Eisuke Hanada

Electromagnetic interference on medical equipment by low-power mobile telecommunication systems

There have been a number of reports of electromagnetic interference (EMI) on electronic medical equipment caused by mobile telecommunication systems. In Japan, the use of the personal handy-phone system (PHS) has greatly expanded within urban areas, PHS handsets transmit EM signals at a frequency of 1.9 GHz and have a peak radiated power of 80 mW. This power level is lower than that of other mobile telecommunication systems. Two studies were carried out. One was to determine whether or not PHS interferes with electronic medical equipment in hospitals. We observed no EMI on electronic medical equipment when the PHS handset was in either the speaking mode or on standby. The second study was to observe EMI from 1.9-GHz signals at several radiation power levels. Although EMI was not observed at the radiated peak power of the PHS handset, EMI on some of the tested equipment was observed when the radiated power was ten or more times higher than that of the PHS handset.

Possible Electromagnetic Interference with Electronic Medical Equipment by Radio Waves Coming from Outside the Hospital

Electromagnetic interference (EMI) with electronic medical equipment by radio waves from mobile telephone handsets has been reported and is currently receiving wide attention. The possibility of EMI with electronic medical equipment by radio waves coming into the hospital has also been pointed out. But so far, there are no reports measuring the frequency distribution of electric field intensity induced by incoming radio waves. Therefore, we measured electric field intensity induced by radio waves coming into our 11-floor hospital, which was under construction. The maximum intensity observed was about 200 V/m at 2.79 GHz, from airport surveillance radar waves. The maximum intensity induced by radio waves from cellular phone base stations was 1.78 V/m. These data show that various frequencies of radio waves are common in this urban area, and that they induce strong electric field intensity. This strong electric field intensity might cause EMI with electronic medical equipment. Measurement of the electromagnetic environment should be done by each hospital in urban areas to prevent EMI with electronic medical equipment.

A Practical Procedure to Prevent Electromagnetic Interference with Electronic Medical Equipment

Problems involving electromagnetic interference (EMI) with electronic medical equipment are well-documented. However, no systematic investigation of EMI has been done. We have systematically investigated the causes of EMI. The factors involved in EMI were determined as follows: 1) Electric-field intensity induced by invasive radio waves from outside a hospital. 2) Residual magnetic-flux density at welding points in a building. 3) Electric-field intensity induced by conveyance systems with a linear motor. 4) The shielding capacity of hospital walls. 5) The shielding capacity of commercial shields against a wide range frequency radio waves. 6) The immunity of electronic medical equipment. 7) EMI by cellular telephone and personal handy-phone system handsets.From the results of our investigation, we developed a following practical procedure to prevent EMI. 1) Measurement of electric-field intensity induced by invasive radio waves from outside the hospital and industrial systems in the hospital. 2) Measurement of residual magnetic-flux density at electric welding points of hospital buildings with steel frame structures. 3) Control of the electromagnetic environment by utilizing the shielding capacity of walls. 4) Measurement of the immunity of electronic medical equipment. And 5) Installation of electronic gate equipment at the building entrance to screen for handsets.

Advantages of Low Output Mobile Communication Systems in Hospitals

Mobile telephone systems using radio waves with very low power outputs rarely interfere with electronic medical equipment, which allows them to be safely installed in hospitals. The Personal Handy-phone System, PHS, which was developed and is widely used in Japan, is one such system. It has many useful functions including voice communication, string message transfer, e-mail, an answering system limited to selected persons or groups, paging, automatic call transfer, and handset positioning. In this paper we discuss the benefits of these functions confer to hospital communication systems.

A Filter That Prevents the Spread of Mail-Attachment-Type Trojan Horse Computer Worms

The malicious code “W32/Sircam” is spread via e-mail and potentially through the file space shared by local area networks. Such Trojan-horse-type computer worms easily penetrate Internet firewalls and propagate via the “backdoor” to other computers. Once a malicious code, such as “W32/Sircam,” has been executed on a system, it may reveal or delete confidential data, such as clinical records. In order to protect against the leakage of clinical records, we devised a mail filter that successfully prevents the spread of mail containing this malicious code. It is significant that neither access control nor packet filtering is guaranteed to prevent the spread of this mail-attachment-type Trojan horse computer worm.

A screening gate to prevent entry of mobile telephone handsets in the speaking/standby mode into prohibited and restricted areas

Electromagnetic interference to electronic equipment by mobile telephone handsets is well known. We present an automatic screening gate that detects concealed mobile telephone handsets and classifies them by type. The screening method used in the gate does not require any additions to or reconstruction of mobile telephone systems.

Electromagnetic Interference with Electronic Medical Equipment Induced by Automatic Conveyance Systems

Electromagnetic interference (EMI) with electronic medical equipment induced by automatic conveyance systems is estimated. We measured the electric intensities of electromagnetic waves transmitted by three self-controlled electric truck systems. We also observed EMI with an infusion pump and a syringe pump set 1 m from the rail. The maximum electric field intensity was observed at the supplied current frequency in two systems with non-contact power supply mechanisms. The highest value, 137.0 dBμV/m, was measured just beside the rail. This is higher than the international electromagnetic immunity standard limit for electronic medical equipment. EMI may occur if electronic medical equipment is used within 2 m of the rail when the system contains an inductive power supply mechanism. With a contact power supply mechanism, the electric field intensity was much lower than that of the immunity standard. EMI should not occur even when electronic medical equipment is used just beside the rail.

Remote Connection to the Kyushu University Medical Center LAN Using Digital and Analog Telephone Lines

SOHO (Small Office/Home Office) has recently become popular, as it makes working at home possible. Computers or Local Area Networks(LAN) connected to the office network from home are necessary for the implementation of this concept. Kyushu University has begun a service connecting home computers to the campus LAN for researchers, staff and students of the Faculty of Medicine. We have two different telephone connection methods. One connects the campus LAN and the home computer LAN using routers through the Integrated Services Digital Network (ISDN). The other connects computers at home to the workstation in the university, using modems and the PPP (Point to Point Protocol) through a public telephone analog line. This paper outlines our university SOHO connection system and discusses the merits and demerits of using telephone line connections.

A Simple Method for Calculating the Financial Balance of a Hospital, Based on Proportional Dividing

It is necessary to estimate financial status to determine hospital management policy. The costs and revenues (financial balance) of each hospital division are one good index. However, it is difficult to calculate the financial balance for each division, since clinics and central services are intricately involved with each other. There are no reports on a pragmatic method for calculating the financial balance. We devised a simple method based on proportional dividing. Consequently, one individual was able to complete the calculation for our hospital, which consists of 1300 beds and 23 clinics, without using the central hospital computer system.

A simple computerized program for the calculation of the required sample size necessary to ensure statistical accuracy in medical experiments

We developed a sample size estimation program (SSEP) with which medical researchers can easily estimate the appropriate sample size for a specific significance level and statistical power using their favorite WWW browsers. SSEP can estimate the sample sizes for six statistical methods by Monte-Carlo simulation: Students t-test, Welchs t-test, Analysis of variance, Wilcoxons rank sum test, Kruskal-Wallis test, and the Cochran-Armitage test for linear trends. The SSEP simulation programs were created using the SAS software macro language. Medical researchers can interactively use this program and determine reliable sample sizes when planning new prospective clinical studies and animal experiments.