ABSTRACT
The metrological quality of a measurement is characterised by evaluating the uncertainty in the measurement. In this paper, uncertainty in personal dose measured using individual monitoring CaSO4:Dy-based thermoluminescence dosimeter badge is evaluated by application of the guide to the expression of uncertainty in measurement method. The present dose reporting quantity, whole body dose (WBD) and the proposed quantity, personal dose equivalent, Hp(10) has been used as measurands. The influence of various input quantities on the measurement were analyzed through tests that conform to the requirements of the International Electrotechnical Commission IEC 62387. The study found that the expanded uncertainties for WBD and Hp(10) measurements were 63.4% and 41.4%, respectively, corresponding to a 95% coverage probability for workplace fields covering a wide photon energy range (33-1250 keV). However, the uncertainty estimates were quite lower for the type of workplaces that are identified using the dose evaluation algorithm. The input quantities, namely, the response to a mixture of photon beam qualities and photon energy and angular dependence contribute the most to the total uncertainty.
Subject(s)
Occupational Exposure , Radiation Dosage , Thermoluminescent Dosimetry , Workplace , Thermoluminescent Dosimetry/instrumentation , Thermoluminescent Dosimetry/methods , Humans , Occupational Exposure/analysis , Uncertainty , Radiation Monitoring/methods , Algorithms , Dysprosium/chemistry , Photons , Radiation Protection/methods , Radiation Protection/standards , Radiation DosimetersABSTRACT
The radiation protection programme is aimed at safe usage of radiation at workplace, ensuring minimum possible dose to radiation workers, patients and members of the public. Verification of the adequacy of protective measures in actual workplace is important, especially for diagnostic radiology facilities, as a substantial number of suspected overexposures are reported from these facilities. To address this issue, a study was conducted for mapping workplace radiation field at various locations in nine Diagnostic Radiology Facilities of two hospitals in India. The cumulative doses were measured for a period of 1-3 months, using personnel monitoring TLD badges. The dosemeters were placed at positions representative of two exposure situations: (1) probable locations of workers during procedures, leading to genuine exposure and (2) inappropriate storage locations of personal dosemeters at user end for probing claims of nongenuine exposures. The results indicate that the measured doses at locations (1) were just a fraction of the permissible dose, provided all safety practices are adhered to. However, the measured doses at certain locations (2) exceeded the investigation levels and indicate that any inadvertent storage of the dosemeters at such locations could lead to reporting of the overexposure from these radiology facilities. The outcome of the study will be useful for the investigation of such exposures and better understanding of the readout patterns of TLD badges in radiology workplaces.