Quality Control and reliability of reportes doses

In the EU Basic Safety Standards (1) it is regulated in Article 25 that the exposure of occupationally exposed persons must be monitored using dosemeters that are issued by a dosimetric service that is approved by the competent national authorities. The authorities will impose a set of requirements on services seeking approval (2). These requriements must ensure that the quality of the individual monitoring provided by the service is such that both the users and the authorities can fully rely on the dose data reported. The quality of the end result in individual monitoring for external radiation by an approved dosimetric service depends on a number of factors: (1) Dosimetric chracteristics of the dosemeter. (2) Metrological properties of the evaluation system. (3) Data processing and administrative systems of the service. Added to these are factors that are largely outside the direct control of the dosimetric service: (1)Proper use of the dosemeter by the user. (2) Returning the dosemeter to the service at the end of a period. (3) Reliability of the mailing (postal) system. General guidance on requirements for dosimetric systems and for operational procedures such that adequate radiological protection and exposure monitoring can be achieved are contained in the safety guidelines issued by the International Atomic Energy Agency (IAEA) (3,4) and the recommendations of the European Commission (EC) (5) performance of dosimetric systems can be found in international standards (6). Of the six aspects listed, most attention in the literature is directed towards the performance of the dosementers and in particular to the energy and angular dependence of the response and detection thresholds. There is also literature on the effects of wearing conditions in particular with relation to the use of lead aprons (7). However, there is hardly any information in the open literature relating to the uncertainty in a dose measurement or in the annual dose being increased by failure of the system. Some sources of increased uncertainty are as follows: (1) Inappropriate use of the dosemeter. (2) Damage to the dosemeter during use (e.g.breakage, sterilisation or washing). (3) Loss of the dosemeter during use. (4) Damage to the dosemeter during processing. (5) Faulty conditions in the evaluating equipment (e.g. wrong temperature of the developer or of the thermoluminescence dosemeter - TLD, heating system). (6) Loss of data during data processing. The result of most of the above conditions will be that no dose can be assessed. The radiological protection aspect of this is that the exposed person may be left in the dark about her or his exposure. In the case where the dosemeter is lost or damaged during use, the user or employer are essentially not complying with the legal obligation to have the exposure monitored. It will be impossible for the services to prevent the occasional occurrence of fatal error conditions during evaluation. However, the inability to report a dose of dosemeter that was returned by the user will in theory be a violation of the requirements for approval set by the authorities. In the current study, an attempt is made to estimate the importance of the above-mentioned conditions. This is achieved by sending questionnaires to about 200 approved dosimetric services in Europe (8). In total 88 questionnaires were returned. In the questionnaires, the frequency of occurrence of the various error conditions was investigated. Participants were also asked to evaluate the impact of the error condition from a dosimetric point of view and what actions are taken, for example, assigning a zero or a nominal dose and whether or not the customer is charged for lost dosemeters