Communication Dans Un Congrès Année : 2023

3D Whole Body images for dosimetry of 177Lu-PSMA treatments using a 360° CZT gamma camera

Résumé

Aim/Introduction: Monitoring and dosimetry of patients treated with 177Lu-PSMA require wide field of view SPECT/CT acquisitions (4-5 beds instead of 2) and therefore, a longer acquisition time. This time can be reduced with 360° CZT gamma cameras which are more sensitive than conventional cameras. However, they acquire only the peak at 113 keV whereas the peak at 208 keV is recommended. Therefore, we tested the feasibility of dosimetry for patients treated with 177Lu-PSMA based on whole body 3D SPECT images. Materials and Methods: Thirteen patients with castration-resistant metastatic prostate cancer were treated with 177Lu-PSMA at the Léon Bérard centre. They received between 1 and 6 injections of 6601±437 MBq of 177Lu at six week intervals. Three SPECT/CT acquisitions were performed with a 360° CZT gamma camera after the first treatment at 4H, 24H and between 96H and 144H and then a single acquisition after each other treatment at 24H. Attenuation and scatter corrections were applied during the reconstruction process which includes 12 iterations and 8 subsets. For each time-point, a dose-rate map was calculated using low-statistic Monte Carlo simulations and CT-based contours of the organs at risk (kidneys, liver and spleen) were made to compute mean organ dose-rates. A tri-exponential function was used to model the time dose-rate curve and to estimate the absorbed doses by time integration. For cases with a single acquisition, the procedure used is described in article [1]. Results: Absorbed doses by left and right kidneys, liver and spleen for all cycles and all patients were 0.56 ± 0.19 Gy/GBq (mean ± std), 0.61 ± 0.18 Gy/GBq, 0.12 ± 0.10 Gy/GBq and 0.11 ± 0.07 Gy/GBq. The acquisition time is about 25 minutes for a 3D whole body, three times less than with a conventional gamma camera (4-5 beds of 15 minutes). Conclusion: Dosimetry of 177Lu-PSMA patients is feasible using whole-body 3D SPECT acquisition and gives results comparable to those in the literature although the acquisition time is reduced compared to conventional cameras. References: [1] Vergnaud et al. EJNMMI Physics, 2022

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Dates et versions

hal-04887639 , version 1 (15-01-2025)

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  • HAL Id : hal-04887639 , version 1

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Laure Vergnaud, Anne-Laure Giraudet, Emilie Paquet, Thomas Baudier, Jean-Noël Badel, et al.. 3D Whole Body images for dosimetry of 177Lu-PSMA treatments using a 360° CZT gamma camera. 36th Annual Congress of the European Association of Nuclear Medicine, Sep 2023, Vienne (Austria), France. ⟨hal-04887639⟩
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