Device, system and method for evaluating an area of ​​interest on the surface of a patient's body

Abstract

The invention relates to a device for evaluating an area of ​​interest on the surface of a patient's body to be monitored during irradiation treatment, wherein the device comprises an evaluation unit, wherein the area of ​​interest is stored in the evaluation unit in the form of area data processable by the evaluation unit, furthermore irradiation position data relating to the position of irradiation components arranged in an irradiation room for the planned irradiation treatment and monitoring position data relating to the position of monitoring components arranged in the irradiation room for monitoring the area of ​​interest are stored in the evaluation unit, and the evaluation unit is configured to, based on the area data,The invention relates to the use of irradiation position data and monitoring position data to determine the visibility of the area of ​​interest by the monitoring components during the planned irradiation treatment and to evaluate the area of ​​interest depending on the determined visibility. The invention also relates to a corresponding system and method.

Description

The invention relates to a device for evaluating an area of ​​interest on the surface of a patient's body that is to be monitored during radiation therapy. The invention also relates to a corresponding system and method. In radiation therapy for tumors, surface detection systems, including cameras, are used to monitor the patient's position during treatment. This is known as Surface Guided Radiation Therapy (SGRT). A key component is the definition of a region of interest (ROI), which is a carefully defined portion of the patient's external surface, typically in relation to the area of ​​the patient's body being irradiated. During patient positioning on a treatment table and radiation therapy, the area of ​​interest is monitored based on the temporal variation of the so-called six degrees of freedom. These six degrees of freedom typically include translations along three mutually perpendicular spatial directions and rotations around three axes of rotation, also perpendicular to each other. The area of ​​interest must be defined with careful consideration of the patient's anatomy and the planned radiation treatment. From EP 3 756 730 B1, a patient motion tracking system is known in which an area of ​​interest is automatically generated on a three-dimensional surface of a patient's body. The automatic generation of the area of ​​interest is based on reference areas of interest and a three-dimensional patient surface, which can be created, for example, using an imaging technique such as a CT scan. While the established system takes individual patient anatomy into account when creating the area of ​​interest, problems can arise with patient monitoring during radiation therapy based on the automatically generated area of ​​interest. For example, the automatically generated area of ​​interest may not be reliably captured at all times by a surface detection system, including cameras. This limits the reliability of monitoring the patient's position during radiation therapy or at least makes it temporarily impossible. The radiation therapy may have to be interrupted while the patient is on the treatment table in the treatment room, especially if the patient's position falls outside a predefined tolerance.Such situations prolong treatment time and lead to frustration for both the patient and the medical staff performing the radiation treatment. Based on the prior art described above, the invention aims to provide a device, a system and a method of the type mentioned at the outset, with which position monitoring of a patient during radiation treatment is possible at all times reliably without unnecessary delays and loss of comfort, using an area of ​​interest to be monitored on the surface of a patient's body during the radiation treatment. The invention solves the problem through independent claims 1, 12 and 14. Advantageous embodiments can be found in the dependent claims, the description and the figures. For a device of the type mentioned at the outset, the invention solves the problem in that the device comprises an evaluation unit, wherein the area of ​​interest is stored in the evaluation unit in the form of area data that can be processed by the evaluation unit, that the evaluation unit also contains irradiation position data relating to the position of irradiation components arranged in an irradiation room for the planned irradiation treatment and monitoring position data relating to the position of monitoring components arranged in the irradiation room for monitoring the area of ​​interest, and that the evaluation unit is configured to use the area data toto determine the visibility of the area of ​​interest through the monitoring components during the planned irradiation treatment using the irradiation position data and the monitoring position data, and to evaluate the area of ​​interest depending on the determined visibility, As explained earlier, the area of ​​interest (ROI) is a crucial element in SGRT treatment. During radiation therapy, the ROI is captured on the patient's body using, for example, a camera-based surface scanning system and compared to a stored reference. This allows the patient to be positioned in the treatment room during the setup phase before radiation therapy begins, for example, by moving the treatment table and / or the patient accordingly. During radiation therapy, this data allows for the verification of the patient's correct position for the planned