Abstract:

Magnetic Resonance Imaging (MRI) is a widely used means of imaging and becoming increasingly popular for cardiac applications as well. But for patients with im- planted pacemakers, the use of MRI is not allowed in Eu- rope and the United States due to potentially hazardous interactions of the RF pulses with the pacemaker-electrode system. Here heating at the tip of the electrode is regarded as the most important one.In this simulation study, the occurring current densities and E-fields should be determined by employing numerical field calculation. Computer models of metallic objects like straight wires, simplified pacemakers and a replication a commercial bipolar electrode were placed in a plexiglas box positioned inside a birdcage coil. The results con- firmed findings of previous in-vitro studies regarding the influence of size and position of the exposed objects and thereby proved the validity of the presented approach.

Abstract:

Anatomical voxel models are used for example for dosimetric assessment and numerical field calculations. For best matching between models and patients properties an accurate model should be created by Magnetic Resonance Imaging or Computer Tomography images for every patient. Due to complexity, time and costs this is not always possible. In contrast 3D laser scanning is a fast and easy method to gain information about a patients body surface. In this work generic organ models are developed to fit into the laser scan envelope of any patient. One model set was processed as to fit to the volume reference values of the International Commission on Radiological Protections of six different ages. To accomplish a more realistic shape, orthogonal scaling factors are used to simulate growth in three different directions.