Interactive selection method of selecting a solution from a plurality of precalculated solutions stored in a database and displayable on a display device in an interactively controllable manner to the selecting user, wherein the interactive selection comprises the following steps; (a) imaging a DVH diagram, wherein DVH stands for a dose-volume histogram, with a plurality of DVH curves (39;40a,50a,60a), the DVH diagram as a main diagram on a screen of display means, wherein only one of the plurality of precalculated stored solutions at a time is visually displayed as the main diagram; (b) selecting a first starting point (41a, 61a) and setting the starting point on a selected one (40a, 60a) of the plurality of DVH-curves (39; 40a, 50a, 60a) in the main diagram, -- whereby a first straight axis (71, 73, 75) passing through the first starting point (41a, 61a) is also shown in the main diagram, -- like a visually highlighted first control area (72,74,76) located around the first starting point (41a, 61a) and on the first straight axis (71,73,75); -- for visualizing the plurality of solutions stored in the database and currently not represented as DVH curves, whose DVH curves (40b, 40c,...) corresponding to the selected DVH curve intersect the first straight axis (71, 73) and thereby define a longitudinal extension of the first control region (72, 74, 76); (c) wherein said first control section (72,74,76) has upper and lower end values (71b,71c;73a,73b) which are respectively the largest and smallest values of the corresponding stored DVH curves which also intersect said first straight axis (71,73,75); (d) imaging at least one further control element (71e, 75d) on the first straight axis (71, 75), wherein -- the first starting point (41a, 61a) is a first control element used interactively by the user to control the change of the selected DVH-curve (40a, 60a) -- and the further control element (71e, 75d) restricts the first control range (72, 74, 76) by shifting to a smaller longitudinal extent (76a, 72a); (e) further solutions are interactively selected by the user by shifting the starting point and by its displacement (41a', 41b) other DVH curves (40b, 50b, 60b) are displayed in the main diagram by a visualization module, of which a displayed DVH curve also intersects the first, restricted control area. (a) imaging a DVH diagram, wherein DVH stands for a dose-volume histogram, with a plurality of DVH curves (39;40a,50a,60a), the DVH diagram as a main diagram on a screen of display means, wherein only one of the plurality of precalculated stored solutions at a time is visually displayed as the main diagram; (b) selecting a first starting point (41a, 61a) and setting the starting point on a selected one (40a, 60a) of the plurality of DVH-curves (39; 40a, 50a, 60a) in the main diagram, -- whereby a first straight axis (71, 73, 75) passing through the first starting point (41a, 61a) is also shown in the main diagram, -- like a visually highlighted first control area (72,74,76) located around the first starting point (41a, 61a) and on the first straight axis (71,73,75); -- for visualizing the plurality of solutions stored in the database and currently not represented as DVH curves, whose DVH curves (40b, 40c,...) corresponding to the selected DVH curve intersect the first straight axis (71, 73) and thereby define a longitudinal extension of the first control region (72, 74, 76); -- whereby a first straight axis (71, 73, 75) passing through the first starting point (41a, 61a) is also shown in the main diagram, -- like a visually highlighted first control area (72,74,76) located around the first starting point (41a, 61a) and on the first straight axis (71,73,75); -- for visualizing the plurality of solutions stored in the database and currently not represented as DVH curves, whose DVH curves (40b, 40c,...) corresponding to the selected DVH curve intersect the first straight axis (71, 73) and thereby define a longitudinal extension of the first control region (72, 74, 76); (c) wherein said first control section (72,74,76) has upper and lower end values (71b,71c;73a,73b) which are respectively the largest and smallest values of the corresponding stored DVH curves which also intersect said first straight axis (71,73,75); (d) imaging at least one further control element (71e, 75d) on the first straight axis (71, 75), wherein -- the first starting point (41a, 61a) is a first control element used interactively by the user to control the change of the selected DVH-curve (40a, 60a) -- and the further control element (71e, 75d) restricts the first control range (72, 74, 76) by shifting to a smaller longitudinal extent (76a, 72a); -- the first starting point (41a, 61a) is a first control element used interactively by the user to control the change of the selected DVH-curve (40a, 60a) -- and the further control element (71e, 75d) restricts the first control range (72, 74, 76) by shifting to a smaller longitudinal extent (76a, 72a); (e) further solutions are interactively selected by the user by shifting the starting point and by its displacement (41a', 41b) other DVH curves (40b, 50b, 60b) are displayed in the main diagram by a visualization module, of which a displayed DVH curve also intersects the first, restricted control area.