PURPOSE The commissioning of treatment planning systems and beam modeling requires measured input parameters. The measurement of relative output in-air, Sc is particularly difficult for small fields. The purpose of this study was to investigate the influence of miniphantom design and detector selection on measured Sc values for small fields and to validate the measurements against Monte Carlo s...

The concept of in-air output ratio Sc was introduced to characterize how the incident photon fluence per monitor unit or unit time for a Co-60 unit varies with collimator settings. However, there has been much confusion regarding the measurement technique to be used that has prevented the accurate and consistent determination of Sc. The main thrust of the report is to devise a theoretical and m...

The concept of in-air output ratio (Sc) was introduced to characterize how the incident photon fluence per monitor unit (or unit time for a Co-60 unit) varies with collimator settings. However, there has been much confusion regarding the measurement technique to be used that has prevented the accurate and consistent determination of Sc. The main thrust of the report is to devise a theoretical a...

The use of electronic portal imaging devices (EPIDs) is a promising method for the dosimetric verification of external beam, megavoltage radiation therapy-both pretreatment and in vivo. In this study, a previously developed EPID back-projection algorithm was modified for IMRT techniques and applied to an amorphous silicon EPID. By using this back-projection algorithm, two-dimensional dose distr...

The Radiological Physics Center (RPC) has been utilizing TLD to verify photon-beam output, and electron-beam output and energy for many years. The RPC currently monitors over 1200 institutions, monitoring 4000 photon and 3500 electron beams per year. Control TLD, irradiated on one specific Co-60 machine, are used for a performance check of our TLD system. Analysis of these data over 5 years, re...

Introduction: Small field dosimetry is challenging for radiotherapy dosimetry. measurement of the output factor in the air and water (Sc, Scp) is one of the input parameters for commissioning of treatment planning systems and beam modeling. The aims of this study are to measured Sc,Scp for small fields with EBT2 and Ion chamber and design a appropriate mini-phantom for small fi...