The International journal of applied radiation and isotopes最新文献

Parameters of calibrating CaF₂ : Tm for in-phantom dosimetry of therapeutically used fast neutron and ⁶⁰Co γ-ray beams have been studied. For ⁶⁰Co γ-ray beams the over-response, outside the main beam and at depths in phantom for large fields of irradiations is significant, and is higher for its 240°C glow peak than for its 150°C peak. The difference in the photon energy dependences of the two peaks of CaF₂ : Tm (Z_eff = 16.3), which is responsible for the above effect, is discussed. For therapeutically used cyclotron-produced fast neutron beams, the γ-ray absorbed dose component from photons of energy less than 200 keV is negligible.

The radiolytic reduction of dichromate ion in acidic aqueous solution has been investigated as a potential dosimetry system for the 10–40 kGy range of absorbed dose. Dilute sulphuric acid has been shown to be unsuitable as a solvent, and the use of 0.1 mol·dm⁻³ perchloric acid is recommended. A previously reported effect of silver ion in supressing reaction with hydrogen has been confirmed, and in addition, silver ions have been shown to be effective in eliminating dose rate effects. The temperature coefficient during irradiation has been determined as −0.2% per degree and post-irradiation storage effects are shown to be negligible. The precision of the system is about 0.5% at a dose of 25 kGy, and a suggested composition for a working dosimeter is given.

A method is described for the synthesis of [1-¹¹C]palmitic acid,in which ¹¹CO₂ is reacted with a Grignard reagent trapped within the pores of microporous polypropylene powder in a column. The free acid is liberated by passing gaseous HCl through the column. The apparatus is very simple, facilitating automation and miniaturization of the synthesis.

In these studies it has been shown that there are two main segments of background measured in a liquid-scintillation counter. One segment is unquenchable and is the result of background events which occur outside of the scintillation solution. The other segment is quenchable and is the result of interactions of cosmic rays, natural radioactivity and radioactive sources in the vicinity of the counter with liquid-scintillator solution.

The purpose of present investigation was to determine optimal condition for obtaining a stable Sn(II) complex with sodium flouride.

Measurements were performed by a potentiometric titration method, using a selective electrode with a flouride membrane, at pH 5, constant ionic strength and 22 ± 1°C. Stability constants were determined for both water and water-ethanol mixtures.

The obtained types of tin(II) complexes with flouride anion varied in dependence of Sn(II)/F molar ratio, which also influences the biological behavior of the tin colloid obtained by ^99mTc labelling of tin flouride complexes observed on experimental animals.

Lyoluminescence sensitivity of five different saccharide powders to electron irradiation has been determined using luminol solution as a solvent. Effect of electron energy variation in the range of 5–20 MeV on the lyoluminescence yield has been measured. The light conversion efficiencies of different saccharides irradiated with x-rays, β-particles, γ-rays, fast electrons, $\text{170-MeV}\text{c π}{}^{\mathrm{-}}$ mesons and 8-MeV neutrons have been calculated. Factors affecting light conversion efficiency, sensitivity and accuracy of measurements are discussed.