Douk HS, Aghamiri MR, Ghorbani M, Farhood B, Bakhshandeh M, Hemmati HR. Accuracy evaluation of distance
inverse square law in determining virtual electron source location in Siemens Primus linac.
Rep Pract Oncol Radiother 2018;
23:105-113. [PMID:
29681773 DOI:
10.1016/j.rpor.2018.01.002]
[Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Revised: 10/14/2017] [Accepted: 01/20/2018] [Indexed: 11/26/2022] Open
Abstract
Aim
The aim of this study is to evaluate the accuracy of the inverse square law (ISL) method for determining location of virtual electron source (SVir) in Siemens Primus linac.
Background
So far, different experimental methods have presented for determining virtual and effective electron source location such as Full Width at Half Maximum (FWHM), Multiple Coulomb Scattering (MCS), and Multi Pinhole Camera (MPC) and Inverse Square Law (ISL) methods. Among these methods, Inverse Square Law is the most common used method.
Materials and methods
Firstly, Siemens Primus linac was simulated using MCNPX Monte Carlo code. Then, by using dose profiles obtained from the Monte Carlo simulations, the location of SVir was calculated for 5, 7, 8, 10, 12 and 14 MeV electron energies and 10 cm × 10 cm, 15 cm × 15 cm, 20 cm × 20 cm and 25 cm × 25 cm field sizes. Additionally, the location of SVir was obtained by the ISL method for the mentioned electron energies and field sizes. Finally, the values obtained by the ISL method were compared to the values resulted from Monte Carlo simulation.
Results
The findings indicate that the calculated SVir values depend on beam energy and field size. For a specific energy, with increase of field size, the distance of SVir increases for most cases. Furthermore, for a special applicator, with increase of electron energy, the distance of SVir increases for most cases. The variation of SVir values versus change of field size in a certain energy is more than the variation of SVir values versus change of electron energy in a certain field size.
Conclusion
According to the results, it is concluded that the ISL method can be considered as a good method for calculation of SVir location in higher electron energies (14 MeV).
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