Generation of clinical 177Lu SPECT/CT images based on Monte Carlo simulation with GATE

Gunjan Kayal (1, 2) , Maxime Chauvin (1) , Alex Vergara Gil (1) , Naomi Clayton (1) , Ludovic Ferrer (3, 4) , Tumelo Moalosi (5) , Peter Knoll (6) , Lara Struelens (2) , Manuel Bardiès (7, 8)

1 CRCT - Centre de Recherches en Cancérologie de Toulouse
2 SCK-CEN - Belgian Nuclear Research Centre [Mol, Belgique]
3 CRLCC René Gauducheau
4 CRCINA - Centre de Recherche en Cancérologie et Immunologie Nantes-Angers
5 Stellenbosch University
6 IAEA - International Atomic Energy Agency [Vienna]
7 ICM - Institut régional de Cancérologie de Montpellier
8 IRCM - U1194 Inserm - UM - Institut de Recherche en Cancérologie de Montpellier

Purpose: Patient-specific dosimetry in MRT relies on quantitative imaging, pharmacokinetic assessment and absorbed dose calculation. The DosiTest project was initiated to evaluate the uncertainties associated with each step of the clinical dosimetry workflow through a virtual multicentric clinical trial. This work presents the generation of simulated clinical SPECT datasets based on GATE Monte Carlo modelling with its corresponding experimental CT image, which can subsequently be processed by commercial image workstations. Methods: This study considers a therapy cycle of 6.85 GBq 177Lu-labelled DOTATATE derived from an IAEA-Coordinated Research Project (E23005) on "Dosimetry in Radiopharmaceutical therapy for personalised patient treatment". Patient images were acquired on a GE Infinia-Hawkeye 4 gamma camera using a medium energy (ME) collimator. Simulated SPECT projections were generated based on experimental time points and validated against experimental SPECT projections using flattened profiles and gamma index. The simulated projections were then incorporated into the patient SPECT/CT DICOM envelopes for processing and their reconstruction within a commercial image workstation. Results: Gamma index passing rate (2% - 1 pixel criteria) between 95 and 98% and average gamma between 0.28 and 0.35 among different time points revealed high similarity between simulated and experimental images. Image reconstruction of the simulated projections was successful on HERMES and Xeleris workstations, a major step forward for the initiation of a multicentric virtual clinical dosimetry trial based on simulated SPECT/CT images. Conclusions: Realistic 177Lu patient SPECT projections were generated in GATE. These modelled datasets will be circulated to different clinical departments to perform dosimetry in order to assess the uncertainties in the entire dosimetric chain.

Mots clés: Clinical dosimetry; DosiTest; GATE Monte Carlo modelling; SPECT/CT

Domaines: Physique [physics]

Gunjan Kayal, Maxime Chauvin, Alex Vergara Gil, Naomi Clayton, Ludovic Ferrer, et al.. Generation of clinical 177Lu SPECT/CT images based on Monte Carlo simulation with GATE. Physica Medica, 2021, 85 (4), pp.24-31. ⟨10.1016/j.ejmp.2021.04.002⟩. ⟨hal-03304053⟩