Two determinations of the (223)Ra half-life

Area of Science:

• Nuclear Physics
• Radiochemistry
• Medical Physics

Background:

• Radium-223 (Ra-223) is a bone-seeking alpha-emitter utilized in radiotherapeutic applications.
• The existing evaluated half-life of Ra-223 has a significant uncertainty (0.26%), hindering precise activity assays.
• Accurate Ra-223 half-life determination is crucial for effective dosimetry in targeted alpha therapy.

Purpose of the Study:

• To determine new, highly precise values for the half-life of Radium-223 (Ra-223).
• To realistically assess uncertainty components affecting half-life measurements across different timescales.
• To improve the accuracy of Ra-223 activity assays for clinical applications.

Main Methods:

• Two independent series of measurements were conducted using an ionization chamber (IC).
• A NaI(Tl) well counter (γ-wc) was employed for gamma-ray detection.
• Uncertainties were evaluated beyond simple fit parameters to include multi-timescale components.

Main Results:

• Ionization chamber measurements yielded a Ra-223 half-life of 11.447(6) days.
• NaI(Tl) well counter measurements resulted in a Ra-223 half-life of 11.445(13) days.
• These new values align with the evaluated half-life but possess substantially reduced combined uncertainties.

Conclusions:

• The study provides more precise half-life values for Radium-223.
• Reduced uncertainty in Ra-223 half-life enhances the reliability of therapeutic activity measurements.
• These findings contribute to more accurate dosimetry and optimized use of Ra-223 in cancer treatment.