RADEM - recombination ambient dose equivalent meter for neutron dosimetry around medical accelerators

摘要

A dose equivalent meter based on a recombination principle has been designed for routine measurements of ambient dose equivalent in mixed (gamma + neutrons) radiation fields outside the irradiation fields of linear medical accelerators. Two recombination chambers were used as detectors. The device applies sequentially four different voltages to the chamber electrodes and measures the ionization current values for each voltage. The absorbed dose rate and ambient dose equivalent are calculated taking into account the relationship between the initial recombination of ions and radiation quality factor. Tests at 15 MV Varian Clinac 2300C/D accelerator confirmed that the ambient dose equivalent of mixed radiation in clinical conditions could be determined with accuracy of about 10%.