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Chair for Computer Aided Medical Procedures & Augmented Reality
Lehrstuhl für Informatikanwendungen in der Medizin & Augmented Reality

D. I. Shakir, A. Hartl, N. Navab, S. I. Ziegler
Evaluation of an ad hoc model of detection physics for navigated beta-probe surface imaging
Proceedings of SPIE Visualization, Image-Guided Procedures, and Modeling Conference, Lake Buena Vista (Orlando Area), FL, USA, February 2011 (bib)

Intraoperative surface imaging with navigated beta-probes has been shown to be a possibility to enable control of tumor resection borders. By employing ad hoc models of the detection physics the image quality can be improved. Our model computes the amount of radiation from a single point source that reaches the detector, with the solid angle subtended by the detector on the source, assuming perfect shielding. The sensitivity of the detector to the source due to the angle between the detector axis and the source-to-detector vector is also considered. A set of experiments was performed with three sources (two 10x10mm2 and one 20x10mm2 pieces of cellulose saturated with FDG) on a plate as phantom. Five sets of measurements were taken, three of them at a distance of 10mm from the plate und two at 30mm. At both distances one measurement set was taken in a random manner and the other ones systematically covering the whole area. The same experiments were simulated with our model and the GATE simulation framework. The resulting measurements from the experiments and simulations were then used to perform a reconstruction of the sources. The real measurements were compared to those simulated with our model and GATE, with a mean NCC of 80.64% for our model and 70.14% for GATE. In the reconstructions of the real measurements the sources were visually quite well separated, however the reconstructions of the measurements simulated by the model show that there is still room for further improvement.
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