Objective To study the percentage depth dose difference (PDD) between Monte Carlo method and the measurement method.
Methods Based on the detail treatment head structure designing by the manufacture, the BEAMnrc Monte Carlo code was used to simulate the 6 MV photon beams of a Siemens Primus linear accelerator. DOSXYZnrc program generated 6 MV X-ray parameters such as PDD, and it was measured by MP3 three-dimensional water of PTW corporation phantom. The deviation of PDD was calculated using formulas ((measured value-simulation algorithm value)/measured value×100%).
Results Distance from the surface of the water was less than 1.2 cm, the deviation of PDD was>2%. Distance from the surface greater than 1.2 cm, the deviation of PDD was<2%.
Conclusion In the built-up areas, PDD obtained by the Monte Carlo simulation algorithm is more accurate.
NI Xin-ye*,TANG Xiao-bing,GENG Chang-ran et al. Study on accurateness of percentage depth dose with Monte Carlo simulation algorithm[J]. Chinese Journal of Radiation Oncology, 2013, 22(1): 64-66.
[1] 胡逸民.放射治疗的质量保证与质量控制 胡逸民,张红志,戴建荣.肿瘤放射物理学.北京:原子能出版社,1999:114. [2] Juste B, Miro R, Gallardo S, et al. Considerations of MCNP Monte Carlo code to be used as a radiotherapy treatment planning tool IEEE. Proceedings of the 2005 IEEE. Engineering in medicine and biology 27th annual conference,Shanghai,2005. Shanghai:IEEE Engn Med& Biol Soc,2005:2828-2831. [3] Verhaegen F, Seuntjens J. Monte Carlo modelling of external radiotherapy photon beams. Phys Med Biol,2003,48:107-164. [4] Sheikh-Bagheri D, Rogers DWO, Ross CK, et al. Comparison of measured and Monte Carlo calculated dose distributions from the NRC linac. Med Phys,2000,27:2256-2266. [5] Rogers DWO, Faddegon BA, Ding GX, et al. BEAM:a Monte Carlo code to simulate radiotherapy treatment units. Med Phys,1995,22:503-524. [6] Ni XY,Tang XB, Geng CR,et al. The prospect of carbon fiber implants in radiotherapy. J Appl Clin Med Phys,2012,13:152-159. [7] Deng J, Jiang SB, Kapur A, et al. Photon beam characterization and modelling for Monte Carlo treatment planning. Phys Med Biol,2000,45:411-427. [8] 白彦灵,肖雪夫,邵文成.直线加速器8 MV X射线能谱及结构研究.中华放射肿瘤学杂志,2012,21:181-184. [9] 张黎,邓小武,黄晓延,等.应用辐射直接显色剂量胶片测量高能光子线的表面和建成区剂量.中国医学物理学杂志,2007,24:157-159. [10] Klein EE, Esthappan J, Li ZF, et al. Surface and buildup dose characteristics for 6, 10, and 18 MV photons from an Elekta Precise linear accelerator. J Appl Clin Med Phys,2003,4:1-7. [11] Fraass B, Doppke K, Hunt M, et al. American association of physicists in medicine radiation therapy committee task group 53:quality assurance for clinical radiotherapy treatment planning. Med Phys,1998,25:1773-1829. [12] Jaffray DA, Battista JJ, Fenster A, et al. X-ray sources of medical linear accelerators:focal and extra focal radiation. Med Phys,1993,20:1417-1427.