The present invention relates to a dosimetry device for verification of the quality of a radiation beam in standard and conformal radiation therapy, and in particular for IMRT (Intensity Modulated Radiation Therapy) applications, comprising an active area comprising individual radiation detectors, wherein the active area comprises a limited number of lines of radiation detectors, and the active area further comprises extra radiation detectors dedicated to the energy measurement of electrons or photons, and it comprises a build-up plate, with energy degraders, said energy degraders being located upstream said extra radiation detectors in the path of said radiation beam.
