Journal of Medical Physics
ORIGINAL ARTICLE
Year
: 2019  |  Volume : 44  |  Issue : 3  |  Page : 156--175

Out-of-field dose calculation by a commercial treatment planning system and comparison by monte carlo simulation for varian TrueBeam®


NS Shine1, Raghukumar Paramu2, M Gopinath3, RC Jaon Bos3, PM Jayadevan3 
1 Department of Physics, Banasthali University, Jaipur, Rajasthan, India
2 Division of Radiation Physics, Regional Cancer Center, Thiruvananthapuram, Kerala, India
3 Department of Radiation Oncology, Aster Medcity, Kochi, Kerala, India

Correspondence Address:
Mr. N S Shine
“Shangri-La,” Alathara, Sreekariyam P.O., Thiruvananthapuram - 695 017, Kerala
India

Purpose: The calculation accuracy of treatment planning systems (TPSs) drops drastically when the points outside the field edges are considered. The real accuracy of a TPS and linear accelerator (linac) combination for regions outside the field edge is a subject which demands more study. In this study, the accuracy of out-of-field dose calculated by a TPS, used with a TrueBeam® (TB) linac, is quantified. Materials and Methods: For dose calculation, Eclipse™ version 13.7 commissioned for TB machine was used. For comparison, Monte Carlo (MC) methods, as well as the measurements, were used. The VirtuaLinac, a Geant 4-based MC program which is offered as a cloud solution, is used for the generation of input phase-space (PS) files. This PS file was imported into PRIMO (PENELOPE based MC program) for the simulation of out-of-field dose. Results: In this study, the accuracy of the out-of-field dose calculated by a TPS for a TB linac was estimated. As per the results in comparison with MC simulations, the TPS underestimated the dose by around 45% on an average for the off-axis-distance range considered in this study. As the off-axis distance increased, the underestimation of the dose also increased. Conclusion: In this work, it was observed that the TPS underestimates doses beyond the edges of treatment fields for a clinical treatment executed on a TB machine. This indicates that the out-of-field dose from TPSs should only be used with a clear understanding of the inaccuracy of dose calculations beyond the edge of the field.


How to cite this article:
Shine N S, Paramu R, Gopinath M, Jaon Bos R C, Jayadevan P M. Out-of-field dose calculation by a commercial treatment planning system and comparison by monte carlo simulation for varian TrueBeam®.J Med Phys 2019;44:156-175


How to cite this URL:
Shine N S, Paramu R, Gopinath M, Jaon Bos R C, Jayadevan P M. Out-of-field dose calculation by a commercial treatment planning system and comparison by monte carlo simulation for varian TrueBeam®. J Med Phys [serial online] 2019 [cited 2019 Dec 7 ];44:156-175
Available from: http://www.jmp.org.in/article.asp?issn=0971-6203;year=2019;volume=44;issue=3;spage=156;epage=175;aulast=Shine;type=0