Abstract: A scenario-based treatment plan optimization method for radiotherapy treatment is proposed, in which a first and a second possible scenario are defined. Different optimization functions are defined for the scenarios and the treatment plan is optimized applying the first optimization function under the first scenario and the second optimization function under the second scenario, thereby obtaining a first optimized radiotherapy treatment plan.

Abstract: A method of evaluating a radiotherapy treatment plan for ion based radiotherapy, is proposed, comprising the steps of determining multiple elastic scattering of ions for scattering angles in a first angular interval having an upper limit at a selected cut-off angle by means of a model for Coulomb scattering; determining multiple elastic scattering of ions for scattering angles in a second angular interval having a lower limit at the selected cut-off angle; determining the scattering for angles in a range comprising at least a part of the first angular interval and at least a part of the second angular interval, based on the results obtained for the first and second angular interval, respectively. The method avoids the double counting of particles at large scattering angles that occurs when using conventional methods.

Abstract: It is provided a method for determining arc costs. The method comprises the steps of: determining a plurality of beam orientations; evaluating a set of at least one cost function comprising an intermediate exposure cost function that is evaluated by performing the substeps of: projecting the at least one target volumes on a beam plane; determining an alignment angle based on a collimator angle value; finding any intermediate area in the beam plane along the alignment angle between areas of the at least one target volume projection; determining a value of the intermediate exposure cost function. The method further comprises the steps of: finding a plurality of arcs, wherein each arc comprises a sequence of a plurality of beam orientations; and calculating, for each arc in the plurality of arcs, at least one arc cost based on the cost function values of the beam orientations of the arc.

Abstract: A method of correcting a first CT image for shading artefacts using another CT image as reference, comprising the steps of creating a difference image between the images and a correction map based on the difference image. The correction map is used to correct the first CT image. A method of converting a CT image to the value range of another CT image is also disclosed.

Abstract: It is provided a method for optimizing a treatment plan for use in radiation therapy. The method is performed in a treatment planning system and comprises the steps of: obtaining a first quality function of the treatment plan, the first quality function yielding an output value based on an input treatment plan; obtaining a first pair of input values and a slope indicator, the input values associating a value of the first quality function to a value of a score; constructing a score function that maps values of the first quality function to values of the score by fitting a curve to the first pair of input values and the slope indicator; and optimizing the treatment plan with respect to the score function, by varying the treatment plan such that the value of the score function is either improved or constrained to a feasible range of score values.

Abstract: The present disclosure generally relates to the field of radiation treatment. More specifically, the present disclosure generally relates to methods and radiation treatment systems for generating a radiation treatment plan. According to one example embodiment, a method may comprise dividing at least one dose characteristic related to a dose distribution for a ROI into a plurality of subintervals. The method may further comprise partitioning the ROI into a plurality of different partitions based on the subintervals. All voxels of the ROI with values within the same subinterval are partitioned into the same partition. For each of the plurality of different partitions, the method may comprise establishing a weight and specifying an optimization function for an obtainable dose distribution based on the respective subinterval of dose characteristics. The method may further comprise generating the radiation treatment plan based on said established weights and specified optimization functions.

Abstract: A method for ion based radiation therapy treatment planning for avoiding dose delivery to a distal risk organ, said risk organ being located after the target seen from a first beam angle, the method comprising defining an optimization function comprising at least one objective function related to at least one desired property of the treatment plan, wherein the objective function is related to limiting a parameter ? defining the fraction of the total number ?OAR of ions that reach the risk organ relative to the total number ?a of ions. In addition, one can assume a different density when calculating ? which will result in a plan that is more robust with respect to density perturbations.

Abstract: It is provided a method for determining a distribution of spots for use with ion beam therapy for providing the spots in a target volume, wherein each spot represents a collection of ions of a specific energy level and of a specific size at a specific lateral location. The method is performed in a treatment planning system and comprises the steps of: dividing the target volume in a plurality of target sections based on a user configuration comprising at least one spot size strategy defining a maximum spot size at the location of a Bragg peak; assigning a spot size strategy to each one of the target sections based on the location of the respective target section; and determining, within each target section, spots in accordance with its spot size strategy.

Abstract: A method of optimizing a radiation treatment plan of ion treatment, in which the optimization procedure is interrupted, some but not all low-weight spots are discarded and the optimization procedure is resumed with a reduced set of spots. The weight of one or more remaining spots may be increased before resuming the optimization procedure, for example by adding the spot weight of one or more of the discarded spots to one or more of the remaining spots.

Abstract: According to a first aspect, it is presented a method for determining a treatment plan comprising a distribution of spots for use with ion beam therapy for providing the spots in a target volume. The method comprises the steps of: selecting energy layers to be used in the treatment plan; determining a number of spot sizes to use; generating, for each energy layer, one copy of the energy layer for each spot size to use and populating each copy with spots of the spot size for that copy; optimizing spots of all copies of all energy layers, by repeatedly varying a weight of at least a subset of the spots and calculating an effect on a performance measurement, wherein the performance measurement is calculated by combining a plurality of evaluation criteria, comprising a first criterion related to total treatment time and a second criterion related to a desired dose distribution.

