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Sci‐Thur AM: YIS – 01: New technologies for astatine‐211 targeted alpha therapy research
Author(s) -
Crawford Jason,
Yang Hua,
Schaffer Paul,
Ruth Thomas
Publication year - 2016
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.4961750
Subject(s) - dosimetry , astatine , nuclear medicine , physics , radiochemistry , nuclear physics , chemistry , medicine , quantum mechanics , voltage
Purpose: The short‐range, densely ionizing α‐particles emitted by 211 At (t 1/2 =7.2h) are well suited for the treatment of diffuse microscopic disease, using cancer targeting biomolecules. 211 At availability is limited by the rarity of α‐cyclotrons required for standard production. Image‐based dosimetry is also limited for 211 At, which emits low intensity X‐rays. Our goal was to leverage state‐of‐the‐art infrastructure at TRIUMF to produce and evaluate two related isotopes, 211 Rn (t 1/2 =14.6h, 73% decay to 211 At) as a generator for 211 At, and 209 At (t 1/2 =5.4h, X‐ray/gamma‐ray emitter) as a novel 211At surrogate for preclinical imaging studies. Methods: Produced by spallation of uranium with 480 MeV protons, mass separated ion beams of short‐lived francium isotopes were implanted into NaCl targets where 211 Rn or 209 At were produced by radioactive decay, in situ . 211 Rn was transferred to dodecane from which 211 At was efficiently extracted and evaluated for clinical applicability. High energy SPECT/CT was evaluated for measuring 209 At activity distributions in mice and phantoms. Results: Our small scale 211 Rn/ 211 At generator system provided high purity 211 At samples. The methods are immediately scalable to the level of radioactivity required for in vivo experiments with 211 At. 209 At‐based high energy SPECT imaging was determined suitable for pursuing image‐based dosimetry in mouse tumour models. In the future, we will utilize quantitative 209 At‐SPECT for image‐based dose calculations. Conclusion: These early studies provided a foundation for future endeavours with 211 At‐based α‐therapy. Canada is now significantly closer to clinical targeted α‐therapy of cancer.