Dual-isotope imaging method for Actinium-225 and Bismuth-213 using alpha imaging detector

Area of Science:

• Nuclear medicine
• Radiochemistry
• Medical physics

Background:

• Actinium-225 (²²⁵Ac) is promising for targeted alpha therapy due to its decay chain producing multiple alpha particles.
• Assessing the distribution of both ²²⁵Ac and its daughter Bismuth-213 (²¹³Bi) is critical to mitigate renal toxicity and ensure treatment safety.

Purpose of the Study:

• To develop and validate a spectrum decomposition method for dual-isotope imaging of ²²⁵Ac and ²¹³Bi.
• To demonstrate the feasibility of using an alpha imaging detector for imaging therapeutic amounts of ²²⁵Ac.
• To evaluate the accuracy of the imaging method through Monte Carlo simulations.

Main Methods:

• Developed a spectrum decomposition technique for differentiating ²²⁵Ac and ²¹³Bi signals.
• Utilized an alpha imaging detector with specific detection efficiency and energy resolution.
• Conducted experiments with therapeutic amounts of ²²⁵Ac and validated findings with Monte Carlo simulations under realistic conditions.

Main Results:

• The alpha imaging detector achieved a detection efficiency of 18.5% and energy resolution of 13.4% at 5.5 MeV.
• Monte Carlo simulations demonstrated the ability to accurately determine the distribution of ²²⁵Ac and ²¹³Bi with a 5% relative error.
• Confirmed the feasibility of the dual-isotope imaging method for discriminating alpha-emitters.

Conclusions:

• The validated spectrum decomposition method enables effective dual-isotope imaging of ²²⁵Ac and ²¹³Bi.
• This imaging capability is essential for optimizing targeted alpha therapy and managing potential toxicities.
• The study confirms the potential of alpha imaging detectors for precise theranostic applications.