A. Okur, D. I. Shakir, P. Matthies, A. Hartl, M. Essler, S. I. Ziegler, T. Lasser, N. Navab Freehand Tomographic Nuclear Imaging Using Tracked High-Energy Gamma Probes Bildverarbeitung für die Medizin 2013 (BVM), Heidelberg, Germany, March 2013. The original publication is available online at www.springerlink.com (bib)
	Systems allowing freehand SPECT imaging inside the operating room have been introduced previously. In this work, we aim to take one step further and enable 3D freehand imaging using positron emitting radio-traces such as [18F]FDG. Our system combines a high-energy gamma probe with an optical tracking system. Detection of the 511keV annihilation gammas from positron-emitting radio-tracers is modeled analytically. The algorithm iteratively reconstructs the radioactivity distribution within a localized volume of interest. Based on the PET/CT data of 7 patients with tumors and lymph node metastates in the head and neck region, we build a neck phantom with [18F]FDG-filled reservoirs representing tumors and lymph nodes. Using this phantom, we investigate the limitations and capabilities of our method. Finally, we discuss possible improvements and requirements needed so that our approach becomes clinically applicable.
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