cards, solid-state drives).

[0037] The data processing system may include at least one of, for example, cloud computing systems, distributed computing systems, computer networks, computers, tablet computers, smartphones, etc. The data processing system may include hardware and / or software. The hardware may be, for example, a processor system, a memory system, or a combination thereof. The hardware may be configurable and / or operable by software. The calculations for the actions of performing the method may be executed in the processor.

[0038] It can receive data, particularly initial 4D CT data and supplementary 4D CT data, especially via a data interface, such as by receiving data-carrying signals and / or by reading data from a computer memory and / or by manual user input, such as via a graphical user interface. It can also provide data, particularly adapted 4D CT data and / or radiation treatment planning data, especially via a data interface, such as by sending data-carrying signals and / or by writing data to a computer memory and / or by displaying data on a monitor.

[0039] In the context of this invention, the expression "based on" can be specifically understood to mean "used, among other things". In particular, accordingly, the phrase "based on the second feature to calculate (or generate, determine, etc.) the first feature" does not preclude the possibility of calculating (or generating, determining, etc.) the first feature based on the third feature.

[0040] Please take into account the fact that the described methods and systems are merely preferred exemplary embodiments of the present invention, and that variations can be made to the invention by those skilled in the art without departing from the scope of the invention as defined by the claims. Attached Figure Description

[0041] The invention will now be described using exemplary embodiments with reference to the accompanying drawings. The illustrations in the drawings are schematic and highly simplified, and are not necessarily to scale.

[0042] Figure 1 A flowchart is shown of a computer-implemented method for providing adapted 4D CT data.

[0043] Figure 2 Anatomical structures are shown.

[0044] Figure 3 A respiratory cycle diagram is shown.

[0045] Figure 4 A medical imaging device is shown. Detailed Implementation

[0046] Figure 1 A flowchart is shown of a computer-implemented method for providing adapted 4D CT data.

[0047] Figure 2 The anatomical structure N, including lesion L, is shown. The radiation field RL of the partial 4D CT scan is significantly reduced compared to the radiation field R of the first 4D CT scan. The scan range of the first 4D CT scan is the extension of the radiation field R along the scan direction Z. The scan range of the partial 4D CT scan is the extension of the radiation field RL along the scan direction Z, and is significantly smaller than the scan range of the first 4D CT scan.

[0048] for Figure 2 The example shown shows that, compared to the first 4D CT scan, the radiation dose of the partial 4D CT scan is reduced, the scanned volume fraction of the anatomical structure N is reduced, the scan range of the partial 4D CT scan is reduced, and the extension of the irradiation field along the X-ray fan direction X is reduced compared to the first 4D CT scan.

[0049] Figure 3 A respiratory cycle diagram with amplitude M over time T is shown, covering the inspiratory phase PI, the expiratory phase PE, and individual phases P1, P2, P3, and P4. A prospective phase-selective 4D CT scan can be prospectively triggered, for example, to cover the maximal inspiratory state of individual phase P2 at time point T2. In this case, the fraction of the respiratory cycle covered by the partial 4D CT scan is reduced compared to the first 4D CT scan, which covers the entire respiratory cycle.

[0050] Figure 4A medical imaging apparatus 1 in the form of a computed tomography (CT) device is shown. The medical imaging apparatus 1 includes a gantry 20, a support frame 21, a tilt frame 22, a rotor 24, an opening 9 for receiving a patient support structure 12, a radiation interaction region 4 (located within the opening 9), a radiation source 26 for generating an X-ray fan 27, and a radiation detector 28. The medical imaging apparatus 1 also includes a patient table 10, which includes a patient pedestal 11 and a patient support structure 12 in the form of a patient table plate. The patient table structure 12 is movably mounted on the patient pedestal 11 along the system axis AS of the radiation interaction region 4. A patient 13 is located on the patient support structure 14. The medical imaging apparatus 1 includes a data processing system comprising a data interface and a processor, configured to execute methods for providing adapted 4D CT data. The medical imaging device 1 is configured to perform a first 4D CT scan in relation to the anatomical structure N to obtain initial 4D CT data, and to perform a partial 4D CT scan in relation to the anatomical structure N to obtain supplementary 4D CT data.

