Multidata Systems was started in 1980 to provide medical physics solutions for radiation oncology. The RTD Real Time Dosimetry product line includes 1D and 3D water phantoms (field analyzers) for measuring the output of a treatment machine as used in radiation therapy. Three-dimensional datasets are required for the commissioning of such treatment machines, for the subsequent modeling of the radiation beam in the treatment planning software and for the calculation of dose to be delivered. A water phantom or field analyzer may also be used for periodical quality assurance measurements on an annual or semi-annual basis.