is contemplated that support 14 and platform member 16 may together comprise a conventional operating room table more particularly it is one of the objects of the present invention to provide support structure to be used with a conventional operating table to enable use of an electromagnetic field generator while still preventing inaccuracies or other unreliability in the readings from the system associated with the electromagnetic field generator the torso of the patient is supported by central portion 22 referring to fig1 and 3 central portion 22 is designed to support electromagnetic field generator 12 referring to fig5 7 central portion 22 supports a central support member 23 central support member 23 includes a well 24 which is configured to receive electromagnetic field generator 12 the portion of central support member 23 which supports electromagnetic field generator 12 has a thickness 25 greater than u00bc inch preferably greater than u00bd inch and most preferably greater than three quarters of an inch although this thickness will vary depending on the characteristic of the electromagnetic field generator and other associated system components a pair of steps 26 and 28 fig2 define the lengthwise limits of well 24 and have a height which substantially matches the thickness of electromagnetic field generator 12 a head support member 32 is positioned on one side of central support member 23 to provide support for the head of the patient.