Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
  • A61N5/00—Radiation therapy
  • A61N5/10—X-ray therapy; Gamma-ray therapy; Particle-irradiation therapy
  • A61N5/103—Treatment planning systems
  • A61N5/1031—Treatment planning systems using a specific method of dose optimization
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
  • A61N5/00—Radiation therapy
  • A61N5/10—X-ray therapy; Gamma-ray therapy; Particle-irradiation therapy
  • A61N5/1077—Beam delivery systems
  • A61N5/1081—Rotating beam systems with a specific mechanical construction, e.g. gantries
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
  • A61N5/00—Radiation therapy
  • A61N5/10—X-ray therapy; Gamma-ray therapy; Particle-irradiation therapy
  • A61N5/1077—Beam delivery systems
  • A61N5/1083—Robot arm beam systems
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
  • A61N5/00—Radiation therapy
  • A61N5/10—X-ray therapy; Gamma-ray therapy; Particle-irradiation therapy
  • A61N5/1048—Monitoring, verifying, controlling systems and methods
  • A61N2005/1074—Details of the control system, e.g. user interfaces
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
  • A61N5/00—Radiation therapy
  • A61N5/10—X-ray therapy; Gamma-ray therapy; Particle-irradiation therapy
  • A61N2005/1085—X-ray therapy; Gamma-ray therapy; Particle-irradiation therapy characterised by the type of particles applied to the patient
  • A61N2005/1087—Ions; Protons
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
  • A61N5/00—Radiation therapy
  • A61N5/10—X-ray therapy; Gamma-ray therapy; Particle-irradiation therapy
  • A61N2005/1085—X-ray therapy; Gamma-ray therapy; Particle-irradiation therapy characterised by the type of particles applied to the patient
  • A61N2005/1089—Electrons

Definitions

• the invention relates to the optimization of a method for calculating doses deposited by an ionizing beam, for example used by a therapeutic treatment device by radiotherapy. Due to recent technologies in radiotherapy (arc therapy, tomotherapy, cyberknife), the ionizing beam can be in motion.
• the geometry of a patient's body, its tissues and possible tumors can be established. Zones with the same electronic density can be grouped together.
• the doctor determines the areas to be irradiated and preserved, possibly with certain margins of safety (organs in slight movement, know-how of the doctor, protocols, etc.) as well as the associated doses (minimum and / or maximum).
• the general technical problem then consists in optimizing the dose deposition by ionizing beams in the tissues so as to irradiate at least the tumors, maximally the healthy tissues and not reach some others if possible (for example the spinal cord) .
• the beams are controlled (position in space, intensity or fluence) and recovery of a treatment plan aims to optimize the distribution of these radiation doses.
• the patent EP10732960 entitled “Method for calculating doses deposited by ionizing radiation” (Blanpain, Mercier, Barthe), a process called “Doséclair” thereafter, discloses, as stated in its summary, a method of calculation comprising at least a first step of calculating a dose distribution function in meshes of a meshed phantom, a second step of calculating the dose deposited in a set of voxels, the value of the dose deposited for a voxel being given by the function of distribution of the dose specific to the mesh to which the voxel belongs.
• the invention applies to intensity-modulated radiation therapy (fluence).
• This method although powerful, is not yet fast enough to allow a method of exhaustive optimization of the irradiation parameters (that is to say by testing all the possible solutions in order to select the best of them ) in order to better respect the doctor's prescription.
• a method eg, computer implemented of estimating a dose gradient with respect to the parameters of a beam of ionizing particles, the dose being deposited by the beam in a voxel of a meshed phantom of a patient, each mesh comprising voxels of the same material, the parameters of the beam comprising a fluence parameter and geometric parameters, the method comprising the determination of the analytical function of the gradient of the dose, deposited by mesh, by ratio to the beam parameters; and determining the dose gradient estimate in the voxel.
• Some methods for estimating the deposited dose are described. Developments include multiple irradiating beam configurations, independent or partially dependent, processing plane optimizations using cost functions and moving beam management along paths. The use of one or more slave robotic arms or helical or moving systems is described.
