The Electromagnetic Interference of Mobile Phones ...

ORIGINAL ARTICLE

The Electromagnetic Interference of Mobile Phones on the Function of a F-Camera Hamid Javadi, MD,* Zahra Azizmohammadi, MD,Þ Ali Mahmoud Pashazadeh, MSc,þ Isa Neshandar Asli, MD,Þ Taleb Moazzeni, PhD,§ Nastaran Baharfar, MD,Þ Babak Shafiei, MD,Þ Iraj Nabipour, MD,þ and Majid Assadi, MDþ Purpose: The aim of the present study is to evaluate whether or not the electromagnetic field generated by mobile phones interferes with the function of a SPECT F-camera during data acquisition. Methods: We tested the effects of 7 models of mobile phones on 1 SPECT F-camera. The mobile phones were tested when making a call, in ringing mode, and in standby mode. The F-camera function was assessed during data acquisition from a planar source and a point source of 99mTc with activities of 10 mCi and 3 mCi, respectively. A significant visual decrease in count number was considered to be electromagnetic interference (EMI). Results: The percentage of induced EMI with the F-camera per mobile phone was in the range of 0% to 100%. The incidence of EMI was mainly observed in the first seconds of ringing and then mitigated in the following frames. Conclusions: Mobile phones are portable sources of electromagnetic radiation, and there is interference potential with the function of SPECT F-cameras leading to adverse effects on the quality of the acquired images. Key Words: electromagnetic interference, mobile phones, F-camera, SPECT (Clin Nucl Med 2014;39: 232Y236)

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ommunication in the 21st century changed drastically with the advent of mobile phones. Today, this invaluable means of communication has infiltrated many aspects of human life and become an indispensable tool. Given that mobile phones offer an easyto-use and portable form of communication, medical practitioners, like so many other professionals, keep pace with mobile technological developments.1,2 However, the application of this technology in medical centers, despite its numerous benefits, is accompanied by some risks. These risks are based on the premise of the electromagnetic interference (EMI) of mobile phones with medical devices that are near, which results in the potential malfunction of life-supporting equipment. Although serious medical errors as a result of mobile phone interference with medical devices have not been established definitively, incidents of interference and concomitant medical errors have been reported extensively in the literature.3Y9 According to studies performed on various types of medical devices, different levels of vulnerabilities relative to EMI have been observed, ranging from no effect to total malfunction. Because of the differences in function, shielding, and electronic devices used in the design of various medical devices, it is expected that the vulnerabilities associated with 1 type of Received for publication June 19, 2013; revision accepted December 11, 2013. From the *Golestan Research Center of Gastroenterology and Hepatology, Golestan University of Medical Sciences, Gorgan; †Department of Nuclear Medicine, Taleghani Hospital, Shahid Beheshti University of Medical Sciences, Tehran; and ‡The Persian Gulf Nuclear Medicine Research Center, Bushehr University of Medical Sciences, Bushehr, Iran; and §Department of Electrical and Computer Engineering, University of Nevada, Las Vegas, NV. Conflicts of interest and sources of funding: none declared. Reprints: Majid Assadi, MD, The Persian Gulf Nuclear Medicine Research Center, The Persian Gulf Biomedical Sciences Institute, Boostan 19 Alley, Sangi St, Bushehr, Iran. E-mail: [email protected]; [email protected]. Copyright * 2014 by Lippincott Williams & Wilkins ISSN: 0363-9762/14/3903Y0232

