Add a Dynamic Swing to Monte Carlo simulation — Modeling Dynamic Jaw Motion Using Three Sampling Techniques

Liu, H. Helen; Verhaegen, Frank

doi:10.1007/978-3-642-59758-9_170

Cited by 3 publications

(4 citation statements)

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“…The result for the 6 MV photons is in agreement with target pulse counting measurements and telescopic techniques used by Yu et al (1996) and also with target charge integration and telescopic techniques employed by Lam et al (1998). Our results for 10 MV photons are within the uncertainties in agreement with Monte Carlo simulations presented by Liu et al (2000). The statistical standard deviation on the Monte Carlo data is less than 0.5%.…”

Section: Photon Beams (6 10 Mv)supporting

confidence: 87%

“…Alternatively, for the case of output factors, the backscatter correction can be included in the formalism to obtain MUs from Monte Carlo simulations. For asymmetric fields, an appropriate correction for all jaw positions separately has to be performed, as described by Liu et al (2000). For example, figures 5(a) and 5(b) allow derivation of the backscatter contribution of a single upper or lower jaw, after dividing the results in the graphs by a factor of two.…”

Section: Photon Beams (6 10 Mv)mentioning

confidence: 99%

“…Experimental data for 6 MV photon beams from Varian linacs, using a slightly less sophisticated measurement technique, were presented earlier by Lam et al (1998). The only Monte Carlo simulations on monitor ion chamber backscatter in Varian linacs available in the literature are for a 10 MV photon beam (Liu et al 2000). We will present a consistent set of Monte Carlo calculated and measured data on monitor ion chamber backscatter in photon and electron beams on a Varian 2100C linac.…”

Section: Introductionmentioning

confidence: 99%

“…This is usually achieved by using sufficiently thick windows in the monitor chamber or by insertion of an additional backscatter plate. Linear accelerators that are known to be affected by backscatter towards the monitor chamber are the 23 MV CGR Saturne 25 (Luxton and Astrahan 1988), the 18 MV AECL Therac-20 (Patterson and Shragge 1981, Kubo and Lo 1989, Kubo 1989) and the Varian 2100/2300 series linacs (Duzenli et al 1993, Yu et al 1996, Lam et al 1998, Liu et al 2000. By using measurements or Monte Carlo simulations it has been reported that in several other linacs, such as the 4 MV Varian Clinac-4 and a series of Siemens 6-15 MV linacs backscatter to the monitor chamber does not affect the linac output (Huang et al 1987, Verhaegen andDas 1999).…”

Section: Introductionmentioning

confidence: 99%

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Backscatter towards the monitor ion chamber in high-energy photon and electron beams: charge integration versus Monte Carlo simulation

et al. 2000

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In some linear accelerators, the charge collected by the monitor ion chamber is partly caused by backscattered particles from accelerator components downstream from the chamber. This influences the output of the accelerator and also has to be taken into account when output factors are derived from Monte Carlo simulations. In this work, the contribution of backscattered particles to the monitor ion chamber response of a Varian 2100C linac was determined for photon beams (6, 10 MV) and for electron beams (6, 12, 20 MeV). The experimental procedure consisted of charge integration from the target in a photon beam or from the monitor ion chamber in electron beams. The Monte Carlo code EGS4/BEAM was used to study the contribution of backscattered particles to the dose deposited in the monitor ion chamber. Both measurements and simulations showed a linear increase in backscatter fraction with decreasing field size for photon and electron beams. For 6 MV and 10 MV photon beams, a 2-3% increase in backscatter was obtained for a 0.5 x 0.5 cm2 field compared to a 40 x 40 cm2 field. The results for the 6 MV beam were slightly higher than for the 10 MV beam. For electron beams (6, 12, 20 MeV), an increase of similar magnitude was obtained from measurements and simulations for 6 MeV electrons. For higher energy electron beams a smaller increase in backscatter fraction was found. The problem is of less importance for electron beams since large variations of field size for a single electron energy usually do not occur.

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Section: Photon Beams (6 10 Mv)supporting

confidence: 87%

Section: Photon Beams (6 10 Mv)mentioning

confidence: 99%