KEK Pro ceedings June R Pro ceedings of the Third International Workshop on EGS August KEK Tsukuba Japan Edited by Y Namito H Hirayama and S Ban High Energy Accelerator Research Organization FOREWARD The First International Workshop on EGS was held at KEK during August and the Second International Workshop on EGS was held at KEK during August to exchange information ab out EGS itself as well as researches related to EGS internationally These provided useful information among researchers who use EGS as the to ol in various elds The third workshop was held at KEK during August The workshop sp onsored by High Energy Accelerator Research Organization in Japan KEK attracted over EGS users from seven nations Short course on EGS was held on the rst and second day of the workshop using test version of EGS co de At the workshop talks including p oster session were presented from lowenergy problems to the highenergy ones in the various research elds like the medical physics radiation detector simulation etc These pro ceedings include most of the presentations at this workshop Finallywewould like to express our great appreciation to all authors who have prepared manuscript quickly for the publication of this pro ceedings The organizing committee S Ban KEK A F Biela jew U Michigan H Hirayama KEK Y Namito KEK W R Nelson SLAC CONTENTS Mo died Random Hinge Transp ort Mechanics and Multiple Scattering StepSize Selection in EGS S J Wilderman and A F Bielajew New Photon Physics in EGS Y Namito and H Hirayama Benchmark Calculation for EGS W R Nelson JCLiu HHirayama YNamito AFBielajew and SWilderman The CrossSection Dividing Metho d and the Simultaneous Distribution Between the Deection Angle and the Spatial Displacement for Charged Particles Penetrating through Matters T Nakatsuka and K Okei TrackTracing of Charged Particles with Simultaneous Disribution between the Deection Angle and the Spatial Displacement K Okei and T Nakatsuka A Visual User Interface Program EGSWIN for EGS R Qiu J L Li and Z Wu Interfacing EGS with Geant An Example of Virtual Monte Carlo Approach K Murakami LSCATGISMO an ob jectoriented Framework for Particle Simulation J Giersch and A A Weidemann ROSI A Monte Carlo Simulation for XrayTub es F Sukowski Examination of the Program to Avoid Roundo Error Y Shiota K Tabushi K Shimomura S Kito and TKusunoki Research for Deciding the Numb er and Each Width of Bins of the Energy Sp ectrum of the Xrays Used for Radiotherapy S Kito K Tabushi K Shimomura Y Shiota and T Kusunoki Comparison Convolution Metho d with Monte Carlo Simulation by EGS T Kusunoki Y Obita K Tabushi K Shimomura S Kito and Y Shiota Application of EGS to Intensity Monitor Dev elopmentfor Synchrotron Radiation at SPring N Nariyama i Investigation of Feasibility and Unfolding Metho d of a Measured Sp ectra Using EGS Co de G H Yoo K J Chun S H Hah and H M Kim Verication for the Disagreementbetween EectivePointand Geometrical Center of Thimble Ionization Chamber K Shimomura and K Tabushi Outline of the Dose Calculation System IMAGINE for Radiotherapy K Saito E Kunieda Y Narita H Kimura M Hirai H M Deloar K Kaneko M Ozaki T Fujisaki A Myojoyama and H Saitoh Development of EGS User Co des for IMAGINE S Takagi J Funabiki Y Oyatsu O Sato K Saito H Kimura M Hirai H Saito and A Myojoyama Optimal Parameters for Energy Sp ectral Calculations of Mega Voltage Photon Beam Using Monte Carlo Simulations A Myojoyama H Saitoh T Fujisaki Y Narita and K Saito Soft Tissues in the Patient Digitizati on for the Monte Carlo RadiotherapyTreatment Planning M Hirai J Funabiki S Takagi H Saitoh and K Saitoh Monte Carlo Simulations for Stereotactic Radiotherapy System with Various Kilo Voltage Xray Energy HM Deloar E Kunieda T Kawase H Saitoh M Ozaki T Fujisaki A Myojoyama K Saito S Takagi O Sato and A Kudo Monte Carlo Simulations of Dose Distributions for and MV Photon Beams from a Varian Clinac C Accelerator F Araki Monte Carlo Calculation of Inair Output Factors P I Wang R D Sheu C J Lo C S Chui U T Lin W L Chen Mon te Carlo Calculations and GafChromic Film Measurements for Leksell Gamma Knife Unit H W Lee R D Sheu U T Lin and W L Chen EGS Particle Tra jectory and Geometry Display Program CGVIEW Ver A Takamura T Sugita Y Namito and H Hirayama Development and Validation of a Monte Carlo Dosimetric Quality Assurance System for Dynamic IntensityMo dulated Radiotherapy T Yamamoto Y Miyabe S Yano T Teshima T Mizowaki Y Nagata and M Hiraoka ii Comparison with a MeV Xray Dose and Monte Carlo Simulation using a Human Bo dy Phantom A Chadani K Koshida K Minami K Ejiri M Shimo Y Hibino K Egami S Arakawa H Nakagawa C Kawabata and M Hayakawa Monte Carlo Simulation for ElectronLoss and PhotonScattering Corrections for ParallelPlate FreeAir Chambers T Kurosawa N Takata and Y Koyama Q Measurement Using A Total Absorption Detector With EGS Generated Resp onse Functions H Hayashi I Miyazaki M Shibata K Kawabe Y Kojima A Taniguchi