• the method makes it possible to calculate simultaneously the gradient on the fluences and, at the same time, the gradient of the dose with respect to the geometrical parameters (of which no document of the state of the art makes mention). This implies a major practical advantage.
• a new configuration of the beams and associated fluences can be optimized, all the parameters being taken into account simultaneously.
• the beams according to the invention are "determined" simultaneously: the irradiation process according to a beam can be adapted according to what the other beams do.
• the speed of calculation allowed by the proposed method makes it possible to derive the analytical formulation, for example provided by "Doseclair", and to apply an iterative optimization process, for example by descent of the gradient, which plays on all the parameters. beam. Since a cost function is defined to qualify the suitability of a treatment plan for minimum or maximum dose objectives in the different organs, the proposed method makes it possible to provide an analytical formulation of the gradient of this cost function. in the meshes, always in relation to the parameters of the beams.
• An advantage associated with the disclosed method also lies in the fact that the calculations can be fast.
• the calculation codes can be optimized and parallelized (each elementary beam then each voxel can be evaluated independently of the others, this in correspondence with the multi-core architectures of the processors).
• the corresponding speed of calculation makes it possible to propose a treatment plan quickly (typically less than 20 minutes, eg the time of a consultation and a discussion on the principle of the treatment), for example that the appointments can be made immediately at the end of the consultation.
• FIG. 1 illustrates by examples the notion of " ghost "of a patient, of" mesh “of ghost and” voxel "of a mesh;
• FIG. 2 illustrates an example of advantageous coordinate system for defining the geometrical parameters of an ionizing beam
• FIGS. 3A and 3B illustrate various examples of embodiments of the invention, the beam of ionizing particles being in motion
• Figure 4 schematically illustrates process steps, including estimation of the dose gradient.
• FIG. 1 illustrates the concepts of ghost, voxel and mesh.
• the phantom of a patient 1 10 is a three-dimensional matrix representation of a part of the body of the patient 100.
• a phantom 1 10 consisting of meshs 130 (for example a mesh of water 131, a bone mesh 132 or lung 133), each voxel (for example 140) is characterized by the fact that it consists of the same material and / or the same electron density.
• a voxel e.g., 140
• the term voxel must be interpreted in a generic sense, in its broadest acceptation.
• the voxel is the "atomic" unit.
• the voxel generally corresponds to the unit of resolution of the apparatus.
• a tumor can be of the same density as the surrounding tissues.
• the voxel descent is necessary to see anatomical elements that can not be distinguished at the scale of the mesh.
• a mesh (131, 132, 133) corresponds to a grouping of adjacent voxels.
• the mesh may be regular or irregular, the mesh may be of different sizes.
• the deposited dose is calculated using an analytical form.
• an analytical form may correspond to the composition of a projection function and a pre-calculated dose distribution function. By multiplying this normalized dose distribution by the initial fluence of an elementary beam, an associated dose distribution is obtained.
• analytic function To all the voxels of the same mesh is associated a single analytic function. In other words, to know which analytic function is associated with a given cell, the voxel of interest is examined. This voxel is associated with a certain position within a certain mesh of the phantom. The same analytical function is used for several voxels of the same mesh. The evaluation of the analytic function may be different from one voxel to another. Two voxels given can correspond to two different meshes. The evaluation of the analytic function can also be different from one voxel to another, even within the same mesh, since the position is an input variable ⁇ "input" in English) of the analytic function (c is the P in the equations)
• the analytic functions according to the invention are concretely implemented in the form of algorithms (or a collection of algorithms). There is a wide variety of algorithms that can be used to implement the same analytic (mathematical) function. There is also a variety of analytical functions that lend themselves to the different embodiments of the invention. These functions may therefore take different forms and / or be obtained by different paths than those currently disclosed ("Doséclair").
• the analytic functions according to the invention correspond to continuous, differentiable and additive functions.
