engleski

3D printed eye lens dosimeter holder for IR and IC

Dosimetry services using Panasonic dosimeters have been put in a difficult position after the introduction of the new eye lens dose limit for Hp(3) prescribed by the Euratom BSS Directive and the recommendations by the IAEA to monitor the eye lens dose for exposed workers working in non-uniform radiation fields. There are currently no commercially available eye lens dosimeters holders that could fit Panasonic TLD pellets. Therefore, inexpensive, waterproof and comfortable holders have been designed and 3D printed to fit Panasonic Li2B4O7 but also other producers’ single dosimeter element. The Panasonic Li2B4O7 is a tissue equivalent TLD material with quite a horizontal energy response and well documented characteristics. The eye lens dosimeter consists of an acrylonitrile butadiene styrene (ABS or ABS+) plastic holder with a quadratic slot for a TLD pellet with approximately 3 mm front filtration. After the insertion of the pellet, the slot part was covered by a heat-shrink tube and shortly heated with a hot air to wrap. The dosimeter is to be worn fixed to a headband, close to either eye, on the side of the head. The energy and angular response of a new holder with a single Panasonic UD- 807ATN TLD element were tested in the Secondary Standard Dosimetry Laboratory of the Ruder Boskovic Institute (RBI-SSDL). The testing was performed using a cylinder phantom with a 20 cm diameter and 20 cm height, water-filled with PMMA walls for radiation qualities, R, narrow beam series, defined in ISO 4037-1, N-30, N-60, N-100, as the reference R, N-120, and S-Cs at 0˚, +30˚, +60˚ and +75˚ (due to bilateral symmetry of the dosimeter). Applied conversion coefficients hpK(3 ; R, α)cyl from air kerma to Hp(3) for different R and angles of incidence in Sv/Gy were taken from R. Behrens, Radiat.Prot.Dosim. 151, 450 (2012). A total of 100 dosimeters in groups of 5 were irradiated in 20 separate irradiations with a Hp(3) value of 2 mSv. Measurement results for energy/angular response for all radiation qualities used were within IEC 62387:2012 limits: 0, 71 ≤ response ≤ 1, 67. Further testing shall include exposure to IEC 61267 RQR spectra for selected angles. Furthermore, the stability of the ABS+ plastic holder itself under the influence of irradiation was investigated by electron spin resonance (ESR) spectroscopy. Continuous wave (CW) ESR spectra were recorded on a Varian E-109 X-band (≈9.5 GHz) spectrometer equipped with a Bruker ER 4111 VT variable- temperature unit with a flow of N2 gas. The concentration of radicals, intrinsic and radiation induced, was monitored before and after the radiation process. Both the shape of the ESR spectra and the signal intensities indicated that the ABS+ holders were stable for the dose range required in the application. According to all testing results, the new holder is suitable for use in eye lens dosimetry in IR and IC.

Eye lens dosimetry ; Hp(3) ; Li2B4O7 ; Eye lens dosemeter holder ; Personal dosimetry

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