Transactions on Science and Technology, 3(2), 336 - 344, 2016
ISSN: 2289-8786
Monte Carlo Investigation of Inhomogeneity Phantom Effects in 6 MV Photon Beam

Sitti Yani, I Gde Eka Dirgayussa, Mohamad Fahdillah Rhani, Freddy Haryanto, Idam Arif

ABSTRACT
The objective of this study is to investigate the inhomogeneity effect in inhomogeneous phantom using dosimetric parameters which are the percentage depth dose (PDD) and lateral profile. The accelerator treatment head used in this study was Varian Trilogy Clinac iX 6 MV photon beam. BEAMnrc Monte Carlo (MC) code system was used to design this linear accelerator (linac) based on manufacturer's details information. The resulting phase space scoring plane after multi-leaf collimator (MLC) component form BEAMnrc was used as an input for the DOSXYZnrc code, which gives the dose distributions of the inhomogeneous phantom. The inhomogeneous phantom consists of solid water (Sun Nuclear) and styrofoam material with varied thickness of 1, 2 and 3 cm. The PDD and lateral profile resulted from MC simulation and measurement data from Tan Tock Seng Hospital Singapore was compared for field size 5×5 and 10×10 cm2. The results show that the PDD and lateral profile trends are similar. However, there is a discrepancy of approximately 4% between measured and predicted values which can be associated with the field angle and the degree of inhomogeniety.
Keywords

Inhomogeneity; Styrofoam; solid water; Monte Carlo; photon beam

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© Transactions on Science and Technology 2016

References

[1]       Cardoso, S. C., Alves, V. G. L., da Rosa, L. A. R., Campos, L. T., Batista, D. V. S. & Facure, A. (2010). Monte Carlo Simulation of Bony Heterogeneity Effects on Dose Profile for Small Irradiation Field in Radiotherapy. Plos One, 5(5), e10466.

[2]       Chandola, R. M., Tiwari, S., Painuly, N. K., Choudhary, V., Azad, S. K. & Beck, M. (2011). Monte Carlo Study of Dosimetric Parameters and Dose Distribution Effect of Inhomogeneities and Source Position of GammaMed Plus Source. Journal of Cancer Research and Therapeutics, 7(1), 29-34.

[3]       Chow, J. C. L., Leung, M. K. K. & Dyk, J. V. (2009). Variations of Lung Density and Geometry on Inhomogeneity Correction Algorithms: A Monte Carlo Dosimetric Evaluation. Medical Physics, 36(8), 3619-30.

[4]       Dirgayussa, I. G. E., Yani, S., Rhani, M. F. & Haryanto, F. (2015). Commissioning process of Varian Clinac iX 6 MV photon beam. AIP Conference Proceedings, 1677, 040006.

[5]       Han, T., Mikell, J. K., Salehpour, M. & Mourtada, F. (2011). Dosimetric Comparison of Acuros XB Deterministic Radiation Transport Method with Monte Carlo and Model-based Convolution Methods in Heterogeneous Media. Medical Physics, 38(5), 2651-64.

[6]       Kawrakow, I. & Rogers, D. W. O. (2011). The EGSnrc Code System: Monte Carlo Simulation of Electron and Photon Transport. Ottawa: National Research Council of Canada

[7]       Lloyd, S. A. M. & Ansbacher, W. (2013). Evaluation of an Analytic Linear Boltzmann Transport Equation Solver for High-density Inhomogeneities. Medical Physics, 40(1), 011707-1-5.

[8]       Nedaie, H. A., Mosleh‑Shirazi, M. A. & Allahverdi, M. (2013). Monte Carlo N Particle Code - Dose Distribution of Clinical Electron Beams in Inhomogeneous Phantoms. Journal of Medical Physics, 38(1), 15-21.

[9]       Robinson, D. (2008). Inhomogeneity Correction and The Analytic Anisotropic Algorithm. Journal of Applied Clinical Medical Physics, 9(2), 1-11.

[10]   Rogers, D.W.O., Walters, B. & Kawrakow, I. (2011). BEAMnrc Users Manual. Ottawa: National Research Council of Canada.

[11]   Sterpin, E., Tomsej, M., Smedt, B. D., Reynaert, N. & Vynckier, S. (2007). Monte Carlo Evaluation of The AAA Treatment Planning Algorithm in A Heterogeneous Multilayer Phantom and IMRT Clinical Treatments for An Elekta SL25 Linear Accelerator. Medical Physics, 34(5), 1665-77.

[12]   Walters, B., Kawrakow, I. and Rogers, D.W.O. (2011). DOSXYZnrc Users Manual. Ottawa: National Research Council of Canada.

[13]   Yani, S., Dirgayussa, I. G. E., Rhani, M. F., Haryanto, F. & Arif, I. (2015). The Effect of Voxel Size on Dose Distribution in Varian Clinac iX 6 MV Photon Beam using Monte Carlo Simulation. AIP Conference Proceedings, 1677, 040002.