Standardization of 223Ra by live-time anticoincidence counting and gamma-ray emission determination.

From a commercial supplier, three independent lots of an aqueous solution containing 223Ra in equilibrium with its deteriorating progeny were considered for standardization, by using live-time anticoincidence counting (LTAC) in the Laboratório Nacional de Metrologia das Radiações Ionizantes (LNMRI) Brazil. The ionization chamber calibration factors were obtained using measurements of independent lots of 223Ra in LTAC considering the absolute method in order to evaluate the constancy and reproducibility of the standardization. The calibration factors of three high-performance well-type ionization chamber systems and four commercial well-type ionization chambers were determined. The LTAC results showed that lots 2 and 3 were 1069.88 and 1097.44 kBq/kg, with corresponding relative standard uncertainties 0.12% and 0.20%, respectively. The spectrometry method results of each lot value were classified as positive by ANOVA hypothesis testing. The emission probabilities relating to the X- and γ-rays in region from 81 to 830 keV ware determined. Hence, LNMRI can provide calibration services for 223Ra.

Radiometric survey of teletherapy treatment rooms in Brazil.

The Brazilian national regulatory authority, National Commission of Nuclear Energy, requires that dose rates in the vicinity of teletherapy treatment rooms do not exceed the permissible limits for workers as well as members of the public, depending on the place considered. At the end of 2005, the Brazilian national regulatory authority reduced the permissible dose limit for controlled areas from 1000 to 400 microSv week(-1). Therefore, the aim of this work is to verify the adequacy of structural shielding to this new limit for telecobalt units that had their sources changed and clinic linear accelerators (ALs) installed before the end of 2005. Considering the ALs, measurements of dose rates in controlled areas did not exceed the new permissible limit, excepting for a single case. In the case of (60)Co units, a similar situation is observed for controlled areas, although several non-conformities to the limit of uncontrolled area could be observed.

The effects of the Brazilian regulatory inspection programme on nuclear medicine facilities.

This paper aims to demonstrate the importance of the regulatory inspections carried out by the Brazilian regulatory body in the area of nuclear medicine. The main aspects observed during the inspections are presented as well as the time evolution of the non-compliances, according to their occurrence by type. We also evaluate factors concerning the working of the nuclear medicine facility responsible for solving the non-compliances. The results suggest a decrease of occurrence of non-compliances with time that can be related to the strictness of the inspections and the awareness of the personnel in the nuclear medicine facilities. An analysis of radiation dose exposure levels for the professionals involved in nuclear medicine was carried out; although dose values are below regulatory dose limits, their occurrence is not decreasing satisfactorily. Results indicate the need for staff training and commitment of the responsible nuclear medicine facility staff to the radiological protection procedures. Our results also emphasise the importance of continuous coercive actions to improve the level of radiological protection in nuclear medicine facilities in compliance with the standards established by the national regulatory authority and international recommendations.