  The EndoTOFPET-US project aims to jointly exploit Time-Of-Flight Positron
Emission Tomography (TOFPET) and ultrasound endoscopy with a multi-modal
instrument for the development of new biomarkers for pancreas and prostate
oncology. The paper outlines the functionality of the proposed instrument and
the challenges for its realization. The high level of miniaturization and
integration poses strong demands to the fields of scintillating
crystallography, ultra-fast photon detection, highly integrated electronics and
system integration. Solutions are presented to obtain a coincidence time
resolution better than 200 ps and a spatial resolution of ~1 mm with an
asymmetric TOFPET detector. A tracking system with better than 1 mm spatial
resolution precision enables the online alignment of the system. The detector
design, the production and test status of the single detector
