The British Journal of Radiology, 73 (2000), 994998
2000 The British Institute of Radiology

Short communication

GSM cell phones can interfere with ionizing radiation dose monitoring equipment
P GILLIGAN, BSc, MSc, 2S SOMERVILLE, BSc and 1J T ENNIS, MD, FRCR
Institute of Radiological Sciences/Mater Private Hospital/University College Dublin, 52 Eccles Street, Dublin 7 and 2Radiological Protection Institute of Ireland, 3 Clonskeagh Square, Dublin 14, Ireland
Abstract. Cell phone use is growing worldwide. These phones transmit to adjacent base stations using radiofrequency signals in the microwave range (,900,1800 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 m21 to over 100 V m21, depending on the distance from the phone, and were strongest at the beginning of a call. Personal electronic dosemeters (n57), portable dose monitors (n54) and contamination monitors (n52) 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 h21. 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 specication protocol for new dose monitoring equipment. There has been a dramatic increase in mobile phone, or cell phone, usage in recent years. A 1998 study showed that up to 54% of the Irish population use cell phones [1]. Mobile phone use is commonplace among radiation workers who need to be in contact for emergencies, particularly among engineers, industrial radiographers, doctors and medical radiographers [2]. Electronic ionizing radiation dose monitoring is widespread in modern institutions [3]. Dose monitoring devices have provided a mechanism for monitoring low doses of radiation (in the range of microSieverts) with an instant read-out. This has provided a cost effective solution to dose monitoring and can be more pragmatic than the use of lm or thermoluminescent dosemeter badges. Electronic dosemeters are based on a number of technologies. These include Geiger Muller (GM) and diode-based detectors. The majority of units contain alarms to alert the user when a pre-set dose rate is exceeded. Quantitative readings are available in most cases using a liquid crystal display (LCD). Dose and contamination monitors are widely used for a
Received 21 December 1999 and in revised form 17 May 2000, accepted 9 June 2000. 994
variety of purposes. They rely on a number of detector technologies, including scintillation crystals, proportional counters, ionization chambers and GM tubes [4]. Cell phones have caused concerns regarding interference with medical devices; consequently, mobile phone use is generally restricted in hospitals [5]. Assessment of the effects of cell phones is complex, as cell phone technology has evolved rapidly in recent years [6]. GSM mobile phones emit low levels of radiofrequency energy in the microwave range (,900 MHz to ,1800 MHz). Phones now being marketed use transmitters to locate an adjacent base station and to communicate with that base station (location updating). The base station re-transmits any information received to a phone network. Speech and other information are encoded using frequency modulation and digital signal processing techniques [68]. The output of the phones can be measured in terms of power density (W cm22) or electric eld strength (V m21). Output in this paper has been expressed in electric eld strength for comparison with other papers [9, 10]. The mobile phone dynamically controls the amount of output power it needs to facilitate a call. This level will depend on the distance from
The British Journal of Radiology, September 2000
Short communication: GSM cell phones can interfere with dose monitoring equipment
and the sophistication of the base station transmitter [6]. The maximum output power of the phone will broadly depend on the class, as dened by the GSM standard. Recent hand-held phones are generally dual band, and are class IV with a maximum power output of 2 W at 900 MHz, and class I with a maximum output power of 1 W at 1800 MHz [7]. Testing protocols for electronic dosemeters have shown that these may be susceptible to electromagnetic interference in the 500 kHz to 1 GHz range [9, 10]. Indeed, some manufacturers now offer electromagnetically shielded housing for dosemeters and advertise reduced electromagnetic susceptibility levels in their dosemeters (Siemens, Germany; NDS, Texas, USA). It is the purpose of this paper to investigate the effects of modern cell phones on electronic ionizing radiation dose monitoring equipment already in service.

