Journal of Medical Physics
TECHNICAL NOTE
Year
: 2017  |  Volume : 42  |  Issue : 2  |  Page : 90--95

The influence of acquisition mode on the dosimetric performance of an amorphous silicon electronic portal imaging device


Omemh Bawazeer1, Sisira Herath2, Siva Sarasanandarajah3, Tomas Kron4, Pradip Deb6 
1 Discipline of Medical Radiations, School of Medical Science, RMIT University, Melbourne, Victoria, Australia; Discipline of Sciences, School of Medical Physics, Umm Al.Qura University, Mecca, Saudi Arabia
2 Department of Physical Sciences, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
3 Discipline of Medical Radiations, School of Medical Science, RMIT University; Department of Physical Sciences, Peter MacCallum Cancer Centre; Department of Medical Imaging and Radiation Sciences, Faculty of Medicine and Health Sciences, Monash University, Melbourne, Victoria, Australia
4 Department of Physical Sciences, Peter MacCallum Cancer Centre; The Sir Peter MacCallum Department of Oncology, The University of Melbourne, Melbourne, Victoria, Australia

Correspondence Address:
Omemh Bawazeer
211/50, Janfield Drive, Bundoora, Melbourne, Victoria

Aims: This study investigates the impact of cine acquisition mode on the dosimetric characteristics of a Varian aS500 amorphous silicon electronic portal imaging device (a-Si EPID). Materials and Methods: The performance of an a-Si EPID operated in cine mode was assessed and compared to its performance when operated in an integrated mode and dose measurements using an ionization chamber. This study was conducted at different photon energies and the EPID performance was assessed as function of the delivered dose, dose rate, multileaf collimator speed, field size, phantom thickness, and intensity-modulated radiation therapy fields. Results: The worst nonlinearity was observed at low monitor unit (MU) settings < 100 MU with the highest dose per frame. The nonlinearity of response at a low MU setting was attributed due to the loss of four cine images during each delivery. The EPID response with changing dose rate for 10 MU delivered had similar results to its performance in an integrated mode and ionization chamber. Despite the nonlinearity of response with low MU delivered, EPID performance operated in cine and integrated acquisition modes had comparable responses within 2%. Conclusions: For EPID dosimetry application using cine mode, this study recommends the calibration of the EPID images to be undertaken at a large MU. There were no additional corrections that were required when the EPID operated in cine acquisition mode as compared to calibration in integrated mode.


How to cite this article:
Bawazeer O, Herath S, Sarasanandarajah S, Kron T, Deb P. The influence of acquisition mode on the dosimetric performance of an amorphous silicon electronic portal imaging device.J Med Phys 2017;42:90-95


How to cite this URL:
Bawazeer O, Herath S, Sarasanandarajah S, Kron T, Deb P. The influence of acquisition mode on the dosimetric performance of an amorphous silicon electronic portal imaging device. J Med Phys [serial online] 2017 [cited 2020 Feb 25 ];42:90-95
Available from: http://www.jmp.org.in/article.asp?issn=0971-6203;year=2017;volume=42;issue=2;spage=90;epage=95;aulast=Bawazeer;type=0