System for thermal ablation treatment planning - Patents.com

Abstract

A system 100 for thermal ablation treatment planning is provided that allows providing approach conditions 21a, 21b; 22a, 22b indicating how a trajectory of a thermal ablation source 50 should approach a treatment region 60. A configuration space is provided that includes as configurations: a) candidate positions corresponding to candidate trajectories 311a, 311b; 312a, 312b for approaching the treatment region according to the provided approach conditions, and b) candidate thermal control parameter values ​​32i, 32ii for each candidate position. Based on the candidate thermal effects 10a, 10b, 10c, 10d provided for each configuration, a treatment plan that satisfies a thermal effect goal is determined.

Description

[Technical field]

[0001] The present invention relates to a system, method and computer program for thermal ablation treatment planning. [Background technology]

[0002] Treatment of lesions by thermal ablation requires careful planning to adequately ablate the lesion without unnecessarily damaging healthy tissue. However, because of the many variables involved, optimizing a thermal ablation treatment plan is a complex challenge, even assuming perfect navigation capabilities. It would therefore be desirable to provide a more efficient means of planning thermal ablation treatments.

[0003] US 2011 / 0015628 A1 discloses a system for planning an ablation procedure for ablation of a tissue mass of a patient, the system including a graphical user interface that presents a representation of the tissue mass to a user, and an optimization component that generates a planned target volume including the tissue mass, receives image data related to the tissue mass, generates a surrounding elliptical ablation volume that encompasses the planned target volume, identifies a number of spherical ablation regions that cover the surrounding ellipsoid, executes a mathematical algorithm to extend axes of the spherical ablation regions to form elliptical ablation regions, and outputs graphical information to the user displaying the elliptical ablation regions superimposed on the planned target volume.

[0004] In the paper "Development of a Multi -objective Optimized Planning Method for Microwave Liver Tumor Ablation" by Libin Lian et al., Medical Image Computing and Computer Assisted Intervention-MICCAI 2019, Proceedings, Part V, pp. 110-118 (2019), a set covering based method is presented that provides a solution for microwave ablation planning that is useful for finding the right trade-off between the number of electrode trajectories and damage to normal tissue. Summary of the Invention [Problem to be solved by the invention]

[0005] It is an object of the present invention to provide a more efficient means for planning thermal ablation treatments. [Means for solving the problem]

[0006] In a first aspect, the present invention relates to a system for thermal ablation treatment planning, the system comprising: an approach condition providing unit for providing an approach condition indicating how a trajectory of a thermal ablation source to be planned should approach a treatment region including an ablation target region; a configuration space providing unit for providing a configuration space including as configurations: a) candidate positions corresponding to a plurality of candidate trajectories of a thermal ablation source through a treatment region; and b) candidate thermal control parameter values ​​for each candidate position, the candidate trajectories entering the treatment region according to a provided entry condition; a candidate thermal effect providing unit for providing a candidate thermal effect generated in the vicinity by a thermal ablation source in each configuration; The present invention includes a treatment plan determination unit that determines a thermal ablation treatment plan including: a) a planned trajectory of a thermal ablation source; and b) planned thermal control parameter values ​​along the planned trajectory, wherein the treatment plan is determined based on candidate thermal effects provided for each configuration such that the treatment plan meets a predetermined thermal effect target.

[0007] Because the configuration space considered to determine the treatment plan includes trajectories of thermal ablation sources that satisfy the approach conditions, the complexity in determining a treatment plan that satisfies a given thermal effect target is significantly reduced, thereby significantly improving the efficiency of planning thermal ablation treatments.

[0008] As used herein, thermal ablation treatment preferably refers to a treatment using heat or cold for ablation, where the heat or cold is generated by a thermal ablation source. For example, heat can be generated in an ablation target, such as a tumor, by irradiating microwaves on and / or within the ablation target. For this purpose, an electrode, which may be located in the distal portion of a suitable applicator device, can be brought close to, in contact with, or within the ablation target, and the electrode can then be electrically controlled to emit microwaves.

[0009] The entry condition providing unit may be a receiver configured to receive the entry condition and provide the received entry condition for further processing. For example, the entry condition may be received via a user interface. The entry condition providing unit may be a memory that stores the entry condition for access by other parts of the system, in particular the configuration space providing unit. The entry condition providing unit may be a processor configured to determine the entry condition based on data input or access to stored data. The provided entry condition may also be referred to as a candidate entry condition, since the candidate trajectory of the provided configuration space enters the treatment area according to the provided entry condition.

[0010] Preferably, the entry condition refers to the surface of the treatment area, for example the skin of the patient, and / or does not refer to the interior of the treatment area, such as a sub-area within the treatment area.

[0011] The configuration space providing unit may in particular provide as configurations a configuration space consisting of a) candidate positions corresponding to a plurality of candidate trajectories of the thermal ablation source through the treatment area and b) candidate thermal control parameter values ​​for each candidate position, the candidate trajectories entering the treatment area according to the provided entry condition. The configuration space providing unit may be a processor coupled to a memory for storing a default configuration space including all geometrically and / or technically possible configurations, i.e. including, for example, candidate positions corresponding to all geometrically and / or technically possible candidate trajectories and all technically possible candidate thermal control parameter values ​​for each candidate position. The processor may be configured to retrieve the default configuration space from the memory, restrict it to configurations that satisfy the entry condition and provide the restricted configuration space directly or by storing it in the memory for further access for further processing. However, the configuration space providing unit may also be configured to build the configuration space itself. For example, the processor may be configured to build a data structure corresponding to the configuration space, i.e. the configuration space whose configurations already satisfy the entry condition, and this data structure may be provided for further processing directly or by storing it in the memory for further access.

[0012] A candidate trajectory of a thermal ablation source is often a linear trajectory that can be followed by an applicator device with a thermal ablation source at its distal portion. However, the candidate trajectory may also be curvilinear. The candidate locations corresponding to a given candidate trajectory preferably refer to points that collectively constitute the given candidate trajectory. If the candidate trajectory is represented discretely, a finite set of points on the candidate trajectory can be identified.

[0013] Candidate thermal control parameter values ​​are candidate values ​​of one or more thermal control parameters and indicate candidate thermal effects, i.e., thermal effects that would be generated in the vicinity if a thermal ablation source were placed at each candidate location and controlled according to the candidate thermal control parameters. Candidate locations for which the thermal control parameters result in at least some thermal effects can be considered candidate operating locations, since the thermal ablation source will be operated at these locations. Thermal effects generated at nearby points by the thermal ablation source are understood herein to preferably refer to thermal energy transferred to or extracted from the point, which may be indicated by an increase or decrease in temperature.

[0014] The candidate thermal effect providing unit may, for example, be a processor coupled to a memory that stores control characteristics of the thermal ablation source and possibly thermal characteristics of the treatment area, and the processor may be configured to determine candidate thermal effects to be generated in the vicinity by the thermal ablation source in each configuration based on the respective candidate thermal control parameter values ​​and the stored characteristics, and to provide the determined candidate thermal effects for further processing, either directly or by storing them in the memory for further access.

[0015] For a given candidate location and given thermal characteristics of the vicinity of the candidate location, the candidate thermal control parameters may suggest the thermal effects generated in the vicinity by the thermal ablation source when at the candidate location. Thus, the configuration space may be considered as including, in particular, the positions corresponding to the multiple candidate trajectories as configurations, and the candidate thermal effects provided for each position, respectively, for different candidate thermal control parameter values. The thermal effects generated in the vicinity by the thermal ablation source may also be considered as local thermal effects. On the other hand, the thermal effect goal that the determined treatment plan meets preferably refers to a global thermal effect. The global thermal effect may indicate multiple local thermal effects generated during the thermal ablation treatment, and / or a thermal effect evaluated over the entire treatment area.

[0016] The treatment plan determination unit may be configured to determine a thermal ablation treatment plan consisting of a) a planned trajectory of the thermal ablation source and b) planned thermal control parameter values ​​along the planned trajectory. The treatment plan determination unit may be a processor configured to evaluate each configuration, in particular a subset of configurations, against a thermal effect target using candidate thermal effects provided by the candidate thermal effect providing unit for each configuration provided by the configuration space providing unit. In particular, any combination of configurations that meets the thermal effect target at least to a predetermined extent may be considered to form a feasible treatment plan.

[0017] The planned thermal ablation treatment may refer in particular to a percutaneous ablative tumor treatment, in particular to a cancer treatment. The thermal ablation source may be part of a thermal ablation modality, in particular a needle-like applicator, which includes a thermal ablation source at or near its tip. The thermal ablation modality used may be selected, for example, based on the organ containing the tumor, the size of the tumor, and the location of the tumor (e.g., relative to the organ). For example, any of the ablation modalities based on radio frequency (RF), focused ultrasound (FU), microwave (MW), laser, cryoablation, and irreversible electroporation (IRE) may be selected.

[0018] The entry condition providing unit may be configured to provide a plurality of entry conditions, the configuration space providing unit may be configured to provide a configuration space such that each candidate trajectory enters the treatment region according to one of the entry conditions, and the treatment plan determining unit may be configured to determine the thermal ablation treatment plan, such that the thermal ablation treatment plan includes, in particular consists of, a) a plurality of planned trajectories to be followed during treatment, and b) planned thermal control parameter values ​​along the planned trajectories. By planning a plurality of trajectories that may have different entry conditions, more complex thermal effect goals can be met. However, even in this case, it is not necessary to try all possible entry conditions. Instead, only reasonable entry conditions may be tried, where reasonableness may refer to, for example, a trained physician's judgment based on his or her own experience.

[0019] Sequentially following multiple planned trajectories may refer to following trajectories using one or more applicators corresponding to respective thermal ablation sources. There may be multiple applicators simultaneously in the treatment area. It should be understood that the provided approach conditions do not necessarily have to all be realized in the finally determined treatment plan. However, it is preferable that the finally determined treatment plan does not include a trajectory that does not satisfy any of the provided approach conditions.

