Biomedical subjects

Yoshio Hino

Publications and source records attributed to Yoshio Hino.

6 recordsLinked to original sources

PubMed2006

Standardization of 152Eu and 154Eu by 4pibeta-4pigamma coincidence method and 4pi(beta+gamma) integral counting.

The 4pibeta-4pigamma coincidence counting and 4pi(beta+gamma) integral counting techniques were applied for the standardization of 152Eu and 154Eu. In these techniques, the beta-detector is composed of two thin plastic scintillators sandwiching the source coupled with a slender photomultiplier tube. This beta-detector was inserted into a large well-type NaI(Tl) scintillation detector for gamma-ray detection, making a 4pibeta-4pigamma detector configuration. The results obtained by the above two techniques were in good agreement and consistent with the results of international comparisons.

Algorithms↗

PubMed2006

Response calculation for standard ionization chambers in the APMP using EGS4 Monte Carlo code.

In the APMP radioactivity group (TCRI), a series of intercomparisons were conducted between member laboratories, with the aim to improve the calibration of ionization chambers used as secondary standards for radioactivity measurement. Several sources were sent to the participating institutes and the measurement results of calibration factors have been compared. Good agreement between laboratories was found for radioisotopes where the major contribution to the ionization current stems from high-energy gamma rays. It was expected in this energy region that these ratios would become unity for any type of chamber by normalizing with the same type of reference sources. However, where the dominating contribution to the measured ionization current is due to the presence of low-energy gamma rays, there were some serious discrepancies between participating institutes. In order to understand these differences, Monte Carlo simulation has been utilized by studying the effects of changing the wall thickness of the re-entrant well, the materials of the sample holder and the composition of the ionizing gas.

Algorithms↗

PubMedDate not supplied

Absolute radioactivity measurements by the use of a 4pibeta-4pigamma detector configuration.

The radioactivity of 60Co and 134Cs sources were measured using a 4pibeta-4pigamma detector configuration with a well-type NaI(Tl) crystal and a sandwich type 4pibeta detector composed of two sheets of NE102A plastic scintillator coupled to a slender photomultiplier tube. The beta-detector was inserted into the well of the gamma-detector. Since counting efficiencies in both the beta- and gamma-channels can be kept high, excellent counting statistics were attainable even when weak sources were measured. This configuration can also be used for radioactivity measurements based upon the direct integral counting of 4pibeta + 4pigamma logic sum signals, and two independent results can be obtained for every measurement. This technique is especially useful for the standardization of complex decaying nuclides.

Beta Particles↗

PubMedDate not supplied

The new fabrication method of standard surface sources.

We developed a new fabrication method for standard surface sources by using an inkjet printer with inks in which a radioactive material is mixed to print on a sheet of paper. Three printed test patterns have been prepared: (1) 100mm x 100mm uniformity-test patterns, (2) positional-resolution test patterns with different widths and intervals of straight lines, and (3) logarithmic intensity test patterns with different radioactive intensities. The results revealed that the fabricated standard surface sources had high uniformity, high positional resolution, arbitrary shapes and a broad intensity range.

Calibration↗

PubMedDate not supplied

Determination of the emission probabilities of the principal gamma-rays for 134Cs to a high precision.

While multi-gamma-ray emitting nuclides such as 75Se, 134Cs and 152Eu have reasonably well-defined decay scheme, some inconsistencies still remain. Detailed evaluations and weighted-mean analyses result in the recommendation of gamma-ray emission probabilities with small uncertainties, although significant deviations exist in the measured values. Therefore, the gamma-ray emission probabilities of 134Cs have been measured to a high precision after an extremely accurate calibration of detection efficiency. The resulting data agree extremely well with the evaluated values in IAEA-TECDOC-619 (IAEA, X-ray and gamma-ray standards for detector calibration, IAEA-TECDOC-619, IAEA, Vienna, 1991).

Journal Article↗

PubMedDate not supplied

Results from APMP comparisons on radioactivity measurements of 58Co, 88Y and 166mHo.

International comparisons on radioactivity measurements of 55Co, 88Y and 166mHo were carried out within the framework of the Asia-Pacific Metrology Programme. Radioactive sources were also sent to the International Reference System (SIR) at the Bureau International des Poids et Mesures (BIPM) in order to link the results of these regional comparisons to the BIPM key comparison-reference values. The arithmetic mean for the activity results of 166mHo was in good agreement with the SIR reference value, but some disagreements were found for 58Co and 88Y results. The mean values for 58Co and 88Y were both higher than the existing SIR values by about 1.5% and 0.9%, respectively. Although there were some disagreements, it was successfully demonstrated that these regional comparisons could be linked to other international key comparisons through the SIR. The present results were also evaluated to estimate a reasonable uncertainty level for each laboratory, which is very important in the establishment of an adequate traceability scheme for radioactivity standards.

Journal Article↗