INVESTIGATION OF THE EXTENDED RANGE REM-COUNTER SMARTREM-LINUS IN REFERENCE AND WORKPLACE FIELDS EXPECTED AROUND HIGH-ENERGY ACCELERATORS.

Radiation survey instrumentation is adequate for the use around high-energy accelerators if capable to measure the dose arising from neutrons with energies ranging from thermal up to a few gigaelectronvolts. The SmartREM-LINUS is a commercial extended range rem-counter, consisting of a central (3)He-proportional counter surrounded by a spherical moderator made of borated polyethylene with an internal shield made of lead. The dose rate indicated by the SmartREM-LINUS was investigated for two different irradiation conditions. The linearity and the angular dependence of the indicated dose rate were investigated using reference neutron fields produced by (241)AmBe and (252)Cf. Additional measurements were performed in two different workplace fields with a component of neutrons with energies >20 MeV, namely the CERN-EU high-energy reference field and near the beam dump of the SwissFEL injector test facility. The measured dose rates were compared to a commercial rem-counter (WENDI2) and the results of Monte Carlo simulations.

Quantitative assessment of bowel wall vascularisation in Crohn's disease with contrast-enhanced ultrasound and perfusion analysis.

Patients with inflammatory bowel disease (IBD) often undergo several radiologic imaging studies, which - with the exception of magnetic resonance imaging (MRI) and B-scan ultrasound (US) - subject patients to ionizing radiation. With contrast enhanced ultrasound microvascular imaging of the bowel is possible. Hence, the aim of our study was to assess the perfusion pattern of inflamed bowel walls in Crohn's disease compared with healthy volunteers quantitatively using a specific quantification software. We evaluated 4 volunteers and 20 patients with proven Crohn's disease, who went through an active episode based on clinical symptoms and complementary imaging by MRI (19 patients) and computed tomography (1 patient), respectively, with dynamic contrast-enhanced ultrasound (CEUS) using a second generation contrast agent (SonoVue, Bracco, Germany). Retrospectively, we applied the quantification software Qontrast (Bracco, Italy) to obtain contrast-enhanced sonographic perfusion maps for each lesion. Patients had significant higher peak values (median 46.86, lower quartile 37.91, upper quartile 53.20) and significant higher regional blood volume (median 2133.65, lower quartile 1202.90, upper quartile 2820.44) than volunteers. Considering the very low peak value of the healthy, it is easy to understand that the time-to-peak was significantly shorter in the volunteers (median 4.45, lower quartile 1.82, upper quartile 6.88) than in the patients (median 12.15, lower quartile 9.18, upper quartile 15.74). Our study showed clear differences between inflamed and normal bowel wall vascularity regarding all perfusion parameters. These results show that a quantitative assessment of the bowel wall vascularisation and inflammation, respectively, is possible. The software used here enables us to collect data, not only in a semi-quantitative but also in a reproducible, quantitative manner which is comparable with the evaluation of CT or MRI generated data.