• a gradient is an operator that quantifies first-order the variation of a function induced by the variations of the variables on which it depends.
• a SBIM (Sub-Beam In Mesh) 131 appearing in FIG. 1 and detailed in "Doséclair" represents a sub-part of the elementary beam in a mesh, corresponding to all the photons that have a primary interaction with the material in a particular volume. the ghost so that: the middle of this volume is homogeneous; the fluence on a section is constant or a very small variation. If this is necessary then, the beam can be cut into SBIMs sufficiently narrow so that the variations of their fluence are not significant on the section.
• the use of SBIMs should be seen as a convenience of calculation and is by no means an essential feature. Reference is made to the patent "Doséclair".
• the dose calculation method is not directly differentiable, at least not analytically. There is indeed a parameter that can not be processed analytically and it is this parameter whose derivative is calculated by propagation. This parameter reflects the heterogeneities of the medium, including the "void" zone between the beam origin and the patient's body.
• Axial propagation consists of calculating step by step, recursively, the deposited dose. Lateral propagation corresponds to the fact that a change of material in the neighboring mesh can have consequences on the lateral decay of the dose. Finally, multiple lateral propagation is also possible using the principle of propagation mesh mesh. The tensor calculation associated with the propagation step according to the invention integrates all of these modes of propagation.
• FIG. 2 illustrates the degrees of freedom of a beam in a particular embodiment.
• a beam of ionizing particles (“irradiating beam” or “irradiation beam”) is characterized by its direction in space and its fluence (more precisely the spatial modulation in fluence corresponds to the intensity of the beam).
• FIG. 2 illustrates a particular and optional coordinate system that lends itself to the tensor calculation for determining the gradients and the propagation operations of the analytical parameters in a particularly advantageous manner.
• a beam has five degrees of freedom, corresponding to the origin, rotation and direction information of the beam in space: the origin P of the beam is determined from the origin center of the phantom 210 via the angles ⁇ (longitude, 223) and ⁇ (colatitude, 221) and R the radius of the sphere which is considered constant here (and therefore not as a parameter).
• the orientation of the beam is determined by the triplet (cr; ⁇ ; y) according to the Euler angles (here the variant named Tait-Bryan zyx or the succession of rotations in defined by a rotation by a around the z axis , a rotation by ⁇ around the new y-axis (sometimes also denoted by y), a rotation around the new x-axis (sometimes also denoted x ")
• the M-beam is entirely determined by the quintuplet ( ⁇ ; ⁇ ; o; ⁇ According to this coordinate system, it is possible to demonstrate by tensor calculus operations that it is possible to obtain the gradient of the dose deposited at each point of the phantom with respect to the parameters of the beam. that this frame of reference as well as the associated mathematical notations are optional, in the sense that it can not be an essential characteristic but only a convenience of calculation (by compensation in the tensor calculation).
• each gradient tensor can be defined analytically. It is possible to calculate gradients only at points of interest. It is possible to obtain the gradient of the dose deposited at each point of the phantom with respect to the parameters of the elementary beam.
• a method of estimating a dose gradient with respect to the parameters of a beam of ionizing particles the dose being deposited by said beam in a voxel of a phantom of a patient, said phantom being meshed, each cell of the phantom having voxels of the same material, the parameters of the beam comprising a fluence parameter and geometric parameters, said method comprising determining the analytic function of the gradient of the dose, deposited by mesh, with respect to the parameters of the beam; and determining the dose gradient estimate in the voxel.
• the term “voxel” should be interpreted, if necessary, in a generic sense (for example by analogy with the "pixel" of an image).
• the analytical function of the mesh-deposited dose gradient is determined with respect to the beam parameters, which parameters include both the beam fluence parameter and the geometrical parameters of the beam.
• the term “estimate” may (inter alia) be interpreted as a “calculation” (approximated or approximate).
• the "real" value of the gradient exists but this value is not directly accessible, ie there is no formal explanation of a formula for its direct and exact computation (its most precise approximation is precisely the object of the present disclosure). Subject to these reservations, the term “estimate” may be substituted by the term “calculation”.
