Yttrium-90 selective internal radiation therapy, examining dose rates and radiation protection precautions

Dose rates from 30 patients, treated over a 3-year period (2016-2018) were measured post therapy in contact with the patients' upper abdomen and at distances of 0.3 m and 1 m. Dose rates were compared with theoretical predictions and used as model inputs for calculating radiation doses received by family members and carers based on interaction patterns previously described in the literature.

The average dose rate per activity from SIRT patients were:- In contact: 29 ± 23 µSv.h^-1.GBq^-1; 0.3 m: 4.1 ± 2.34 µSv.h^-1.GBq^-1 and 1 m: 0.59 ± 0.42 µSv.h^-1.GBq^-1. Dose rates measured at 0.3 and 1 m followed a predictable distribution. Estimated doses based on proximity models demonstrated restrictions to be advisable, depending on the administered activity, considering the dose constraint and limit of 0.3 and 1 mSv, respectively, employed within the EU.

In accordance with local dose constraints, and depending on administered activities, radiation protection precautions may be necessary for those individuals in regular contact with patients who have receive ⁹⁰Y SIRT. A radiation protection precautions calculator has been devised to offer personalised instructions taking into account the administered activity and proximity models.