Basis material decomposition in spectral CT using a semi-empirical, polychromatic adaption of the Beer-Lambert model.

Following the development of energy-sensitive photon-counting detectors using high-Z sensor materials, application of spectral x-ray imaging methods to clinical practice comes into reach. However, these detectors require extensive calibration efforts in order to perform spectral imaging tasks like basis material decomposition. In this paper, we report a novel approach to basis material decomposition that utilizes a semi-empirical estimator for the number of photons registered in distinct energy bins in the presence of beam-hardening effects which can be termed as a polychromatic Beer-Lambert model. A maximum-likelihood estimator is applied to the model in order to obtain estimates of the underlying sample composition. Using a Monte-Carlo simulation of a typical clinical CT acquisition, the performance of the proposed estimator was evaluated. The estimator is shown to be unbiased and efficient according to the Cramér-Rao lower bound. In particular, the estimator is capable of operating with a minimum number of calibration measurements. Good results were obtained after calibration using less than 10 samples of known composition in a two-material attenuation basis. This opens up the possibility for fast re-calibration in the clinical routine which is considered an advantage of the proposed method over other implementations reported in the literature.

Increasing the field of view in grating based X-ray phase contrast imaging using stitched gratings.

Grating based X-ray differential phase contrast imaging (DPCI) allows for high contrast imaging of materials with similar absorption characteristics. In the last years' publications, small animals or parts of the human body like breast, hand, joints or blood vessels have been studied. Larger objects could not be investigated due to the restricted field of view limited by the available grating area. In this paper, we report on a new stitching method to increase the grating area significantly: individual gratings are merged on a carrier substrate. Whereas the grating fabrication process is based on the LIGA technology (X-ray lithography and electroplating) different cutting and joining methods have been evaluated. First imaging results using a 2×2 stitched analyzer grating in a Talbot-Lau interferometer have been generated using a conventional polychromatic X-ray source. The image quality and analysis confirm the high potential of the stitching method to increase the field of view considerably.

Global health education in Swedish medical schools.

AIMS: Global health education is increasingly acknowledged as an opportunity for medical schools to prepare future practitioners for the broad health challenges of our time. The purpose of this study was to describe the evolution of global health education in Swedish medical schools and to assess students' perceived needs for such education. METHODS: Data on global health education were collected from all medical faculties in Sweden for the years 2000-2013. In addition, 76% (439/577) of all Swedish medical students in their final semester answered a structured questionnaire. RESULTS: Global health education is offered at four of Sweden's seven medical schools, and most medical students have had no global health education. Medical students in their final semester consider themselves to lack knowledge and skills in areas such as the global burden of disease (51%), social determinants of health (52%), culture and health (60%), climate and health (62%), health promotion and disease prevention (66%), strategies for equal access to health care (69%) and global health care systems (72%). A significant association was found between self-assessed competence and the amount of global health education received (p<0.001). A majority of Swedish medical students (83%) wished to have more global health education added to the curriculum. CONCLUSIONS: Most Swedish medical students have had no global health education as part of their medical school curriculum. Expanded education in global health is sought after by medical students and could strengthen the professional development of future medical doctors in a wide range of topics important for practitioners in the global world of the twenty-first century.

Unwrapping differential x-ray phase-contrast images through phase estimation from multiple energy data.

We present a spectral phase unwrapping approach for grating-based differential phase-contrast data where the unwrapped interferometer phase shift is estimated from energy discriminated measurements using maximum likelihood principles. We demonstrate the method on tomographic data sets of a test specimen taken at different x-ray energies using synchrotron radiation. The proposed unwrapping technique was demonstrated to successfully correct the data set for phase wrapping.

Naked barley-Optimized recipe for pure barley bread with sufficient beta-glucan according to the EFSA health claims.

Naked barley is an underutilized crop that is suitable for the production of functional food: it contains remarkable amounts of ß-glucans, which are well known for their blood cholesterol and short-time blood sugar regulating properties and their impact on weight regulation. The aim of the present work was to develop naked barley bread with satisfying sensory characteristics and good baking qualities that could augment the intake of dietary fiber, especially ß-glucans and therefore meet the requirements of the EFSA health claim for ß-glucans. The results of the multiple response optimization suggest that the elevated use of water, malt flour and margarine in pure naked barley bread augment the sensory attractiveness whereas the use of acidifier and pre-gelatinized flour has a negative effect on the sensory quality.