[0020] Each of the one or more approach conditions may include a prescribed approach direction. For each of the one or more prescribed approach directions, a number of candidate approach points at which one or more candidate trajectories enter the treatment area in the prescribed approach direction can be determined based on the prescribed approach direction and the treatment area. In this way, a geometrically complete approach condition can be obtained for all the candidate trajectories. If the candidate trajectories correspond to parts of straight lines, as may be preferred, these lines are fixed. In particular, a number of candidate approach points at which one or more candidate trajectories enter the treatment area in the respective prescribed approach directions may be determined such that the resulting candidate trajectories intersect with the ablation target area. It should be understood that the one or more "prescribed" approach directions do not necessarily all have to be realized in the finally determined treatment plan. However, it is preferable that the finally determined treatment plan does not include a trajectory that does not enter the treatment area in any of the one or more prescribed approach directions. Preferably, the one or more prescribed approach directions are defined by a user.

[0021] In one example, one or more prescribed entry directions may be given by unit vectors, the treatment region may be a sub-volume of the patient's body, and the ablation target region may be a tumor within that sub-volume of the patient's body. For example, the unit vector may be determined based on a user input indicating two consecutive points in a 3D rendered image of the patient. For each treatment, a plane may be defined that is perpendicular to the respective unit vector and extends outside the sub-volume of the patient's body. A set of projection points may be defined on each plane by virtually projecting the tumor onto the plane in a direction opposite to the direction of each prescribed entry direction, i.e., the respective unit vector. The projection points may be defined as all points located within the projection, possibly as grid points of a discrete two-dimensional coordinate system on the respective plane. To obtain the candidate entry points, the projection points may be projected back onto the surface of the sub-volume of the patient's body, i.e., preferably onto the patient's skin, in the respective prescribed entry condition directions, i.e., in the direction of the respective unit vector. Some of the candidate entry points may then be discarded, specifically if it is determined that the trajectory of entry through the respective entry point in the respective prescribed entry direction passes through an area within a partial volume of the patient's body that is not intended to come into contact with the thermal ablation source.

[0022] Each of the one or more approach conditions may include a prescribed approach condition point instead of or in addition to a prescribed approach direction. If each of the one or more approach conditions includes a prescribed approach point but does not include a prescribed approach direction, then for each of the one or more prescribed approach points, multiple candidate approach directions can be determined based on the prescribed approach point and the treatment region, in which one or more candidate trajectories enter the treatment region at the prescribed approach point. In this way, a geometrically complete approach condition can still be obtained for all candidate trajectories, and if the candidate trajectories correspond to parts of straight lines (as may be preferred), these lines are fixed. In particular, multiple candidate approach directions in which one or more candidate trajectories enter the treatment region at their respective prescribed approach points may be determined such that the resulting candidate trajectories intersect the ablation target region. It should be understood that the one or more "prescribed" approach points do not necessarily have to all be realized in the finally determined treatment plan. However, it is preferable that the finally determined treatment plan does not include trajectories that do not enter the treatment region at any of the one or more prescribed approach points.

[0023] Preferably, the one or more defined entry points are defined by a user.

[0024] The one or more approach conditions may include, in particular consist of, one or more predefined approach condition directions and one or more predefined approach condition points means that the approach condition providing unit may be configured to provide approach conditions based on one or more predefined approach condition directions and one or more predefined approach condition points, such that each provided approach condition includes, in particular consists of, one of the predefined approach condition directions and one of the predefined approach condition points. In that case, no further processing steps are necessary to arrive at a geometrically complete approach condition for all candidate trajectories. However, the set of provided approach conditions can be further reduced, for example, by discarding approach conditions whose candidate trajectories do not intersect with the ablation target area. The one or more approach conditions resulting from the one or more predefined approach directions and one or more predefined approach points do not necessarily have to be all realized in the finally determined treatment plan. However, it is preferable that the finally determined treatment plan does not include trajectories that do not satisfy any of the provided approach conditions, i.e. trajectories that do not enter the treatment area in a) at least one of the one or more predefined approach directions and b) at least one of the one or more predefined approach points.

[0025] For example, the prescribed entry points may be provided by detecting radiopaque marks on the patient's skin or in response to a user virtually marking the patient's skin on a 3D rendered image of the patient. The prescribed entry points may be specifically provided at predetermined intervals. In this way, the use of a stiffness / leading grid template to aid in the insertion of a thermal ablation probe may be mimicked.

[0026] Radiopaque marks on the patient's skin defining defined entry points having predetermined intervals may be created by a user using a flexible radiopaque grid, where the user may create the marks through holes in the flexible radiopaque grid, or in particular "tattoo" the marks with radiopaque ink.

[0027] For thermal ablation treatments performed using a rigid / leading grid template, such as thermal ablation treatments of prostate cancer, the prescribed approach condition points may be assumed to correspond to where the holes in the rigid / leading grid template reach the surface of the treatment area, such as the patient's skin. Furthermore, a single prescribed approach condition direction may be assumed that is orthogonal to the grid template plane, i.e., corresponds to the direction of the holes in the grid template.

[0028] Candidate thermal control parameter values ​​along the candidate trajectory may be selected such that the thermal ablation source is activated only within the ablation target region. In other words, the "active" portion of the candidate trajectory may be limited to the intersection of the candidate trajectory with the ablation target region. In this way, the number of configurations that need to be considered to determine a treatment plan may be further reduced.

[0029] The candidate thermal control parameter values ​​may indicate activation positions along each candidate trajectory where the thermal ablation source is activated and candidate thermal effects of the activated thermal ablation source at each activation position. The indicated thermal effects may be thermal effects provided by the candidate thermal effect providing units. The thermal effects may be indicated in terms of an ablation zone corresponding to an area receiving thermal energy above a predefined threshold. For example, the ablation zone may be elliptical. For example, if the thermal ablation source is elongated, the ablation zone typically has an elongated elliptical shape. The thermal effects may be defined in terms of ablation power and ablation time at a particular activation position. For example, if the thermal ablation source remains at a particular activation position, the ablation zone may expand over time even if the ablation power is constant.

[0030] The candidate thermal control parameter values ​​may indicate a fixed set of actuation positions along each candidate trajectory and / or a fixed set of candidate thermal effects, which further reduces the size of the configuration space and improves the efficiency of the planning. In particular, the candidate thermal control parameter values ​​may indicate a fixed set of actuation positions along each of the candidate trajectories within the ablation target region and / or a fixed set of candidate thermal effects within the ablation target region. The candidate thermal effects sets may correspond, for example, to a set of shapes of the ablation zone.

[0031] The thermal effect goal that the treatment plan must meet may relate to either the overall thermal effect on the ablation target area, the overall thermal effect on areas outside the ablation target area, the number of actuation locations, and / or the geometric relationship of the actuation locations to the ablation target area. The overall thermal effect on a portion (e.g., a sub-area) of the treatment area may refer to the total amount of thermal energy delivered to or extracted from that portion of the treatment area, or the percentage of that portion where the amount of thermal energy delivered or extracted exceeds a predefined threshold. Thus, the overall thermal effect on a portion of the treatment area may refer to the coverage rate of that portion by the ablation zone. Areas outside the ablation target area may be particularly critical structures that may need to be avoided from significant thermal effects. The geometric relationship between the actuation locations and the ablation target area may include, among other things, a symmetrical arrangement of the actuation locations within the ablation target area. For example, the thermal effect goal may be to maximize the overall thermal effect on the ablation target area, or to minimize the overall thermal effect on areas outside the ablation target area.

[0032] Determining a treatment plan such that one or more thermal effect goals are met may correspond to an optimization over all configurations considered, but the configurations considered are preferably limited, as described above, for example, by considering only candidate trajectories having particular approach conditions and / or only particular candidate thermal control parameter values.

[0033] The thermal effect goal may include several sub-goals, which may be ranked by priority, and to determine the treatment plan, the candidate treatment plans may be compared against the sub-goals according to priority. A candidate treatment plan preferably refers to one or more candidate trajectories having associated candidate thermal control parameter values ​​along which the candidate trajectories are followed in sequence during the treatment to be planned while the thermal ablation source is controlled according to the associated candidate thermal control parameter values. Thus, a candidate treatment plan may refer to a set of candidate configurations to be followed during the treatment, i.e., candidate trajectories through a configuration space.

[0034] Comparing candidate treatment plans against sub-goals according to the sub-goal's priority may refer, for example, to first comparing the candidate treatment plan against the highest priority sub-goal, then comparing the candidate treatment plan that meets the highest priority sub-goal to a predetermined first tolerance against the second highest priority sub-goal, then comparing the candidate treatment plan that also meets the second highest priority sub-goal to a predetermined second tolerance against the third highest priority sub-goal, etc.

[0035] The ranking of the sub-objectives in priority order may be: 1) maximum target coverage, 2) minimum coverage of critical structures, 3) minimum coverage rate of healthy tissue, 4) minimum number of ablation zones, 5) ablation symmetry (i.e., providing symmetric ablation locations with respect to the ablation target area). Coverage may refer to the geometric coverage by the ablation zones.

[0036] The determined treatment plan that satisfies the thermal effect goal can be modified by removing ablation events that can be removed without generating a portion of the ablation target area that is thermally affected below a predefined threshold. An ablation event is to be understood as an ablation performed by a thermal ablation source along a planned trajectory. Thus, in other words, the determined treatment plan that satisfies the thermal effect goal can be modified by removing actuation positions along the planned trajectory that can be removed without generating a portion of the ablation target area that is thermally affected below a predefined threshold. For example, an actuation position can be removed if its associated planned ablation zone is completely contained in one or more other planned ablation zones, i.e. completely covered by one or more other planned ablation zones.

[0037] The entry condition providing unit may be configured to provide the entry conditions based on previous treatment plans and / or other clinical data, thereby allowing the treatment plan to be determined fully automatically.

[0038] The system may include an artificial intelligence providing unit that provides an artificial intelligence trained to provide an output approach condition of a thermal ablation treatment plan that meets a thermal effect goal when a three-dimensional input image of an input region including an input ablation target region is provided, and the approach condition providing unit may provide the three-dimensional image of a treatment region including a thermal ablation target region to be treated to the artificial intelligence, and provide the output approach condition provided by the artificial intelligence as the approach condition to be used for the treatment to be planned. The artificial intelligence may include a machine learning architecture, such as an artificial neural network, in particular a convolutional neural network.

[0039] The entry condition providing unit may be configured to a) determine an intersection length between at least a subset of the candidate trajectories entering the treatment region according to at least a subset of all possible entry conditions and the ablation target region, and the entry condition may be provided based on the determined intersection length. For example, an entry condition with a long intersection length may be preferred. The entry condition providing unit may also be configured to b) determine an ablation target distance for at least a subset of the candidate trajectories entering the treatment region according to at least a subset of all possible entry conditions, the ablation target distance being the length of each candidate trajectory from entering the treatment region to reaching the ablation target region, and the entry condition may be provided based on the ablation target distance. For example, an entry condition that shortens the ablation target distance may be preferred. Providing the entry condition based on the intersection length with the ablation target region and / or the ablation target distance results in a configuration space that includes candidate trajectories that are more likely to result in a sufficient treatment plan, thereby further improving the efficiency of the planning process.

[0040] A further aspect relates to an apparatus for thermal ablation treatment planning, the apparatus comprising: a display device for displaying an image of the treatment area; an input receiving unit for receiving user input relating to the image; A system according to any one of claims 1 to 12, The approach condition providing unit provides the approach condition based on a user input on the image and / or the display device visualizes the treatment plan in the image.

[0041] A further aspect relates to a method for thermal ablation treatment planning, the method comprising: Providing an approach condition indicating how a trajectory of a thermal ablation source to be planned should approach a treatment region including an ablation target region; providing a configuration space including as configurations: a) candidate locations corresponding to a plurality of candidate trajectories of a thermal ablation source through a treatment region; and b) candidate thermal control parameter values ​​for each candidate location, the candidate trajectories entering the treatment region according to a provided entry condition; providing candidate thermal effects to be generated proximately by a thermal ablation source in each configuration; determining a thermal ablation treatment plan including: a) a planned trajectory of a thermal ablation source; and b) planned thermal control parameter values ​​along the planned trajectory, wherein the treatment plan is determined based on candidate thermal effects provided for each configuration such that the treatment plan meets a predetermined thermal effect goal.

[0042] A further aspect relates to a method for user-directed thermal ablation treatment planning, the method comprising: Displaying an image of the treatment area; Receiving user input regarding the image; The method steps described above, Entry conditions are provided based on user input on the image and / or the treatment plan is visualized within the image.

[0043] A further aspect relates to a computer program for thermal ablation treatment planning, the program comprising program code means for causing a system according to any one of claims 1 to 12 to perform the method according to claim 14.

[0044] A further aspect relates to a computer program for thermal ablation treatment planning, the program comprising program code means which, when executed on a computer controlling an apparatus according to claim 13, causes the apparatus to carry out the above-mentioned user-directed method.

[0045] It will be understood that the system of claim 1, the device of claim 13, the method of claim 14 and the computer program of claim 15 have similar and / or identical preferred embodiments, in particular as set out in the dependent claims.

[0046] It is to be understood that a preferred embodiment of the invention can also be any combination of the dependent claims or above embodiments with the independent claims.

[0047] These and other aspects of the invention will be elucidated and elucidated with reference to the embodiments described hereinafter. [Brief description of the drawings]

[0048] [Figure 1] FIG. 1 illustrates, in a schematic and exemplary manner, a system for thermal ablation treatment planning. [Figure 2A-2B] 2A and 2B show schematic and exemplary candidate trajectories in two different configuration spaces. [Diagram 3] FIG. 3 shows, in a schematic and exemplary manner, candidate thermal control parameter values ​​that result in different thermal effects of a thermal ablation source on its vicinity. [Figure 4A-4F] 4A-4F show schematic and exemplary different configurations of actuation positions and ablation zones along candidate trajectories through the ablation target area. [Diagram 5] FIG. 5 shows a schematic and exemplary intersection of a candidate trajectory with an ablation target region. [Figures 6A-6G] 6A-6G show, in a schematic and exemplary manner, certain steps that may be performed to arrive at a thermal ablation treatment plan. [Figure 7A-7B] 7A and 7B show, in a schematic and exemplary manner, a user interface that may be provided on a display of a device including the system shown in FIG. [Figure 8] FIG. 8 illustrates, diagrammatically and exemplarily, a method for thermal ablation treatment planning. [Figure 9] FIG. 9 shows, generally and exemplarily, a flow chart summarizing certain elements. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0049] FIG. 1 illustrates a schematic and exemplary thermal ablation treatment planning system 100 , including an approach condition providing unit 110 , a configuration space providing unit 120 , a candidate thermal effect providing unit 130 , and a treatment plan determining unit 140 .

[0050] The approach condition providing unit 110 is configured to provide approach conditions 21a, 21b; 22a, 22b indicating how the trajectory of the thermal ablation source 50 to be planned should approach the treatment region 60 including the ablation target region 70.

[0051] The configuration space providing unit 120 is configured to provide a configuration space. The configuration space includes as configurations: a) candidate positions corresponding to a plurality of candidate trajectories 311a, 311b; 312a, 312b of the thermal ablation source 50 through the treatment region 60, and b) candidate thermal control parameter values ​​32i, 32ii for each candidate position. The candidate trajectories 311a, 311b; 312a, 312b enter the treatment region 60 according to the provided approach conditions 21a, 21b; 22a, 22b, i.e. the approach conditions provided by the approach condition providing unit 110.

[0052] The configuration space can be thought of as a set of pairs of a) the coordinates of each candidate location and b) the corresponding candidate thermal control parameter values ​​32i, 32ii. Geometrically, the configuration space can be thought of as including candidate locations, i.e., points along the trajectories, corresponding to a number of candidate trajectories 311a, 311b; 312a, 312b of the thermal ablation source 50 through the treatment region 60, and labels including the corresponding candidate thermal control parameter values ​​32i, 32ii labeling each point.

[0053] The candidate thermal effect providing unit 130 is configured to provide nearby candidate thermal effects 10a, 10b to be generated by the thermal ablation source 50 in each configuration, i.e. in each configuration within the configuration space provided by the configuration space providing unit 120. The candidate locations, candidate thermal control parameter values ​​32i, 32ii, and candidate thermal effects should be understood as possible or hypothetical locations, thermal control parameter values, and thermal effects, respectively, which provide a basis for determining the treatment plan, although at least all of them are not the actual locations, actual thermal control parameter values, and actual thermal effects to be provided in the planned treatment.

[0054] The treatment plan determination unit 140 is configured to determine a thermal ablation treatment plan, the thermal ablation treatment plan comprising: a) a planned trajectory 41 a, 41 b of the thermal ablation source 50; and b) planned thermal control parameter values ​​along the planned trajectory 41 a, 41 b. The treatment plan determination unit 140 is configured to determine the treatment plan based on the candidate thermal effects 10 a, 10 b provided for each configuration, i.e. for each configuration in the configuration space provided by the configuration space providing unit 120, such that the treatment plan satisfies a predetermined thermal effect target.

[0055] The treatment plan determination unit 140 may take the form of a mathematical solver that determines the best treatment plan including a set of best trajectories for entering the treatment region 60, e.g., the patient's skin, and ablation settings corresponding to particular thermal control parameter values ​​along the trajectories. The treatment plan determination unit 140 may be beneficial in simplifying the treatment planning process, improving the quality of ablation target region coverage according to the treatment plan, further standardizing the overall planning process, and making the overall planning process more efficient.

[0056] It is clear that the entry condition providing unit 110, the configuration space providing unit 120, the candidate thermal effect providing unit 130, and the treatment plan determining unit 140 can perform their respective operations with reference to a representation of the treatment region 60 and the ablation target region 70, which may be provided, for example, as a three-dimensional image, in particular as a segmented image. In particular, if the treatment region 60 corresponds to a partial volume of the patient's body and the ablation target region 70 corresponds to a tumor in the partial volume, the representation may be given as a three-dimensional medical image of the partial volume of the patient's body and the tumor therein. The tumor and possibly other anatomical structures may be segmented in the image. The tumor may in particular be a cancer lesion to be destroyed by thermal ablation treatment. For example, if the cancer is a kidney cancer, the imaged partial volume of the patient may correspond to the patient's abdomen. Optionally, the system 100 further includes a treatment region representation providing unit configured for providing, i.e. providing, a representation of the treatment region 60 including the ablation target region 70. This representation may be, for example, a three-dimensional image.

[0057] It is also clear that the treatment plan is determined to meet a predetermined thermal effect target, and thus the determined treatment plan preferably depends on the predetermined thermal effect target. Optionally, the system 100 further comprises a thermal effect target providing unit configured for providing, i.e. providing, a predetermined, i.e. predeterminable thermal effect target. The thermal effect target may be predetermined and / or provided based on a clinical prescription. It may also be considered as a goal of a treatment protocol.

[0058] The candidate thermal effect providing unit 130 may provide candidate thermal effects 10a, 10b to be generated in its vicinity by the thermal ablation source 50 in any configuration based on the results of the calibration. The calibration may correspond to measuring or simulating thermal effects in the vicinity of the real or simulated thermal ablation source 50 for a number of thermal control parameter values ​​32i, 32ii. The thermal ablation source 50 is therefore preferably a trial run device where it is known, at least roughly or in ideal circumstances, what ablation characteristics are obtained from a given device ablation setting. This is explained in more detail below with reference to FIG. 3.