treatment. The ROI can be defined before the radiation therapy is performed, for example, by a radiation therapist, as explained in more detail below.According to the invention, the area data defining the area of ​​interest are stored in an evaluation unit. The automatic generation of an area of ​​interest proposed in the previously described prior art is associated with the disadvantages also outlined therein. While the automatically generated area of ​​interest does take into account the individual patient's anatomy based on the three-dimensional patient body, it overlooks problems with the area of ​​interest caused by the relative movement between the patient body and components located in the treatment room, such as radiation equipment, which regularly occurs during radiation therapy. This relative movement can cause shadowing of the area of ​​interest for cameras, for example, meaning that the surface detection system cannot always adequately capture the area of ​​interest.This leads to the disadvantages explained at the beginning regarding an interruption of the radiation treatment and the associated subsequent problems. According to the invention, the evaluation unit therefore provides that it also stores irradiation position data relating to the position of irradiation components arranged in the irradiation room and monitoring position data relating to the position of monitoring components arranged in the irradiation room for monitoring the area of ​​interest. Thus, in addition to information on the area of ​​interest defined, for example, by a radiation therapist, the evaluation unit also contains information on the position of irradiation components, such as a linear accelerator (LINAC), as well as on the position of monitoring components for monitoring the area of ​​interest, such as cameras. The monitoring position data can, for example, include data on the orientation and / or field of view of monitoring components, such as cameras.The irradiation position data and / or the monitoring position data may also include data on the shape and / or size and / or orientation of the respective components. Based on this data, the evaluation unit determines the visibility of the area of ​​interest to the monitoring components during the planned irradiation procedure and assesses the area of ​​interest depending on this determined visibility. As explained in more detail below, the evaluation unit can, in particular, take into account relative movement between, for example, irradiation components and the patient's body and / or the monitoring components during the irradiation treatment. In this way, according to the invention, it can be verified whether the area of ​​interest is sufficiently stable and visible, considering all degrees of freedom of the irradiation treatment system, so that, for example, an interruption of the irradiation treatment can be avoided.This allows potential shadowing of the area of ​​interest by the radiation components moving during treatment, for example, rotating them, to be identified in advance and taken into account for the evaluation of the area of ​​interest. For this purpose, the evaluation unit processes the visibility of the area of ​​interest through different treatment sequences, encompassing different positions of the radiation components. As explained in more detail below, the evaluation of the area of ​​interest can, for example, be output to an operator. Based on the visibility assessment, the stability of the area of ​​interest throughout the planned treatment can be evaluated, ensuring that the treatment can be carried out safely, taking into account all degrees of freedom and planned movements. The problems described in the prior art regarding the interruption of radiation therapy due to lack of visibility or instability of the area of ​​interest, and the associated frustration for patients and medical staff, can be avoided according to the invention. For this purpose, more parameters are considered for evaluating the area of ​​interest, in particular the positions of the monitoring components in space or relative to the radiation components or relative to an isocenter of the radiation, as well as the position and geometry of the radiation components, especially a linear accelerator. As already mentioned, the area of ​​interest can be defined by a radiation therapist.Further parameters regarding patient treatment can be considered, such as a radiation treatment plan and a radiation treatment structure set, i.e., the components planned for use in the treatment and / or their position in space. The radiation treatment plan and the radiation treatment structure set can also be stored in the evaluation unit. The corresponding data for the radiation treatment plan and the radiation treatment structure set can be generated by a treatment planning system. This data includes both the so-called "external body surface" and the coordinates of the isocenter of the radiation device, which are typically described in the radiation treatment plan. Thus, with this data, the patient's external body surface is known, as is its location relative to the isocenter of the radiation device.Furthermore, the angular position of the irradiation components throughout the entire irradiation sequence is known from this data. A 3D model of the irradiation components used is also available. Based on this, an area of ​​interest can be defined and evaluated according to the invention. Furthermore, it is also possible to have multiple areas of interest for different stages of radiation therapy, for example, for initial patient positioning, for different radiation