Two-dimensional “transXend” detector for third-generation energy-resolved computed tomography

The “transXend” detector measures X-rays as electric currents and provides the energy distribution of the measured X-rays after analysis. Capabilities of material distinction, effective atomic number measurement, and low-dose exposure computed tomography (CT) with high K-edge contrast agent from the use of the transXend detector in energy-resolved CT have been demonstrated via the first-generation CT measurements. For application of the principle of the transXend detector to the third-generation CT for human subjects in future work, a method for fabrication of a two-dimensional transXend detector is proposed and demonstrated using a commercial two-dimensional detector and two kinds of strip absorbers. The energy-resolved CT is performed by placing a proposed absorber system in front of a two-dimensional detector, which is used for conventional current measurement CT.     

Absorbed dose estimation using LET dependence in glow curve of thermoluminescent phosphor Li3B7O12:Cu in therapeutic carbon beams

A high temperature ratio (HTR) method has been proposed to correct the linear energy transfer (LET) dependence of thermoluminescent (TL) efficiency. To realize the use of the slab-type thermoluminescence detector (TLD) that based on the phosphor Li₃B₇O₁₂:Cu for heavy charged particle beam, the HTR method has been considered. To improve the reproducibility of HTR, the slow heating rate method is introduced in this report and the coefficient variations of HTR decreased from 10%–20% to 8%. The relation between TL-efficiency, HTR, and LET for Li₃B₇O₁₂:Cu was manifested and the TL-efficiency as a function of HTR was derived in an attempt to measure the absorbed dose without LET information. The feasibility of the HTR method in therapeutic carbon beams was evaluated by comparing the dose estimated by Li₃B₇O₁₂:Cu and by an ionization chamber. The accuracy of dose estimation in carbon beams was improved by using the HTR method, but there is room for further improvement. The use of Li₃B₇O₁₂:Cu in heavy charged particle beams can be materialized with further improvement of HTR sensitivity.     

Self‐Degradable Lipid‐Like Materials Based on “Hydrolysis accelerated by the intra‐Particle Enrichment of Reactant (HyPER)” for Messenger RNA Delivery

RNA‐based therapeutics is a promising approach for curing intractable diseases by manipulating various cellular functions. For eliciting RNA (i.e., mRNA and siRNA) functions successfully, the RNA in the extracellular space must be protected and it must be delivered to the cytoplasm. In this study, the development of a self‐degradable lipid‐like material that functions to accelerate the collapse of lipid nanoparticles (LNPs) and the release of RNA into cytoplasm is reported. The self‐degradability is based on a unique reaction “Hydrolysis accelerated by intra‐Particle Enrichment of Reactant (HyPER).” In this reaction, a disulfide bond and a phenyl ester are essential structural components: concentrated hydrophobic thiols that are produced by the cleavage of the disulfide bonds in the LNPs drive an intraparticle nucleophilic attack to the phenyl ester linker, which results in further degradation. An oleic acid‐scaffold lipid‐like material that mounts all of these units (ssPalmO‐Phe) shows superior transfection efficiency to nondegradable or conventional materials. The insertion of the aromatic ring is unexpectedly revealed to contribute to the enhancement of endosomal escape. Since the intracellular trafficking is a sequential process that includes cellular uptake, endosomal escape, the release of mRNA, and translation, the improvement in each process synergistically enhances the gene expression.     

γ-Ray measurements in boron neutron capture therapy using BeO ceramic thermoluminescence dosimeter

Journal of Materials Science: Materials in Electronics - In boron neutron capture therapy (BNCT), neutrons and γ-rays cause different biological effects, and it is necessary to discriminate...