• the method of "Doseclair” is invoked to estimate or determine the deposited dose.
• This combination remains optional, other methods of calculation of deposited dose are possible.
• a method of estimate of a dose gradient the estimate of the dose gradient being the gradient of the dose estimate, and for which the estimate of the dose deposited in the voxel includes the determination of an analytical function of dose calculation deposited by mesh, said function being obtained by propagation of the parameters of analyte functions of dose deposited step by step in the neighboring cells and traversed by the beam, and the determination of the estimate of the dose deposited in the voxel.
• the dose gradient is the gradient of the dose estimate.
• Doseclair discloses a dose estimation (dose calculation) method.
• Doseclair dose dose can be summarized or interpreted as follows: "estimation of the dose deposited in the voxel [including] the determination of an analytic function of dose calculation deposited by mesh, said function being obtained by propagation of the parameters of analytical functions of dose deposited gradually in the neighboring meshes and traversed by the beam; and determining the estimate of the dose deposited in the voxel.
• This estimation method is advantageous but it is not the only one possible. In other words, this calculation method remains entirely optional, that is to say optional.
• the method may provide for the use of a plurality of independent beams.
• the method may furthermore comprise the determination of the dose deposited in the voxel by summation of the doses deposited by each independent beam.
• the beams may be dependent or independent.
• the displacement of a beam can - or not - affect the displacement of other beams.
• the deposited doses are additive.
• the determination of the total dose deposited can be done in different ways. For example, it is possible to determine the overall dose by summation of the doses deposited by each beam (additivity). The global or total gradient is obtained by summation of the gradients of each beam.
• the (geometrical) parameters associated with the beams are independent, that is to say that there is no mathematical relationship between them. In other words, independent beams do not have interdependent geometric parameters. Knowing some parameters of certain beams does not allow to deduce the others.
• the parameters are dependent, at least in part, that is, there is a relationship between them. For example, if the centers of four beams form a square, the knowledge of the first three centers leads to the determination of the fourth center at the fourth vertex of the square). If there is independence, such a deduction is impossible. In the case of "Cyberknife” (described below) or so-called "step and shout” bundles, there may be independence.
• the method may include estimating the dose gradient deposited in the voxel by summing the dose gradients deposited by each independent beam.
• the global or total gradient is obtained by summation of the gradients of each beam.
• this addition is done on gradients, which can be described as "extended", i.e. in a mathematical notation format that makes summation possible.
• the method may further comprise a step of determining the dose deposited in the voxel.
• the gradient is then evaluated relative to a set of parameters selected in the union of the parameters of the different beams so as to be all independent and / or meta-parameters from which are deduced certain parameters of several beams, summing the "extended" gradients of each beam.
• the "main" beam is the sum of the adjacent small beams.
• the dependence is therefore double. All directions of the small beams constituting the "main” beam are identical (alphas, betas, gamma).
• the centers of the small beams are distributed on a regular grid (generalization of the simplified example of the square previously described).
• the dependence is partial for the IMRT because the fluences are indeed independent and in the presence of three beams
• the irradiation configuration continuously along a path is particular.
• arc therapy is a dynamic approach that varies both the position of the blades and the arm angle of the device during irradiation.
• An arc is defined by two extreme positions between which the beam is present throughout the irradiation.
• the complete arc is approximated by a series of uniformly spaced fixed fields called control points. Intensity is optimized for each control point.
• the tomotherapy is in the form of a ring that rotates around the treatment table on which the patient is installed, said ring being composed of a linear accelerator with a binary collimator.
• Each complete rotation of the linear accelerator can be approximated by a series of discrete steps.
• Tomotherapy (by the nature of the trajectory and the binary collimator) can be considered as a very special case of arc therapy.
• the cyberknife is a device linking a linear accelerator producing a fine beam to a robotic arm, the so-called arm allowing to freely move the linear accelerator around the patient, thus being able to produce almost any trajectory for the fine beam.
