Design of apparatus for precise x-ray dose chamber calibrations

An apparatus for precision calibration of ion chambers in the x‐ray region from 16 to 320 kV is described. The development of a fast‐acting shutter with ‘‘opening’’ and ‘‘closing’’ times of less than 3‐ms eliminates the requirement for operating time corrections. Controls from outside the radiation room permit changing x‐ray filters and alternately positioning both test and standard ion chambers in the x‐ray beam. Thus, the remote controls eliminate the need to enter the x‐ray room in the course of a series of calibrations. The potential advantages resulting from the capabilities of this apparatus are described in this Technical Report.