personal dosimetry

History and developing procedure of personal dosimetry services from start of film badge and TLD dosimetry services by legal authority as well as out sourcing of services presented in this article. Also results obtained from participation in regional intercomparisondosimetryprogramme (phases 1 and 2) planned by international atomic energy agency (IAEA) presented and discussed. Results of film badge and TLD shows that these methods meet the criteria of external dosimetry standards as well as acceptable uncertainty. Average ratio of measured dose to true dose for film badge was measured to be 1.17 and 1.03 in phase 1 and 2 respectively which shows theimprovement of the results.TLD shows a better results comparing to film badge, for which average of response measured to be 1.1 and 0.94 for phase 1 and 2 respectively.

Lowness of the registered doses by the personal dosimeters (film badge in Iran) for most of dental radiology practitioners has made some of them doubtful about the rightness of the employed dosimetry method. On the other hand, some relatively considerable occupational exposures in dental radiology have been reported. These two opposite facts propose a comprehensive statistical and analytical research on the exposure levels in this practice. A thorough investigation on the available personal dosimetry data for dental radiology was carried out to define the occupational dose distribution of the practitioners. Furthermore, employing a supplementary assessment through questioners on the cases exceeding the investigation dose level, validity of such cases was verified. The results showed that more than 90% of the dental radiology practitioners receive doses near to the background level and 99% of them receive doses less that the annual dose limit for the public (1mSv/y). The investigations showed that only few cases have been registered doses over the investigation level, out of which, only one case has been the real exposure of the person to the ionizing radiation. In sum, occupational exposure in dental radiology is negligible and needlessness of the practice to personal dosimeters can be concluded.

Neutron individual dosimetry is challenging subject in dosimetry field. Thermoluminescent dosimeter (TLD) is one of the types of personal dosimeters that is extremely used to determine the doses of neutron sources. Typically, this type of dosimeter is used in different centers with a variety of applications after calibration with a standard neutron radiation sources. Usually, materials of TL crystal that used in personal dosimetry purposes have the effective atomic number of soft tissue such as (LiF). But, importantly, the heavy dependence of the neutron spectrum to geometry of the source location makes the estimation of doses particularly the dose equivalent very difficult. This research is studied on TLD600-700 HARSHAW that used in individual neutron - gamma dosimetry services in Iran. This dosimeters are irradiated with standard sources 241Am-Be and 252Cf at low doses to high doses and their behavior are studied and analyzed. Also the important information about relative response of these dosimeters that irradiated by 241Am-Be and 252Cf sources is presented.