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medical device may differ from other types. One of the medical devices that may be susceptible to mobile phones’ electromagnetic radiation is the SPECT F-camera. SPECT is a medical imaging system routinely used in nuclear medicine centers to take images of radionuclide distribution inside the human body. The vulnerability of the SPECT F-camera to electromagnetic fields is mainly due to the photomultiplier tubes (PMTs) used in its structure.10 The adverse effects of magnetic fields on the function of PMTs were reported before 1980 in former models of SPECT F-cameras in which PMTs were easily affected by the earth’s magnetic field during SPECT.11 In newer F-cameras, PMTs are well shielded to eliminate such interference. Although this shielding has lessened the adverse effects of the earth’s magnetic field, its protection against electromagnetic waves generated by mobile phones may be debatable. The incentive to investigate the validity of this notion was derived from a case reported during renal scintigraphy in our nuclear medicine center. We observed that during renal scintigraphy, when the F-camera was near the patient’s mobile phone, which was located in her pocket, the ringing of the mobile phone induced adverse effects on the function of the F-camera, causing bright spots on frame 6 of the flow phase in the acquired image.4 This observation led to the hypothesis, at least for our model of SPECT F-camera, that the electromagnetic field produced by a mobile phone can interfere with the function of the PMTs of a F-camera and that, despite having shielding against the earth’s magnetic field, they are still vulnerable to electromagnetic fields. Therefore, we decided to make a basic attempt to evaluate the function of a F-camera during SPECT in terms of EMI from mobile phones.

PATIENTS AND METHODS Medical Equipment

A rotating dual-head digital F-camera (ADAC Pegasys; model SH Genesys Epic, Milpitas, Calif ) was used to assess the possible EMI of mobile phones on the function of a F-camera. The representative F-camera was equipped with a low-energy all-purpose parallel whole collimator with a 20% window centered at 140 keV to provide energy discrimination for 99mTc, which was the source of radioactivity.

Radioactivity Source

To assess radionuclide imaging using a F-camera, 2 sources of Tc (ie, a planar source and a point source) were provided. Planar distribution of the radionuclide consisted of 10 mCi of 99mTc strewn on sterile gauze with dimensions of approximately 10 cm 5 cm. The sterile gauze was covered by a plastic bag then inserted under the F-camera to be imaged as the planar distribution of radioactivity, whereas the point source of radioactivity included 3 mCi of 99mTc in a vial. 99m

Mobile Phone Seven different models of cellular phones from different manufacturers were used in this study. The representative cellular phones were the HTC 1, HTC 2, Sony Ericsson Xperia, Samsung B7300, Nokia N86, Nokia N97, and Chinese mobile phone model Clinical Nuclear Medicine

& Volume 39, Number 3, March 2014

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Clinical Nuclear Medicine

EMI Effect on a F-Camera


H9600+. All of the cellular phones were operating with the global system for mobile communications in the frequency of 900 MHz and a maximum output power of 2 W.

TABLE 2. The Effects of an HTC 2 Mobile Phone on the Function of a F-Camera During SPECT Acquisition

Data Acquisition Protocol

Detector Angle

Calling Is Installed

Ringing Started

Ringing Stopped

Reduction in Count Number Was Observed

0 (ANT) 6 12 30 66 84 96 108 114 240

3 4 3 8 3 3 9 3 3 2

3 4 3 8 3 3 9 3 3 2

18/17 18/17 16/16 20/20 18/18 17/17 20/20 17/17 17/17 17/17

3 V V 8, 9 V V V V 2, 3 V

The F-camera was used for the planar and SPECT acquisition of the point source and planar sources of 99mTc, respectively. Each source was used individually on the SPECT couch, and imaging was performed at fixed distance of 20 cm from the radioactive source to the surface of the F-camera. A reduction in the count number of radioactivity in the acquired data, recognized by visual interpretation, was considered to be induced EMI in the function of the F-camera. Two mobile phones were used for the test during planar acquisition, and 6 mobile phones were used during SPECT acquisition. (The Nokia N86 was used for both planar and SPECT acquisition.) The effect of each mobile phone was tested individually on the function of the F-camera. To study the effects of mobile phones in all of their states, scans were performed on dynamic mode. Results of mobile phone EMI in the function of F-camera were assessed qualitatively by visual interpretation of 2 expert nuclear medicine physicians. Each mobile phone was placed on the couch next to the radioactive source. The connection was installed in a certain frame and then continued for a few of the next frames. To observe the EMI of the cellular phone under test conditions exclusively and prevent the effects of any other potentially interfering sources, no portable electromagnetic equipment (eg, cordless phones and 2-way radios) was allowed in the SPECT room during the performance of the tests. The evaluation of the mobile phones’ EMI was tested in 3 states, namely, standby mode, ringing mode, and when making a call, that is, before the connection is made. When making a call, before the receiving mobile phone rings, some electromagnetic frequencies are developed to find the location of the desired mobile phone. In this mode, which starts shortly after dialing to the receiving mobile phone and ends when it starts ringing, the receiving mobile phone generates high intensity electromagnetic radiation. The noise heard in a speaker, seconds before a receiving mobile phone rings, is a common experience in daily life.