• the determination of an analytical function of dose gradient calculation deposited in any voxel of the phantom is obtained by the gradient of the composition of the projection function with the function of the dose deposited in a voxel; the determination of the analytical function of gradient calculation of dose being calculated step by step in the meshes traversed by the beam.
• the geometrical parameters of a beam may comprise five degrees of freedom, corresponding for example to the origin, rotation (ie two degrees) and direction of the beam in space (ie three degrees of freedom). degrees).
• degrees corresponding for example to the origin, rotation (ie two degrees) and direction of the beam in space (ie three degrees of freedom). degrees).
• Other coordinate systems are possible.
• the coordinate system presented is well suited for calculations.
• a method comprising the steps of selecting a differentiable cost function; determining the gradient of said cost function with respect to the beam parameters, said gradient being obtained by composition of the derivative of the cost function with respect to the dose with the gradient of the dose with respect to the parameters; and minimizing said cost function corresponding to obtaining a local minimum of the cost function.
• the method can indeed aim at optimization (in particular the treatment plan).
• a differentiable (or at least differentiable) cost function can be used.
• the method includes determining and minimizing the cost function for a plurality of voxels, whether or not they belong to the same mesh.
• the method includes determining and minimizing the cost function for a plurality of voxels.
• the expression "belonging or not to the same mesh” is optional and constitutes an explicit reference to the fact that the irradiation can reach many meshes (overflows and overlaps for example). Irradiation can indeed "overflow” on neighboring or adjacent meshes.
• the cost function evaluates well for a plurality of voxels, which is the smallest unit or subdivision used.
• the treatment plan may aim to deliver minimal doses at the level of the tumor, and maximum otherwise (sensitive tissues). Each voxel can have its own threshold. At the tumor level, a minimal dose can be imposed to ensure that all tumor cells are destroyed.
• a maximum dose may be imposed to limit the side effects of treatment on healthy cells, particularly induced tumors that occur a few years later.
• the maximum dose is not necessarily the same everywhere, as some tissues (optic nerve, spinal cord) are much more sensitive and vital than others.
• the calculation method according to the invention therefore also uses a cost function.
• a "cost function” is a real-valued mathematical application (or function) that evaluates the performance of a parameterized model, according to a certain criterion.
• the parameters can be the fluences, directions and positions of the beams.
• an example of the objectives that the cost function must translate may be: a) if a minimum dose is sought, then the dose deposited is less than this dose and the cost function must be to be important.
• the cost function must increase rapidly if the dose deposited exceeds this threshold. At the same time, it must be low when the delivered level is lower, but ideally zero if (and only if) no dose is deposited, c) overall doses or widely distributed errors are preferred. For example, for a total of 1 mGy deposited on 2 voxels, preference will be given to a solution which deposits 0.5mGy in each voxel rather than 1 mGy in one and 0 in the other. In all cases, the cost function must be differentiable (or at least differentiable).
• FIGS. 3A and 3B illustrate examples of embodiments of the invention, the beam of ionizing particles being in motion.
• FIG. 3A illustrates a robotic arm carrying one or more beams, the slave robotic arm being movable around the patient, in a configuration called "Cyberknife".
• FIG. 3B illustrates an example of a "helical" system combining translations and rotations. It should be noted that the arc therapy covers configurations or situations beyond such helical systems.
• one or more beams are moving.
• a beam may be moving along a trajectory comprising at least two control points and intermediate trajectory points.
• This system may include an arc therapy system (mobile irradiation beam during irradiation).
• an optimization of the treatment plan can be based on the optimization of the irradiation parameters associated with the control points.
• the irradiation parameters associated with the intermediate trajectory points can be deduced by interpolation of the irradiation parameters associated with the control points.
• trajectories can be defined by broken lines.
• the doses can then be interpolated.
• the dose delivered on the trajectories can be optimized.
• a reduced number of control points can control dose delivery.
• Other interpolation methods can be used, particular optimizations of trajectories can be calculated.
