ABSTRACT
Grating based X-ray phase contrast imaging is on the verge of being applied in clinical settings. To achieve this goal, compact setups with high sensitivity and dose efficiency are necessary. Both can be increased by eliminating unwanted absorption in the beam path, which is mainly due to the grating substrates. Fabrication of gratings via deep X-ray lithography can address this issue by replacing the commonly used silicon substrate with materials with lower X-ray absorption that fulfill certain boundary conditions. Gratings were produced on both graphite and polymer substrates without compromising on structure quality. These gratings were tested in a three-grating setup with a source operated at 40 kVp and lead to an increase in the detector photon count rate of almost a factor of 4 compared to a set of gratings on silicon substrates. As the visibility was hardly affected, this corresponds to a significant increase in sensitivity and therefore dose efficiency.
Subject(s)
Artifacts , Refractometry/instrumentation , X-Ray Diffraction/instrumentation , Absorption, Radiation , Equipment Design , Equipment Failure Analysis , Radiation Dosage , Reproducibility of Results , Scattering, Radiation , Sensitivity and Specificity , Tomography, X-Ray Computed/instrumentation , X-RaysABSTRACT
Micropaque CT, a new suspension of barium sulphate, has recently become available for clinical use in abdominal CT. The attenuation of the 1.5 per cent solution, measured in vitro, was 222 HU (without artifacts). In about 45 per cent of the clinical examinations artifacts occurred which, however, were not disturbing. Sufficient opacification of stomach and bowel was achieved in 65 per cent. 55 per cent of patients found the suspension pleasant to take, ten per cent complained of mild diarrhoea. Micropaque CT is particularly suitable for upper abdominal CT in outpatients.