Monte Carlo Calculations of FreeAir Ionization Chamb er Correction Factors for Electron Loss and Photon Scatter at INER U T Lin R D Sheu and W S Hwang Development of EGSbased D Brain SPECT Simulator DBSS T Yokoi T Hashimoto and H Shinohara Implementation and Performance Evaluation of DepthDep endent Correction in SPECT for Myo cardial Numerical Phantom A Simulation Study Using EGS T Hashimoto T Imae D Usuba T Momose H Shinohara and T Yokoi Exp osure Doses to Medical Workers Concerning Positron Emission Tomography I Yamaguchi H Narita and Kobayashi Evaluation of External Radiation Exp osure of Personnel Involved in Veterinary Nuclear Medicine N Komatsubara N Ito M Natsuhori T Sano T Ishikawa S Hatakeyama S Futatsugawa K Terasaki and H Hirayama Application of EGS Co de for the Evaluation of Sp ecic Absorb ed Fractions and S values for Internal Dosimetry S Kinase Monte Carlo Calculation of Normalized Glandular Dose in Mammography J L Hsu U T Lin and W L Chen Dose Distribution in the Human Bo dy in General Radiography Using Monte Carlo Simulation M Hayakawa K Koshida C Kawabata A Chadani H Nakagawa and K Kuwamura Dose Distribution of Stray Radiation for Interventional Radiology C Kawabata K Koshida H Nakagawa M Hayakawa A Chadani A Fukuda K Noto and T Matsubara iii Development of the User Co de UCBEAM and Comparison of the Measured Doses using a Torso Phantom and the Calculated Doses using Otoko S Ohnishi N Nariyama K Saito N Odano K Sawada and A Konnai Estimation of Eective Dose Caused byStray Radiation of Photons Electrons and Positrons Around a Small Storage Ring for a Synchrotron Radiation Facility Y Takashima and K Kobayakawa iv MODIFIED RANDOM HINGE TRANSPORT MECHANICS AND MULTIPLE SCATTERING STEP-SIZE SELECTION IN EGS5 S. J. Wilderman and A. F. Bielajew University of Michigan, Ann Arbor, MI, USA Abstract The new transport mechanics in EGS5 allows for significantly longer electron transport step sizes and hence shorter computation times than required for identical problems in EGS4. But as with all Monte Carlo electron transport algorithms, certain classes of problems exhibit step-size dependencies even when operating within recommended ranges, sometimes making selection of step-sizes a daunting task for novice users. Further contributing to this problem, because of the decoupling of multiple scattering and continuous energy loss in the dual random hinge transport mechanics of EGS5, there are two independent step sizes in EGS5, one for multiple scattering and one for continuous energy loss, each of which influences speed and accuracy in a different manner. Further, whereas EGS4 used a single value of fractional energy loss (ESTEPE) to determine step sizes at all energies, to increase performance by decreasing the amount of effort expended simulating lower energy particles, EGS5 permits the fractional energy loss values which are used to determine both the multiple scattering and continuous energy loss step sizes to vary with energy. This results in requiring the user to specify four fractional energy loss values when optimizing computations for speed. Thus, in order to simplify step-size selection and to mitigate step-size dependencies, a method has been devised to automatically optimize step-size selection based on a single material dependent input related to the size of problem tally region. In this paper we discuss the new transport mechanics in EGS5 and describe the automatic step-size optimization algorithm. 1 Introduction Because of the very large number of scattering collisions per unit path which electrons undergo as they pass through matter, Monte Carlo simulation of individual electron collisions (sometimes referred to as “analog Monte Carlo electron transport”) is computationally feasible only in limited situations. Computationally realistic simulations of electron transport must therefore depart from the physical situation of linear, point-to-point, translation between individual scattering collisions (elastic or inelastic) and instead transport particles through long “multiple-scattering steps,” over which thousands of collisions may occur, a technique commonly referred to as the “condensed history” [1] method. If we assume that most electron Monte Carlo simulation algorithms exhibit Larsen convergence1 [2], then all algorithms exhibit an accuracy/speed trade-off which is driven by solely the length of the multiple scattering step they can take while still remaining faithful to the physical processes which might occur during those long steps. Models describing energy loss, angular deflection, and secondary electron production over long steps are quite well known. Descriptions of the longitudinal and transverse displacement coupled to energy loss and deflection over a long transport step, even in homogeneous media, however, require complete solutions of the transport equation, and so models which are sometimes quite approximate are used.