The aim of this research is to develop a novel radiation dosimeter based on Digital Holographic Interferometry (DHI) for novel applications, such as e.g. microbeam radiotherapy or our small animal proton IGRT facility. DHI is an optical technique, which is capable of detecting miniscule radiation-induced temperature changes in a water phantom by means of a laser interferometer. The approach is based on digitally capturing laser interference patters, which are governed by the change in temperature of the irradiated medium. From these patterns the phase changes can be extracted and mathematically directly related to the radiation absorbed dose. The dosimeter is independent of radiation type and can resolve spatial variations in absorbed dose. A schematic overview of the approach is shown below. The current experimental set-up is based on a Lensless Fourier digital holography (LFTDH) approach and uses a CMOS camera for recording as shown in the second picture below.