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EP-4412706-B1 - A COMPUTER-IMPLEMENTED MEDICAL METHOD FOR RADIATION TREATMENT (RT) PLANNING FOR TREATING MULTIPLE LESIONS OF A PATIENT

EP4412706B1EP 4412706 B1EP4412706 B1EP 4412706B1EP-4412706-B1

Inventors

  • KAMERLING, Cornelis
  • SCHELL, STEFAN

Dates

Publication Date
20260506
Application Date
20221221

Claims (15)

  1. A computer-implemented medical method for radiation treatment , RT, planning for treating multiple lesions of a patient, the method comprising the following steps: (S1) determining for at least one lesion of the patient, preferably for all lesions of the patient, one or more conformal apertures to be used during radiation treatment; (S2) performing a treatment plan optimization based on conformal shapes for one or more, preferably all, lesions of the patient using a dynamic conformal arc, DCA optimizer thereby calculating a first irradiation treatment plan; (S3) using the calculated first irradiation treatment plan as initialisation of a volumetric intensity modulated arc therapy, VMAT, optimizer; (S4) performing an optimization for all lesions of the patient using the initialized VMAT optimizer, and (S5) wherein the VMAT optimizer keeps all conformal apertures, which were determined in step S1, conformal during performing the optimization in step S4.
  2. The method according to claim 1, wherein the determination of step S1 is carried out for at least one irradiation angle, preferably for all irradiation angles, facilitated by the RT apparatus, and wherein an irradiation angle is defined by a combination of a patient table angle and a gantry angle.
  3. The method according to claim 1 or 2, wherein the determination of step S1 is dependent from at least one of - a shape of the respective lesion of the patient, - an organ at risk, OAR, of the patient, - a previous result of this determination of step S1 for another irradiation angle, wherein an irradiation angle is defined by a combination of a patient table angle and a gantry angle, - one or more mechanical constraints, for example, of a Multi Leaf Collimator, MLC of the RT apparatus, or of an irradiation source of the RT apparatus, - proximity of other lesions, - size of the respective lesion, and - location of the respective lesion in a body of the patient.
  4. The method according to any of the preceding claims, the method comprising the step providing the VMAT optimizer with a dose prescription for said patient, and wherein the dose prescription defines prescribed dose values to be delivered to one or more of the lesions of the patient, and/or one or more dose limits for organs at risk/risk structures of the patient.
  5. The method according to any of the preceding claims, wherein the determination of step S1 is carried out by receiving a user input about the at least one lesion of the patient, preferably about all lesions of the patient, and about information whether the at least one lesion is to be irradiated with conformal apertures or with modulated apertures.
  6. The method according to any of the preceding claims, wherein the determination of step S1 is carried by a computer-implemented method of automatically determining for the at least one lesion of the patient, preferably for all lesions of the patient, one or more conformal apertures to be used during radiation treatment, and wherein said automatic determination is based on data analysis of customer data, and/or is based on a simulation.
  7. The method according to any of the preceding claims, wherein the determination of step S1 is carried out before the optimization for all lesions of the patient using the VMAT optimizer is carried out in step S4, or wherein the determination of step S1 is carried out during the optimization for all lesions of the patient using the VMAT optimizer in step S4.
  8. The method according to any of the preceding claims, wherein during the optimization step S4 using the VMAT optimizer a second irradiation treatment plan is calculated, preferably wherein the calculated second irradiation treatment plan uses at least one hybrid arc containing both conformal apertures of the MLC of the RT apparatus and modulated apertures of the MLC of the RT apparatus.
  9. The method according to any of the preceding claims, wherein during the optimization of step S4 using the VMAT optimizer a respective dose distribution for all lesions of the patient is optimized at the same time.
  10. The method according to any of the preceding claims, wherein at each iteration of the optimization of step S4 using the VMAT optimizer the respective dose for each lesion of the patient is known.
  11. The method according to any of the preceding claims, wherein the initialisation of the VMAT optimizer in step S3 contains a provision of initialized apertures based on the calculated first irradiation treatment plan; the method comprising the step - using, by the VMAT optimizer and during the optimization of step S4, the initialized apertures for further optimizing at least one of conformity, iso-dose line prescription of all lesions at the same time, normal tissue dose and dose to risk structures, gradient index, treatment time, and modulation complexity.
  12. The method according to any of the preceding claims, the method comprising - performing an arc setup optimization, preferably wherein the arc setup optimization comprises - acquiring a first arc setup comprising a plurality of arcs, each arc being defined by a combination of a patient table angle, a gantry start angle and a gantry stop angle, - distributing a plurality of target volumes, which describe the lesions of the patient, to the arcs of the first arc setup thereby providing a packed first arc setup, - comparing said first packed arc setup with one or more predefined arc setup constraints, - wherein the one or more predefined arc setup constraints are selected from: the number of patient table angles per target volume, the number of passes, the sum of gantry span per metastasis over all arcs, the minimum table span, and the total number of patient table angles, and the method comprising the step of - automatically suggesting at least a second arc setup based on a result of the comparison; and - using the suggested second arc setup during performing the treatment plan optimization based on conformal shapes using the DCA optimizer in step S2, more preferably wherein for each of the one or more predefined arc setup constraints a minimum and a maximum is defined.
  13. A program which, when running on a computer or when loaded onto a computer, causes the computer to perform the method steps of the method according to any of the preceding claims.
  14. A non-transitory program storage medium on which a program according to claim 13 is stored.
  15. A medical system, comprising: a) at least one computer; b) at least one electronic data storage device storing at least patient data describing the multiple lesions of the patient; and c) a medical device (200) for carrying out a medical procedure on the patient, wherein the at least one computer is operably coupled to - the at least one electronic data storage device for acquiring, from the at least one data storage device, the patient data describing the multiple lesions of the patient, and - the medical device for issuing a control signal to the medical device for controlling the operation of the medical device on the basis of a result of the optimization carried out in step S4 according to any of the claims 1 to 12.

