“…The value of f c,Q may be obtained by Monte Carlo simulation provided an accurate geometrical description of the detector is available. Equation ( 1) was employed to evaluate the beam quality correction factor corresponding to various chambers irradiated with both photon and electron beams and using different Monte Carlo codes [4,[9][10][11][12][13][14][15][16]. The aim of the present work is to use the Monte Carlo code PENELOPE [17] to estimate k Q,Q 0 , in case of electrons beams, for three ionization chambers: the NE2571, permitting a comparison with the results of Muir and Rogers quoted above, and the NE2571A and the NE2581A thimble ionization chambers, both manufactured by QADOS (Sandhurst, UK).…”