[0059] The treatment plan determination unit 140 may be configured to determine the treatment plan based on multiple further types of data that may be related to treatment workflow priorities, such as, for example, whether a pullback of the thermal ablation source 50 should be considered / allowed. The system 100 may comprise further providing units for providing such further types of data.

[0060] The entry condition providing unit 110 may be configured to provide the entry conditions 21a, 21b; 22a, 22b based on input provided via a suitable user interface by a user of the system 100 or an apparatus including the system 100. The user may be a physician seeking assistance in planning a thermal ablation treatment.

[0061] The system 100 preferably provides as output an optimal treatment plan, which corresponds to a thermal ablation source 50 that is inserted into the treatment area 60, e.g. through the patient's skin, according to the provided approach conditions 21a, 21b; 22a, 22b, and optimally provides a thermal effect on its way through the treatment area 60. The treatment plan may be determined for a plurality of thermal ablation sources. In that case, the approach condition providing unit 110 may be configured to provide a plurality of approach conditions 21a, 21b; 22a, 22b, the configuration space providing unit 120 may be configured to provide a configuration space such that each candidate trajectory 311a, 311b; 312a, 312b enters the treatment area 60 according to one of the approach conditions 21a, 21b; 22a, 22b, and the treatment plan determining unit 140 may be configured to determine the thermal ablation treatment plan, such that the thermal ablation treatment plan includes a) a plurality of planned trajectories to be followed during treatment, and b) planned thermal control parameter values ​​along the planned trajectories. The multiple planned trajectories may be followed sequentially or at least partially simultaneously, in particular by different ones of the multiple thermal ablation sources, for example, two planned trajectories may be followed sequentially by a single ablation source or at least partially simultaneously by two ablation sources.

[0062] In general, the task performed by the treatment plan determination unit 140 is relatively complex when considering any configuration space, especially a configuration space that includes a relatively high density of candidate locations. This may be especially true when the treatment region 60 is represented with a relatively high level of detail, e.g., with a relatively high resolution image, since the number of candidate treatment plans that the treatment plan determination unit 140 must evaluate with respect to a given thermal effect target is relatively large. However, since a configuration space limited to trajectories that satisfy one or more provided approach conditions is considered, the set of configurations that the treatment plan determination unit 140 must consider to evaluate with respect to the thermal effect target is reduced, and a treatment plan can be determined within an acceptable time frame.

[0063] The complexity of the task to be performed by the treatment plan determination unit 140, due to the cardinality of the general configuration space, becomes even more significant when the planned treatment includes multiple planned trajectories 41a, 41b that are followed in sequence during the treatment and planned thermal control parameter values ​​along the planned trajectories 41a, 41b. In this case, multiple entry conditions 21a, 21b; 22a, 22b are typically provided, with each candidate trajectory 311a, 311b; 312a, 312b entering the treatment region 60 according to one of the entry conditions 21a, 21b; 22a, 22b.

[0064] System 100 is particularly useful for improving the workflow of thermal ablation treatment planning when the planned treatment is performed freehand. When performing thermal ablation treatment freehand, i.e., without a system or device such as a leading grid template, the planning task is typically considered to be a relatively difficult problem due to the relatively large number of degrees of freedom involved.

[0065] The number of degrees of freedom is reflected in the cardinality of the considered configuration space. Cardinality is understood to refer to the number of elements in the configuration space, where the elements correspond to pairs of a) candidate positions corresponding to multiple candidate trajectories 311a, 311b; 312a, 312b of the thermal ablation source 50 through the treatment region 60, and b) candidate thermal control parameter values ​​32i, 32ii for each candidate position. In some situations, i.e. when there is not a single optimal treatment plan but rather an entire solution space of acceptable treatment plans, the cardinality of the solution space may also be so large that it may be difficult to select from the solution space a treatment plan to actually follow.

[0066] As will become apparent below, the system 100 may be implemented to function semi-automatically or fully automatically, depending in particular on how one or more entry conditions 21a, 21b; 22a, 22b are provided.

[0067] 2A and 2B show schematic and exemplary configuration spaces provided by the configuration space providing unit 120 for the same treatment region 60 including the same ablation target region 70. The treatment region 60 further includes two risk regions 80 corresponding to anatomical structures where ablation creates high medical risk. The risk regions 80 can therefore also be considered as no-go zones for the thermal ablation source 50 and / or the insertion device including the thermal ablation source 50. Any planned trajectory must avoid the risk regions 80. For example, the risk regions 80 may correspond to certain organs, ureters, colons, blood vessels, nerves, muscles, etc., while the ablation target region 70 may correspond to a kidney cancer lesion. In FIGS. 2A and 2B, the treatment region 60 corresponding to the patient's abdomen is shown to be also displayed in an axial slice of a three-dimensional medical image.

[0068] As shown diagrammatically and exemplarily in Fig. 2A, each approach condition 21a, 21b; 22a, 22b may include a prescribed approach direction 21a, 21b. For each prescribed approach direction 21a, 21b, based on the prescribed approach direction 21a, 21b and the treatment area 60, a number of candidate approach points 22a', 22b' can be determined where one or more candidate trajectories 311a, 311b enter the treatment area 60 in the prescribed approach direction 21a, 21b. For example, first, in a given approach direction 21a, all directed lines that are necessarily parallel to each other and have a predetermined distance from each other are considered, and then, for all these directed lines, intersections with the treatment area 60 are determined. These intersections correspond to the candidate trajectories 311a that pass through the treatment area 60. Similarly, the candidate trajectories 311b can be determined based on the provided prescribed approach direction 21b. Based on the candidate trajectories 311a, 311b, the candidate entry points 22a', 22b' may be determined as points where the respective candidate trajectories 311a, 311b enter the treatment region 60. The candidate entry points 22a', 22b' thus correspond to intersections of directed lines of the respective candidate directions 21a, 21b with a surface or boundary of the treatment region 60 (which may correspond, for example, to the patient's skin).

[0069] FIG. 2B shows, in a schematic and exemplary manner, that each approach condition 21a, 21b; 22a, 22b may include a prescribed approach point 22a, 22b, for which, based on the prescribed approach point 22a, 22b and the treatment area 60, a number of candidate approach directions 21a', 21b' can be determined in which one or more candidate trajectories 312a, 312b enter the treatment area 60 at the prescribed approach point 22a, 22b. For example, first, all directed lines having a predetermined angular distance from each other that enter the treatment area 60 through the prescribed approach point 22a may be considered, and then the intersections of each directed line with the treatment area 60 may be determined. The candidate trajectories 312a, 312b may correspond to these intersections. Similarly, the candidate trajectories 312b may be determined based on the provided prescribed approach point 22b. The directions of the candidate trajectories 312a, 312b thus generated correspond to the respective directions of the initially considered directed lines intersecting with the respective prescribed approach points 22a, 22b in the direction towards the interior of the treatment area 60, and are preferably considered as candidate directions 21a', 21b' if and only if they correspond to the prescribed approach directions, in particular if they correspond to the prescribed approach directions.

[0070] FIG. 3 shows, in a schematic and exemplary manner, the type of data that the candidate thermal effect providing unit 130 can use to provide candidate thermal effects 10a, 10b that the thermal ablation source 50 generates in its vicinity in each configuration in the configuration space. This type of data may be provided, for example, by a supplier of the thermal ablation source. FIG. 3 shows the results of several simulations performed on the thermal ablation source 50 using different thermal control parameter values ​​32i, 32ii. The thermal control parameters considered in this example correspond to the ablation power and the ablation time, with the ablation power value shown in watts and the ablation time value shown in minutes, as shown in FIG. 3. In the illustrated example, the thermal ablation source 50 corresponds to the distal part of a needle-shaped thermal applicator, also called the ablation probe. According to the simulation results, depending on the values ​​32i, 32ii of the thermal control parameters controlling the thermal applicator, in particular the thermal ablation source 50, a generation of different thermal effects was observed in the vicinity of the thermal ablation source 50. The thermal effect produced decreases with increasing distance from the thermal ablation source 50. In this case, since the thermal ablation source 50 at the distal portion of the thermal applicator is elongated, the area subjected to the same or similar thermal effect also has an elongated shape, in particular an elliptical shape.

[0071] For each combination of thermal control parameter values ​​32i, 32ii, an ablation zone may be defined as a geometric characteristic of the corresponding generated thermal effect. Thus, the corresponding generated thermal effect may also be identified by the ablation zone. The ablation zone may be defined as an area in the vicinity of the thermal ablation source 50 that receives thermal energy above a certain threshold. Since the thermal ablation source 50 is elongated, the ablation zone is also generally elongated and has an elliptical shape in particular. In FIG. 3, for each simulation result, the length (L) and diameter (D) of each generated ablation zone are shown, as well as the forward distance (F) that indicates how far the ablation zone extends from the thermal ablation source 50, or tip of the thermal applicator, in the axial direction of the applicator. Thus, the forward distance indicates the position of the ablation zone relative to the thermal ablation source 50 and / or tip of the applicator, and the length and diameter of the ablation zone indicate its unique shape.

[0072] The simulation results shown in FIG. 3 assume models of heating and / or cooling in the vicinity of the thermal ablation source. It will be understood that these models may not accurately fit the tissue in the actual treatment region 60 targeted by the thermal ablation treatment plan. Thus, the thermal effects generated by the thermal ablation source 50, and thus the shape of the ablation zone, are expected to differ from the simulation results in practical applications. Thus, the thermal effects, and in particular the shape of the ablation zone, shown in FIG. 3 may also be understood as "expected" thermal effects or ablation zones, respectively. Factors that may cause deviations in the actual ablation event results relative to the simulation include the environment of the ablation target region 70, such as the environment of the tumor, microperfusion in the tissue, and the proximity of the location of the ablation event to large blood vessels. In general, the thermal effects generated by the thermal ablation source 50 also depend on the type of thermal ablation source 50. For example, FIG. 3 shows the simulation results of a microwave ablation probe with an electrode at its distal portion as the thermal ablation source 50. The simulation was performed using finite element analysis.

