In cases of diagnosis, the radiophamaceuticals are compounded with γ-ray emitting nuclides such as99mTc, 67Ga, 201Tl and18F, and routine radioactivity measurements are mainly performed with re-entrant ionization chambers. In cases of radiotherapeutic purposes, β-emitting nuclides such as89Sr and90Y 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 of89Sr solution whose radioactivity was determined by the CIEMAT/NIST method with a liquid scintillation counter and filled89Sr solution in three different type containers. Calibration factors of each ionization chamber to89Sr 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 in89Sr 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 of89Sr therapeutic pharmaceuticals can be performed within an acceptable uncertainty with ordinal re-entrant dose calibrators using in hospitals.
Five blended spice sample were prepared by mixing irradiated and un-irradiated black pepper and paprika at different ratios. Blended black pepper containing 2% (w/w) of 5.4 kGy-irradiated black pepper showed no maximum at glowl. Irradiated black pepper samples, mixed to 5or 10% (w/w), were identified as“irradiated”or“partially irradiated”or “un-irradiated”. All samples with un-irradiated pepper up to 20% (w/w) were identified as“irradiated”. In the case 5.0 kGy-irradiated paprika were mixed with un-irradi-ated paprika up to 5% (w/w), all samples were identified as“irradiated”. The glowl curves of samples, including irradiated paprika at 0.2% (w/w) or higher, exhibited a maximum between 150 and 250°C. The results suggest the existence of different critical mixing ratio for the detection of irradiation among each spices. Temperature range for integration of the TL glow intensity were compared between 70-400°C and approximate 150-250°C, and revealed that the latter temperature range was determined based on the measurement of TLD100. Although TL glow ratio in 150-250°C was lower than that of 70- 400°C range, identification of irradiation was not affected. Treatment of un-irradiated black pepper and paprika with ultraviolet rays had no effect on the detection of irradiation.