Mensuration of equivalent dose with personal dosemeters and instruments of radiological protection in the new operative quantities ICRU, for external fields of beta radiation. Part II. I study of the angular response of personal dosemeters TLD-100 in secondary patron fields of beta radiation (90Sr / 90Y)

The objective of this work is to carry out one of the possible ones test type for personal dosemeters TLD, under the recomendations of the ICRU 39, ICRU 43 and the draft of the norm ISO 6980,(1992), with the purpose of verifying the capacity of these detectors to carry out the operative unit: H' (0.07;α). Since H' (O. 07;α) this defined one in an expanded field, one of these tests type consist on determining the angular response of these detectors. 20 personal dosemeters TLD-100 was used, (card marks: Harshaw, Model: G-1, with two glasses of TLD-100 absorbed in teflon; the portadosemeters has two windows, a free one and another with a filter of Pb of 171.0 mg cm-2); these dosemeters they were previously selected, [to see, Study of the Homogeneity of the response of Personal Dosemeters (Cards G-l, TLD-100) in Radiation of Countrysides of 60Co, J.T. Alvarez R. Technician Report GSR/IT/0001/94].The irradiations to effectued in secondary countryside of radiation beta of 90Sr/90Y. The study was undertaken by means of an experimental design of blocks random that contemplate the following variables: intensity of the radiation source, (1850 MBq and 74 MBq); position of irradiation, (four positions); incidence of angle of the radiation (0, 15, 30, 45, 60 and 75 grades) and the absorbed dose in air, (0.005, 0.010, 0.020, 0.050 and 0.100 Gy). Then null hypothesis it was to suppose that there was not difference among the stockings of each treatment, to used the statistical of Duncan to carry out tests of stockings at a level of significance of 5%.These tests of stockings throw the following results in those variables of the experimental design: The irradiations carried out so much with the source pattern secondary of 90Sr/90Y of 1850 MBq and of 74 MBq, they are equivalent reason why they can be used indistinctly. The responses of each one of the glasses of the card are strongly anisotropic for each glass; four positions of irradiation is used: glass 1 (window of 171 mg cm-2 of Pb) it presents six populations in the angular response being from maximum to minimum: 15, 30, 0, 45, 60 and 75 grades. Glass 2 (free window) it presents four populations in the angular response being from maximum to minimum: 15, 30; 45, 0; 60 and 75 grades. - The Doses absorbed in air imparted to the dosimetros were the following ones: T1 = 0.005, T2 0.010, T3 = 0.020, T4 0.050 and - T5 = 0.10 Gy, being the responses of both glasses significantly for each treatment: glass 1 present four populations in the response to those treatments being from maximum to minimum: T5; T4; T3 and T2=T1, (that is to say to low dose the glass cannot differentiate them). Glass 2 present the same four populations in the response to the treatments. Finally it was determined the angular response for each glass in accordance with the ICRU 43 and using the coefficients of conversion, (of transmission and angular) of the norm IS0 6980 (1992), considering as the operative unit to H(0.07;angulo). (Author)