Patient Positioning Using Magnetic Implants and Magnetic Field Sensors

Abstract

A phantom study was conducted in order to evaluate the precision and reproducibility of a magnetic field positioning system using magnetic implants and magnetic field sensors. Three implants and three magnetic field sensors were used to position a phantom on a Simulix Y simulator; x-ray films were used as reference. The reproducibility of the position determination of the three magnetic field sensors was checked three times in five different positions in both the X and Y dimensions of the sensors. The phantom was then positioned by the system five times and the displacement errors of four markers in the periphery of the phantom were noted. A reference x-ray film was exposed before the positioning procedure. An error of one millimetre was permitted in each dimension in one sensor. Only the maximum displacement errors of one of the four markers were noted. In the first reproducibility test the system was found to miss 1 mm in one reading out of 90 position readings. In the second part, the mean for the maximum displacement error was 0.46 and 0.6 mm for the maximum frontal and lateral displacements respectively, with a maximal error of 1.3 mm.