Introduction to suspension levels: nuclear medicine.

In 2007, the European Commission (EC) commissioned a group of experts to undertake the revision of Report Radiation Protection (RP) 91, written in 1997, on 'Criteria for acceptability of radiological (including radiotherapy) and nuclear medicine installations'. The revised draft report was submitted to the EC. Before publication, the EC issued this document for public consultation and has commissioned the same group of experts to consider the comments of the public consultation in further improving the revised report. The EC intends to publish the final report under its Radiation Report Series with the number RP 162. This paper introduces the project and presents the methodology adopted to devise the criteria of acceptability/suspension levels for nuclear medicine equipment.

Ambient radiofrequency power: the impact of the number of devices in a Wi-Fi network.

This paper considers how the total radiofrequency power varies as the number of devices in a Wi-Fi network increases. Under the assumption that all devices in the network always have data to transmit, we show that work from network engineering can be adapted to calculate the total transmitted power, accounting for the possibility of multiple devices transmitting at the same time. The paper focuses on total transmitted power as it gives an upper bound on exposure and makes the impact of multiple devices clear. The results show that the number of devices does have a significant impact on the radiated power. For example, one station transmitting small packets in unicast mode gives about half the nominal power value; to reach nominal value around 25 devices are required, and 150% of the nominal value is achieved around 350 devices. We see that 802.11's transmission protocol is usually effective in limiting the power even in very large 802.11 networks.