Description

FIELD OF THE INVENTION The present invention relates to a computer-implemented method for radiation treatment (RT) planning for treating multiple lesions of a patient, a corresponding computer program, a non-transitory program storage medium storing such a program, as well as a medical system. TECHNICAL BACKGROUND For radiation treatment planning in the field of radiotherapy and/or radiosurgery, very sophisticated software programs are applied in order to find an appropriate or even the best radiation plan for the given medical and technical circumstances. In particular, such state of the art radiation treatment planning software solutions allow the medical practitioner to provide details about the following considerations to the software system. Typically, a planning target volume associated with or representing e.g. a lesion (referred to herein also as target) or metastasis is specified along with a desired prescribed dose. The prescribed dose should preferably be deposited in at least a partial volume, also referred to as coverage volume, of the planning target volume in order to ensure biological effectiveness of the irradiation treatment. Apart from that, one or more constraints to be fulfilled during irradiation treatment can be specified. Typically, an organ at risk like e.g. an eye of the patient, which preferably is to be spared during irradiation treatment or which should not receive more than an allowed dose in at least a partial volume thereof, can be specified as constraint. An optimization is carried out, which considers the specified planning target volume, a desired dose value defined by the radiologist, the one or more constraints, usually the coverage volume of the planning target volume is determined and a corresponding irradiation treatment plan is generated. This is done by an optimization algorithm, a so-called optimizer, in the software that is available since years. The irradiation treatment plan can then be utilized to carry out the actual irradiation treatment. However, particularly for multiple brain metastases treatment planning the difficulty arises how to define the arc setup, which is then used by the gantry of the radiation treatment apparatus to carry out the irradiation of the patient. Such an arc setup comprises a plurality of arcs, each arc being defined by a combination of a patient table angle, a gantry start angle and a gantry stop angle. In other words, an arc setup defines a set of arc trajectories, wherein each trajectory is defined by a gantry start and gantry stop angle and a unique table angle. Prior art solutions of the Brainlab AG are described in e.g., the documents WO 2015/039903 A1 and WO 2013/075743 A1. One available software solution of Brainlab AG called "Multiple Brain Mets SRS" software is a treatment planning software that produces treatment plans consisting of dynamic conformal arcs (a treatment modality for linac-based radiation therapy in which the linac head rotates around a patient, utilizing a gantry) with a single iso-center as described in WO 2013/075743 A1. The software has a high degree of automation, to allow for optimization of arc geometry and conformal shapes. Fields are collimated dynamically using a multi-leaf collimator while the gantry of the linac rotates around the patient's head. The fields are shaped according to projections of the metastases for a finite set of gantry angles (control points). For each control point, a projected shape can be either opened or blocked to alter the dose contribution. Moreover, a negative or positive 2D margin can be added to the projected shape to influence the dose profile. Finally, monitor units (arc-weights) must be set per arc (single rotation of the gantry). Monitor units are a measure of linac output and influence treatment time and efficiency. Further, a combination of dynamic conformal arc and volumetric intensity modulated arc therapy (DCA-VMAT) plans may be calculated to treat multiple lesions (Damodar Pokhrel, Allison N. Palmiero, Mark E. Bernard, William St Clair, Dynamic conformal arcs-based single-isocenter VMAT planning technique for radiosurgery of multiple brain metastases, Medical Dosimetry, Volume 46, Issue 2, 2021, Pages 195-200, ISSN 0958-3947, https://doi.org/10.1016/j.meddos.2020.11.005.) Moreover, Brainlab's Cranial SRS provides software to generate modulated treatment plans for single targets using volumetric intensity modulated arc therapy (VMAT). As is understood by the skilled reader, using VMAT means using modulated apertures of the collimator, and thus, the apertures are independent of the target's projection. The software has a high degree of automation, allowing for optimization of arc geometry and modulated shapes. Some customers may create manual hybrid treatment plans by planning a subset of targets using Multiple Brain Mets SRS and (a) specific target(s) using Cranial SRS subsequently. This is rather cumbersome as the total plan cannot be conveniently reviewed and