title: Direct time-of-flight for quantitative, real-time in-beam PET: a concept and feasibility study.
abstract: We extrapolate the impact of recent detector and scintillator developments, enabling sub-nanosecond coincidence timing resolution (tau), onto in-beam positron emission tomography (in-beam PET) for monitoring charged-hadron radiation therapy. For tau < or = 200 ps full width at half maximum, the information given by the time-of-flight (TOF) difference between the two opposing gamma-rays enables shift-variant, artefact-free in-beam tomographic imaging by means of limited-angle, dual-head detectors. We present the corresponding fast, TOF-based and backprojection-free, 3D reconstruction algorithm that, coupled with a real-time data acquisition and a fast detector encoding scheme, allows the sampled beta+-activity to be visualized in the object during the course of the irradiation. Despite the very low statistics scenario typical of in-beam PET, real-treatment simulations show that in-beam TOF-PET enables high-precision images to be obtained in real-time, either with closed-ring or with fixed, dual-head in-beam TOF-PET systems. The latter greatly alleviates the installation of in-beam PET at radiotherapeutic sites.
authors.affiliation: Forschungszentrum Dresden-Rossendorf, Institute of Radiation Physics, Bautzner Landstr. 128, PO Box 510119, 01314 Dresden, Germany. crespo@lip.pt <crespo@lip.pt>
authors.forename: Paulo
authors.initials: P
authors.lastname: Crespo
authors.forename: Georgy
authors.initials: G
authors.lastname: Shakirin
authors.forename: Fine
authors.initials: F
authors.lastname: Fiedler
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Enghardt
authors.forename: Andreas
authors.initials: A
authors.lastname: Wagner
mesh_terms: D000465:Algorithms; D003199:Computer Systems; D005240:Feasibility Studies; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D016247:Information Storage and Retrieval / Q000379:methods*; D049268:Positron-Emission Tomography / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity