Radiation Protection Dosimetry in Pulsed Radiation Fields

The application of pulsed radiation fields for research, security screening and medical examinations has increased remarkably in the last years. Testing of active personal and area dosemeters for the operation in pulsed radiation fields is a necessity to judge the suitability of the dosemeter. Up to now, radiation protection dosemeters have only been tested in continuous fields, although they are used for measurements in pulsed radiation fields as well. Many of the conventional electronic dosemeters do not determine reliable dose values in these pulsed fields any more. The reasons for this are based on the measurement principle (mostly the counting technique) in combination with the characteristics of the pulsed radiation field (e.g. high dose rate during the short radiation pulse). The definition of reference fields is a basic requirement for the development, testing and calibration of radiation protection dosemeters as well as for the further development of radiation sources for the range of pulsed radiation. Therefore, a new international ISO 18090 TS standard for pulsed reference fields [1], dealing with the requirements for such fields, is in preparation. Thus, in cooperation with the Siemens Company, a novel equipment has been developed which will make it possible for the first time to adjust all parameters of pulsed X-ray reference fields and to determine the performance limits of dosemeters with respect to pulsed radiation. Worldwide, it is the first equipment of its kind. For active direct reading dosemeters, which use pulse counting techniques to determine the measured dose value, a concept of requirements and testing procedures have been developed and tested. This concept is included in the new international IEC 62743 TS standard for the type testing of dosemeters [2].