Secondary standard dosimetry system with automatic dose/rate calculation

The novel design of a versatile and automated secondary standard ionization chamber is described. It is intended for use in radiation protection and therapy level dosimetry and provides a quick and accurate dose or dose rate measurement in a wide range of radiation intensity and quality. The ionization chamber uses walls and electrodes made from polyacetal resins, thus providing long term stability of dimensions. By adding teflon and small amounts of higher Z-material, chambers can be made tissue, water or air equivalent. The energy response for γ rays is +- 2% between 0.02 and 1 MeV. The output is connected to a precision digital current integrator with microprocessor circuitry for data evaluation and control. The system can cover a wide range of measurement between 1 μR and 100 kR, and is useful for daily measurements in a secondary standard dosimetry laboratory or radiotherapy centre. (U.K.)