The special circular chamber and the related two channel electronics enables simultaneous measurement of air kerma, air kerma rate, dose area product (DAP), DAP rate and exposure time. By means of an ASCII protocol the handling and display of measuring results is managed by the X-ray unit control console or display unit. The double display unit kerma is used for operating the measuring system and indicate air kerma and air kerma rate independently. By means of three membrane keys all settings and parameter can be adjusted. The system VacuDAP - C Bluetooth duo enables wireless datatransfer between measuring chamber and display unit.