A beam range monitor based on scintillator and multi-pixel photon counter arrays for heavy ions therapy

Fast beam range measurements are required to maximize the time available for patient treatment, given that the beam range requires verification with respect to quality assurance to maintain accelerator commissioning standards and ensure patient safety. A novel beam range monitor based on a plastic scintillator and multi-pixel photon counter (MPPC) arrays is therefore proposed in this paper. The monitor was constructed using 128 plastic scintillator films with a thickness of 1 mm and an active area of 50 × 50 mm^(2). A customized MPPC array read the scintillation light of each film. The advantage of dividing the active detector volume into films is that it intercepts the particle beam and enables direct differential light yield measurement in each film, in addition to depth-light curve generation without the need for image analysis A GEANT4 simulation, including scintillator quenching effects, was implemented, and the results revealed that Birks’ law exhibited a slight little influence on the position of the beam range, only changing the shape and absolute normalization of the Bragg curve, which is appropriate for the calculation of the beam range using the depth-light curve. The performance of the monitor was evaluated using a heavy-ion medical machine in Wuwei City, Gansu Province, China. The beam range measurement accuracy of the monitor was 1 mm, and the maximum difference between the measured and reference ranges was less than0.2%, thus indicating that the monitor can meet clinica carbon ion therapy requirements.

Association between new onset type 1 diabetes and real-world antibiotics and neonicotinoids’exposure-related gut microbiota perturbation

Background The real-world exposure levels of non-therapeutic antibiotics and neonicotinoids in type 1 diabetes(T1D)children and their associations as environmental triggers through gut microbiota shifts remained unknown.We thus investigated the antibiotics and neonicotinoids’exposure levels and their associations with gut microbiota in pediatric T1D.Methods Fifty-one newly onset T1D children along with 67 age-matched healthy controls were recruited.Urine concentrations of 28 antibiotics and 12 neonicotinoids were measured by mass spectrometry.Children were grouped according to the kinds of antibiotics’and neonicotinoids’exposures,respectively.The 16S rRNA of fecal gut microbiota was sequenced,and the correlation with urine antibiotics and neonicotinoids’concentrations was analyzed.Results The overall detection rates of antibiotics were 72.5%and 61.2%among T1D and healthy children,whereas the neonicotinoids detection rates were 70.6%and 52.2%(P=0.044).Children exposed to one kind of antibiotic or two or more kinds of neonicotinoids had higher risk of T1D,with the odd ratios of 2.579 and 3.911.Furthermore,co-exposure to antibiotics and neonicotinoids was associated with T1D,with the odd ratio of 4.924.Antibiotics or neonicotinoids exposure did not affect overall richness and diversity of gut microbiota.However,children who were exposed to neither antibiotics nor neonicotinoids had higher abundance of Lachnospiraceae than children who were exposed to antibiotics and neonicotinoids alone or together.Conclusion High antibiotics and neonicotinoids exposures were found in T1D children,and they were associated with changes in gut microbiota featured with lower abundance of butyrate-producing genera,which might increase the risk of T1D.