Improved ¹⁴⁰Nd Production for the ¹⁴⁰Nd/¹⁴⁰Pr In Vivo Generator through Target Recycling and Radiochemical...

Area of Science:

• Nuclear Medicine
• Radiochemistry
• Materials Science

Background:

• f-block therapeutic radionuclides lack suitable positron emission tomography (PET) imaging counterparts, often necessitating the use of 68Ga as a surrogate.
• The 140Nd/140Pr in vivo PET generator, an f-block element, presents a potential solution but faces challenges in radionuclidic and chemical purity due to target impurities and lanthanide separation difficulties.
• Stable neodymium (Nd) impurities and the separation of adjacent lanthanides hinder the production of high-purity 140Nd.

Purpose of the Study:

• To address the limitations in 140Nd production by developing a method for purifying and recycling praseodymium (Pr) target material.
• To optimize the separation of Nd and Pr to achieve high radionuclidic and chemical purity of 140Nd.
• To evaluate the suitability of the purified 140Nd for PET imaging applications using DOTA and Macropa chelators.

Main Methods:

• Developed a target material purification and recycling method for monoisotopic 141Pr to remove stable Nd impurities, achieving a 90.3% recovery.
• Irradiated purified 141Pr with 24 MeV protons to produce 140Nd, followed by purification using an optimized DGA normal method, yielding 71.6% pure 140Nd.
• Assessed the impact of target purification on apparent molar activity (AMA) and evaluated the in vitro stability of 140Nd-labeled chelators (DOTA and Macropa).

Main Results:

• Reduced stable Nd impurities from >340 ppm to <250 ppb after three target purification cycles.
• Significantly increased the AMA of [140Nd]-Nd-DOTA and [140Nd]-Nd-Macropa from ~70 MBq/μmol to over 8000 MBq/μmol after target purification.
• [140Nd]-Nd-DOTA demonstrated stability in various biological media, while [140Nd]-Nd-Macropa showed stability in all except human serum.

Conclusions:

• Established a practical method combining target recycling and radiochemical separation for scaled-up production of high-molar activity 140Nd.
• The developed methodology enables the production of 140Nd/140Pr in vivo PET generators suitable for preclinical imaging.
• These advances support the broader development of 140Nd/140Pr as a PET analogue for f-block therapeutics.