sequences, or for motion monitoring, such as patient respiration monitoring. It is also possible to monitor daily variations in the area of ​​interest due to potential anatomical changes in the patient during treatment and, if necessary, to modify the area of ​​interest. For future radiation treatments, it is expected that direct measurement of radiation output, particularly by measuring the proportion of radiation passing through the patient's body, will be used more frequently to monitor the actual dose delivered to the patient during each treatment session and, if necessary, to adjust treatment plans accordingly. This will result in additional radiation components, especially measuring devices, being present in the treatment room, which can also lead to undesirable shadowing of the area of ​​interest. Consequently, assessing the visibility and thus the stability of the area of ​​interest will become increasingly important. In one configuration, the monitoring components can include cameras for capturing the three-dimensional surface of the patient's body, encompassing the area of ​​interest, during radiation therapy. These can be, in particular, stereoscopic cameras. As explained, such cameras are used in SGRT procedures to monitor the patient's surface. The three-dimensional surface of the patient's body captured by the SGRT system contains at least the area of ​​interest, which thus represents a subset of the captured three-dimensional patient surface. In a further embodiment, the irradiation components may include a movable, in particular swiveling, irradiation device within the treatment room, especially a movable, in particular swiveling, linear accelerator (LINAC), and / or an imaging system movable within the treatment room, especially an electronic portal imaging system (EPID). The irradiation device, in particular a linear accelerator, is, for example, rotatable around a patient table located within the treatment room, using a treatment head. The treatment room may also contain various irradiation and / or imaging devices (kV, MV devices) that can be selected and used depending on the treatment plan.Using an imaging system located in the treatment room, in particular an electronic portal imaging system (EPID), the dose of the radiation power actually delivered to the patient's body can be recorded, as explained. Such imaging systems can be used in the form of panels, depending on the desired treatment procedure. The radiation therapy components may also include a patient table that is movable within the treatment room, in particular a sliding and / or rotating table. The patient table may, in particular, have the six degrees of freedom of movement described above. By moving the patient table within the treatment room, the patient's body can be positioned for the respective radiation treatment. Changing the position of the patient table may alter the relative positions of the components within the treatment room. This, in turn, can lead to shadowing, which is taken into account in the aforementioned design. Further development may envisage that the evaluation unit continues to store treatment plan data for the planned radiation therapy and that the evaluation unit is designed to also consider this treatment plan data when determining the visibility of the area of ​​interest by the monitoring components during the planned treatment. Furthermore, it may be possible for the treatment plan data to include the area of ​​the patient's body to be irradiated and / or the type of radiation components used and / or the radiation power and / or duration used. Before a treatment, for example, a treatment plan is created by a medical physicist and reviewed by a physician.The treatment plan is approved, and in addition to the treatment duration, planned radiation doses, and corresponding dates, it specifies in particular the target volume of the patient's body to be irradiated. Depending on the treatment plan data stored in the evaluation unit, the evaluation unit can assess any potential impairment of the visibility of the area of ​​interest, for example, due to the movement of the radiation components resulting from the treatment plan. In a further refinement, the radiation position data can include expected changes in the position of the radiation components within the treatment room during the planned radiation therapy. In particular, the evaluation unit can be configured to consider these expected changes in the position of the radiation components when determining the visibility of the area of ​​interest by the monitoring components during the planned radiation therapy. These changes in position affect the relative positions of the components arranged within the treatment room, including the patient table with the patient's body and, for example, the cameras used for capturing the patient's surface. Any resulting shadowing of the defined area of ​​interest can be appropriately accounted for in the aforementioned configuration. In a further refinement, it can be provided that the area of ​​interest, which is available to the evaluation unit in the form of area data that can be processed by the evaluation unit, is an area of ​​interest defined by a radiation therapist, in particular an area of ​​interest defined by the radiation therapist within the framework of radiation treatment planning. As already explained, the area of ​​interest can be defined by a radiation therapist. In contrast to the prior art described at the beginning, the radiation therapist can take additional parameters into account, such as the radiation plan and the radiation structure present in the treatment