Deep Brain Stimulation (DBS) has resulted in a renaissance as an alternative way for treatment of parkinson's disease and essential tremor. Deep brain stimulation employ the use of high electric field to stimulate some brain centers. The final position of the electrodes in the brain is specified by the aid of CT and MRI scans for the patient's head before and after the operation. A study of electric field distribution in the brain is required to interpret and improve the action of DBS. In this master thesis project, Voreen was extended to visualize a multimodal volume of the CT and MR images....