A detector using liquid Xenon (LXe) in the scintillation mode is studied for Positron Emission Tomography (PET) of small animals. Its specific design aims at taking full advantage of the Liquid Xenon scintillation properties. This paper reports on energy, time and spatial resolution capabilities of the first LXe prototype module equipped with a Position Sensitive PhotoMultiplier tube (PSPMT) operating in the VUV range (178 nm) and at 165 K. The experimental results show that such a LXe PET configuration might be a promising solution insensitive to any parallax effect.

This work, using an adult anthropomorphic phantom, aimed to establish an optimised technique for ladies of child-bearing age undergoing antero-posterior (AP) pelvis and AP and lateral lumbar spine examinations. Phase one of the work involved introducing the following dose-reducing measures individually: increased kVp, increased focus-film distances, a carbon fibre cassette, a faster film/screen combination. The second phase established an optimised technique based on a combination of the parameters listed above. Radiation dose was measured using thermoluminescent dosimeters and image quality was evaluated using anatomical criteria. All dose-reducing methods were compared with a standard technique, currently being used in a Dublin hospital. The results demonstrated that the optimised procedure reduced effective dose by 77, 62 and 66% for AP pelvis and AP and lateral lumbar spine respectively (p < 0.05) compared with the standard technique, with no significant changes in image quality. Dose-reducing measures used in combination offer substantial potential for optimisation of radiological procedures.

Summary Bulk density was determined indirectly in peat samples by X‐ray computed tomography (X‐ray CT) and compared with density values obtained by standard laboratory methods. Five Histosols were collected in the same cut‐over peatland, representing various degrees of disturbance related to the process of peat extraction. Soil cores were fully imaged by X‐ray CT with a voxel size of about 0.25 mm. Each one of these five attenuation profiles was analysed and compared with direct density measurements. A linear relationship, to convert attenuation values into density values, is proposed to determine the variation in bulk density with a spatial resolution clearly greater than standard laboratory determinations. It is also shown that X‐ray‐based density values can be effectively used to characterize the structure of peat soils and the possible consequences of disturbances after drainage and peat mining. Under the accepted limitations of the method, X‐ray CT opens up new opportunities to determine the structural quality of peat and to monitor its modifications with time. This indirect diagnostic could be particularly useful to study peatlands' hydraulic systems or evaluate the effectiveness of restoration measures.

International audienceA detector with a very specific design using liquid Xenon (LXe) in the scintillation mode is studied for Positron Emission Tomography (PET) of small animals. Two prototype modules equipped with Position Sensitive Photo Multiplier Tubes (PSPMTs) operating in the VUV range (178 nm) and at 165 K were built and studied in coincidence. This paper reports on energy, time and spatial resolution capabilities of this experimental test bench. Furthermore, these experimental results were used to perform the first image reconstruction of a 22Na source placed in the experimental setup