sensor 119 z and temperature sensor ts 128 z form pair 372 magnetic field sensor 120 z and temperature sensor ts 128 z form pair 373 fig1 and 15a show an improved catheter assembly 375 and guidewire assembly 379 to be used with the gci apparatus 501 the catheter assembly 375 is a tubular tool that includes a catheter body 376 which extends into a flexible section 378 that possesses increased flexibility for allowing a more rigid responsive tip 377 to be accurately steered through a torturous path the magnetic catheter assembly 375 in combination with the gci apparatus 501 reduces or eliminates the need for the plethora of shapes normally needed to perform diagnostic and therapeutic procedures this is due to the fact that during a conventional catheterization procedure the surgeon often encounters difficulty in guiding the conventional catheter to the desired position since the process is manual and relies on manual dexterity to maneuver the catheter through a tortuous path of for example the cardiovascular system thus a plethora of catheters in varying sizes and shapes are be made available to the surgeon in order to assist him her in the task since such tasks require different bends in different situations due to natural anatomical variations within and between patients by using the gci apparatus 501 only a single catheter would be needed for most if not all patients because the catheterization procedure is now achieved with the help of an electromechanical system that guides the magnetic catheter and guidewire assembly 375 and 379 to the desired position within the patient 39 s body 390 as dictated by the surgeon 39 s manipulation of the virtual tip 405 without relying on the surgeon pushing the catheter quasi blindly into the patient 39 s.