The A1 and A2 values of the Q System described in the advisory material SSG-26 have been developed to provide maximum allowable contents in packages not designed to withstand ac-cidents. Current values were determined in 1996 according to specific scenarios for five expo-sure pathways. Since then, the ICRP has published revised radiological data. In September 2013, an international working group was created to discuss the improvement of calculation methods described in the Q System. Within this framework, it has been decided to change the current deterministic and empiric method to a more accurate one based on Monte-Carlo calculations. This evolution allows the working group to be more flexible and to get more accurate results, for instance by taking into account all particles created. Monte-Carlo calculations let assess fluences of each type of particle (at one meter in the case of the Q System). Fluence-to-dose conversions are done separately from the Monte-Carlo cal-culations by using dose conversion factors (DCF) from the ICRP 116 by log-log interpolations during post processing. The main asset of this process is that it allows to easily assess the equivalent dose to different organs (skin, lens of the eye…) and the effective dose to the whole body, by using the correct DCF, without running any new Monte-Carlo calculations. It also allows the working group to present result for different irradiation geometries (ISO, AP…) at the same time and to easily update the A1 and A2 values, for any radionuclide, should the ICRP provide new spectra data and/or DCF. To perform an exhaustive and accurate dose assessment, some DCF, not available in the ICRP publications or in the literature, were required, such as local skin dose due to neutrons and photons. Therefore, new DCF have been evaluated (publication in progress). The new Q System would, once validated by the TRANSCC, be able to provide A1 and A2 values based on exposure from all radiations to all sensible organs and to the whole body and for at least two irradiation field.