Generally, individual monitoring is performed with a small personal dosemeter which responds to radiation by giving a necessary operational quantity such as personal dose equivalent. In space, however, such a personal dosemeter has not yet been available and a dose equivalent is estimated through elaborate work using etched track detectors. It would be advantageous if we could simply measure the personal dose of an astronaut using conventional integrating dosemeters only. This possibility is discussed based on the concept of efficiency combination.