Abstract: A method is proposed for evaluating the robustness of a radiotherapy treatment plan. The method comprises, defining a number of scenarios, each comprising one or more errors for each fraction of the plan, including interfractional and/or intrafractional errors, and calculating a dose distribution resulting from the scenario; The robustness of the plan is then evaluated based at least one of the following i. the probability of fulfilling a set of clinical goals estimated as the clinical goal fulfillment over the scenarios ii. the range of DVH values over the scenarios iii.

Abstract: A method of evaluating the robustness of a radiotherapy treatment plan for ion based radiotherapy, comprises the steps of: obtaining information related to the incident energy of ions that will stop in each voxel of the treatment volume; calculating a quantity value representative of the incident energy of these ions; and using the quantity values calculated for the first and second portion as a measure of the quality of the radiotherapy treatment plan, in particular its robustness. The information may include the mean incident energy for all ions, and/or an indication of the distribution of the energy values for all the ions.

Abstract: A method of evaluating a radiotherapy treatment plan for ion based radiotherapy, is proposed, comprising the steps of determining multiple elastic scattering of ions for scattering angles in a first angular interval having an upper limit at a selected cut-off angle by means of a model for Coulomb scattering; determining multiple elastic scattering of ions for scattering angles in a second angular interval having a lower limit at the selected cut-off angle; determining the scattering for angles in a range comprising at least a part of the first angular interval and at least a part of the second angular interval, based on the results obtained for the first and second angular interval, respectively. The method avoids the double counting of particles at large scattering angles that occurs when using conventional methods.

Abstract: A method of performing dose calculations for ion radiotherapy compensating for tissue in which the density within a voxel may be inhomogeneous by approximating a portion of the voxel as an air cavity. For each dose voxel, the voxel is inscribed in a three-dimensional grid comprising a number of cells and the propagation of ions through the voxel is calculated based on the cell pattern in the at least one cell overlapping the voxel. Preferably, the voxel is inscribed in the three-dimensional grid in such a way that it overlaps at least one cell fully. Each cell comprises a first portion representing a first density corresponding to a density of a tissue and a second portion representing a second density corresponding to the density of air, the first and second portions forming a cell pattern.

Abstract: The present disclosure relates to a system, a method, a computer program and a computer readable medium for determining the thickness of a range shifter to attain target dose coverage in ion beam treatment, wherein the range shifter is for use in a machine for radiation treatment of a target volume, by: receiving, in a processor, input parameters comprising a radiation energy parameter, a range shifter material parameter, object geometry information, and beam characteristic parameters; and further calculating, for each of at least one delivery direction, a range shifter thickness, based on the input parameters, which will deliver the optimum dose conformity.

Abstract: An interpolation of deliverable radiotherapy treatment plans is facilitated by restricting the movement of the multi-leaf collimator leaves between optimization steps.

Abstract: A system plans a radiation therapy treatment of a target volume based on inputs in the form of: a set of candidate beams (B), where each beam defines an arrangement of a therapeutic beam relative to the target volume; a treatment plan (x) for the radiation therapy treatment that uses a subset of the candidate beams (B); an objective function (F) describing a quality of the treatment plan (x); and a feasible region (X) describing requirements on the treatment plan (x) that must be fulfilled. The objective function (F) and/or the feasible region (X) also reflect a first complexity criterion (?(x)?{circumflex over (?)}) limiting a first complexity measure (?(x)) to be less than or equal to a maximum first complexity ({circumflex over (?)}). An optimization step is executed repeatedly; whereby, in each iteration, an updated treatment plan (x?) is calculated by optimizing the treatment plan (x) with respect to the objective function (F) and the feasible region (X).

Abstract: A system for determining a treatment plan in active ion beam treatment, to minimize unwanted dose, while maintaining or improving target dose coverage, whereby a beam is split into at least two sub-beams and where each sub-beam has a range shifter of different settings.

Abstract: A method of evaluating the robustness of a radiotherapy treatment plan for ion based radiotherapy, comprises the steps of: obtaining information related to the incident energy of ions that will stop in each voxel of the treatment volume; calculating a quantity value representative of the incident energy of these ions; and using the quantity values calculated for the first and second portion as a measure of the quality of the radiotherapy treatment plan, in particular its robustness. The information may include the mean incident energy for all ions, and/or an indication of the distribution of the energy values for all the ions.

Abstract: A data processing unit receives a reference image (IMG13D) of a deformable physical entity, a target image (IMG23D) of said physical entity, and a first region of interest (ROI13D) defining a first volume in the reference image (IMG13D) representing a reference image element. The reference image (IMG13D), the target image (IMG23D) and the first region of interest (ROI13D) all contain 3D datasets. In response to user commands (c1; c2), the data processing unit defines a first contour (C12D) in a first plane through the target image (IMG23D), which is presented to a user via a display unit together with graphic data reflecting the reference image (IMG13D), the target image (IMG23D) and the first region of interest (ROI13D). The first contour (C12D) is aligned with at least a portion of a first border (IEB1) of a target image element (IE3D) in the target image (IMG23D). The target image element (IE3D) corresponds to the reference image element in the reference image (IMG13D).