Following the proposal of the ICRP for the reduction of the dose limit for the lens of the eye, which has been adopted by the International Atomic Energy Agency and the European Council, concerns have been raised about the implementation of proper dose monitoring methods as defined in national regulations, and about the harmonisation between European countries. The European Radiation Dosimetry Group organised a survey at the end of 2017, through a web questionnaire, regarding national dose monitoring regulations. The questions were related to: double dosimetry, algorithms for the estimation of the effective dose, methodology for the determination of the equivalent dose to the lens of the eye and structure of the national dose registry. The results showed that more than 50% of the countries that responded to the survey have legal requirements about the number and the position of dosemeters used for estimation of the effective dose when radiation protection garments are used. However, in only five out of 26 countries are there nationally approved algorithms for the estimation of the effective dose. In 14 out of 26 countries there is a legal requirement to estimate the dose to the lens of the eye. All of the responding countries use some kind of national database for storing individual monitoring data but in only 12 out of 26 countries are the estimated effective dose values stored. The personal dose equivalent at depth 3 mm is stored in the registry of only seven out of 26 countries. From the survey, performed just before the implementation of the European Basic Safety Standards Directive, it is concluded that national occupational exposure frameworks require intensive and immediate work under the coordination of the competent authorities to bring them into line with the latest basic safety standards and achieve harmonisation between European countries.

No abstract

The exposure of the fingers is one of the major radiation protection concerns in nuclear medicine (NM). The purpose of this paper is to provide an overview of the exposure, dosimetry and protection of the extremities in NM. A wide range of reported finger doses were found in the literature. Historically, the highest finger doses are found at the fingertip in the preparation and dispensing of 18F for diagnostic procedures and 90Y for therapeutic procedures. Doses can be significantly reduced by following recommendations on source shielding, increasing distance and training. Additionally, important trends contributing to a lower dose to the fingers are the use of automated procedures (especially for positron emission tomography (PET)) and the use of prefilled syringes. On the other hand, the workload of PET procedures has substantially increased during the last ten years. In many cases, the accuracy of dose assessment is limited by the location of the dosimeter at the base of the finger and the maximum dose at the fingertip is underestimated (typical dose ratios between 1.4 and 7). It should also be noted that not all dosimeters are sensitive to low-energy beta particles and there is a risk for underestimation of the finger dose when the detector or its filter is too thick. While substantial information has been published on the most common procedures (using 99mTc, 18F and 90Y), less information is available for more recent applications, such as the use of 68Ga for PET imaging. Also, there is a need for continuous awareness with respect to contamination of the fingers, as this factor can contribute substantially to the finger dose.

Staff handling radiopharmaceuticals in nuclear medicine (NM) may receive significant extremity doses. Especially over the last decade there is an increase in NM procedures and new radiopharmaceuticals have been introduced. However, literature provides limited recent data on the exposure of the extremities. In addition, proper assessment of the equivalent dose to the skin can be difficult when applied to the fingertips. In order to gain insight in the actual exposure and to find out how the European countries are dealing with monitoring of the extremities, a survey was performed amongst European regulatory authorities. The questions covered general aspects of the National Dose Registries (NDRs), the measured extremity doses and the practice of the monitoring of workers. The survey shows that extremity dosimetry is performed for about 25-50% of the monitored workers in NM. Also, the recorded extremity doses in the NDRs are low (mean values 5-29 mSv per year) compared to the dose limit . Despite the recommendations that have been published in the last 10 years, few countries provide guidance on the wearing position of extremity dosemeters and the correction factor to estimate the maximum equivalent skin dose from the measured dose. This may lead to an underestimation of the maximum skin dose. Thermoluminescence ring dosemeters are widely used but wrist dosemeters are also very common, even though the correlation of the measurement with the maximum skin dose is worse than for ring dosemeters. Furthermore, not all countries had a central registration of the extremity dose at the time the survey was performed.

No abstract