Claims

1. A computer-implemented method for providing adapted 4D CT data, the method comprising: - Receive initial 4D CT data, which corresponds to a first 4D CT scan relating to an anatomical structure (N) on a first examination date. - Receive supplemental 4D CT data corresponding to a partial 4D CT scan relating to the anatomical structure (N) on a second examination date, wherein the second examination date occurs at least two days after the first examination date. - The adapted 4D CT data is calculated based on the initial 4D CT data and the supplementary 4D CT data, the adapted 4D CT data corresponding to a second 4D CT scan relating to the anatomical structure (N) on the second examination date. - Provide the adapted 4D CT data.

2. The method according to claim 1, - The radiation dose of the partial 4D CT scan is reduced compared to the first 4D CT scan.

3. The method according to claim 1 or 2, - Compared to the first 4D CT scan, the scanned volume fraction of the anatomical structure (N) in the partial 4D CT scan is reduced.

4. The method according to claim 1 or 2, - The scan range of the partial 4D CT scan is selected based on the initial 4D CT data. - The scanning range of the partial 4D CT scan is reduced compared to the scanning range of the first 4D CT scan.

5. The method according to claim 1 or 2, - Compared to the first 4D CT scan, the extension of the irradiation field along the X-ray fan-shaped direction (X) in the partial 4D CT scan is reduced.

6. The method according to claim 1 or 2, - Compared to the first 4D CT scan, the fraction of respiratory cycles scanned in the partial 4D CT scan is reduced.

7. The method according to claim 6, - The adapted 4D CT data is calculated based on the initial 4D CT data and the supplementary 4D CT data by applying image registration from a given phase of the respiratory cycle scanned during the first 4D CT scan to the corresponding phase of the respiratory cycle skipped during the partial 4D CT scan.

8. The method according to any one of claims 1, 2, and 7, - The aforementioned partial 4D CT scan is a prospective phase-selective 4D CT scan of a single phase of the respiratory cycle.

9. The method according to any one of claims 1, 2, and 7, - The motion vector field of the respiratory motion of the anatomical structure (N) is calculated based on the initial 4D CT data. - The adapted 4D CT data is calculated based on the motion vector field and the supplementary 4D CT data.

10. The method according to any one of claims 1, 2, and 7, - Wherein the initial radiation treatment planning data for the anatomical structure (N) is calculated based on the initial 4D CT data, and / or - The adapted radiation treatment planning data for the anatomical structure (N) is calculated based on the adapted 4D CT data.

11. A computer program product or computer-readable storage medium comprising instructions that, when executed by a computer, cause the computer to perform the method according to any one of claims 1 to 10.

12. A data processing system, comprising a data interface and a processor, the data processing system being configured to perform the method according to any one of claims 1 to 10.

13. A medical imaging device (1) comprising the data processing system of claim 12, and configured to perform a first 4D CT scan in relation to the anatomical structure (N) to obtain the initial 4D CT data, and / or to perform a partial 4D CT scan in relation to the anatomical structure (N) to obtain the supplementary 4D CT data.

14. The medical imaging device (1) according to claim 13, wherein the medical imaging device is a computed tomography device and / or a cone beam CT device.

15. A radiation treatment planning system, comprising the data processing system of claim 12, and configured to provide initial radiation treatment planning data regarding the anatomical structure, and / or to provide adapted radiation treatment planning data regarding the anatomical structure. The initial radiation treatment planning data for the anatomical structure (N) is calculated based on the initial 4D CT data. The adapted radiation treatment planning data for the anatomical structure (N) is calculated based on the adapted 4DCT data.

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