[0073] 4A-4F show, in a schematic and exemplary manner, that the configuration space providing unit 120 can select candidate thermal control parameter values ​​32i, 32ii along the candidate trajectories 311a, 311b; 312a, 312b such that the thermal ablation source 50 is activated only within the ablation target region 70. This can be effectively understood as cutting or limiting the candidate trajectories 311a, 311b; 312a, 312b to their intersection with the ablation target region 70, as also explained with reference to FIG. 5. In this way, the size of the configuration space considered for determining the treatment plan can be further reduced, and even fewer configurations need to be considered for determining the treatment plan. FIGS. 4A-4F focus on the ablation target region 70, with the border of the ablation target region 70 highlighted, towards the peripheral portion of the treatment region 60.

[0074] 4A-4F also show, in a schematic and exemplary manner, that the candidate thermal control parameter values ​​32i, 32ii may indicate activation positions along respective candidate trajectories 311a, 311b, 312a, 312b at which the thermal ablation source 50 is activated and the thermal effects 10a, 10b of the activated thermal ablation source at the respective activation positions. In particular, the activation positions may all be within the target ablation region 70 and along a single candidate trajectory 311a, 311b; 312a, 312b. The trajectory 311a, 311b; 312a, 312b itself is not shown in FIGS. 4A-4F. As can be readily seen from FIGS. 4A-4F, the wide range of possible thermal control parameter values ​​32i, 32ii along the trajectory, including the choice of activation positions, may result in a substantial number of configurations to be considered, even for a single candidate trajectory that also intersects with the ablation target region 70.

[0075] The configuration space providing unit 120 may determine a first class of candidate trajectories 311a, 311b; 312a, 312b in association with thermal ablation control parameter values ​​along the trajectories. These candidate trajectories include only single actuation positions with fixed thermal control parameter values ​​32i, 32ii. Such trajectories are shown in Fig. 4A and Fig. 4B, which differ only in the magnitude of the thermal control parameter values ​​32i, 32ii at each single actuation position, and thus only in the corresponding thermal effects 10c, 10d shown by the shape of the ablation zone shown. As shown in Fig. 4A and Fig. 4B, a single actuation position needs to be selected from among multiple candidate actuation positions along each candidate trajectory 311a, 311b; 312a, 312b.

[0076] 4C and 4D show multiple operating positions 311a, 311b; 312a, 312b along a single candidate trajectory, specifically the candidate trajectories 311a, 311b; 312a, 312b for three and two operating positions, respectively, and associated candidate thermal control parameter values ​​32i, 32ii along the trajectory.

[0077] As can be seen from the shapes of the ablation zones shown, the candidate thermal control parameter values ​​32i, 32ii in the different actuation positions shown in Figures 4C and 4D are the same and correspond to those in Figures 4A and 4B, respectively.

[0078] The configuration space providing unit 120 can also take into account different thermal control parameter values ​​32i, 32ii at actuation positions along a single candidate trajectory 311a, 311b; 312a, 312b. This is the case shown in Figures 4E and 4F, where the different ablation zone shapes already shown in Figures 4A-4D are mixed up along a single candidate trajectory 311a, 311b; 312a, 312b.

[0079] Similar to Fig. 4A and Fig. 4B, Fig. 4C-F show that multiple actuation positions (two or three in this case) may be located at different positions along the respective candidate trajectories 311a, 311b; 312a, 312b, i.e., different candidate actuation positions. It can also be seen from Fig. 4C-F that reference actuation positions may be defined at predetermined intervals along the intersection of the respective candidate trajectories 311a, 311b; 312a, 312b with the ablation target region 70. Each reference actuation position may be considered in terms of an offset relative to a certain reference actuation position. If the offset considered is limited, for example, within half of a predetermined interval in the anterior-posterior direction, it is possible to avoid considering an equivalent configuration multiple times and thus redundancy. For example, in Fig. 4C three reference actuation positions are defined, and for each reference actuation position, two actuation positions are considered in front of the reference actuation position and two actuation positions are considered behind the reference actuation position. The offset considered may be an integer multiple of a unit offset or may be selected to be non-uniformly distributed.

[0080] The candidate thermal control parameter values ​​32i, 32ii may indicate a fixed set of actuation positions along each candidate trajectory 311a, 311b; 312a, 312b, and / or a fixed set of candidate thermal effects 10a, 10b, 10c, 10d. This may further reduce the number of configurations to be considered when determining a treatment plan, further increasing the efficiency of the plan. For example, actuation positions may be defined to be equidistant along the candidate trajectories 311a, 311b; 312a, 312b, and the number of actuation positions along the candidate trajectories 311a, 311b; 312a, 312b may be further limited. More specifically, actuation positions may be defined to be no more than one, two, or three along each candidate trajectory 311a, 311b; 312a, 312b within the ablation target region 70, as shown in Figures 4A-4F. Fixing the set of candidate thermal effects 10a, 10b, 10c, 10d may correspond in particular to defining a limited number of possible ablation zones, e.g., the size and / or shape of the ablation zones. More specifically, the set of considered thermal effects, in particular ablation zones, along each candidate trajectory within the ablation target region 70 may be limited to one or two types 10c, 10d, etc., as shown in Figures 4A-4F.

[0081] The configurations shown in Figures 4A-4F need to be considered for each candidate trajectory 311a, 311b; 312a, 312b, i.e., for candidate trajectories 311a, 311b; 312a, 312b that intersect the ablation target area 70 at different heights and / or different angles. Thus, the total number of configurations considered to determine a treatment plan can be huge, e.g., more than 10,000, especially when dealing with a relatively large ablation target area 70, several types of relatively small ablation target areas 70, multiple prescribed approach directions 21a, 21b, and a relatively high approach point sampling density. Due to the several factors involved and their variations, the time required to determine a treatment plan can vary significantly.

[0082] Figure 5 shows, in a schematic and exemplary manner, the intersection of different candidate trajectories 311a, 311b having the same prescribed approach direction 21a, 21b with an ablation target region 70. The candidate trajectories 311a, 311b are shown in Figure 5 as multiple tubular path segments to illustrate the actual or realistic extension of a thermal applicator including a thermal ablation source 50 such as a needle when following the candidate trajectories 311a, 311b. The path segments shown in Fig. 5 are generated by tracking candidate trajectories 311a, 311b that enter the surface or boundary of the treatment area 60 at respective entry points 22a', 22b' determined for the prescribed entry directions 21a, 21b (the prescribed entry directions 21a, 21b can also be considered as projections of the prescribed directions 21a, 21b onto the segmented treatment area 60) and then pruning the tracked trajectories, or projected directions, in this case to segments that intersect with the ablation target area 70 and prevent intersections with no-go areas. In this pruning process, the offset of the ablation zone relative to the tip of the thermal applicator including the thermal ablation source 50 may also be taken into account. To obtain a final set of candidate paths or trajectory segments, i.e. those that can be used to perform treatment planning decisions, the planning of ablation events at locations that cannot actually be reached can be prevented, taking into account the length of the thermal applicator, by further shortening the segments that intersect with the ablation target area 70.

[0083] 6A-6G show, in a schematic and exemplary manner, steps performed for thermal ablation treatment planning. According to FIG. 6A-6G, one or more prescribed approach directions 21a, 21b are provided as approach conditions. Furthermore, FIG. 6A-6G show that the prescribed approach directions 21a, 21b can be provided based on user input. For example, they can be provided manually by a clinical expert via an instruction tool including a user interface in a semi-automatic treatment planning process.

[0084] 6A and 6B show how to initialize the planning process via the approach condition providing unit 110. For the initialization, the user can specify the desired approach direction 21a, 21b, for example, by freely specifying two points 231, 232; 241, 242 in a representation of the treatment area 60 and possibly of an area surrounding the treatment area 60, which representation may in particular correspond to a medical image. The two specified points 231, 232; 241, 242 and the order in which they are specified already imply the approach direction 21a, 21b defined by the user, and therefore also the side 61, 62 of the treatment area 60 (for example, the side of the body of the patient to be treated) in which the thermal ablation applicator should be inserted into the treatment area 60 during the ablation treatment. The two points 231, 232; 241, 242 can be indicated, for example, by clicking on a screen on which a medical image is displayed.

[0085] Two points 231, 232; 241, 242 are connected to a three-dimensional vector

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[0086] If the spatial relationship is the same, it does not matter where the user indicates the two points 231, 232; 241, 242, because in that case the indicated directions 21a, 21b and the corresponding calculated unit direction vectors remain unchanged. Thus, the user can freely move the indicated unit direction vectors or the arrows 23, 24 connecting the indicated pairs of points 231, 232; 241, 242 on the representation of the treatment area 60 without changing the desired approach direction 21a, 21b in which the ablation applicator is inserted. This can be useful, for example, when the clinician wants to infer the desired approach direction 21a, 21b from a first part of the medical image, but then wants to conclude what this means for a second part of the medical image, or when the indication given by the clinician in the first part of the medical image is barely visible due to the particular anatomical structure visualized in the first part, and the indication of the desired approach direction 21a, 21b is more easily visible in the second part of the medical image.

[0087] Based on the unit direction vector determined based on the user input, the prescribed approach directions 21a, 21b provided by the approach condition providing unit 110 are determined, and the candidate trajectories 311a, 311b to be considered for optimization of the treatment plan by the treatment plan determining unit 140 are determined by the configuration space providing unit 120. This will be described later with reference to Figures 6C to 6G.