room, i.e., the presence and arrangement of specific radiation components.The area of ​​interest is defined by the radiation therapist before the start of the first radiation treatment based on the provided radiation plan and the radiation structure set located in the radiation room, and can also be evaluated in the manner according to the invention before the start of the first treatment. The evaluation unit can be configured to output the result of the assessment of the area of ​​interest to an operator. Based on this, the operator, who may be, for example, the radiation therapist, can assess the risk of instability of the area of ​​interest during radiation treatment and, if necessary, react by adjusting the area of ​​interest. The area of ​​interest, adjusted, for example, by the radiation therapist, can subsequently be re-evaluated according to the invention, and this re-evaluation result can also be output to the operator, for example, the radiation therapist. In a further configuration, the evaluation unit can be designed to issue a warning signal to an operator if the monitoring components detect insufficient visibility of the area of ​​interest during the planned radiation treatment and / or adjust the area of ​​interest to improve visibility. In this configuration, the evaluation unit can even suggest an adjustment to the area of ​​interest that ensures its visibility or stability. The suggested adjustment can be displayed to an operator, such as the radiation therapist. The operator can then accept or reject the adjustment, or make a further adjustment.In one embodiment, for example, the evaluation unit for adjusting the area of ​​interest could remove sections of the area of ​​interest that would be subject to shadowing during the planned radiation treatment or that are only clearly visible at excessively large angles, such as above 80°, and thus could lead to a lack of stability. Furthermore, it is conceivable that the evaluation unit for adjusting the area of ​​interest could add one or more new sections to the area of ​​interest, thereby improving its visibility or stability. The invention also solves the problem by a system for evaluating an area of ​​interest defined for monitoring a radiation treatment on the surface of a patient's body, comprising radiation components arranged in a treatment room for the planned radiation treatment and monitoring components arranged in the treatment room for monitoring the area of ​​interest, further comprising a device according to the invention. The system according to the invention can include a patient table adjustable in its position for a patient's body. The patient table can, for example, have the six degrees of freedom of movement described above. For a method of the type mentioned at the outset, the invention solves the problem by the following steps: • Providing the area of ​​interest in an evaluation unit in the form of area data that can be processed by the evaluation unit, • Providing irradiation position data for the position of irradiation components arranged in an irradiation room for the planned irradiation treatment and monitoring position data for the position of monitoring components arranged in the irradiation room for monitoring the area of ​​interest in the evaluation unit, and • Determining the visibility of the area of ​​interest by the monitoring components during the planned irradiation treatment using the evaluation unit based on the area data, the irradiation position data and the monitoring position data, and evaluating the area of ​​interest using the evaluation unit depending on the determined visibility. The method according to the invention can be carried out with the device or system according to the invention. Accordingly, the device and / or system according to the invention can be configured to carry out the method according to the invention. This applies in particular to the evaluation unit according to the invention. An embodiment of the invention is explained in more detail below with reference to the drawings. These show schematically: Fig. 1 a system according to the invention with a device according to the invention in a perspective view, Fig. 2 an area of ​​interest defined for irradiation treatment with the system shown in Fig. 1 without shadowing, and Fig. 3 the area of ​​interest from Fig. 2 with shadowing. Unless otherwise stated, the same reference symbols in the figures denote the same objects. The system according to the invention, shown in Fig. 1, is arranged in a treatment room for the irradiation of a tumor of a patient body 10, which is shown only schematically and partially in Fig. 1. The patient body 10 is located on a patient table 12 that is movable within the treatment room. The patient table 12 rests on the floor of the treatment room via a foot section 14 and can be moved, for example, along six degrees of freedom, in particular along three vertical spatial axes, and tilted about three, for example, also vertical rotation axes. In this way, the patient body 10 can be positioned in the treatment room as required. The system further comprises a radiation therapy device 16, including a radiation head 18 rotatable about the longitudinal axis of the patient table 12. The radiation therapy device 16 includes a linear accelerator (LINAC) that delivers high-energy radiation above the radiation head 18 to irradiate a tumor in the patient's body 10. The system also includes a first electronic portal imaging system (EPID system) 20, which measures the radiation emitted from the patient's body 10 after it has been irradiated. The EPID system 20 may include an MV panel for