Attenuation correction for small animal PET tomographs

Attenuation correction is one of the important corrections required for quantitative positron emission tomography (PET). This work will compare the quantitative accuracy of attenuation correction using a simple global scale factor with traditional transmission-based methods acquired either with a small animal PET or a small animal x-ray computed tomography (CT) scanner. Two phantoms (one mouse-sized and one rat-sized) and two animal subjects (one mouse and one rat) were scanned in CTI Concorde Microsystem's MicroPET(R) Focus(TM) for emission and transmission data and in ImTek's MicroCAT(TM) II for transmission data. PET emission image values were calibrated against a scintillation well counter. Results indicate that the scale factor method of attenuation correction places the average measured activity concentration about the expected value, without correcting for the cupping artefact from attenuation. Noise analysis in the phantom studies with the PET-based method shows that noise in the transmission data increases the noise in the corrected emission data. The CT-based method was accurate and delivered low-noise images suitable for both PET data correction and PET tracer localization

The DREAMS experiment on the ExoMars 2016 mission for the study of Martian environment during the dust storm season

International audienceThe ExoMars programme, which is carried out by European Space Agency (ESA) in cooperation with the Russian federal Space Agency (Roscosmos), foresees a two-steps mission to Mars. The first mission consists of an orbiter and an Entry Descent and Landing Demonstrator Module (EDM) to be launched in January 2016 and is scheduled to land on the planet during the statistical dust storm season; the second mission includes a descent module, a surface platform and a rover and will be launched in 2018. The DREAMS (Dust characterization, Risk assessment and Environment Analyser on the Martian Surface) experiment for ExoMars 2016 is an autonomous meteorological station designed to study the effect of dust on Martian environment which will operate for two Martian days (sols) relying on its own power supply after landing. DREAMS includes a suite of sensors able to analyse temperature, pressure, humidity, wind speed and direction and solar irradiance as well as an electric field probe which will perform the first electrical characterization of Mars surface atmosphere