What is latent period in radiation biology?

Latent Period After the prodromal reaction comes a latent period, during which the exposed person shows no signs or symptoms of radiation sickness. The extent of the latent period is also dose related, lasting hours or days after supralethal exposures (approximately >5 Gy) to a few weeks after exposures of about 2 Gy.   Oral radiology ; White and Pharaoh 7th edition page no 24