Methods and materials

Dose monitoring equipment that was in service and considered to be fully functioning was selected for the study. The equipment is used either in a hospital or as part of the national regulatory inspectorate and dosimetry service of the Radiological Protection Institute of Ireland. All the units had been calibrated in the previous 12 months by a certied laboratory. The devices tested in this paper are listed in Table 1. All the units were tested in a laboratory where good mobile phone reception was known to be available. Radiofrequency eld measurements were recorded using a CA 43 portable eld meter (Chauvin Arnoux, France). This was calibrated in
Table 1. List of equipment tested and mode of operation Manufacturer/distributor
the previous 24 months, in accordance with the French BNM-COFRAC standard (Nr2-1035), which is equivalent to the UKAS standard in the UK. Two types of GSM phones were tested in this study, the Siemens C25 (Siemens, Germany) and the Motorola CD930 (Motorola, Ireland). Both phones are GSM class IV at 900 MHz and class I at 1800 MHz. Electric eld strength was measured during connection at the start of a call and throughout a call. This was done for outgoing and incoming calls. Information was kept constant in the outgoing call by phoning a disconnected number and using a voice recording for the incoming call. A 4 s integration period of average eld strength was used to facilitate monitoring of the continuous eld density. The instantaneous peak (400 ms) uctuated too rapidly to permit reasonable recording. Field strength was measured at various locations around the phone to nd a maximum. Field strength was also measured at 1 m and 2 m from each phone, and the results are given in Table 2. Maximum eld strength was found in the area underneath the aerial. Each dosemeter was placed adjacent to the phone at the maximum eld strength point. If an effect was observed, the unit was moved until the effect was no longer observed. The unit was then placed at 1 m from the phone. If an abnormal response was still observed, the unit was placed at 2 m from the phone, and so on. The results of the tests are shown in Table 3. Dose readings before and after were documented, as well as any activation of alarms. Alarm settings on each device were those set by the user or manufacturer and are not documented here.
Detector Diode Diode GM GM GM GM GM Ion chamber Proportional GM GM Proportional Scintillation
Display Audio & LED Audio, Audio, Audio, Audio, Audio, Audio, LED, LCD quantitative LED, LCD quantitative LCD quantitative LCD quantitative LCD quantitative LCD quantitative
Electronic personal dosemeters Los Alamos Rad alarm Chirper F&J speciality products Inc. (FL, USA) EPD-2 Siemens (UK) Pocket dosemeter with LED Appleford Instruments (UK) Pocket dosemeter without LED Appleford Instruments (UK) Stephen 6000 R.A. Stephen/Centronics (UK) Gammacom 4200 R.A. Stephen/Centronics (UK) Gothic Crellon Bleeper 3 Gothic Crellon (UK) Portable dose monitors 1015 MDH Berthold LB133 N/E PDR1 Mini Instruments Series 1000 Contamination monitors Berthold LB1210 Series 900 Radcal (CA, USA) Berthold (Germany) NE Technology (UK) Mini-Instruments (UK) Berthold (Germany) Mini-Instruments (UK)

LCD Analogue meter Analogue meter Analogue meter Analogue meter Analogue meter
LED, light emitting diode; LCD, liquid crystal display; GM, Geiger Muller.
P Gilligan, S Somerville and J T Ennis Table 2. Mobile phone electric eld strength (V m21) variation with distance Phone Adjacent Max. Siemens C25 Motorola CD114 During call 1m Max. 3.1 1.8 During call 0.13.1 0.10.5 2m Max. 0.5 0.9 During call 0.21.1 0.10.8

Results

Maximum electric eld strength was measured at the start of the call when the phone set up the call with the base station (Table 2). During the call the eld strength levels were lower and uctuated throughout the call (Table 2). The same range of levels was noted for incoming and outgoing calls. Table 3 shows that cell phones can interfere with dose monitoring equipment. In the majority of cases this interference happens only when the phone is adjacent to the dose monitoring device. The responses were the same regardless of whether the call was incoming or outgoing. In the case of one audible alarm dosemeter, the effect was observed at up to 2 m from the phone. The most marked effect was in the Siemens EPD-2 electronic personal dosemeter. This device showed dose rate levels up to 99 mSv h21 at up to 60 cm from both phones tested. The displayed dose climbed more slowly (,1 mSv s21) than that anticipated by a dose rate of 99 mSv h21. Two models of Appleford pocket dosemeter were tested. The Appleford pocket dosemeter tted with a light emitting diode (LED) showed a rapid initial increase in dose (335 mSv) but no effect thereafter. This effect was difcult to reproduce consistently and required changing the
environment a number of times before it was observed. The same effect was not seen in the Appleford device without the LED. The type of detector did not determine which dose monitoring devices were susceptible to abnormal response. A Radcal MDH 6 cc ionization chamber registered a dose of 5 mR upon exposure to the electric eld strengths from each phone. The Berthold LB133 portable dosemeter showed an abnormal response that depended on eld strength. A reduced effect was noted at a distance of 1 m compared with that adjacent to the phone. The Berthold contamination monitor (LB1210) registered high count rates when the phones were operated adjacent to the meter. None of the devices were affected at distances of 3 m. All the units were fully functional after exposure to a mobile phone.

