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