414 DETECTION RATES AND TUMOUR CHARACTERISTICS OF PROSTATE CANCERS IDENTIFIED FROM PRIMARY CARE REFERRALS BASED ON NATIONAL GUIDELINES IN A NON-SCREENED POPULATION

Batch experiments of 226Ra uptake by recrystallized gypsum CaSO4.2H2O(s), monitored over 200 days, have shown that the published value for the distribution coefficient of 226Ra between gypsum and an aqueous phase, 0.03 (Gnanapragasam and Lewis, 1995), is an upper limit. This suggests that this value needs to be confirmed. A solid solution between gypsum and radium sulfate (Ca,Ra)SO4.2H2O(s) cannot be considered per se, which is not surprising considering gypsum's high solubility product (lg Ks = -4.58) and the ionic radius of VIIIRa (1.48 Å), when compared to that of VIIICa (1.12 Å).