Abstract

London health sciences center is a frequent user of Lu-177 Dotatate for the treatment of neuroendocrine disease. We began using this radionuclide therapy as an in-patient procedure, where patients were released at 20 hours’ post therapy administration with minimal restrictions. Over the course of 2013, we worked to transform this therapy into an outpatient procedure, where patients were released at 4-6 hours’ post therapy administration with major restrictions.

The previous methods and data we presented in December 17, 2013 [1] were based on dose rates derived from cumulated doses measured over approximately 16 hours, and an assumption of Lu-177 clearance based on radioactive decay only

Since 2013, our hospital has gained more experience with Lu-177 Dotatate, enabling us to develop a better understanding of dosimetry. We describe new dose measurements, a new model we developed to describe our observations, and a revised schedule of patient release and restriction duration.

Compared against previous measurements from 2013, our new measurements are of instantaneous (not cumulative) dose rates, and we now consider Lu-177 clearance to proceed both by physical decay and biologic excretion. Our new proposed model combines our experimental results with results from literature. The model will state the dose rate from time of discharge can be modeled as a decaying double exponential function.

Keywords: Dotatate; Dosimetry; Lu-177; Neuroendocrine; Lu-TATE

Abbreviation: LHSC: London Health Science Center; DRF: Dose Reduction Factor; EED: Estimated Effective Dose; EEDR: Estimated Effective Dose Received