New calibration service for high energy X-radiation at NPL

The United Kingdom National Physical Laboratory is about to introduce a new X-ray calibration service for radiotherapy with the following features: (a) The primary standard will be a calorimeter measuring absorbed dose to graphite; (b) Secondary standard dosimeters will be calibrated in absorbed dose to water with the chamber in a water phantom; (c) Calibration qualities will include cobalt-60 gamma radiation, and X-radiation between 4 and 19 MW; (d) Effective photon energies of the calibration beams will be specified in terms of tissue-phantom ratios. The new calibration service will be introduced in the UK as of 1988, and will be made available to other countries as soon as possible. (author). 6 refs