Ligonnet T, Pistone D, Auditore L, Italiano A, Amato E, Campennì A, Schaefer N, Boughdad S, Baldari S, Gnesin S. Simplified patient-specific renal dosimetry in
177Lu therapy: a proof of concept.
Phys Med 2021;
92:75-85. [PMID:
34875425 DOI:
10.1016/j.ejmp.2021.11.007]
[Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 11/17/2021] [Accepted: 11/20/2021] [Indexed: 12/25/2022] Open
Abstract
PURPOSE
The aim of this proof-of-concept study is to propose a simplified personalized kidney dosimetry procedure in 177Lu peptide receptor radionuclide therapy (PRRT) for neuroendocrine tumors and metastatic prostate cancer. It relies on a single quantitative SPECT/CT acquisition and multiple radiometric measurements executed with a collimated external probe, properly directed on kidneys.
METHODS
We conducted a phantom study involving external count-rate measurements in an abdominal phantom setup filled with activity concentrations of 99mTc, reproducing patient-relevant organ effective half-lives occurring in 177Lu PRRT. GATE Monte Carlo (MC) simulations of the experiment, using 99mTc and 177Lu as sources, were performed. Furthermore, we tested this method via MC on a clinical case of 177Lu-DOTATATE PRRT with SPECT/CT images at three time points (2, 20 and 70 hrs), comparing a simplified kidney dosimetry, employing a single SPECT/CT and probe measurements at three time points, with the complete MC dosimetry.
RESULTS
The experimentally estimated kidney half-life with background subtraction applied was compatible within 3% with the expected value. The MC simulations of the phantom study, both with 99mTc and 177Lu, confirmed a similar level of accuracy. Concerning the clinical case, the simplified dosimetric method led to a kidney dose estimation compatible with the complete MC dosimetry within 6%, 12% and 2%, using respectively the SPECT/CT at 2, 20 and 70 hrs.
CONCLUSIONS
The proposed simplified procedure provided a satisfactory accuracy and would reduce the imaging required to derive the kidney absorbed dose to a unique quantitative SPECT/CT, with consequent benefits in terms of clinic workflows and patient comfort.
Collapse