A system for providing a radiation therapy treatment plan (s c), the system comprising: a database storing pre-calculated solutions () each of which defines a radiation therapy treatment plan for a treatment volume, the treatment volume being associated with at least one target, for instance corresponding to a tumor to be treated, and the treatment volume being associated with at least one organ-at-risk, for instance healthy tissues in which the radiation dose should be kept below certain levels; a first user interface (141, 142) configured to receive operator commands (c1, c2) specifying criteria for selecting radiation therapy treatment plans from the database, the criteria defining a set of parameters for the treatment volume; a data processor configured to establish any solutions () which meet the criteria; and a second user interface configured to present at least one radiation therapy treatment plan that is established by the data processor as a radiation therapy treatment plan (s c) meeting the criteria, the pre-calculated solutions () being divided into at least two groups each of which comprises at least one pre-calculated solution, and the pre-calculated solutions in a given group represent radiation therapy treatment plans which share a common beam configuration; and the operator commands (c1, c2) comprising commands which jointly specify criteria for selecting radiation therapy treatment plans from more than one of the at least two groups, wherein the data processor is configured to apply a preference function on at least one pre-calculated solution in the at least two groups to establish one and only one solution per group of the at least two groups as the radiation therapy treatment plan (s c) meeting the criteria to be presented via the second user interface, wherein the common beam configuration shared by the radiation therapy treatment plans in a group of the at least two groups is defined in terms of: a number of radiation beams used being equal, a set of mutual angles between the radiation sources used being equal, and a type of particles emitted from the radiation sources being equal. a database storing pre-calculated solutions () each of which defines a radiation therapy treatment plan for a treatment volume, the treatment volume being associated with at least one target, for instance corresponding to a tumor to be treated, and the treatment volume being associated with at least one organ-at-risk, for instance healthy tissues in which the radiation dose should be kept below certain levels; a first user interface (141, 142) configured to receive operator commands (c1, c2) specifying criteria for selecting radiation therapy treatment plans from the database, the criteria defining a set of parameters for the treatment volume; a data processor configured to establish any solutions () which meet the criteria; and a second user interface configured to present at least one radiation therapy treatment plan that is established by the data processor as a radiation therapy treatment plan (s c) meeting the criteria, the pre-calculated solutions () being divided into at least two groups each of which comprises at least one pre-calculated solution, and the pre-calculated solutions in a given group represent radiation therapy treatment plans which share a common beam configuration; and the operator commands (c1, c2) comprising commands which jointly specify criteria for selecting radiation therapy treatment plans from more than one of the at least two groups, wherein the data processor is configured to apply a preference function on at least one pre-calculated solution in the at least two groups to establish one and only one solution per group of the at least two groups as the radiation therapy treatment plan (s c) meeting the criteria to be presented via the second user interface, a number of radiation beams used being equal, a set of mutual angles between the radiation sources used being equal, and a type of particles emitted from the radiation sources being equal.