• Figure 3A illustrates a so-called "Cyberknife” configuration showing a robotic robotic arm 300 carrying one or more irradiating beams 310.
• the arm moves around the patient.
• the driving of the robotic arm can be fully automatic or preprogrammed.
• the driving may also possibly be remote controlled by the operator (in some cases of radio surgery).
• Driving can at least be assisted, ie partially automated.
• the arm can be controlled remotely if network latency times allow (there are techniques to reduce latency to a minimum by optimizing the processing chains of the system. signal).
• FIG. 3B shows a so-called "helical" configuration 320, combining translations 321 and rotations 322). This configuration allows practically all beam placements (especially irradiations directed under the body of the patient).
• the hospitals are equipped with such devices that can be modified accordingly (adaptation of ionizing beam control software layers or irradiating heads).
• the slave robotic arm may optionally include the appropriate instrumentation, such as one or more position and movement sensors (accelerometer, gyroscope, etc.) making it possible to know and with sufficient precision the geometrical parameters as well as the fluence of the beam.
• an adaptation of the fluence of the beam can be carried out, for example according to the movements of the ionizing beams.
• a guidance in the authorized movement ranges can be (optionally) provided to the operator (visual guidance by laser projection and / or sound in case of exit from the authorized or planned spatial ranges or "corridors", haptic feedback etc.) .
• Augmented or virtual reality systems e.g. helmet or immersive, semi-transparent or opaque goggles
• Block 480 is a general diagram illustrating the operation of the process and its main steps. Some process steps can be performed sequentially, others in parallel. The indications of the diagram are thus illustrative and not limiting.
• Block 490 illustrates that the method can be implemented by computer.
• An optimization loop 470 comprises a step of calculating or estimating the function of the deposited dose 460 (by propagation in the cells so as to obtain the deposited dose analytical function).
• step 472 are estimated the total dose deposited by the different beams (if any) as well as the gradient of the deposited dose, for example for the voxels of interest.
• step 473 using a cost function and its gradient, the optimized parameters of the independent 474 and / or dependent beams 475 can then be determined. The preceding steps are iterated as long as the improvements are significant (loop 471). ). Predefined thresholds or different other quantitative criteria can be used to establish that the improvement of the dose distribution is optimal (step adjustments, etc.).
• the program of the treatment plan is determined in step 476 and optionally displayed (in whole or in part) at step 477.
• the dose calculation 460 comprises different sub-steps. For each beam 461, for each cell traversed or neighboring 462, the analytical function of the deposited dose is calculated (or estimated) in step 466. More specifically, an analytical function of deposited dose can be determined. Different methods exist to do this. One way of proceeding corresponds to the method described in "Doséclair" (but it is not the only possible method).
• the analytical function of the gradient of the dose estimate is determined at step 464. The analytical function of the dose gradient is obtained. The iteration continues, with the passage to the next beam 465 for each mesh traversed or adjacent.
• the process is iterated until all the ionizing beams (if any) are taken into account.
• the total dose can be estimated or calculated (i.e. on all meshes and bundles).
• a method of estimating a dose gradient with respect to the parameters of a beam of ionizing particles the dose being deposited by said beam in a voxel of a phantom of a patient, said phantom being a mesh, each cell of the phantom comprising voxels of the same material, the parameters of the beam comprising a fluence parameter and geometric parameters (including, for example, origin, rotation and direction information of the beam in space), said method comprising determining the analytical function of the gradient of the dose, deposited by mesh, with respect to the parameters of the beam; and determining the dose gradient estimate in the voxel.
• the step corresponds to the estimate of the gradient of the dose, estimate (or calculation) which in detail is obtained by means of an analytical function of this dose gradient (deposited).
• the gradient of the composition of a projection function is calculated with a dose function deposited in a homogeneous medium (in a voxel); this analytical function of calculating the dose gradient is calculated gradually in the meshes traversed by the beam.
