1478 IEEE TRANSACTIONS ON MAGNETICS, VOL. 44, NO. 6, JUNE 2008 The Use of TLM and Kriging Methods for Electromagnetic Compatibility Management in Health Care Facilities Wilson Valente Jr. , Alexandre Dalla’Rosa , Adroaldo Raizer ,and Lionel Pichon Grupo de Engenharia em Compatibilidade Eletromagnética-GEMCO, Universidade Federal de Santa Catarina-UFSC, Florianópolis SC 88040-970, Brazil Laboratoire de Génie Electrique de Paris-LGEP-SUPELEC, Université Paris Sud and Université Pierre et Marie Curie, Gif-sur-Yvette 91192, France This paper promotes the use of numerical methods as an alternative tool in order to evaluate and manage electromagnetic compatibility in health care facilities. Numerical analysis is performed employing the Transmission Line Modeling (TLM) Method and Kriging, which are supported by measurement tests, providing a reliable assessment of the electromagnetic profile established in clinical environments. Index Terms—Electric field measurement, health care facilities, numerical analysis, transmission line modeling method. I. INTRODUCTION A DVANCES in technology and the increased use of elec- tromedical equipments (EME) to support medical proce- dures are considered as greatly responsible for the improvement of electromagnetic energy within health care facilities (HCF) environments. In such circumstances, the electromagnetic en- ergy presented in these areas can reach a critical level in which EME were not developed to operate. This situation can provide an environment which is favorable to the appearance of electro- magnetic interference (EMI) phenomenon. Thus, the knowledge of electromagnetic behavior shown by these environments can represent an important tool in order to promote electromagnetic compatibility (EMC) and avoid the ap- pearance of undesirable phenomena. Although electromagnetic profile in health care facilities can become quite complex, due to a number of sources operating in a wide spectrum, measure- ment methods have been used as a first approach in attempt to evaluate the electromagnetic profile established in these areas. On the other hand, since field measurements surveys are costly and time consuming, it may be more effective to investigate the electromagnetic environment by computational means [1]. As far as computational simulation is concerned, several methods have been developed to deal with electromagnetic fields and wave propagation problems, such as Finite Elements Method (FEM), Moment Method (MoM), Finite Difference Time Domain (FDTD), Transmission Line Modeling Method (TLM), and so forth. In order to truly represent the problem at hand, the method to be applied in this work must be able to discretize the entire area under test, since HCF environments are usually delineated by complicated geometric features. For many years, the TLM method has been successfully applied with the purpose of evalu- ating wave propagation in such complex areas [3]. In this sense, the present work proposes the use of two numerical methods (TLM and Kriging) as an alternative solution in order to inves- tigate clinical environments. Digital Object Identifier 10.1109/TMAG.2007.915985 Color versions of one or more of the figures in this paper are available online at http://ieeexplore.ieee.org. Attempting to optimize this process, a preliminary field mea- surement is used to define all critical points to be evaluated by numerical methods. Therefore, it promotes the employment of measurement and prediction techniques as a coordinate tool for electromagnetic compatibility management in health care facilities. II. METHODOLOGY The methodology used to investigate critical areas in HCF (e.g., operating rooms) is developed in two stages. During the first stage is performed a number of in locu measurements con- cerning electrical fields established within the clinical environ- ment. The main sources and all critical frequencies are identified through spectral analysis and then evaluated according to EMI risk stated by IEC 60601-1-2 [6]. During the second stage is developed a numerical treatment using the TLM method. Based on preliminary measurement re- sults, electric field distribution is estimated over the area under test in order to evaluate the influence of significant sources of energy, such as electrosurgical unit (ESU), TV broadcasting and telecom systems. A further point concerning numerical calculus is performed in attempt to define a safety area for the proper op- eration of mobile sources (cell phones), which minimize EMI risk in EME. A. Measurement Methods Electric field strength measurements are carried out using a control system (laptop satellite—Toshiba), a FSH-3 spectrum analyzer and a set of three antennas (Rohde & Schwarz). All measurements performed are narrow band and can evaluate emissions in a frequency range from 30 MHz to 3 GHz. A typ- ical measurement session is developed in order to adequately characterize the worst case established in the HCF environment under test. The methods used are based on IEEE Std.139 and IEEE Std. C95-3 standards. It is developed in two main stages, as follows. 1) With all EME turned off: Measurements can verify the in- fluence of external sources within the HCF environment under test. 2) With EME turned on: Measurement can evaluate EME contribution in the environment under test. 0018-9464/$25.00 © 2008 IEEE