GSM cell phones can interfere with ionizing radiation dose monitoring equipment

Cell phone use is growing worldwide. These phones transmit to adjacent base stations using radiofrequency signals in the microwave range (approximately 900-approximately 1800 MHz). Portable electronic dose monitoring equipment is used in hospitals and other institutions to monitor and control levels of exposure to ionizing radiation, and to reassure staff. The objective of this paper is to investigate the effect of mobile phones on a sample of dose monitoring devices. Two mobile phones (Siemens C25 and Motorola CD930) were used in the study. Field strengths were measured to be in the range 0 V m-1 to over 100 V m-1, depending on the distance from the phone, and were strongest at the beginning of a call. Personal electronic dosemeters (n = 7), portable dose monitors (n = 4) and contamination monitors (n = 2) were assessed. All the units were in service. Three of the personal dosemeters showed abnormal responses when exposed to mobile phone transmission. One dosemeter (Siemens EPD-2) registered doses equivalent to a dose rate of 99 mSv h-1. In addition, two of the portable dosemeters and one of the contamination monitors also gave an abnormal response. Interference was observed across a number of detector types from a number of manufacturers. Modern cell phones can interfere with ionizing radiation dose monitoring equipment. This should be taken into account when distributing these devices and when assessing results generated by them. Electromagnetic compatibility testing should form part of the commissioning and specification protocol for new dose monitoring equipment.