A direct ion storage(DIS) detector integrates MOS field effect transistor with cavity ionization chamber and is used for monitoring personnel dose. As part of our efforts to develop DIS detector

we report in this paper a tissue-equivalent cavity ionization chamber

including the wall material

gas composition

shape and size of cavity

wall thickness and insulated material. Using 60Co γ -rays and 70～180 keV X-rays

the test results show that saturation characteristics of the cavity ionization chamber meet the requirement of DIS detector.