Radiation sensing fibres – talking papers #5

Imagine:

  • clothing that can detect radiation
  • a tiny probe to reduce side effects of cancer treatment

Work from a PhD student mixes together two IPAS research themes and demonstrates a novel dosimetry architecture capable of supporting these and many other innovations.

It’s a great story on the way IPAS can boost the career of young researches through access to world leaders in six discipline spanning research themes. PhD student Christopher Kalnins has been with IPAS since commencing honours, just a few short years ago. Even before finishing his PhD, Christopher is now lead author on a significant research paper published in Optical Materials Express which shows a novel architecture for dosimetry – the measurement of radiation in an environment. He has been able to mix together expertise from two of the six IPAS trans-disciplinary research themes, namely ‘Optical Materials & Structures’ and ‘Chemical & Radiation Sensing’. Normally a student would have to choose between the opportunity to work on the development of a new material or the testing of the application of a new material in a field of science.

Armed with some fairly rudimentary radiation sources, shields and detectors, a few home-made black boxes (literally!) to keep things dark and a rather basic soft fluoride phosphate glass drawn to a fiber of very simple geometry Christopher was able to demonstrate and measure Optically Stimulated Luminescence or OSL. I spent some time with Chris to talk about his work and to take a look at some of the equipment he used.

BlackBoxLids     black box

RadiationDosimetryBeam

It turns out that one of the major challenges in this work was the ‘signal to noise ratio’, meaning a fairly weak signal in the presence of a lot of background noise. To overcome this challenge Christopher used a bundle of six fibres and went to great pains to eliminate as much background noise, in this case – light, as possible. The lab used looks like a fairly traditional darkroom, with windows blacked out and a ‘safe’ red light in which it is possible to see equipment. Closer inspection shows that any piece of equipment with a screen or light has been modified by disabling or removing any such light. The next step was for Christopher to build a black box with a lid to contain most of the equipment. Finally, he had to learn to operate his equipment by feel in total darkness as even the ‘safe-light’ interfered with the results. Listen to this short audio recording for more detail.

Working with IPAS director Professor Tanya Monro and theme leaders Heike Ebendorff-Heidepriem & Nigel Spooner, Christopher published the findings of his work in a paper entitled “Radiation dosimetry using optically stimulated luminescence in fluoride phosphate optical fibres” published in Optical Materials Express by the Optical Society of America. This paper marks the first demonstration of an intrinsic architecture for OSL meaning the fibre acts as both the sensing and light guiding component. From the paper:

In this study we focus on advancing the intrinsic fibre architecture, for the purposes of distributed and environmental sensing in situations where an increase in the radiation field is possible. There are many potential environments that would benefit from this method of sensing, primarily any environment in which leakage of ionising radiation from equipment or facilities could potentially occur.

This paper shows shows this novel intrinsic platform / architecture is feasible. Further work to improve the signal noise ratio, starting with new materials then repeating the whole exercise with more precise detectors has already begun. Some time in the not too distant future we may see radiation sensing fibres woven into clothing or formed into tiny probes that measure radiation doses inside a patient during cancer therapy.

Mike Seyfang for IPAS “talking papers” series.

– – – the information below may help the reader to better understand the paper – – –

Definitions:

OSL – Optically Stimulated Luminescence: Optically stimulated luminescence or (OSL) is a method for measuring doses from ionizing radiation (commonly known as radioactive radiation) , wikipedia has a definition that mentions two important application areas.

PhotoDarkening – has been defined as: the phenomenon that the optical power losses in a medium can grow when the medium is irradiated with light at certain wavelengths.

Scintillation – can be defined as: a flash of light produced in a transparent material by an ionization event.

Units:

luminescence – cnts / g / microJ: counts of photons emitted per gram of material per micro joule of energy

scintillation – cnts / s: counts of photons emitted per second

dose – Gray (Gy) is the SI unit of absorbed dose. Joules of energy absorbed per kilogram of material

radiation BQ – emissions per sec: One Becquerel is that quantity of a radioactive material that will have 1 transformations in one second

Links:

paper – http://digital.library.adelaide.edu.au/dspace/handle/2440/68551

YouTube – http://youtu.be/yFB8Kqp-_pk

Audio – http://media.ipas.edu.au/2012/TalkingPapers05ChrisTanya.mp3

Mike Seyfang for IPAS “talking papers” series.

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About mseyfang

Interruptus Digitalis

Posted on September 13, 2012, in talkingpapers. Bookmark the permalink. Leave a comment.

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