[0088] As shown in FIG. 6C, the user indicates two desired or prescribed approach directions 21a, 21b, for example by clicking four points in the image of the treatment area 60 in sequence, thereby generating two corresponding unit vectors

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[0089] FIG. 6D shows the reference point

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[0090] This is shown in FIG. 6D, where the representation of the treatment region 60 corresponds to axial slices of the treatment region 60, so that these planes are reference points

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[0091] The generated plane, shown in FIG. 6D, is then expressed by the unit vector

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[0092] On the displaced plane, a planar coordinate system perpendicular to the respective unit vectors can be established, which can be used to sample the projection points, based on which candidate entry points can be determined. To that end, as shown in FIG. 6E, one or more meshes of one or more ablation target regions 70 are projected onto one or more planes, thereby generating two-dimensional ablation target projections on each plane. The two-dimensional ablation target projections can then be used to determine a bounding box 71′ that encloses each projection on the one or more planes, i.e., completely encloses the ablation target projections. The determined bounding box can also be considered as a field of view (FoV).

[0093] Within each bounding box 71', projection points may be (regularly) sampled at a predefined interval s in the planar direction of the respective planar coordinate system, which produces, for example, the points 711', 712' shown in FIG. 6E. Some of these projection points may then be discarded, in particular if the candidate trajectories 311a, 311b originating from or passing through the projection points in the normal direction of the respective planes hit the risk area 80. In FIG. 6E, points that may be discarded for this reason include the point 711'. The remaining projection points 712' may be projected onto the boundary or surface of the treatment area 60, such as the skin surface of the patient's body, or onto the corresponding mesh, in order to determine the candidate entry points 22a', 22b', as shown in FIG. 6F. A list of all sampled prescribed entry directions 21a, 21b and the corresponding determined candidate entry points 22a', 22b' may then be collected and sent as input for subsequent processing steps. Subsequent processing steps include, in particular, the determination of the intersections of the corresponding candidate trajectories 311a, 311b with the ablation target region 70, as described above with reference to FIG.

[0094] As mentioned above, Figs. 6A-6G do not show that one or more prescribed approach directions 22a, 22b are provided as approach conditions. However, similar principles can be applied to determine candidate approach directions 21a', 21b' from the prescribed approach points 22a, 22b. For example, for a given prescribed approach point 22a, 22b, all directed straight lines that enter the treatment region 60 through the prescribed approach point 22a, 22b can be considered, and from this set of lines, lines that pass through one or more ablation target regions 70, particularly without crossing the risk region 80, can be identified. The remaining identified directed straight lines, possibly a subset thereof that are oriented toward the prescribed approach directions, uniquely identify the candidate approach directions 21a', 21b' of the prescribed approach point 22a, 22b. The final generated list of pairs of candidate approach points and candidate approach directions can include the prescribed approach points 22a, 22b and the corresponding determined candidate approach directions 21a', 21b'. The prescribed entry points 22a, 22b may be indicated for one or more insertion areas, such as skin insertion areas, of the patient's body, for example, by a clinical expert. The skin insertion areas may be indicated using a suitable radiopaque marker, and the indicated insertion areas may be segmented, for example, in a medical image, or by indicating a set of virtual skin insertion areas in a three-dimensional rendered image of the treatment area 60 (in particular on the skin of the imaged patient's body). Regardless of how the insertion areas are indicated, the insertion areas can be used to sample a set of prescribed entry points 22a, 22b within the indicated insertion areas. For each of the sampled prescribed entry points 22a, 22b (which may in particular be points on the patient's skin), a fan-like divergence direction may be simulated and used for the subsequent optimization step as described above. Also, when the prescribed entry points 22a, 22b are provided, a subsequent processing step may be performed fully automatically to identify promising ones of the indicated skin insertion areas and / or promising entry points within the indicated skin insertion areas.

[0095] It is also possible to provide both the prescribed approach points 22a, 22b and the prescribed approach directions 21a, 21b. For example, if prescribed approach directions 21a, 21b are subsequently provided in addition to the initially provided prescribed approach points 22a, 22b, then for each prescribed approach direction 21a, 21b a corresponding one of a number of diverging directions may be selected from each fan direction emanating from the sampled prescribed approach points 22a, 22b. For example, within the illustrated inset area,

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[0096] Regardless of whether predefined approach directions 21a, 21b or predefined approach points 22a, 22b are initially provided, the final set of candidate approach directions 21a, 21b and candidate approach points 22a, 22b can be determined, for example, further based on a clinical history database, heuristic criteria, etc. Thus, in addition to criteria such as whether the candidate trajectories 311a, 311b, 312a, 312b intersect the ablation target region 70 without intersecting the risk region 80, other criteria can also be applied. These further criteria can be applied, for example, to pick out certain candidate approach directions together with their corresponding candidate approach points from those following the above procedure, which may be stored in a corresponding (possibly large) list, as described above.

[0097] Given the set of final candidate trajectories 311a, 311b; 312a, 312b (possibly only after considering the intersections of the resulting candidate trajectories 311a, 311b; 312a, 312b with one or more ablation target regions 70, as described above with reference to FIG. 5, and / or further based on a clinical history database, and following a set of final candidate approach directions and candidate approach points), and given the possible candidate thermal control parameter values ​​32i, 32ii corresponding to the candidate ablation events along the final candidate trajectories 311a, 311b, 312a, 312b, i.e. based on the final configuration space, an optimized treatment plan can be determined. For this purpose, the candidate thermal effect providing unit 130 can provide, for each configuration in the configuration space, a thermal effect characterized by a corresponding ablation zone. A heuristic mathematical solver acting as the treatment plan determining unit 140 can then solve a geometric combination problem in order to find, among all the considered candidate configurations, a configuration that results in an "optimal" plan for the planned thermal ablation treatment.

[0098] To define what is meant by "optimal," thermal effect goals may be defined. These can be considered as mathematical goals that serve as proxies for user-created considerations. The thermal effect goals that the treatment plan must meet may relate to either the overall thermal effect on the ablation target area 70, the overall thermal effect on areas outside the ablation target area 70, the number of actuation locations, and / or the geometric relationship of the actuation locations to the ablation target area 70. A single thermal effect goal may relate to several of these goals, or several similar goals, in which case they can be considered as sub-goals. In particular, a thermal effect goal may include several sub-goals, which are ranked by priority, and to determine the treatment plan, the candidate treatment plans are compared against the sub-goals according to their priority.

[0099] For example, sub-objectives such as maximum target coverage rate, minimum coverage within critical structures, minimum healthy tissue coverage rate, minimum number of ablation zones, and ablation symmetry (i.e., providing symmetric ablation locations relative to the target segmentation) may be ranked by importance in that order. The optimization problem may then be split into a series of single-objective optimization problems, where at each optimization step, treatment plans are first compared based on target coverage, and if the two solutions are equivalent, then based on coverage within healthy tissue, particularly critical structures, and so on. Lexicographical set-covering methods for multi-objective optimization may be used, as described in EP 3 777 748 A1, the entirety of which is incorporated herein by reference, and in the article by V. Chvatal, "A Greedy Heuristic for the Set-Covering Problem," Mathematics of Operations Research, Vol. 4, No. 3, pp. 233-235 (1979).

[0100] FIG. 6G shows some of the ablation events along the corresponding planned trajectories 41a, 41b and corresponding thermal effects characterized by ablation zones 11a, 11b that can be planned according to the finally determined treatment plan.

[0101] The determined treatment plan that meets the thermal impact goal can be modified by removing ablation events that can be removed without generating a portion of the ablation target area 70 that is thermally affected below a predefined threshold. This may also be referred to as a redundancy check. The redundancy check is advantageous and may further improve the overall efficiency, since the previous optimization may already aim to select a configuration set from the configuration space that uses as few ablation events as possible, but after this optimization there may still be redundant ablation events. In a treatment plan, an ablation zone in the ablation target area 70 may be considered as redundant if it is completely covered by other ablation zones in the same treatment plan. Such redundant ablation events may be present after optimization, since the set of selected trajectories corresponding to the treatment plan may include one ablation event that is essential for target coverage, while other ablation events in the same plan may be redundant. Thus, depending on the results of the redundancy check, redundant ablation events may be removed from the previously "optimized" treatment plan.

[0102] The system 100 may be part of an apparatus for thermal ablation treatment planning. The apparatus may further include a display device for displaying an image of the treatment area 60 and an input receiving unit for receiving a user input related to the image, and input conditions 21a, 21b, 22a, 22b may be provided based on the user input related to the image and / or the treatment plan is visualized in the image.

[0103] 7A and 7B show, in a schematic and exemplary manner, a possible user interface provided on the display of the device, which will be described in more detail later. The user interface may be generated by a corresponding program executed on a computer controlling the device. In the illustrated example, the ablation target area 70 corresponds to a kidney tumor. Since the aim of the procedure is to remove the entire tumor and leave as much healthy kidney tissue as possible, the kidney itself is defined in this case as the organ at risk, i.e. the risk area 80. The tabs on the left provide, for example, a button for adding a prescribed approach direction 21a, 21b ("Add Direction"), a button for deleting a prescribed approach direction 21a, 21b ("Delete Direction"), a button for calculating a treatment plan ("Calculate"), and a button for clearing the treatment plan ("Clear Plan").

[0104] The first planning step consists of providing a list of prescribed approach directions 21a, 21b, ie a list of three-dimensional (3D) directions that are used to calculate the optimal treatment plan (FIG. 7A).

[0105] This is done by clicking the "Add direction" button and repeatedly clicking two points on the displayed 3D medical image view (axial, coronal and sagittal) for each predefined approach direction 21a, 21b. The user can provide predefined approach directions 21a, 21b by freely clicking two points in a plane on the same image slice and / or on different slices. In the left tab one can see a dynamically populated list of predefined approach directions 21a, 21b added step by step by the user.

[0106] Once all prescribed approach directions 21a, 21b are properly provided, the user can perform the optimization of the ablation plan by simply clicking the "Calculate" button (Fig. 7B). Finally, a set of optimal elliptical ablation zones 75 is shown that are parallel to the prescribed approach directions 21a, 21b and cover the ablation target areas. The ablation zones 75 correspond to optimally transmitted thermal effects. The ablation coverage percentages of all segmented areas are displayed in the top left corner of the user interface, next to which are the names of the used meshes that correspond to the ablation target area 70 ("ROI1") and the area at risk 80 ("Kidney").

