Renal uptake monitoring during different cycles of 90Y-DOTATOC therapy based on 111In and 90Y SPECT imaging

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Introduction: Unresectable or borderline resectable WHO G1/G2 P-NETs patients with limited liver disease are treated with 6 90Y-DOTATOC therapy cycles within a clinical protocol. Kidney dosimetry is performed at first cycle. Assuming equal absorbed dose for all cycles, cycles are reduced if cumulative dose exceeds kidney toxicity limits.

Aim(s): The study aims to support the hypothesis that kidney absorbed dose estimated at first cycle can be adequately representative for the following.

Materials and methods: At first cycle, each patient received a tracer 111In-OctreoScan activity in addition to 90Y-DOTATOC activity (1.85 GBq), and underwent 111In-SPECT/CT images at 4, 24, 30 and 45 hours post injection (pi) for dosimetry. During next cycles, one 90Y-SPECT/CT acquisition was performed 24 hours pi. For all cycles, the fraction of injected activity in the kidneys 24 hours pi was calculated on 111In- or 90Y-SPECT images (FIA_111In at first cycle, FIA_90Y otherwise). Activity was calculated after camera calibration with phantoms, filled with either 90Y alone or 111In+90Y as for patients. Kidneys absorbed dose was calculated at first cycle.

Conference:

Presenting Author: d'Arcangelo M

Authors: d'Arcangelo M, Botta F, Ferrari M, Ghisini R, Fodor C,

Keywords: dosimetry, PRRT, 90Y,