Dosimetric calibration of solid state detectors with low energy beta sources

作者：Fidanzio Andrea^*; Toni Maria Pia; Capote Roberto; Pena Juan; Pasciuti Katia; Bovi Maurizio; Perrone Franco; Azario Luigi; Lazzeri Mauro; Gaudino Diego; Pierniattei Angelo

来源：Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms , 2008, 266(2): 277-282.

DOI：10.1016/j.nimb.2007.11.023

• dosimetry
• beta source
• low energy

A PTW Optidos plastic scintillation and a PTW natural diamond detectors were calibrated in terms of absorbed dose to water with beta fields produced by Sr-90 + Y-90 and Kr-85 reference sources. Each source was characterized at the Italian National Metrological Institute the Istituto Nazionale di Metrologia delle Radiazioni Ionizzanti of ENEA (ENEA-INMRI) - for two different series, 1 and 2, of ISO reference beta-particle radiation fields. Beam flattening filters were used for the series 1 beta fields to give uniform absorbed dose rates over a large area at a source-to-reference plane distance of 30 cm. The series 2 beta fields were produced at source-to-reference plane distance of 10 cm, without the beam flattening filters, in order to obtain higher absorbed dose rates.
The reference absorbed dose rate values were directly determined by the Italian national standard for beta-particle dosimetry (a PTW extrapolation ionization chamber) for the series 1 beta fields and by a calibrated transfer standard chamber, (a Capintec thin fixed-volume parallel plate ionization chamber) for the series 2 beta fields. Finally the two solid state detectors were calibrated in terms of absorbed dose to water with the series 2 beta field.
The expanded uncertainties of the calibration coefficients obtained for the plastic scintillation dosimeter were 10% and 12% (2SD) for the Sr-90 + Y-90 and the Kr-85 sources, respectively. The expanded uncertainties obtained for the diamond dosimeter were 10% (2SD) and 16% (2SD) for the Sr-90 + Y-90 and the Kr-85 sources, respectively.
The good results obtained with the Sr-90 + Y-90 and the Kr-85 beta sources encourage to implement this procedure to calibrate this type of detectors at shorter distances and with other beta sources of interest in brachytherapy, for example the Ru-106 source.

• 出版日期2008-1