Discussion

The American National Standards Institute (ANSI) [11] N42.20 and other standards give performance criteria for testing dosemeters. Included in such criteria is testing for radiofrequency/microwave interference in the range 5001000 MHz. The Siemens EPD-2 showed
Table 3. Description of observed effects on in-service dose monitoring equipment from mobile phones Effect Electronic personal dosemeters Los Alamos ``Chirper'' Siemens EPD Continuous alarm Increased dose reading (73 mSv in 60 s); increased dose rate (.99 mSv h21 in 5 s); alarm Increased dose (335 mSv in 5 s) Phonesa CD930, C25 CD930, C25 Distance ,2 m ,60 cm

Appleford with LED

CD930, C25

Adjacent

Portable radiation monitoring equipment 1015 MDH Increased dose reading (5 mR in 5 s) Berthold LB133 Increased dose rate (50 mSv h21 in 5 s); alarm N/E PDR1 Increased dose rate (50 mSv h21 in 5 s) N/E PDR1 Increased dose rate (0.2 mSv h21 in 5 s) Contamination monitoring equipment Berthold LB1210 Increased reading to 300400 counts s21
EPD, electronic personal dosemeter; LED, light emitting diode. a CD930, Motorola, Ireland; C25, Siemens, Germany.
CD930, C25 CD930, C25 CD930, C25 CD930, C25
Adjacent Adjacent Adjacent 1m
interference at eld strengths of 100 V m21 and 20 V m21, but not 1 V m21 [9, 10]. The results presented in this paper would corroborate the ndings of these studies. If mobile phone interference had not been seen in any of the devices used in this study, it would not necessarily imply that mobile phones do not interfere with the device in all types of environments. Mobile phones are generally worn in the abdominal area, attached to a belt or stored in a bag or pocket. Electronic personal dosemeters are generally worn in the area of the trunk and are usually attached to a belt clip. It is possible that they could be worn next to an active mobile phone that could generate high eld strengths when setting up an incoming call. The dose and contamination monitors tested above are generally hand-held about 3050 cm from the body. In normal use, these are less likely to register signicant readings from the high electric eld strengths adjacent to a belt-worn mobile phone. The effects that occurred exclusively at high eld strength could be mitigated by issuing instructions with the dose measuring device that it should not be used adjacent to a mobile phone that is switched on. This instruction may become more important as belt-worn ``hands free'' voice-controlled phones and phones that record information in silent mode without alerting the user become more common. Two electronic personal dosemeters showed an abnormal response up to 60 cm and up to 200 cm, respectively, from both mobile phones. These dosemeters could be affected by mobile phone users other than the wearer or if the wearer is using the phone adjacent to the ear. Indeed, abnormal responses from these devices to mobile phone use in other rooms have initiated surveys for ionizing radiation sources in the authors' hospital. Electronic personal dosemeters are often used in short surveys to reassure non-radiation workers in a hospital that they have been designated correctly. Examples of these workers would include pregnant nursing staff in intensive care units concerned about radiation doses from portable X-rays who cannot be reassured by didactic methods. The potential for cell phone interference should be considered when designing such surveys. Assessment for mobile phone interference of dose monitoring equipment already in service and new dose monitoring equipment may provide useful information. In this paper, a simple approach has been used to test dose monitoring devices. This is similar to the technique used by the Medical Devices Agency in the UK for testing electromagnetic immunity of medical devices from mobile phones [12] and may provide the basis for a pragmatic immunity testing protocol. More extensive testing may require specialized

equipment [12, 13]. Compliance with ANSI standards [11] and other test results should be specied in tender documents for new equipment. Such information may also be available for equipment already in service. The potential to improve the susceptibility of problematic devices by replacing shielding or other techniques should be investigated.

Conclusions

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. Interference is observed over a range of detector types and manufacturers. The potential for electromagnetic interference should be assessed when commissioning and specifying these devices.

Acknowledgments

Thanks to Mr Gavan O'Duffy of Eircell Ireland, Ms Katherine Buckley of Ericsson Ireland and Mr Patrick Gilligan Senior for their assistance in this work.

