A CT-based Monte Carlo Dose Calculations for Proton Therapy Using a New Interface Program

Year: 2009 Volume: 3 Issue: 5 341 - 346 Pages

• Authors:
• A. Esmaili Torshabi
• A. Terakawa
• K. Ishii
• H. Yamazaki
• S. Matsuyama
• Y. Kikuchi
• M. Nakhostin
• H. Sabet
• A. Ishizaki
• W. Yamashita
• T. Togashi
• J. Arikawa
• H. Akiyama
• K. Koyata

Abstract: The purpose of this study is to introduce a new interface program to calculate a dose distribution with Monte Carlo method in complex heterogeneous systems such as organs or tissues in proton therapy. This interface program was developed under MATLAB software and includes a friendly graphical user interface with several tools such as image properties adjustment or results display. Quadtree decomposition technique was used as an image segmentation algorithm to create optimum geometries from Computed Tomography (CT) images for dose calculations of proton beam. The result of the mentioned technique is a number of nonoverlapped squares with different sizes in every image. By this way the resolution of image segmentation is high enough in and near heterogeneous areas to preserve the precision of dose calculations and is low enough in homogeneous areas to reduce the number of cells directly. Furthermore a cell reduction algorithm can be used to combine neighboring cells with the same material. The validation of this method has been done in two ways; first, in comparison with experimental data obtained with 80 MeV proton beam in Cyclotron and Radioisotope Center (CYRIC) in Tohoku University and second, in comparison with data based on polybinary tissue calibration method, performed in CYRIC. These results are presented in this paper. This program can read the output file of Monte Carlo code while region of interest is selected manually, and give a plot of dose distribution of proton beam superimposed onto the CT images.

• Keywords:
• Monte Carlo
• CT images
• Quadtree decomposition
• Interface program
• Proton beam

Effect of Rotating Electrode

Year: 2013 Volume: 7 Issue: 7 809 - 815 Pages

• Authors:
• S. Gnapowski
• H. Akiyama
• S. Hamid R. Hosseini
• C. Yamabe

Abstract: A gold coated copper rotating electrode was used to eliminate surface oxidation effect. This study examined the effect of electrode rotation on the ozone generation process and showed that an ozonizer with an electrode rotating system might be a possible way to increase ozone-synthesis efficiency. Two new phenomena appeared during experiments with the rotating electrode. First was that ozone concentration increased to about two times higher than that of the case with no rotation. Second, input power and discharge area were found to increase with the rotation speed. Both ozone concentration and ozone production efficiency improved in the case of rotating electrode compared to the case with a non-rotating electrode. One possible reason for this was the increase in discharge length of micro-discharges during electrode rotation. The rotating electrode decreased onset voltage, while reactor capacitance increased with rotation. Use of a rotating-type electrode allowed earlier observation of the ozone zero phenomena compared with a non-rotating electrode because, during rotation, the entire electrode surface was functional, allowing nitrogen on the electrode surface to be evenly consumed. Nitrogen demand increased with increasing rotation s

• Keywords:
• Rotating electrode
• input power
• onset voltage
• discharge canal.