detecting MV radiation (MV beam - direct beam). From the radiation power received by the first EPID system 20 after the patient's body 10 has been irradiated, the radiation power absorbed by the patient's body 10, and thus the radiation dose absorbed by it in a specific volume, can be determined in a manner known per se.Furthermore, the system includes a second imaging system based on kV energy. An X-ray source 22 is shown opposite an imaging plate 23. Typical 3D kV-CBCT-based images are then constructed to aid patient positioning based on internal anatomy. Depending on the course of radiation therapy, the first EPID system 20 and / or the second imaging system 22, 23 can be used to measure the radiation dose absorbed by the patient's body 10. The system according to the invention further comprises a surface detection system for capturing the three-dimensional surface of the patient's body 10 during radiation therapy. In the illustrated example, the surface detection system comprises three camera arrangements 24 distributed within the radiation room, which are in particular stereoscopic camera arrangements 24. These capture the three-dimensional surface of the patient's body 10 in a manner known per se. During radiation therapy, they are typically arranged in a fixed position within the radiation room. Furthermore, the system according to the invention comprises an evaluation unit 26 in which area data for an area of ​​interest 28, defined, for example, by a radiation therapist taking into account a radiation plan and the radiation structure set in the radiation room, are available. The area of ​​interest 28 is shown enlarged, for example, in Fig. 2 and comprises three area sections 30, 32, 34 in the region of the thighs of the patient's body 10. The evaluation unit 26 also contains irradiation position data for the position of the irradiation components arranged in the irradiation room, in particular the irradiation device 16 with the irradiation head 18, the first EPID system 20 and the second imaging system 22, 23, as well as the patient table 12. Furthermore, the evaluation unit contains monitoring position data for the position of the monitoring components arranged in the irradiation room for monitoring the area of ​​interest 28, in particular the camera arrangements 24. Based on the area data for the area of ​​interest 28, the irradiation position data, and the monitoring position data, the evaluation unit 26 determines the visibility of the area of ​​interest 28 by the monitoring components 24 during the planned irradiation treatment and evaluates the area of ​​interest 28 depending on the determined visibility. The evaluation unit 26 also takes into account any expected change in the position of the irradiation components during the planned irradiation treatment, in particular the irradiation head 18 and, if applicable, the systems 20 and 22, 23. For this purpose, the irradiation position data may include any expected change in position during the planned irradiation treatment. Furthermore, irradiation plan data for the planned irradiation treatment may be stored in the evaluation unit 26.The evaluation unit 26 can also take the treatment plan data into account to determine the visibility of the area of ​​interest 28. The treatment plan data can include the area of ​​the patient's body 10 to be irradiated during the treatment and / or the type of radiation components used in the treatment and / or the radiation power and / or duration used in the treatment. As part of the evaluation of the area of ​​interest 28, the evaluation unit 26 determines the visibility of the area of ​​interest 28, particularly during the planned radiation treatment, taking into account the changing relative position of the system components during the treatment. As illustrated in Fig. 3, this can lead to a shadowing 36 of the area of ​​interest 28. Such shadowing 36, and thus a lack of visibility, can impair the stability of the area of ​​interest 28 during the radiation treatment. To prevent this, the evaluation unit 26 can, for example, issue a warning message to an operator and / or suggest an adjustment of the area of ​​interest 28. In the example shown, the evaluation unit 26 could, for instance, modify the area section 30 so that the shadowing 36 is removed from it.If necessary, for example, area section 30 could be enlarged elsewhere where there is no risk of shading 36. This proposed adjustment can then be issued to the operator, who can accept the adjustment after review or, for example, choose a different adjustment. With the system or device according to the invention and the method according to the invention, undesirable interruptions of the radiation treatment due to a lack of visibility or instability of the area of ​​interest 28 and the resulting time delays and loss of comfort for the patient or the medical staff are reliably prevented. Reference symbol list 10 Patient body 12 Patient table 14 Foot section 16 Radiation device 18 Radiation head 20 EPID system 22 X-ray source 23 Imaging plate 24 Camera array 26 Evaluation unit 28 Area of ​​interest 30 Area section 32 Area section 34 Area section 36 Shadowing

Claims

