Recently the TL and ESR techniques have become very useful dating methods. The accuracy of dating depends on that of measured values for the absorbed dose in an archaeological sample and for the annual average dose. Some important factors in term of radiation dosimetry are discussed. The ratio of average dose to surface dose for a

90

Sr-

90

Y source irradiating quartz as a function of grain size is calculated. Variations of individual contribution of

90

Sr and

90

Y to

the

total dose with depth are also shown.