Dosimetry by means of external dose rate measurements in patients undergoing 131-I thyroid cancer theraphy

Abstract

Dosimetry in patients treated with radiopharmaceuticals needs to be carried out for each individual treatment. No standardized procedure is currently available.

In our study, the dosimetry for each individual treatment has been calculated using the dose protocol of the Sociedad Española de Física Médica for the treatment of thyroid cancer with 131-I. This protocol is currently under review, since it proposes a procedure which only uses the daily external dose rate measurements during the patient hospital stay and an external dose rate measurement performed 7-9 days after the activity administration.

The results obtained seem to be consistent with those found by other authors following different procedures. Moreover, this protocol has proved to be very useful to verify the values of doses established for red marrow are not exceeded. The maximum activity that can be administered in later treatments could also be assessed with this procedure. Additionally, the activity in urine, which cannot be measured directly, was determined. The potential dose which any patient’s relative or any person staying close to the patient might receive during the treatment was determined as well. These results make it possible to establish more realistic criteria regarding radiation protection.