No abstract available

[en] This paper gives a review of the development of the triple-to-double coincidence ratio (TDCR) method for standardizing pure β- and pure electron capture (EC)-radionuclides. The initial idea of Schwerdtel and practical realization and elaboration of the TDCR method by Pochwalski is presented. The main aspects and theoretical principle of the method are summarized and progress on the development of the theoretical model is presented. The details of the activity determination of pure β- and pure EC radionuclides are discussed, along with specific details in the application of the method in each case. The enhanced TDCR method based on the MAC3 electronic system developed in France is also discussed. Different applications of the TDCR method in metrology laboratories around the world are also pointed out

No abstract available

[en] In this paper, counting efficiency vs figure of merit for 19 electron capture radionuclides has been computed. Toluene based s c i n t i l l a t o r solution of 15 cm³ has been assumed in the computation. The relationships to obtain the probability per decay are given and the computed efficiency tabulated.(Author)

[en] A table with physical characteristics of radioisotopes used in biological sciences in presented. The includes data of half-life, decay, electron capture, isomeric transitron, etc

[en] Low energy ¹²⁵I-brachytherapy sources are used for the treatment of retinoblastoma and many other forms of eye cancer. Such sources were prepared by adsorption of ¹²⁵I on palladium coated silver rods and were critically evaluated for safety aspects, as per AERB standards. In order to attain low leachability and to facilitate leak free laser encapsulation of sources within titanium capsules of size 0.8 mm (φ) x 4.75 mm (l), the radioactive source core was coated with polystyrene. With a view to study the radiation stability of such sources over a period of three weeks, both polymer coated radioactive sources and inactive source cores were separately subjected to an integrated gamma dose of ≅ (17.85 x 10⁴) Gy (17.85 MRad), which is the dose expected to be received in three weeks from a source containing ≅ 111 MBq of ¹²⁵I. This was carried out to test their suitability for reuse within such period. SEM pictures of inactive source cores were taken to observe the effect of gamma radiation on palladium coating. Post-irradiation leachability and uniformity of activity of radioactive sources were evaluated and found to be satisfactory. The sources were found to be reusable safely, for repeated brachytherapy procedures over a practically useful time of at least three weeks. (authors)

[en] In this paper, liquid scintillation counting efficiency v.s. a free parameter for E.C. and gamma-ray emitters has been computed. It is assumed that the decay scheme has only a gamma transition coincident with the E.C. Internal-conversion electrons of gamma photons may be emitted. The evaluation has been carried out for three different volumes, 5, 10 and 15 ml, of two scintillators, toluene and INSTAGEL, and thirteen radionuclides: ⁷Be, ⁵¹Cr, ⁵⁴Mn, ⁸¹Kr, ¹¹⁰Sn, ¹¹⁹Sb, ¹²⁵I, ¹³⁹Ce, ¹⁴³Pm, ¹⁴⁵Sm, ¹⁵²Dy, ¹⁵⁹Dy, ¹⁶⁶Yb. (Author)

[en] In comparison to normal gamma spectrometry the application of X-γ coincidence spectrometry improves the detection limit for most of EC-decaying radionuclides. The described arrangement is suitable for low-level measurements of EC-decaying nuclides with atomic numbers higher than 30. (author)

[en] The Chalk River ISOL and ISOLDE are briefly described. Experiments detecting β-delayed protons from the decay of the T/sub z/ = -2 nucleus ³²Ar and measuring the lifetimes of particle-unstable states in light electron-capture nuclei are sketched. Finally, a fictional nucleus (called pandemonium) was created, and its decay was simulated numerically by use of statistical principles. β-transition rates were known exactly, and an analysis of a simulated spectrum of β-delayed γ rays could be made. Transition rates could then be extracted from the simulated numerical data and compared with the known true rates. 14% of the γ intensity above 1.7 MeV was undetected in a peak analysis, and only about 35 out of 1000 gamma rays were identified. If the number of counts had been a factor of 10 less, 45% of the intensity would have been lost. Thus, every complex β-decay scheme that is based on γ-ray peak analysis and intensity balances must now be regarded as doubtful. If significant γ-ray intensity remains unobserved, the derived β-decay branching ratios could be wrong by orders of magnitude. 12 figures

[en] This paper presents the methodology of quality control of ¹²⁵I seeds used for brachytherapy. The ¹²⁵I seeds are millimeter titanium capsules widely used in permanent implants of prostate cancer, allowing a high dose within the tumour and a low dose on the surrounding tissues, with very low harm to the other tissues. Besides, with this procedure, the patients have a low impotence rate and a small incidence of urinary incontinence. To meet the medical standards, an efficient quality control is necessary, showing values with the minimum uncertainness possible, concerning the seeds dimensions and their respective activities. The medical needles are used to insert the seeds inside the prostate. The needles used in brachytherapy have an internal diameter of 1.0 mm, so it is necessary ¹²⁵I seeds with an external maximum diameter of 0.85 mm. For the seeds and the spacer positioning on the planning sheet, the seeds must have a length between 4.5 and 5.0 mm. The activities must not vary more than 5% in each batch of ¹²⁵I seeds. For this methodology, we used two ionization chamber detectors and one caliper. In this paper, the methodology using one control batch with 75 seeds manufactured by GE Health care Ltd is presented. (author)