An
irradiation device for
radiation treatment and a
collimator (1) are used to define a beam of high-energy rays (2) with beam limitation by means of an iris diaphragm (5) having adjusting elements (7), and a mechanism that is used to direct the beams (2′) limited by the
collimator (1) to the object to be treated (4) from all sides, wherein the parameters for direction, surface area, intensity and time of
irradiation can be specified with the help of a control mechanism. An exact three-dimensional
irradiation profile is produced, while keeping the costs and efforts regarding
mechanical engineering, computation and
irradiation time low. This is achieved by using at least one further iris diaphragm (6) located in coaxial alignment in the
optical path, whereby the leaves (9, 9′, 9″, 9′″, 9″″, 9′″″) of the iris diaphragms (5, 6) are arranged in a staggered manner and in a rotational sense around their axis (11), so that the beam limited by the
collimator (1) has the cross-section of a polygon (12), the number of corners of which complies with the number of the leaves of all iris diaphragms (5, 6), so that the leaves (9, 9′, 9″, 9′″, 9″″, 9′″″) allow for linear adjustment movements (13), the control mechanism being suitable to enable the irradiation of an irregular space through the overlaying and adjoining of many irradiated spaces (28).