Device for evaluating an area of ​​interest on the surface of a patient's body (10) to be monitored during irradiation treatment, characterized in that: • the device comprises an evaluation unit (26), wherein the area of ​​interest (28) is stored in the evaluation unit (26) in the form of area data that can be processed by the evaluation unit (26); • the evaluation unit (26) further stores irradiation position data relating to the position of irradiation components (12, 16, 18, 20, 22, 23) arranged in an irradiation room for the planned irradiation treatment and monitoring position data relating to the position of monitoring components (24) arranged in the irradiation room for monitoring the area of ​​interest (28); and • the evaluation unit (26) is configured to, based on the area data,to determine the visibility of the area of ​​interest (28) by the monitoring components (24) during the planned irradiation treatment using the irradiation position data and the monitoring position data, and to evaluate the area of ​​interest (28) depending on the determined visibility. Device according to claim 1, characterized in that the monitoring components (24) comprise cameras (24) for capturing the three-dimensional surface of the patient's body (10) encompassing the area of ​​interest (28) during radiation treatment. Device according to one of the preceding claims, characterized in that the irradiation components (12, 16, 18, 20, 22, 23) comprise an irradiation device (16, 18) movable in the irradiation room, in particular a pivotable linear accelerator (16, 18), and / or an imaging system (20, 22, 23) movable in the irradiation room, in particular an electronic portal imaging system (20, 22, 23). Device according to one of the preceding claims, characterized in that the irradiation components (12, 16, 18, 20, 22, 23) comprise a patient bed (12) that is movable in the irradiation room, in particular movable and / or rotatable. Device according to one of the preceding claims, characterized in that the evaluation unit (26) also stores radiation plan data for the planned radiation treatment, and that the evaluation unit (26) is designed to also take the radiation plan data into account for determining the visibility of the area of ​​interest (28) by the monitoring components (24) during the planned radiation treatment. Device according to claim 5, characterized in that the irradiation plan data includes the area of ​​the patient's body (10) to be irradiated during the irradiation treatment and / or the type of irradiation components (12, 16, 18, 20, 22, 23) used during the irradiation treatment and / or the irradiation power and / or irradiation duration used during the irradiation treatment. Device according to one of the preceding claims, characterized in that the irradiation position data comprise a change in the position of the irradiation components (12, 16, 18, 20, 22, 23) in the irradiation room that is expected to occur during the planned irradiation treatment. Device according to claim 7, characterized in that the evaluation device (26) is designed to take into account, for determining the visibility of the area of ​​interest (28) by the monitoring components (24) during the planned irradiation treatment, the expected change in the position of the irradiation components (12, 16, 18, 20, 22, 23). Device according to one of the preceding claims, characterized in that the area of ​​interest (28) present at the evaluation device (26) in the form of area data processable by the evaluation device (26) is an area of ​​interest (28) defined by a radiation therapy therapist, in particular an area of ​​interest (28) defined by the radiation therapy therapist within the framework of radiation planning. Device according to one of the preceding claims, characterized in that the evaluation device (26) is configured to output the result of the evaluation of the area of ​​interest (28) to an operator. Device according to one of the preceding claims, characterized in that the evaluation unit (26) is configured to issue a warning signal to an operator and / or to adjust the area of ​​interest (28) for improved visibility if the visibility of the area of ​​interest (28) is found to be inadequate during the planned irradiation treatment by the monitoring components (24). System for evaluating an area of ​​interest (28) defined for monitoring a radiation treatment on the surface of a patient body (10), comprising radiation components (12, 16, 18, 20, 22, 23) arranged in a radiation room for the planned radiation treatment and monitoring components (24) arranged in the radiation room for monitoring the area of ​​interest (28), further comprising a device according to one of the preceding claims. System according to claim 12, characterized in that it further comprises a patient bed (12) adjustable in its position for a patient body (10). A method for evaluating an area of ​​interest (28) on the surface of a patient's body (10) to be monitored during irradiation treatment, characterized by the steps of: • providing the area of ​​interest (28) to an evaluation unit (26) in the form of area data processable by the evaluation unit (26), • providing irradiation position data on the position of irradiation components (12, 16, 18, 20, 22, 23) arranged in an irradiation room for the planned irradiation treatment and monitoring position data on the position of monitoring components (24) arranged in the irradiation room for monitoring the area of ​​interest (28) in the evaluation unit (26), and • determining the visibility of the area of ​​interest (28) by the monitoring components (24) during the planned irradiation treatment using the evaluation unit (26) based on the area data.the irradiation position data and the monitoring position data, and evaluating the area of ​​interest (28) using the evaluation device (26) depending on the determined visibility. The method according to claim 14, characterized in that it is carried out with a device according to one of claims 1 to 11 or a system according to one of claims 12 or 13.

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