Beta emitters and radiation protection.
BACKGROUND
Beta emitters, such as (90)Y, are increasingly being used for cancer treatment. However, beta emitters demand other precautions than gamma emitters during preparation and administration, especially concerning shielding.


OBJECTIVE
To discuss practical precautions for handling beta emitters in general, and specifically determine proper shielding for (90)Y, while comparing to (177)Lu and (131)I. The aim is achieved through the application of physical principles combined with results from practical experience.


METHODS
Typical and maximal electron ranges were calculated for (131)I, (177)Lu, and (90)Y, using data from a freely available database. Bremsstrahlung yields were calculated for (90)Y shielded by lead, aluminium, or perspex. Bremsstrahlung spectrum from (90)Y shielded by perspex was measured, and attenuation of spectrum by lead was calculated. Whole-body and finger doses to persons preparing (90)Y-Zevalin were measured.


CONCLUSIONS
Good laboratory practice is important to keep radiation doses low. To reduce bremsstrahlung, (90)Y should not be shielded by lead but instead perspex (10 mm) or aluminium (5 mm). Bremsstrahlung radiation can be further reduced by adding a millimetre of lead on the outside of the primary shielding material. If suitable shielding is used and larger numbers of handlings are divided among several persons, then handling of beta emitters can be a safe procedure.
Jødal
Lars
L
Department of Nuclear Medicine, Aalborg Hospital, Aarhus University Hospital, Aalborg, Denmark. lajo@rn.dk