Unique recognition of test phantom configurations was achieved in the large majority of cases. The method in the general case was further tested using an exhaustive set of inhomogeneity and phantom tissues

and geometries where the phantom thicknesses ranged between 8 and 24 cm. Unique recognition of the test phantom configurations was achieved only for part of the phantom parameter space. The correlations between the remaining false positive recognitions were analyzed.\n\nConclusions: The concept of 3D proton radiography for tissue inhomogeneities of simple geometries was established with the current work. In contrast to conventional 2D proton radiography, the main objective of the demonstrated 3D technique is not proton range. Rather, it is to measure the depth and thickness of an inhomogeneity located in an imaged geometry. Further work is needed see more to extend and apply the method to more complex geometries. (C) 2013 American Association of Physicists in Medicine.”
“A recent analysis of leukaemia mortality in Japanese A-bomb survivors has applied descriptive models, collected together from previous studies, to derive

a joint excess relative risk estimate (ERR) by multi-model inference (MMI) (Walsh and Kaiser this website in Radiat Environ Biophys 50:21-35, 2011). The models use a linear-quadratic dose response with differing dose effect modifiers. In the present Metabolism inhibitor study, a set of more than 40 models has been submitted to a rigorous statistical selection procedure which fosters the parsimonious deployment of model parameters based on pairwise likelihood ratio tests. Nested models were

consequently excluded from risk assessment. The set comprises models of the excess absolute risk (EAR) and two types of non-standard ERR models with sigmoidal responses or two line spline functions with a changing slope at a break point. Due to clearly higher values of the Akaike Information Criterion, none of the EAR models has been selected, but two non-standard ERR models qualified for MMI. The preferred ERR model applies a purely quadratic dose response which is slightly damped by an exponential factor at high doses and modified by a power function for attained age. Compared to the previous analysis, the present study reports similar point estimates and confidence intervals (CI) of the ERR from MMI for doses between 0.5 and 2.5 Sv. However, at lower doses, the point estimates are markedly reduced by factors between two and five, although the reduction was not statistically significant. The 2.5 % percentiles of the ERR from the preferred quadratic-exponential model did not fall below zero risk in exposure scenarios for children, adolescents and adults at very low doses down to 10 mSv. Yet, MMI produced risk estimates with a positive 2.5 % percentile only above doses of some 300 mSv.