caa a22 4500 445304103 CHVBK 20180317142607.0 cr unu---uuuuu 170323e20100301xx s 000 0 eng 10.1007/s13246-010-0005-9 doi (NATIONALLICENCE)springer-10.1007/s13246-010-0005-9 Study of X-ray field junction dose using an a-Si electronic portal imaging device [Elektronische Daten] [Mebratu Madebo, A. Perkins, C. Fox, P. Johnston, T. Kron] Field junctions between megavoltage photon beams are important in modern radiotherapy for treatments such as head and neck and breast cancer. An electronic portal imaging device (EPID) may be used to study junction dose between two megavoltage X-ray fields. In this study, the junction dose was used to determine machine characteristics such as jaw positions and their reproducibility, collimator rotation and the effect of gantry rotation. All measurements were done on Varian linear accelerators with EPID (Varian, Palo Alto, CA). The results show reproducibility in jaw positions of approximately 0.3mm for repeated jaw placement while EPID readings were reproducible within a standard deviation of 0.4% for fixed jaw positions. Junction dose also allowed collimator rotation error of 0.1° to be observed. Dependence of junction dose on gantry rotation due to gravity was observed; the gravity effect being maximum at 180° gantry angle (beam pointing up). EPIDs were found to be reliable tools for checking field junctions, which in turn may be used to check jaw reproducibility and collimator rotation of linacs. Australasian College of Physical Scientists and Engineers in Medicine, 2010 EPID nationallicence Junction dose nationallicence Field junction nationallicence Madebo Mebratu Department of Physical Sciences, Peter MacCallum Cancer Centre, Locked Bag 1 A'Beckett Street, 8006, Melbourne, VIC, Australia aut Perkins A. Department of Physical Sciences, Peter MacCallum Cancer Centre, Locked Bag 1 A'Beckett Street, 8006, Melbourne, VIC, Australia aut Fox C. Department of Physical Sciences, Peter MacCallum Cancer Centre, Locked Bag 1 A'Beckett Street, 8006, Melbourne, VIC, Australia aut Johnston P. RMIT University, Melbourne, Australia aut Kron T. Department of Physical Sciences, Peter MacCallum Cancer Centre, Locked Bag 1 A'Beckett Street, 8006, Melbourne, VIC, Australia aut Australasian Physical & Engineering Sciences in Medicine Springer Netherlands 33/1(2010-03-01), 45-50 0158-9938 33:1<45 2010 33 13246 https://doi.org/10.1007/s13246-010-0005-9 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s13246-010-0005-9 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Madebo Mebratu Department of Physical Sciences, Peter MacCallum Cancer Centre, Locked Bag 1 A'Beckett Street, 8006, Melbourne, VIC, Australia aut NATIONALLICENCE 700 1- Perkins A. Department of Physical Sciences, Peter MacCallum Cancer Centre, Locked Bag 1 A'Beckett Street, 8006, Melbourne, VIC, Australia aut NATIONALLICENCE 700 1- Fox C. Department of Physical Sciences, Peter MacCallum Cancer Centre, Locked Bag 1 A'Beckett Street, 8006, Melbourne, VIC, Australia aut NATIONALLICENCE 700 1- Johnston P. RMIT University, Melbourne, Australia aut NATIONALLICENCE 700 1- Kron T. Department of Physical Sciences, Peter MacCallum Cancer Centre, Locked Bag 1 A'Beckett Street, 8006, Melbourne, VIC, Australia aut NATIONALLICENCE 773 0- Australasian Physical & Engineering Sciences in Medicine Springer Netherlands 33/1(2010-03-01), 45-50 0158-9938 33:1<45 2010 33 13246 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer