Publications by authors named "Takashi Onishi"
Purpose: This study investigated a novel stoichiometric computed tomography (CT) number calibration (SCC) model for megavoltage CT (MVCT). This model was specifically designed to convert CT numbers to mass densities (MDs) for dose calculations when using the TomoTherapy MVCT radiotherapy delivery system.
Materials And Methods: The MVCT-SCC model extended the conventional SCC model originally developed for kilovoltage CT by incorporating additional parameters to account for pair production and water-equivalent CT number corrections, which are specific to MVCT applications.
Article Synopsis
- The study evaluates how different air CT numbers in the image value density table (IVDT) impact dose calculations for head-and-neck radiotherapy using TomoTherapy megavoltage CT (MVCT) images.
- Two IVDTs with distinct air CT numbers are applied to MVCT images of a phantom, allowing for a comparison of dose distributions between different planning scenarios.
- Results indicate that one IVDT provided more accurate dose recalculations compared to the other, improving the alignment with treatment planning doses derived from kVCT images.
Porous metallic materials can have a low Young's modulus, which is approximately equal to that of human bone, by controlling the porosity. On the other hand, certain medical polymers exhibit biofunctionalities that are not intrinsically present in metallic materials. Therefore, a composite consisting of these materials is expected to possess both these advantages for biomedical applications.
View Article and Find Full Text PDFObjective: The authors' goal was to identify differences in regional brain activity between physiological and benzodiazepine-induced sleep to clarify the brain structures involved in the drug's hypnotic effect.
Method: Using positron emission tomography, they compared regional cerebral blood flow during non-REM sleep in nine volunteers treated with placebo or triazolam, a short-acting benzodiazepine, in a double-blind, crossover design.
Results: Blood flow in the basal forebrain and amygdaloid complexes was lower during non-REM sleep when subjects were given triazolam than when they were given placebo.