RESULTS In this study, to assess the mobile phones’ EMI with the function of a SPECT F-camera, 7 different models of mobile phones were used. For SPECT data acquisition of 99mTc, the effects of each of the 6 mobile phones (ie, the HTC 1, HTC 2, Sony Ericsson Xperia, Samsung B7300, Nokia N86, and Chinese mobile phone model H9600+) are summarized in Tables 1 to 4. In Figure 1, the effects of all 6 mobile phones are shown comparatively. According to the TABLE 1. The Effects of the Nokia N86 Mobile Phone on the Function of a F-Camera During SPECT Acquisition Detector Angle 0 (ANT) 45 90 135 180 225 270 315 360 (ANT) 0 (ANT)

Calling Is Ringing Ringing Reduction in Count Number Installed Started Stopped Was Observed 3 3 3 3 3 3 3 3 3 3

3 3 3 3 3 3 3 3 4 4

15/15 15/15 14/14 14/14 14/14 14/14 14/14 14/14 14/14 14/14

ANT indicates Anterior.

* 2014 Lippincott Williams & Wilkins

V V 3 V 3 V V V V V

ANT indicates Anterior.

results of this phase of our study, EMI was observed in 50% of the tested mobile phones (ie, 3 of 6), which corresponds to 38% of all tests (ie, 31 of 81) performed with the 6 cell phones. It was observed that the various models of mobile phones had different effects on the function of the F-camera. The HTC 1 mobile phone induced the highest number of incidents of EMI, followed by the HTC 2 and Nokia N86. The results of the study showed that the F-camera malfunctioned in 100%, 23%, and 22% of the performed tests using the HTC 1 (in all 25 angles), HTC 2 (4/17 angles), and Nokia N86 (2/9 angles), respectively. In addition, the results of the study with the Sony Ericsson TABLE 3. The Effects of an HTC 1 Mobile Phone on the Function of a F-Camera During SPECT Acquisition Detector Angle

Calling Is Installed

Ringing Started

Ringing Stopped

Reduction in Count Number Was Observed

0 (ANT) 6 12 30 66 84 96 108 114 240 270 276 282 288 294 300 306 312 318 324 330 336 348 354 360

2 2 12 2 4 3 2 2 2 21 2 2 2 2 1 1 2 2 2 1 2 2 2 2 2

3 3 13 3 5 4 3 3 3 22 3 3 3 3 2 2 3 3 3 2 3 3 3 3 3

10/11 9/10 18/19 11/12 15/16 12/13 10/11 10/11 10/11 30/30 10/11 10/11 10/11 10/11 10/11 10/11 10/11 10/11 10/11 10/11 10/11 10/11 10/11 10/11 10/11

3 2, 3 12, 13, 14 2, 3 4, 5, 6, 8 4 2, 3 2, 3 2, 3 21, 22 2 2 2 2 1 2 2 2, 3 2, 3 1, 2 2 3 2, 3 2, 3 2, 3

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TABLE 4. The Tests Performed Using the Samsung B7300, Chinese H9600+, and Sony Ericsson Xperia Mobile Phones on the Function of a F-Camera During SPECT Acquisition Samsung B7300 Detector Angle 0 (ANT) 45 90 135 180 225 270 315 360 (ANT) 0 (ANT)

