The aim of this study was to develop an independent dose verification system by using a Monte Carlo (MC) calculation method for intensity modulated radiation therapy (IMRT) conducted by using a Varian Novalis Tx (Varian Medical Systems, Palo Alto, CA, USA) equipped with a highdefinition multi-leaf collimator (HD-120 MLC). The Geant4 framework was used to implement a dose calculation system that accurately predicted the delivered dose. For this purpose, the Novalis Tx Linac head was modeled according to the specifications acquired from the manufacturer. Subsequently, MC simulations were performed by varying the mean energy, energy spread, and electron spot radius to determine optimum values of irradiation with 6-MV X-ray beams by using the Novalis Tx system. Computed percentage depth dose curves (PDDs) and lateral profiles were compared to the measurements obtained by using an ionization chamber (CC13). To validate the IMRT simulation by using the MC model we developed, we calculated a simple IMRT field and compared the result with the EBT3 film measurements in a water-equivalent solid phantom. Clinical cases, such as prostate cancer treatment plans, were then selected, and MC simulations were performed. The accuracy of the simulation was assessed against the EBT3 film measurements by using a gamma-index criterion. The optimal MC model parameters to specify the beam characteristics were a 6.8-MeV mean energy, a 0.5-MeV energy spread, and a 3-mm electron radius. The accuracy of these parameters was determined by comparison of MC simulations with measurements. The PDDs and the lateral profiles of the MC simulation deviated from the measurements by 1% and 2%, respectively, on average. The computed simple MLC fields agreed with the EBT3 measurements with a 95% passing rate with 3%/3-mm gamma-index criterion. Additionally, in applying our model to clinical IMRT plans, we found that the MC calculations and the EBT3 measurements agreed well with a passing rate of greater than 95% on average with a 3%/3-mm gamma-index criterion. In summary, the Novalis Tx Linac head equipped with a HD-120 MLC was successfully modeled by using a Geant4 platform, and the accuracy of the Geant4 platform was successfully validated by comparisons with measurements. The MC model we have developed can be a useful tool for pretreatment quality assurance of IMRT plans and for commissioning of radiotherapy treatment planning.
This is a preview of subscription content, access via your institution.
Buy single article
Instant access to the full article PDF.
Price includes VAT (USA)
Tax calculation will be finalised during checkout.
G. Delaney, S. Jacob, C. Featherstone and M. Barton, Cancer 104, 1129 (2005).
Intensity Modulated Radiation Therapy Collaborative Working Group, Int. J Radiat. Oncol. Biol. Phys 51, 880 (2001).
L. E. Gaspar and M. Ding, Curr. Oncol. Rep. 10, 294 (2008).
V. T. DeVita, Jr. and S. A. Rosenberg, N. Engl. J. Med. 366, 2207 (2012).
D. W. Rogers, Phys. Med. Biol. 51, R287 (2006).
E. Spezi and G. Lewis, Radiat. Prot. Dosimetry 131, 123 (2008).
I. J. Chetty et al., Med. Phys. 34, 4818 (2007).
S. Agostinelli et al., Nucl. Instr. Meth. Phys. Res. A 506, 250 (2003).
C. Z. Jarlskog and H. Paganetti, IEEE 55, 1018 (2008).
J. Apostolakis et al., Radiat. Phys. Chem. 78, 859 (2009).
D. W. O. Rogers, Med. Phys. 22, 503 (1995).
E. Poon and F. Verhaegen, Med. Phys. 32, 1696 (2005).
W. Abdel-Rahman, J. P. Seuntjens, F. Verhaegen, F. O. Deblois and E. B. Podgorsak, Med. Phys. 32, 286 (2005).
C. M. Ma et al., Phys. Med. Biol. 45, 2483 (2000).
N. Tyagi, B. H. Curran, P. L. Roberson, J. M. Moran, E. Acosta and B. A. Fraass, J. Phys. Conf. Series 102, 012025 (2008).
M. K. Fix, W. Volken, D. Frei, D. Frauchiger, E. J. Born and P. Manser, Med. Phys. 38, 5311 (2011).
C. Borges, M. Zarza-Moreno, E. Heath, N. Teixeira and P. Vaz, Med. Phys. 39, 415 (2012).
L. A. Vazquez-Quino, B. Massingill, C. Shi, A. Gutierrez, C. Esquivel, T. Eng, N. Papanikolaou and S. Stathakis, J. Appl. Clin. Med. Phys. 13, 3960 (2012).
H. Okamoto, Y. Fujita, K. Sakama, H. Saitoh, T. Kanai, J. Itami and T. Kohno, Radiol. Phys. Technol. 7, 246 (2014).
L. Grevillot, T. Frisson, D. Maneval, N. Zahra, J. N. Badel and D. Sarrut, Phys. Med. Biol. 56, 903 (2011).
H. Jung, O. Kum, Y. Han, B. Park and K. H. Cheong, J. Korean Phys. Soc. 65, 1829 (2014).
K. Sutherland, S. Miyajima and H. Date, J. Phys.: Conf. Ser. 74, 021020 (2007).
About this article
Cite this article
Jung, H., Shin, J., Chung, K. et al. Feasibility of using Geant4 Monte Carlo simulation for IMRT dose calculations for the Novalis Tx with a HD-120 multi-leaf collimator. Journal of the Korean Physical Society 66, 1489–1494 (2015). https://doi.org/10.3938/jkps.66.1489
- Monte Carlo simulation
- Novalis Tx
- HD-120 MLC