Investigation and Application of High Megavoltage X-Ray Imaging Mode in Radiotherapy

After drawbacks and shortages of using conventional kV or MV imaging mode were analyzed, this study proposes a new position verification mode with using the energy larger than 15 MeV or nominal accelerating potential greater than 25 MV X-Ray. The new position verification mode is named HMV imaging mode. Along with the comparison of theoretical analyses, phantom experiments and clinical results to the original imaging modes, this report is going to demonstrate the HMV imaging mode is superior to traditional kV and MV imaging modes. This report first theoretically analyzed three main effects of X-ray interacting with medium by numerous equations and compared their mass attenuation coefficient with different types of tissue. X-ray irradiated on a “Catphan 500” cylinder phantom with different energies to verify these theoretical results. Furthermore, based on phantom experiments’ results, we have done numerous clinical trials and comparisons with patient’s clinical results. The theoretical and experimental results illustrate that the scanned images from HMV mode have a good quality and have ability to identify different tissue components clearly. HMV imaging mode overcomes drawbacks of position verification from both kV and MV level imaging mode as well as keeping advantages of kV and MV imaging mode. The result indicates that HMV is a good position verification mode in radiotherapy.

Overview of legal traceability of GPS positioning in Australia

Global Positioning System(GPS)position verification and legal traceability in Australia supports industry,trade,science and innovation and is trusted and recognized domestically and internationally.At the end of 2017,the Australia’s national datum was transitioned from the Geocentric Datum of Australia 1994(GDA94)to the Geocentric Datum of Australia 2020(GDA2020).As such,the datum for the legal traceability of GPS positions in Australia has also moved to GDA2020.This paper highlights the importance of legal metrology and measurement in terms of GPS positions in accordance with the National Measurement Act 1960(Commonwealth of Australia).Here we provide an overview of the process of issuing the so-called‘Regulation 13 Certificates’for Continuously Operating Reference Stations(CORS)across Australia.The position verification methodology is detailed,including the quality control,metadata assurance,and dynamic management of the certificates as well as positional uncertainty determination of CORS with varying quality.A quality monitoring system of positions is also discussed along with how measurement traceability is ensured including short-term and long-term position monitoring schemes.