Chinese H9600+

Sony Ericson Xperia

Connection Installed

Ringing Started

Ringing Stopped


Ringing Started

Ringing Stopped


Ringing Started

Ringing Stopped

3 3 3 3 3 3 3 3 3 3

3 3 3 3 3 3 3 3 4 4

15/15 15/15 14/14 14/14 14/14 14/14 14/14 14/14 14/14 14/14

3 3 3 3 3 3 3 3 3 3

3 3 3 3 3 3 3 3 3 3

14/14 14/14 15/15 15/15 14/14 14/14 14/14 14/14 14/14 14/14

3 5 3 4 3 4 4 3 4 V

3 5 3 4 3 4 4 3 5 V

14/14 16/16 14/14 16/16 15/15 15/15 16/16 15/15 15/15 V

Xperia, Samsung B7300, and Chinese mobile phone H9600+, which was performed during data acquisition in 9 detector angles, showed no induced interference in the function of the F-camera. In the planar data acquisition of the source point of 99mTc, EMI was evaluated with the Nokia N86 and Nokia N97 mobile phones in 16 and 24 frames, respectively. The results of the study with the Nokia N86 showed a significant decrease in intensity in frame 6, which occurred simultaneously with the start of the ringing of the mobile phone. It should be mentioned that the other frames were normal in intensity while the mobile phone was ringing (Fig. 2). For the Nokia N97, after it started scanning, there was a significant decrease in intensity in frame 7 (ie, at the same time that the mobile phone started ringing). This interference continued up to frame 19 and ended when the mobile phone stopped ringing (Fig. 3). This finding was in contrast to the findings of the rest of the study in which the incidence of EMI was only observed at the start of the ringing. According to the results of our study, the incidence of EMI was mainly observed in the first seconds of the ringing mode. The signs of EMI gradually lessened or faded completely in the frames

shortly after the start of the ringing (the only exception was seen in the Nokia N97 in which EMI lasted until the ringing stopped).

DISCUSSION The benefits of mobile phones, like all other technologies, are accompanied by some risks and concerns. One of the health concerns associated with mobile phones is based on the fact that they are a portable source of electromagnetic radiation and may interfere with vulnerable life-supporting medical devices. Although this phenomenon is largely based on theoretical principle, there are a number of studies and reports indicating incidents of mobile phone EMI with medical devices. The present study was one of the first of its kind to evaluate mobile phone EMI on the function of one of the common medical devices used in nuclear medicine centers. The findings of this study revealed that mobile phones interfere with the function of the F-camera. In the SPECT acquisition of the planar source, EMI was observed in 100%, 23%, and 22% of the tests performed with an HTC1, HTC2, and Nokia N86, respectively, but interference was not

FIGURE 1. The percentage of tests performed and the resultant EMI according to the different brands and models of mobile phone used during SPECT acquisition. 234

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EMI Effect on a F-Camera

FIGURE 2. The effects of the Nokia N86 on the function of a F-camera during planar acquisition of the point source of 99mTc. There was a significant decrease in intensity in frame 6, which coincided with the time the mobile phone started ringing.

FIGURE 3. The effects of the Nokia N97 on the function of a F-camera during the planar acquisition of the point source of 99mTc. There was a significantly decreased level of intensity in frame 7, which coincided with the time the mobile phone started ringing. This interference continued up to frame 19 and disappeared when the mobile phone stopped ringing. * 2014 Lippincott Williams & Wilkins

