Monte Carlo calculation of the ionization chamber response to beam using PENELOPE

Abstract

The calculation of the ionization chamber response is one of key factors to develop a primary standard of air kerma. Using Monte Carlo code PENELOPE, we simulated the cavity response of the plane parallel ionization chamber to the monoenergetic 60Co beam incident normally on a flat surface of the chamber. Two simulation techniques, namely, the uniform interaction technique and the reentrance technique, were introduced. The effect of the input parameters such as C1 (average angular deflection in a single step between hard elastic events), C2 (maximum average fractional energy loss in a step), S(max) (maximum step length) and W(cc) (the lower energy of secondary electrons created as a result of a hard collision) on the simulated cavity dose was evaluated. We found that the simulated cavity response of the graphite and solid air chambers obtained by PENELOPE to the monoenergetic 60Co beam could be consistent with the value expected from the cross-sections of PENELOPE to within 0.2% (one standard deviation) when W(cc) and S(max) were selected carefully.

A Fano cavity test for Monte Carlo proton transport algorithms

“…In the scope of improving the reference dosimetry of radiotherapy beams, Monte Carlo (MC) simulations are widely used to compute ionization chamber dose response accurately (e.g., Refs. [1][2][3][4][5][6][7][8][9][10][11][12]. However, while MC codes allow computing absorbed dose to a user-defined level of statistical precision, other uncertainties are associated to these algorithms.…”

Response Characteristics of a Cylindrical Ionization Chamber to the Low- and Medium-Energy X-ray Beams

“…Using PENELOPE, Yi et al calculated the mass energy transfer coefficients with the uncertainty of 0.01 %. 6) We can evaluate the simulation accuracy by comparing the simulated cavity dose with the right-hand side of Eq. (2).…”

“…The accuracy of the cavity dose simulated by a code depends on the internal transport parameters of the code and can be investigated using the formalism of Kawrakow 3) . We followed the procedures of Yi et al 6) in the accuracy evaluation of the cavity dose simulated using PENELOPE for the NE2571 chamber modeled in the present study but the re-entrance technique used by Yi et al was switched off since it might perturb the electron fluence at the medium interface.…”

“…To speed-up the calculation of the cavity dose, we used the uniform interaction technique 6) . Skin model 5) was also employed.…”

“…Many authors calculated the ionization chamber response using Monte Carlo codes [1][2][3][4][5][6][7] . Most of the authors focused on the evaluation of the ionization chamber response to relatively high-energy photons such as 60 Co gamma-rays.…”