[0107] The user may indicate the prescribed approach direction 21a, 21b in other ways than by clicking on points on the medical image in sequence as described above with respect to Figs. 7A and 7B. For example, the user may indicate the prescribed approach direction 21a, 21b via a tracking device before placing the applicator. The tracking device may be, for example, an optical or electromagnetic tracking device. The prescribed approach direction 21a, 21b thus indicated may be detected by the apparatus as described above and visualized in real time on the user interface as shown in Figs. 7A and 7B. A mathematical solver corresponding to the treatment plan determination unit 140 may then determine an optimal treatment plan and the user may decide whether to proceed with the execution of the plan or to try again by proposing a new insertion direction as the prescribed insertion direction 21a, 21b.

[0108] The prescribed approach directions 21 a, 21 b can be indicated by simply clicking one point on the user interface, where a second point required to draw a vector corresponding to each prescribed approach direction 21 a, 21 b may then be calculated automatically based on the provided anatomical segmentation of the treatment area 60. For example, as the second point the geometric center of mass of the ablation target area or possibly even the center of mass of all ablation target areas can be used.

[0109] Each time the user modifies, adds and / or deletes one or more prescribed approach directions 21a, 21b, a corresponding new treatment plan may be automatically recalculated and displayed on the user interface.

[0110] A user can provide a set of prescribed approach directions 21a, 21b via a pre-implanted device that can be suitably separated from the clinical image, i.e. a device implanted in the treatment area 60 in preparation for the actual treatment plan.

[0111] A mathematical solver corresponding to the treatment plan determination unit 140 can constrain the plan optimization such that all returned optimal ablation events are located along the track of the installed device.

[0112] The system 100 can also operate fully automatically. The corresponding automatic method performed by the system 100 may include calculating a set of optimal entry directions 21a, 21b based on a set of clinical criteria and / or clinical knowledge and / or a historical database of treatment plans previously optimized by clinical experts. In some cases, the user may provide some additional directional hints to the otherwise automatically operating system 100, as explained in the semi-automatic case above. However, the automatic algorithm is free to choose other different insertion directions 21a, 21b if they are considered more promising compared to the ones recommended by the user.

[0113] In particular, for fully automated treatment planning, the system 100 may further include an artificial intelligence providing unit for providing an artificial intelligence trained to provide as output an output approach condition of a thermal ablation treatment plan that satisfies a thermal effect goal when a three-dimensional input image of an input area including an input ablation target area is provided as an input. The approach condition providing unit 110 may be configured to provide as input a three-dimensional image of a treatment area 60 including a thermal ablation target area 70 to be treated to the artificial intelligence and provide as output the output approach conditions provided by the artificial intelligence as approach conditions 21a, 21b; 22a, 22b used for the treatment to be planned. Thus, for example, the artificial intelligence may be trained to receive as input a medical image as shown in FIG. 7A and provide as output approach directions 21a, 21b that may result in a treatment plan that satisfies a predefined thermal effect goal as shown in FIG. 7A.

[0114] The artificial intelligence may include, among other things, a convolutional neural network (CNN) trained to infer a set of optimal insertion directions for a particular patient on that day. The training of the CNN model may be performed using a historical database that collects a large amount of optimal treatment directions used in actual clinical plans, i.e. treatment plans that were actually used in past clinical practice. Here, each database dataset may store clinical 3D images, and / or components of 3D directional unit vectors of segmented anatomical regions, and a set of performed treatment devices (i.e. ablation applicators). Clinical images may be passed through an input layer of the CNN, and the CNN model may be trained to infer and return as output the associated optimal directional unit vector. The training and / or tuning of the model may be performed by splitting the clinical database dataset into two separate learning and training sets, or possibly into training, validation, and test datasets. The training system may be used to train the artificial intelligence with past treatment plans as training data. The system 100 itself may function as such a training system, in which case the system 100 may comprise technical means configured to receive training input data and training output data.

[0115] The entry condition providing unit 110 may be configured to a) determine an intersection length between at least a subset of the candidate trajectories 311a, 311b; 312a, 312b entering the treatment region 60 according to at least a subset of all possible entry conditions and the ablation target region 70, and the entry conditions 21a, 21b; 22a, 22b are provided based on the determined intersection lengths.

[0116] Additionally or alternatively, the entry condition providing unit 110 may be configured to b) determine an ablation target distance for at least a subset of the candidate trajectories 311a, 311b; 312a, 312b for entering the treatment region 60 according to at least a subset of all possible entry conditions, the ablation target distance being the length of each candidate trajectory 311a, 311b; 312a, 312b from entering the treatment region 60 to reaching the ablation target region 70, and the entry conditions 21a, 21b; 22a, 22b are provided based on the ablation target distance.

[0117] In particular, the set of optimal approach directions may, for example, be automatically selected from an automatically generated, possibly relatively large but discrete number of 3D directions, and this selection may be made based on a set of heuristic selection criteria including criteria corresponding to options a) and / or b) below.

[0118] According to option a), for each candidate approach direction a discrete number of crossing segments can be sampled and calculated which correspond to segments of the candidate trajectories 311a, 311b; 312a, 312b having that candidate approach direction and passing through the ablation target area 60. The longer the crossing segment the better, since a trajectory with a larger crossing segment can cover a larger part of the ablation target area 60.

[0119] According to option b), for each candidate approach direction, a 3D distance from the skin surface to a point (e.g., a vertex of a mesh) of the ablation target area can be calculated along the candidate direction. The average or minimum distance value calculated for each candidate direction can be used as a criterion for selecting one or more optimal approach directions. In particular, a shorter average target-to-skin distance can result in a shorter path that a thermal ablation applicator including thermal ablation source 50 needs to follow to reach the thermal ablation target for treatment and / or a larger portion of the thermal ablation target can be reached by the thermal ablation applicator.

[0120] Directional unit vectors may also be displayed to the clinical professional or other user on the interface shown by Figures 7A and 7B, possibly together with a color-coded scale indicating each selection criterion value or composite selection criterion values.

[0121] FIG. 8 shows a schematic and exemplary thermal ablation treatment planning method 800, comprising the steps of: providing 801 entry conditions 21a, 21b; 22a, 22b indicating how a trajectory of a planned thermal ablation source 50 will enter a treatment region 60 including an ablation target region 70; and providing 802 a configuration space including: a) candidate positions corresponding to a plurality of candidate trajectories 311a, 311b; 312a, 312b of the thermal ablation source 50 through the treatment region 60; and b) candidate thermal control parameter values ​​32i, 32ii for each candidate position, where the candidate trajectories 311a, 311b; 312a, 312b enter the treatment region 60 according to the provided entry conditions 21a, 21b; 22a, 22b. and providing 803 candidate thermal effects 10a, 10b to be generated proximately by the thermal ablation source 50 at each configuration. The method 800 further includes determining 804 a thermal ablation treatment plan including a) planned trajectories 41a, 41b of the thermal ablation source 50 and b) planned thermal control parameter values ​​along the planned trajectories 41a, 41b, where the treatment plan is determined based on the candidate thermal effects 10a, 10b provided for each configuration such that the treatment plan meets a predetermined thermal effect goal.

[0122] The method 800 may be implemented, for example, by executing a computer program for thermal ablation treatment planning that includes program code means for causing the system 100 to perform the method 800.

[0123] 9 shows, in a schematic and exemplary manner, a flow chart summarizing certain aspects of a method 800 executable by the system 100. In the figure, several steps are grouped in block form, which may be considered to represent functionally and / or logically separable stages of the method 800. Given as input a set of provided insertion directions that may be provided by the user as prescribed approach directions 21a, 21b, a proposal for an "optimal" thermal ablation treatment plan to be performed using a given ablation device may be obtained as output. In arriving at the output, all possible ablation zones may also be considered.

[0124] In a first stage, exemplarily described with reference to Figures 6A-6F, body skin entry points are generated to identify a set of skin entry points 22a', 22b' used to insert all medical devices. This may include calculating a set of planes perpendicular to the provided directions 21a, 21b, calculating a set of bounding boxes on each plane that enclose the target projection, sampling a set of points in each bounding box in the respective plane, projecting the sampled points onto the skin surface of the patient's body, and collecting a list of entry trajectories 311a, 311b corresponding to pairs of skin entry points 22a', 22b' and provided directions 21a, 21b.

[0125] In a second stage, which may also be referred to as “geometric intersection”, all applicator trajectories that may potentially intersect the target 70 may be identified, which may involve computing a list of target intersection segments from the list of approach condition trajectories 311 a, 311 b, as exemplarily described above with particular reference to FIG. 5.

[0126] In the third stage, which may be called "geometric combination", all potential configurations (combined ablations) along each remaining trajectory are defined, which may involve computing a table of ablation shape configurations for each target segment. This is illustratively described with reference to Figures 4A-4F, and information such as that illustratively described with reference to Figure 3 may be used for "geometric combination".

[0127] In the fourth stage, which may also be called "optimization," an optimal combination of previously calculated configurations may be selected, which may involve calculating organ volume coverage rates for each table configuration and solving a mathematical set covering problem to find an optimal set of ablation configurations that meets all clinical protocol goals set by clinical experts.

[0128] Known approaches may be used at this stage.

[0129] In a fifth step, a "redundancy check" may be performed to avoid unnecessary ablations, which may include eliminating redundant ablations, as described above.

[0130] The result of this five-stage process may be an optimal thermal ablation treatment plan. The entire process may be implemented as a planning algorithm controllable via a user interface, and the user may be asked to draw a set of insertion directions 21a, 21b using appropriate visualization tools. During the five stages, all provided inputs may be processed to generate internal objects and data that may enable an internal mathematical solver to identify optimal treatment plans and return the best treatment plan as one output. The specific realization of the process shown in FIG. 9 has been described in detail above. In particular, various ways of determining optimal skin entry points 22a′, 22b′ and insertion path directions 21a′, 21b′ in the first stage have been described. The remaining stages, i.e., stages 2-5, may be realized in the same manner, regardless of how the first stage is realized.

