Abstract
To calculate small field output correction factors, \({k}_{{Q}_{clin},{Q}_{msr}}^{{f}_{clin},{f}_{msr}}\), for Gafchromic EBT3 film using Monte Carlo simulations. These factors were determined for a Novalis Trilogy linear accelerator equipped with Brainlab circular cones with diameters of 4.0 to 30.0 mm. The BEAMnrc Monte Carlo code was used to simulate the Novalis Trilogy linear accelerator and the Brainlab cones with diameters 4.0 to 30 mm. The DOSXYZnrc code was used to simulate Gafchromic EBT3 film with the atomic composition specified by the manufacturer. Small field correction factors were calculated according to new IAEA TRS-483 Code of Practice for small field dosimetry. The depth of calculation was 10 cm and a source to surface distance of 100 cm. The X-ray beam used in the simulations was a 6 MV SRS. The correction factors were then used to determine field output factors with Gafchromic EBT3 film. These field output factors were validated using three solid state detectors and applying correction factors from the TRS-483 Code of Practice. The solid state detectors were IBA SFD diode, PTW 60018 SRS diode and PTW 60019 microDiamond. The Monte Carlo calculated output correction factors, \({k}_{{Q}_{clin},{Q}_{msr}}^{{f}_{clin},{f}_{msr}}\), for Gafchromic EBT3 film ranged between 0.998 to 1.004 for Brainlab circular cones with diameters between 4.0 and 30.0 mm. The uncertainty for these factors was 2.0%. The field output factors obtained with Gafchromic EBT3 film were within 2% of the mean results obtained with the three solid state detectors. For field sizes 4 mm diameter and above, Gafchromic EBT3 film has field output correction factors within 1% of unity. Therefore, Gafchromic EBT3 film can be considered to be correction less and supports the assumption made about this film in the TRS-483 Code of Practice.
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References
Das IJ, Ding GX, Ahnesjo A (2008) Small fields: nonequilibrium radiation dosimetry. Med Phys 35:206–215
Agency IAE (2017) Dosimetry of Small Static Fields Used in External Beam Radiotherapy. IAEA, Vienna
Alfonso R, Andreo P, Capote R, Huq MS, Kilby W, Kjäll P, Mackie T, Palmans H, Rosser K, Seuntjens J (2008) A new formalism for reference dosimetry of small and nonstandard fields. Med Phys 35:5179–5186
Sutherland JGH, Rogers DWO (2010) Monte Carlo calculated absorbed-dose energy dependence of EBT and EBT2 film. Med Phys 37:1110–1116
Morales JE, Butson M, Crowe SB, Hill R, Trapp JV (2016) An experimental extrapolation technique using the Gafchromic EBT3 film for relative output factor measurements in small X-ray fields. Med Phys 43:4687–4692
Walters BRB, Rogers DWO (2004) DOSXYZnrc Users Manual. NRC Report PIRS 794 (rev B)
Morales JE, Hill R, Crowe SB, Kairn T, Trapp JV (2014) A comparison of surface doses for very small field size X-ray beams: Monte Carlo calculations and radiochromic film measurements. Australas Phys Eng Sci Med 37:303–309
Kawrakow I, Mainegra-Hing E, Rogers DWO, Tessier F, Walters BRB (2011) The EGSnrc code system: Monte Carlo simulation of electron and photon transport. NRC Report PIRS 701
Kim JH, Hill R, Kuncic Z (2012) An evaluation of calculation parameters in the EGSnrc/BEAMnrc Monte Carlo codes and their effect on surface dose calculation. Phys Med Biol 57:N267–N278
Walters BRB, Kawrakow I (2007) Technical note: overprediction of dose with default PRESTA-I boundary crossing in DOSXYZnrc and BEAMnrc. Med Phys 34:647–650
Popescu IA, Shaw CP, Zavgorodni SF, Beckham WA (2005) Absolute dose calculations for monte carlo simulations of radiotherapy beams. Phys Med Biol 50:3375–3392
Azangwe G, Grochowska P, Georg D, Izewska J, Hopfgartner J, Lechner W, Andersen CE, Beierholm AR, Helt-Hansen J, Mizuno H, Fukumura A, Yajima K, Gouldstone C, Sharpe P, Meghzifene A, Palmans H (2014) Detector to detector corrections: a comprehensive experimental study of detector specific correction factors for beam output measurements for small radiotherapy beams. Med Phys 41:072103
