sentences:  The monitoring and calculation of doses to safeguard human health is called dosimetry and is undertaken within the science of health physics.Key measurement tools are the use of dosimeters to give the external effective dose uptake and the use of bio-assay for ingested dose.The article on the sievert summarises the recommendations of the ICRU and ICRP on the use of dose quantities and includes a guide to the effects of ionizing radiation as measured in sieverts, and gives examples of approximate figures of dose uptake in certain situations.