References

1. Information Society Commission. Ireland's progress as an information society. Dublin, Ireland: Government Publications Ofce, 1999. 2. Chapman S, Schoeld WN. Lifesavers and samaritans: emergency use of cellular (mobile) phones in Australia. Accid Anal Prev 1998;30:8159. 3. Goksu HY, Regulla D, Drexler G, editors. Present status of practical aspects of individual dosimetry, Part1: EU Member states, Radiation Protection 78. Brussels: European Commision, 1994. 4. Cember H. Health physics instrumentation. In: Wonsiewicz MJ, Navrozov M, editors. Introduction to health physics. London: McGrawHill, 1996:342418. 5. ECRI. Cell phones and walkie-talkies. Is it time to relax your restrictive policies? Health Devices 1999; 28:40913. 6. Schiller JH. Mobile communications. London: Addison-Wesley, 1999. 7. Mouly M, Pautet MB. The GSM system for mobile communications. Palasieu, France: published by the authors, 1992. 8. Meurling J, Jeans R. GSM: global systems for mobile telecommunications in ``The Mobile Phone Book''. London: CMP International Publishing, 1994:10111. 9. Hirning CR, Yuen PS. Type testing of the Siemens Plessey electronic personal dosimeter. Health Phys 1995;69:4666. 10. Oak Ridge National Laboratory. Oak Ridge National Instrument Evaluation Summary: Siemens Model EPD-2 Electronic Dosimeter. Tennessee, USA: Oak Ridge National Laboratory, 1998. 997
P Gilligan, S Somerville and J T Ennis 11. American National Standards Institute. ANSI N42.20 ``Performance criteria for active personnel radiation monitors''. New York: American National Standards Institute, 1989. 12. Medical Devices Agency. Device Bulletin DB9702 ``Electromagnetic compatibility of medical devices with mobile communications''. London: MDA, 1997. 13. Robinson MP, Flintoft ID, Marvin AC. Interference of medical equipment from mobile phones. J Med Eng Technol 1997;21:1416.

Who is the BIGGEST Fan of Sony Ericsson.
Billaws 133 posts since Jun 17, 2010
My list of Sony Ericsson phones ( since 2003 ) are:
T610i k700 k500 P910 K750 W550 K600 W800 W810 K610 Z350 P990 M600 W950 K510 W850 W300
Generated by Jive SBS on 2011-06-06+01:00 1
K790 W710 Z610 W880 W960 G900 K550 K810 K850 W660 W580 P1 T650 S500 W910 W890 K660 K770 C902 W980 X1 W350
Generated by Jive SBS on 2011-06-06+01:00 2
W302 G502 W595 C905 W705 W995 W395 T700 C903 C510 SATIO YARI S312 VIVAZ PRO X10 MINI AINO and now using. X10. So whats yours????
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urbot 28 posts since

Generated by Jive SBS on 2011-06-06+01:00 3
Dec 7, 2010 1. Re: Who is the BIGGEST Fan of Sony Ericsson. Dec 21, 2010 8:17 PM

Apparently not me.

Motorola CD930 (ca: 2000) Ericsson R320 no1 (ca:2002) Ericsson R320 no2 (ca:2002) Samsung (R230, I think) (2002-2005) SE T630 2005-2007 (2005-2007) Motorola K1 Krzr (2007-2009) Samsung SGH-i900 (2009-2010) "A terrible overprized combined phone and dated pocket computer" SE T280 (2009-2010) Given to my dear mother, still the "second phone" SE X10 Mini alias E10i (2010-) "The phone with steepest learning curve, short of endurance but SEs best ambassador" SE U5i Vivaz (for two weeks in 2010) "the first had a malfunctioning cardreader, after two weeks I took out my anger on the second Vivaz and pulverized it" SE J20i Hazel (2010-) "I love (the) Hazel" SE M1i Aspen (2010-) "the first was malfunctioning, the second one works but I have toughts about it's usefulness"

For 2011

Generated by Jive SBS on 2011-06-06+01:00 4
Have kind of an urge for a large screen mobile, like 6" or 9" screen, that can double as a computer. If get bored of the Hazel, I really would like a clamshell phone as simpel as the T280i.
Also, having no intention to cure my insane obsession for mobiles.
Billaws 133 posts since Jun 17, 2010 2. Re: Who is the BIGGEST Fan of Sony Ericsson. Dec 22, 2010 8:31 PM
Wait for X12 as it might be possible that you'll get what you want.
foefolkson 1 posts since Feb 21, 2011 3. Re: Who is the BIGGEST Fan of Sony Ericsson. Apr 21, 2011 5:51 AM
I just can say that product quality is excellent, but quality of the phone Sony CMD-J5 is fantastic. My wife uses Sony CMD-J5 from 2001 to present days, and even now, after 10 years, doesn`t want to change it, I think she`s a real fan.
Attachments: Sony CMD-J5 (front).jpg (113.1 K)
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