Bassinet C, Huet C, Derreumaux S, Brunet G, Chéa M, Baumann M, Lacornerie T, Gaudaire-Josset S, Trompier F, Roch P (2013) Small fields output factors measurements and correction factors determination for several detectors for a CyberKnife® and linear accelerators equipped with microMLC and circular cones. Med Phys 40:071725
Moignier C, Huet C, Makovicka L (2014) Determination of the correction factors for detectors used with an 800 MU/min CyberKnife (R) system equipped with fixed collimators and a study of detector response to small photon beams using a Monte Carlo method. Med Phys 41(7):071702
Alexander FIO, Wassim J (2018) Correction factors for diode and diamond detectors in the measurement of small field output factors, using film dosimetry as reference. Biomed Phys Eng Express 4(5):055011
Underwood TS, Rowland BC, Ferrand R, Vieillevigne L (2015) Application of the Exradin W1 scintillator to determine Ediode 60017 and microDiamond 60019 correction factors for relative dosimetry within small MV and FFF fields. Phys Med Biol 60(17):6669–6683
Wegener S, Sauer OA (2017) Separation of scatter from small MV beams and its effect on detector response. Med Phys 44:1139–1148
Girardi A, Fiandra C, Giglioli FR, Gallio E, Ali OH, Ragona R (2019) Small field correction factors determination for several active detectors using a Monte Carlo method in the Elekta Axesse linac equipped with circular cones. Phys Med Biol 64(11):11NT01
Yarahmadi M, Wegener S, Sauer OA (2017) Energy and field size dependence of a silicon diode designed for small-field dosimetry. Med Phys 44:1958–1964
Lynch BD, Kozelka J, Ranade MK, Li JG, Simon WE, Dempsey JF (2006) Important considerations for radiochromic film dosimetry with flatbed CCD scanners and EBT GAFCHROMIC film. Med Phys 33:4551–4556
Rink A, Lewis DF, Varma S, Vitkin IA, Jaffray DA (2008) Temperature and hydration effects on absorbance spectra and radiation sensitivity of a radiochromic medium. Med Phys 35:4545–4555
Cheung T, Butson MJ, Yu PK (2005) Post-irradiation colouration of Gafchromic EBT radiochromic film. Phys Med Biol 50:N281–285
Arjomandy B, Tailor R, Anand A, Sahoo N, Gillin M, Prado K, Vicic M (2010) Energy dependence and dose response of Gafchromic EBT2 film over a wide range of photon, electron, and proton beam energies. Med Phys 37:1942–1947
Desroches J, Bouchard H, Lacroix F (2010) Potential errors in optical density measurements due to scanning side in EBT and EBT2 Gafchromic film dosimetry. Med Phys 37:1565–1570
Fuss M, Sturtewagen E, De Wagter C, Georg D (2007) Dosimetric characterization of GafChromic EBT film and its implication on film dosimetry quality assurance. Phys Med Biol 52:4211–4225
Hartmann B, Martisikova M, Jakel O (2010) Homogeneity of Gafchromic EBT2 film. Med Phys 37:1753–1756
Gonzalez-Lopez A, Vera-Sanchez JA, Lago-Martin JD (2015) Small fields measurements with radiochromic films. J Med Phys 40:61–67
Saur S, Frengen J (2008) GafChromic EBT film dosimetry with flatbed CCD scanner: a novel background correction method and full dose uncertainty analysis. Med Phys 35:3094–3101
Acknowledgements
Some of the calculations were performed on an in-house computer cluster comprising of 64 computing nodes connected in parallel and running on Linux CentOS version 6. This cluster was constructed from funds provided by QUT. Also, some of the computational resources and services used in this work were provided by the HPC and Research Support Group, Queensland University of Technology, Brisbane, Australia. We would like to thank David F. Lewis of Ashland Inc. for providing the information on the atomic composition of Gafchromic EBT3 radiochromic film modelled in this study. We thank Brainlab for providing the specifications of the circular cones and useful discussions.
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Morales, J.E., Butson, M., Hill, R. et al. Monte Carlo calculated output correction factors for Gafchromic EBT3 film for relative dosimetry in small stereotactic radiosurgery fields. Phys Eng Sci Med 43, 609–616 (2020). https://doi.org/10.1007/s13246-020-00860-9
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DOI: https://doi.org/10.1007/s13246-020-00860-9