RESUMO
A theoretical study and computer simulation search program has been developed to calculate the gamma radiation doses from thin sheets of Egyptian phosphogypsum containing an average 226 Ra concentration of 750 Bq/kg. A comparison study using a natural gypsum has been made. The calculations presented in this paper are much more realistic in aspect that they take the geometry of the building materials into account. The methodology outlined in this paper can be used for calculations of gamma doses for any building material which satisfied assumptions used here, in particular that there is no significant absorption of gamma radiation in the air or the source material. The obtained results of this developed program are compared with other published results