Measurement of Strontium-89 Solution Sources for Bone Pain Palliation Using Re-Entrant Ionization Chambers

• Published in: RADIOISOTOPES 2007/03/15, Vol.56(3), pp.93-101
• Main Authors: YAMADA, Takahiro, NAKAMURA, Yoshihide, SATO, Yasushi, YUNOKI, Akira, HINO, Yoshio
• Format: Article
• Language: eng ; jpn
• Subjects: bone pain palliation; dose calibrator; radiopharmaceutical; strontium-89; well-type ionization chamber
• ISSN: 0033-8303; 1884-4111
• DOI: 10.3769/radioisotopes.56.93

In cases of diagnosis, the radiophamaceuticals are compounded with γ-ray emitting nuclides such as 99mTc, 67Ga, 201Tl and 18F, and routine radioactivity measurements are mainly performed with re-entrant ionization chambers. In cases of radiotherapeutic purposes, β-emitting nuclides such as 89Sr and 90Y are used in U.S. or other countries and expected to be used in Japan. Very few γ-transition involved in these nuclides, a re-entrant ionization chamber responds only to weak Bremsstrahlung. The responses are therefore small and differ from those to γ-rays. In order to apply the re-entrant chamber method to routine radioactivity assay for, β-emitting nuclides, detailed studies, i.e., on calibration method, possible effects of radioactive impurities, dependence of vial materials etc. are needed. In this work, a JRIA secondary standard ionization chamber and two different type commercial dose calibrators have been measured by the use of 89Sr solution whose radioactivity was determined by the CIEMAT/NIST method with a liquid scintillation counter and filled 89Sr solution in three different type containers. Calibration factors of each ionization chamber to 89Sr solution were determined, and the dependences of vial size and material and solution volume correction factors also studied. In the present measurements, 85Sr was found in 89Sr solutions as an impurity, and it provided a significant effect on the response of ionization chambers. If this effect was evaluated and corrected by the use of the data obtained in this study, routine assay of radioactivity of 89Sr therapeutic pharmaceuticals can be performed within an acceptable uncertainty with ordinal re-entrant dose calibrators using in hospitals.