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90Y-DOTATOC Dosimetry-Based Personalized Peptide Receptor Radionuclide Therapy
Journal article   Open access   Peer reviewed

90Y-DOTATOC Dosimetry-Based Personalized Peptide Receptor Radionuclide Therapy

Yusuf Menda, Mark T Madsen, Thomas M O'Dorisio, John J Sunderland, G Leonard Watkins, Joseph S Dillon, Sarah L Mott, Michael K Schultz, Gideon K D Zamba, David L Bushnell, …
The Journal of nuclear medicine (1978), Vol.59(11), pp.1692-1698
11/2018
DOI: 10.2967/jnumed.117.202903
PMCID: PMC6225542
PMID: 29523629
url
https://doi.org/10.2967/JNUMED.117.202903View
Published (Version of record) Open Access

Abstract

Pretherapy PET with 86Y-DOTATOC is considered the ideal dosimetry protocol for 90Y-DOTATOC therapy; however, its cost, limited availability, and need for infusion of amino acids to mimic the therapy administration limit its use in the clinical setting. The goal of this study was to develop a dosimetric method for 90Y-DOTATOC using 90Y-DOTATOC PET/CT and bremsstrahlung SPECT/CT and to determine whether dosimetry-based administered activities differ significantly from standard administered activities. Methods: This was a prospective phase 2 trial of 90Y-DOTATOC therapy in patients with somatostatin receptor–positive tumors. 90Y-DOTATOC was given in 3 cycles 6–8 wk apart. In the first cycle of therapy, adults received 4.4 GBq and children received 1.85 GBq/m2; the subsequent administered activities were adjusted according to the dosimetry of the preceding cycle so as not to exceed a total kidney dose of 23 Gy and bone marrow dose of 2 Gy. The radiation dose to the kidneys was determined from serial imaging sessions consisting of time-of-flight 90Y-DOTATOC PET/CT at 5 h after therapy and 90Y-DOTATOC bremsstrahlung SPECT/CT at 6, 24, 48, and 72 h. The PET/CT data were used to measure the absolute concentration of 90Y-DOTATOC and to calibrate the bremsstrahlung SPECT kidney clearance data. The radiation dose to the kidneys was determined by multiplying the time-integrated activity (from the fitted biexponential curve of renal clearance of 90Y-DOTATOC) with the energy emitted per decay, divided by the mass of the kidneys. Results: The radiation dose to the kidneys per cycle of 90Y-DOTATOC therapy was highly variable among patients, ranging from 0.32 to 3.0 mGy/MBq. In 17 (85%) of the 20 adult patients who received the second and the third treatment cycles of 90Y-DOTATOC, the administered activity was modified by at least 20% from the starting administered activity. Conclusion: Renal dosimetry of 90Y-DOTATOC is feasible using 90Y-DOTATOC time-of-flight PET/CT and bremsstrahlung SPECT/CT and has a significant impact on the administered activity in treatment cycles.
Dosimetry 90Y-DOTATOC peptide receptor radiotherapy neuroendocrine radionuclide therapy radiobiology/dosimetry

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