[0131] Cancer treatment with thermal ablation is becoming increasingly popular because it can be applied to unresectable tumors and results in rapid patient recovery, but thermal ablation planning tools remain largely immature.

[0132] In thermal ablation treatment planning, optimal placement of the ablation device is important, which is often determined based on the location and size of the tumor, the device manufacturer's specifications, and the physician's experience. Furthermore, to reduce unwanted damage to nearby healthy tissue, the entire area to be ablated during treatment should match the tumor contour as closely as possible and may need to respect oncological safety margins. Thermal ablation treatment procedures often require the physician to select a set of probe positions, i.e. the applicator device and / or especially the location of the thermal ablation source on the device, and a corresponding set of delivery parameters (which may be derived from the values ​​of ablation power and time given in the probe manufacturer's specifications). To assist in the positioning of the probe, a rigid leading template, such as also used in brachytherapy, or a flexible radiopaque grid can be used to guide and guide the insertion of all treatment devices into the patient's body.

[0133] However, for some cancer types, such as thermal ablation treatment of kidney cancer, no leading grid template is used for guidance and the treatment is performed freehand. In this case, the clinical expert needs to determine a limited set of skin insertion points and probe needle 3D insertion tracks and directions to follow to reach and ablate all target cancer lesions based on medical images of all cancer lesions and nearby risk organs, ureters, colon, blood vessels, nerves, muscles, etc. In addition to solving the device positioning problem, the expert also faces the problem of selecting the best device ablation settings to use for treatment. This manual forward planning procedure can be very long and prone to errors. Generally speaking, there are large degrees of freedom in the thermal ablation treatment planning problem, especially without a grid, so the inherent space of solutions is very large and manual selection of the best plan can easily miss the best solution.

[0134] It has therefore been recognized that improved means for searching for the best plan (i.e., the best set of skin entry trajectories and device ablation settings), which may be implemented in the form of a mathematical solver, may be beneficial for simplifying the planning process, for improving the quality of the plan coverage, for making the entire planning process more standardized, and for making the entire planning process more efficient. It has been found that such means can be realized by the thermal ablation treatment planning system described herein. This thermal ablation treatment planning system works, in particular, on the basis of a segmentation of the cancer lesion and other anatomical structures, as well as a provided set of associated prescriptions (i.e., protocol goals), a provided set of ablation settings of one or more commissioned devices available for treatment, and a provided set of 3D insertion conditions, in particular directions (possibly provided by the user via a suitable user interface). In this case, an optimal treatment plan can be calculated consisting of a set of treatment devices inserted along a trajectory parallel to at least one of the given input directions.

[0135] The treatment may use one or more treatment devices, each including a respective thermal ablation source. As noted above, one or more trajectories corresponding to the treatment plan may be followed by one or more devices sequentially or substantially simultaneously, and there may be no need to remove a device while another device is inserted within the treatment area.

[0136] In the above embodiment, the treatment area includes only one ablation target area, but in other embodiments, the treatment area may include any number, in particular two or more ablation target areas, in which case further configurations may be considered based on one or more additional ablation target areas so that the determined treatment plan covers all ablation target areas within the treatment area.

[0137] Other variations of the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention from the drawings, the disclosure, and the appended claims.

[0138] In the claims, the terms "comprise" and "include" do not exclude other elements or steps and the words "a" or "an" in the singular do not exclude a plurality.

[0139] A single unit or device may fulfill the functions of several items recited in the claims. The mere fact that several measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

[0140] The steps performed by one or more units or devices, such as providing the entry conditions, providing the configuration space, providing the thermal effects, determining the thermal ablation treatment plan, etc., may be performed by any number of units or devices. These steps may be implemented with respect to program code means of a computer program and / or with respect to dedicated hardware.

[0141] The computer program may be stored / distributed on a suitable medium, such as an optical storage medium or a solid-state medium provided together with or as part of other hardware, but may also be distributed in other forms, such as over the Internet or other wired or wireless communication systems.

[0142] Any reference signs in the claims should not be construed as limiting the scope.

[0143] A thermal ablation treatment planning system is provided that allows for providing approach conditions indicating how a trajectory of a thermal ablation source should approach a treatment region, where a configuration space is provided that includes as configurations: a) candidate locations corresponding to candidate trajectories that approach the treatment region according to the provided approach conditions, and b) candidate thermal control parameter values ​​for each candidate location.

[0144] Based on the candidate thermal effects provided for each configuration, a treatment plan that meets the thermal effect goals is determined.

Claims

1. 1. A system for thermal ablation treatment planning, the system comprising: an approach condition providing unit that provides an approach condition indicating how a trajectory of a thermal ablation source to be planned should approach a treatment region including an ablation target region; a configuration space providing unit that provides a configuration space including, as configurations, a) candidate positions corresponding to a plurality of candidate trajectories of the thermal ablation source through the treatment region, and b) candidate thermal control parameter values ​​for each candidate position, wherein the candidate trajectories enter the treatment region according to the provided entry conditions; a candidate thermal effect providing unit for providing a candidate thermal effect generated in proximity by the thermal ablation source in each configuration; a treatment plan determination unit for determining a thermal ablation treatment plan, the treatment plan including a) a planned trajectory of the thermal ablation source; and b) planned thermal control parameter values ​​along the planned trajectory, the treatment plan being determined based on the candidate thermal effects provided for each of the configurations such that the treatment plan satisfies a predetermined thermal effect target; A system comprising:

2. 2. The system of claim 1, wherein the entry condition providing unit provides a plurality of entry conditions, the configuration space providing unit provides the configuration space such that each candidate trajectory enters the treatment region according to one of the entry conditions, and the treatment plan determination unit determines a thermal ablation treatment plan such that the treatment plan includes: a) a plurality of planned trajectories to be followed during treatment; and b) planned thermal control parameter values ​​along the planned trajectories.

3. 3. The system of claim 1, wherein each approach condition includes a prescribed approach direction, and for each prescribed approach direction, a plurality of candidate approach points at which the one or more candidate trajectories enter the treatment area in the prescribed approach direction are determined based on the prescribed approach direction and the treatment area.

4. 3. The system of claim 1, wherein each approach condition includes a prescribed approach point, and for each prescribed approach point, a plurality of candidate approach directions along which the one or more candidate trajectories enter the treatment area at the prescribed approach point are determined based on the prescribed approach point and the treatment area.

5. The system of claim 1 , wherein the candidate thermal control parameter values ​​along the candidate trajectory are selected such that the thermal ablation source is activated only within the ablation target region.

6. 2. The system of claim 1, wherein the candidate thermal control parameter values ​​indicate activation positions along each of the candidate trajectories at which the thermal ablation source is activated and a thermal effect of the activated thermal ablation source at each of the activation positions.

7. The system of claim 1 , wherein the candidate thermal control parameter values ​​indicate a fixed set of operating positions along each candidate trajectory and / or a fixed set of candidate thermal effects.

8. 2. The system of claim 1, wherein the thermal effect goal to be met by the treatment plan relates to any of the overall thermal effect on the ablation target area, the overall thermal effect on areas outside the ablation target area, the number of actuation locations, and / or the geometric relationship of actuation locations to the ablation target area.

9. 2. The system of claim 1, wherein the thermal effect goal includes several sub-goals, the sub-goals are ranked by priority, and candidate treatment plans are compared against the sub-goals according to the priority to determine the treatment plan.

10. 10. The system of claim 1, wherein the determined treatment plan that meets the thermal effect goal is modified by removing ablation events that can be removed without producing a portion of the ablation target region that is thermally affected below a predetermined threshold.

11. 2. The system of claim 1, further comprising an artificial intelligence providing unit that provides artificial intelligence trained to provide output approach conditions for a thermal ablation treatment plan that meets a thermal impact goal when a three-dimensional input image of an input area including an input ablation target area is provided, wherein the approach condition providing unit provides the artificial intelligence with a three-dimensional image of the treatment area including the thermal ablation target area to be treated, and provides the output approach conditions provided by the artificial intelligence as the approach conditions to be used for the treatment to be planned.

12. The entry condition providing unit: a) determining lengths of intersection of at least a subset of candidate trajectories entering the treatment region according to at least a subset of all possible entry conditions with the ablation target region, the entry conditions being provided based on the determined lengths of intersection; and / or The entry condition providing unit:

2. The system of claim 1, further comprising: b) determining an ablation target distance for at least a subset of candidate trajectories that enter the treatment region according to at least a subset of all possible entry conditions, the ablation target distance being a length of each of the candidate trajectories from entering the treatment region to reaching the ablation target region, and the entry conditions being provided based on the ablation target distance.

13. 1. An apparatus for thermal ablation treatment planning, said apparatus comprising: a display device for displaying an image of the treatment area; an input receiving unit for receiving user input relating to the image; The system of claim 1 . wherein the entry condition providing unit provides the entry condition based on a user input regarding the image, and / or the display device visualizes the treatment plan within the image.

14. 1. A method for thermal ablation treatment planning, the method comprising: Providing an approach condition indicating how the trajectory of the thermal ablation source to be planned should approach the treatment region including the ablation target region; providing a configuration space including, as configurations, candidate locations corresponding to a plurality of candidate trajectories of the thermal ablation source through the treatment region; and b) candidate thermal control parameter values ​​for each candidate location, the candidate trajectories entering the treatment region according to the provided entry condition; providing candidate thermal effects to be generated proximately by the thermal ablation source in each configuration; determining a thermal ablation treatment plan comprising: a) a planned trajectory of the thermal ablation source; and b) planned thermal control parameter values ​​along the planned trajectory, wherein the treatment plan is determined based on the candidate thermal effects provided for each configuration such that the treatment plan meets a predetermined thermal effect target.

15. A computer program for thermal ablation treatment planning, comprising program code means for causing a system according to claim 1 to carry out the method according to claim 14.

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