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reported with the Sony Ericsson Xperia, Samsung B7300, or Chinese H9600+. This finding indicates that various brands and models of mobile phones have different levels of interference. In the planar imaging of the point source, the Nokia N86 and Nokia N97 adversely affected the normal views. We observed that, among all models of mobile phones used in the study, the effects of the Nokia N97 on acquired images continued for 9 frames, which was in contrast to the results of the other models of mobile phones. The main observation of the present study was the incidence of EMI in the first seconds of ringing mode. This finding is in a good agreement with our previously reported case in 2011. During the renal scintigraphy of a 32-year-old woman, at the same time as the patient’s mobile phone started ringing, an abnormal view (ie, bright spots) was observed in the imaging frame. However, in the following frames, despite the fact that the mobile phone continued ringing, the imaging frames returned to normal. It has been proved that the different modes (ie, standby mode, ringing mode, and calling mode) of a mobile phone induce different effects on medical devices given that the output power of the mobile phone changes if its working mode changes.12 The produced output signal in ringing mode is more powerful than that in standby mode. In this study, no adverse effects on the function of the F-camera were seen in standby mode. Another important factor that determines the intensity of induced EMI is the proximity of the mobile phone to the medical device.8,13,14 As a fundamental principle, EMI decreases as the distance between the source of electromagnetic radiation (mobile phone) and suspected device (medical device) increases. In this study, to simulate a hypothetical patient’s mobile phone position (ie, usually in his or her pocket) during data acquisition, the mobile phone was placed on the couch at a fixed distance of 20 cm from the source of radioactivity. It is obvious that keeping the mobile phone far from the F-camera may reduce the levels of EMI, whereas bringing it in close contact with the camera intensifies the level of EMI. Likewise, recently a new study evaluated the potential negative influence of cellular phones and digitally enhanced cordless telecommunication (DECT) tools on the quality of static and dynamic scintigraphy.15 The evaluation was done by performing phantom measurements under real situations. A functional renal phantom acting as a pair of kidneys in dynamic scans was developed. Data were gathered using the setup of cellular phones and DECT phones placed in various positions in association to a camera head to test the potential interference of cellular phones and DECT phones with the cameras. Cellular phones frequently interfered with the oldest type of F-camera, which, as its single-head specification, is the device most often applied for renal studies. Curves indicating the renal function were significantly disrupted; cellular phones and DECT phones demonstrated a disruption concerning static acquisition.15 Our study is limited in some respects. First, the test was conducted on a limited number of mobile phones. Various brands and models of mobile phones induce different levels of EMI; therefore, to better understand the effect of mobile phone electromagnetic radiation on the function of a F-camera, a large study with a greater number of mobile phones of different brands and models is necessary. Another limitation pertains to the output power of the mobile phone. It has already been proven that communication technology is the most important factor determining the output level of mobile phones.16 The present study was performed using a global system for mobile communication, which was the only system available in our region. To provide a more generalized finding, it is recommended that similar studies be conducted in regions with other forms of communication systems, such as time division multiple access and code division multiple access. It is also proposed that mobile phone effects on F-camera function be tested at various distances to offer a safe distance 236

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for the operation of a F-camera when it is in the proximity of a mobile phone. Another main limitation was the absence of oscilloscope or spectrum analyzer during the study. To do more quantitative study of mobile phone EMI with the function of F-camera, it is recommended to perform similar study using oscilloscope or spectrum analyzer to measure the intensity of mobile phones during the scan. In this study, in the case of Nokia N97, which was in contrast to other mobile phones with respect to EMI with F-camera, application of oscilloscope would be useful to find the reason of such findings. Finally, our study was performed on dynamic mode, which was restricted in visual interpretation of the affected scans. To quantitatively analyze the count decrease in the acquired images, it is recommended to perform static scan to acquire count decrease and their SD. Despite the limitations of our study, it supports our previous case report in which a ringing mobile phone induced temporary noise on a SPECT image. As a general conclusion, we have revealed that mobile phones may have interference potential on the function of a F-camera. Although the percentage of induced EMI of the mobile phones was in the range of 0% to 100% depending on their brand and model, it was mainly a temporary effect. It is also reasonable to conclude that the rapidly changing technology of mobile phones and F-cameras will affect future levels of mobile phone EMI with respect to F-cameras through the introduction of more compatible mobile phones, more protected F-cameras, and shielded PMTs.

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