• ionizing beams which are either independent or at least partially dependent (through their parameters). Optimization of the treatment plan can be done on the basis of calculations.
• the tissue irradiation can be optimized, which corresponds to the desired objective (maximizing tumor irradiation by minimizing the effects on neighboring tissues).
• the method may include the display of the processing plan (for example optimized) and / or numerical values associated with the geometrical parameters and the fluence of one or more beams.
• the results and different numerical values can be displayed. Due to the construction of the method, sufficiently fast temporal iterations allow irradiations via moving heads (and no longer static) around the patient.
• a computer program product including code instructions performs any of the steps of the method when the program is run on a computer.
• the present invention can be implemented from hardware elements (system 490).
• any of the steps of the method may be implemented on a computer, which generally comprises calculation means 491, random access memory or non-persistent memory 492, input and output means or I / O or network 493 (bus or wired and / or wireless network connectivity or audio-visual capture or rendering devices) as well as storage means 494 (eg mass storage).
• the product computer program can be encoded on a computer-readable medium.
• the support may be electronic, magnetic, optical, or electromagnetic (non-exhaustive).
• An implementation of the method may be local and / or via remote access.
• at least a portion of the computing and / or storage means may be accessible by means hosted in the network (“cloud computing" or “cloud computing") modulo latency requirements, which themselves can be optimized.
• the traffic can be encrypted.
• the display means 493 can in particular comprise one or more projectors (including laser) for guiding the orientation of the sensors and / or their movements, helmets of virtual and / or augmented reality, haptic feedback (force feedback, tactile surface , etc
• an ionizing particle is a photon and / or an electron and / or a hadron and / or a proton.
• the method according to the invention can be applied to hadrontherapy, proton therapy and electron radiotherapy methods.
• Direct orthonormal mark (0; x; y; z) whose origin 0 is the center of the ghost. Said reference "ghost”.
• Direct orthonormal landmark (M ( ⁇ ; e v ; e 2 ; e 3 ) Q ue i called Ji f , is associated with an elementary beam
• the origin is the center of the origin of the beam. .
• This variant facilitates writes for optimizing beam orientation. It is defined by a rotation around the z axis, a rotation by ⁇ around the new y axis, rotation by y around the new x axis. These three rotations are sufficient to define from the orthonormal vector triplet of the "ghost" mark the triplet of orthonormal vectors of the "beam” mark i f according to: cos ⁇ cos cos sin sin ⁇ -cos y sin a cos y cos sin ⁇ + sin sin y cos /? sin a cos cos y + sin sin ⁇ sin y -cos sin y + cos y sin /? sin - sin /? cos ⁇ sin y cos y cos ⁇ cos y cos ⁇
• angles are bounded: a ⁇ ] - ⁇ , ⁇ ], ⁇ G] - ⁇ , ⁇ ], ⁇ G] - ⁇ , ⁇ ]
• the coefficient i) 34 reflects the heterogeneities of the medium, including the "void" zone between the beam origin and the patient's body. This coefficient is calculated by the axial propagation mechanism described in "Doséclair".
• ⁇ (0) is the fluence of the beam as it enters the meshed phantom.
• the weighting k ⁇ s> (P) depends on the position and the shape of the SBIM.
• the total dose Dose (P) is a mixture of the different Dose ⁇ s> (P).
• Spherical coordinates M Q can then be characterized by its spherical coordinates: the angles 9 f (longitude) and ⁇ p f (colatitude).
• ⁇ ( ⁇ ; ⁇ ) is the vector of the parameters of the elementary beam to be optimized
• ⁇ is the vector of the ballistic (or geometrical) parameters, that is to say of the five angles (e f ; (p f ; a f ; f - yf), ⁇ is the fluence of the beam.
• Dose (P) 0.
• RCMI bundles The elementary bundles of this RCMI are oriented by the same triplet ( ⁇ , e2, e3), and therefore all share the same parameter triplet (cr r ; ⁇ ⁇ ; y r ).
• the center-origin of the elementary beam (p, q) is defined by:

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