Nuclear imaging like PET and SPECT has established itself as an indispensable tool in pre-operative diagnostics. This group's aim is to develop new nuclear, tomographic imaging methods for intra-operative applications.

Subproject I: Computational modeling of detection physics for 3D intraoperative imaging with navigated nuclear probes

PI's: Prof. Dr. Nassir Navab, Prof. Dr. Sibylle Ziegler, Prof. Dr. med. Markus Schweiger
PhD Students: Alexander Hartl, Dipl. Inf.; Thomas Wendler, M. Sc.

Intra-operative functional 3D imaging of a radiotracer, used e.g. for cancer labeling, is possible by acquiring the data of a tracked hand-held nuclear probe (a single detector) and computing a tomographic reconstruction. According to the acquisition geometry ad-hoc models of a system matrix are built and the resulting linear system is solved for a discretized volume  of interest. The computation of the system matrix is perfomed by applying a physical model of the detection process of the probe, mapping each measurement to the voxels of the volumeof interest. For accuracy all the physical effects of the acquisition and the geometry need to be addressed, while for use as an intra-operative imaging modality, computation requirements must remain feasible

Subproject II: Computer-assisted navigation and visualization framework for 3D intraoperative imaging with navigated nuclear probes

PI's: Prof. Dr. Nassir Navab, Prof. Dr. Sibylle Ziegler, Prof. Dr. med. Markus Schweiger
PhD Students: Coskun Özgür, M.Sc.; Tobias Lasse, Dipl. Inf., Dipl. Math.

PET/CT has opened new paths in the staging of cancer malignancy and follow-up during therapy. Modern tomographs allow detection of millimetric structures enabling precise definition of location and borders of tumors. Howewer, this information can only be used suboptimally during surgery as intermittent disease progressionor potential treatment effects along with deformation and lack of optical contrast make the search for the detected structures and the definition of secure resection borders extremely hard. Futhermore, these tomographs are too bulky for intra-operative use. To adress these shortcomings, two types of hand-held nuclear probes have been introduced: (i) gamma probe for intra-operative guidance and (ii) beta probe for post-excision residual tumor check. This project aims at the development of a compact computer-assisted framework comprising both probe types and at the optimal integration of this framework into surgical workflow.