Projects

inSPECtor - integrated Spectroscopy Sensor System for Laser-induced Fluorescence and Hyperspectral Imaging

2017/04/01 – 2020/03/31

The core aim of this project is to gather the respective partner competences to upscale an innovative product based on emission and absorption spectroscopy able to identify and map critical elements as rare earth elements in primary resources as drilling cores and secondary products.

Contact person:

Dr. Nadine Schüler (schueler@freiberginstruments.com)


Development of measurement equipment for OSL-dosimetry with BeO

2016/03/15 - 2018/09/14

Personnel working in environments with potential exposure to artificial or increased radiation, like hospitals with CT/X-ray equipment, nuclear power plants, radiation facilities, etc., are required to be monitored for their radiation exposure. The availability of film material, which is one of the most important materials in such personal dosimetry, is not warranted on the long term. Other materials have been sought as possible replacements. The dependency of sintered BeO to radiation energy is close to tissue. Because of this favourable property, BeO is one of the phosphors of choice in personal dosimetry. Combined with the technique of Optically Stimulated Luminescence (OSL) for readout, BeO-OSL dosimetry is believed to supersede film dosimetry and at least to some extend thermoluminescence (TL) dosimetry.

The projects aims towards the development of OSL-equipment (EN/IEC 62387) to efficiently read out a new 2-element BeO-OSL dosimeter (Hp07 and Hp10). The modular equipment provides the manual readout of a single BeO-dosimeter. An automation attachment provides the opportunity to measure batches of 20 dosimeters stored in magazines. A total of 10 of such magazines are located in a wheel, which is software driven for dosimeter measurement according to user definitions. In OSL dosimetry it is sufficient to measure part of the signal, which allows re-reading, for dose determination. This usually requires the zeroing before a dosimeter can be used again. Instead of a separate device the bleaching to zero will be achieved within the OSL-reader, which speeds up the process. For calibration purposes a special beta source for irradiation of the dosimeters is constructed. Some application require on-site immediate analysis (e.g. in a phantom) and dose determination. This will be achieved by a single-element BeO-OSL equipment, which is handheld and can be independently operated from batteries, providing immediate dose assessment.

Figure 1: Photon energy response of various materials with reference to soft tissue (from Bos, 2001)

Reference

Bos AJJ (2001) High sensitivity thermoluminescence dosimetry. Nuclear Instruments and Methods in Physics Research B 184, 3-28.


READ

2016/06/01 - 2019/05/31

READ - Rare EArth ceramic phosphors for 3D optical readout Dosimetry

Dosimetry for radiation processing applications, as used e.g. in sterilization procedures for medical devices, is often tedious due to the constraints of quality assurance  and fulfillment of the required standards (e.g. ISO 11137, ISO/ASTM 51204, 51608, 51649, …). It is moreover time consuming. As an industrial application it is desired to release irradiated products as quickly as possible.

The project aims at the development of a handheld measurement device, which will provide instant dose information for user defined numbers of dosimeters attached to the product/product pallet, which will allow the immediate release if the specified requirements are met. While this can provide 3-D dose information based on the selected measurement spots, more details are sometimes required for product objects of very complex geometries, where it is essential to verify the dose at positions where dosimeters cannot be attached. For this purpose, a dosimeter material which can be sprayed onto surfaces and measured with a 3D-dose-scanner will be developed.

The dosimetric properties of doped NaYF4 will be employed to develop dosimeters as labels and as spray. These ceramic phosphors exhibit an upconversion effect, denoting the transformation of long-wavelength (infrared or near-infrared) light into short-wavelength radiation (luminescence) with higher photon energy. Here, a dependency of the lifetime of the luminescence with dose (Figure 1) has been shown (Härtling et al., 2012; Reitzig et al, 2013; 2016). This allows the use of a broad dose range of few kGy to 150 kGy (Figure 2). Its high stability under ambient conditions corroborates the application of the material for industrial dosimetry, where the dose information is retained and readout is contactless. These properties make the material a promising candidate for optical dosimetry below 5 kGy, a dose range addressed so far only with more complex non-optical systems.

Keywords:
High dose dosimetry, Optical dosimetry, gamma irradiation, Electron beam irradiation, X Ray irradiation, ceramic phosphors, luminescence decay time, industrial radiation processing.

Fig 1: Luminescence lifetime reduction after a 300 kGy electron irradiation (from Reitzig et al., 2016).
Fig 2: Dose dependency of the luminescence lifetime of NaYF4 (from Reitzig et al., 2016).

References

Härtling, T., Reitzig, M., Mayer, A., Wetzel, C., Röder, O., Schreiber, J., and Opitz, J. (2012). Nondestructive testing of electron beam sterilization by means of an optically active marker material. In "Optical Components and Materials IX." pp. 825713-825713-6. Proceedings SPIE 8257.


Reitzig, M., Goodband Rachel, J., Schuster, C., and Härtling, T. (2016). Optical electron beam dosimetry with ceramic phosphors as passive sensor material for broad dose ranges. tm - Technisches Messen 83, 171-179.


Reitzig, M., Härtling, T., Winkler, M., Powers, P., Derenko, S., Toro, C., Röder, O., and Opitz, J. (2013). Time-resolved luminescence measurements on upconversion phosphors for electron beam sterilization monitoring. In "Smart Sensor Phenomena, Technology, Networks, and Systems Integration." (K. J. Peters, W. Ecke, and T. E. Matikas, Eds.), pp. 86930R-86930R-7.

Mr. Florent Kuntz
florent.kuntz@aerial-crt.com 




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