Fabrication and Optimization of a Fiber-optic Dosimeter for Proton Beam Therapy Dosimetry / 의학물리

In this study, we have fabricated a fiber-optic dosimeter for a proton beam therapy dosimetry. We have measured scintillating lights with the various kinds of organic scintillators and selected the BCF-12 as a sensor-tip material due to its highest light output and peak/plateau ratio. To determine the optimum diameter of BCF-12, we have measured scintillating lights according to the energy losses of proton beams in a water phantom. Also, we determined the adequate length of organic scintillator by measuring scintillating lights according to the incident angles of proton beam. Using an optimized fiber-optic dosimeter, we have measured scintillating lights according to the dose rates and monitor units of proton accelerator.

Fabrication and Characterization of a One-dimensional Fiber-optic Dosimeter for Electron Beam Therapy Dosimetry / 의학물리

In this study, we have fabricated a one-dimensional fiber-optic dosimeter for electron beam therapy dosimetry. Each fiber-optic dosimeter has an organic scintillator with a plastic optical fiber and it is embedded and arrayed in the plastic phantom to measure one-dimensional high energy electron beam profile of clinical linear accelerator. The scintillating lights generated from each sensor probe are guided by plastic optical fibers to the multi-channel photodiode amplifier system. We have measured one-dimensional electron beam profiles in a PMMA phantom according to different field sizes and energies of electron beam. Also, the isodose and three-dimensional percent depth dose curves in a PMMA phantom are obtained using a one-dimensional fiber-optic dosimeter with different electron beam energies.

Measuring of the Cerebellar Volume of Normal Koreans in Their 20s and 40s Using Magnetic Resonance Imaging

PURPOSE: This study purposed to measure the standard volume of the cerebellum of normal Koreans who were in their 20s and 40s, and we also wished to find out the difference in the volume of the cerebellum according to gender and age. MATERIALS AND METHODS: This study collected MR brain images from 118 people in their 20s (males: 58, females: 60) and 100 people in their 40s (males: 41, females: 59), for a total of 218 people. For each of sagittal, coronal and axial sections, the cerebellar part of the images was segmented using automatic and manual methods, and the volume was then measured. In order to observe differences according to gender and age and also to observe the interactive effect between gender and age, a two-way ANOVA test was performed using gender (2 levels) and age (2 levels) as independent variables. RESULTS:The average volume of the cerebellum of Koreans in their 20s was 133.74 (cm3) and that of Koreans in their 40s was 121.83 (cm3). The average volume of the cerebellum of male Koreans in their 20s and 40s was 134.55 (cm3) and that of female Koreans was 123.06 (cm3). The volume of the cerebellum was significantly larger in Koreans in their 20s than those volumes of the cerebellum of Koreans in their 40s, and the cerebellum volumes in male Koreans were larger than those of the Korean females. Moreover, the reduction of the volume of the cerebellum with age was significantly larger in male Koreans than in the Korean females. CONCLUSION: According to the results of measuring the volume of the cerebellum for normal Koreans in their 20s and 40s, the volume was significantly different according to gender and age, and the reduction of the volume of the cerebellum with age was significantly larger in men than in women.