Gamma Ray Computed Tomography for Fast Rotating Objects

A. Bieberle and U. Hampel

Institute of Safety Research, Forschungszentrum Dresden - Rossendorf e.V., POB 51 01 19, 01314 Dresden, Germany, Email: A.Bieberle@fzd.de

ABSTRACT

Recently, a high-resolution gamma ray computed tomography measurement system was presented, to analyse processes at hydrodynamic and multi phase flow facilities non-invasively. The detector arc consists of 320 single detectors with an active area of 2 mm x 8 mm each, made of a lutetium yttrium orthosilicate (LYSO) scintillator crystal coupled to a large avalanche photo diode (APD). For the investigation of rapidly rotating objects and phase distributions, such as hydrodynamic couplings or stirred reactors, a high-speed angle synchronised measurement is required. In typical CT systems the radiation detector and the isotopic source rotate around the object of investigation to acquire projections from different angular positions in one plane. For rotating objects, the measurement system may be kept in a fixed position and the rotation of the object may be used for projection acquisition. For the case of rapidly rotating objects, new fast read-out electronics for our existing gamma radiation detector was developed, that is compatible to the existing pulse processing scheme and realises a periodical read-out with 29 μs intervals for all 320 detector counters, enabling acquisition of more than 500 projections per revolution for an object that rotates at 3000 rpm.

Keywords High speed gamma ray tomography, fast read-out electronics