Whole-body dosimetry for targeted radionuclide therapy using spectral analysis

Area of Science:

• Nuclear Medicine
• Medical Physics
• Radiopharmaceutical Dosimetry

Background:

• Whole-body dose (WBD) calculation is crucial for targeted radionuclide therapy (TRT).
• Accurate dosimetry relies on precise characterization of radiopharmaceutical kinetics.
• Current methods for analyzing time-activity curves (TACs) can be time-consuming.

Purpose of the Study:

• To evaluate the feasibility of using spectral analysis (SA) for automatic delineation of decay phases.
• To determine WBD using SA from whole-body (WB) TACs.
• To assess the accuracy and reproducibility of SA compared to existing methods.

Main Methods:

• Spectral analysis (SA) was employed to fit WB TACs using a non-negative least-squares (NNLS) algorithm.
• The cumulated activity (CA) was calculated analytically by integrating the fitted curve.
• Bootstrap techniques were used to estimate the uncertainty in WBD calculations.

Main Results:

• SA accurately calculated WBDs for (186)Re-HEDP and (131)I-mIBG therapies, showing good agreement with a semiempirical method.
• The method successfully determined the number of decay phases and their half-lives.
• Bootstrapping revealed higher coefficient-of-variation for (186)Re-HEDP compared to (131)I-mIBG, indicating therapy-specific kinetic variability.

Conclusions:

• SA is a fast, accurate, and reproducible method for calculating WBD in TRT.
• SA provides precise estimates of radiotracer kinetic parameters.
• The SA method holds potential for broader applications in nuclear medicine dosimetry.