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UC student developing new method for radiation detection

UC postgraduate student developing new method for radiation detection

August 20, 2013

A University of Canterbury (UC) postgraduate is developing a new detector for radiation therapy, which is one of the primary ways of treating cancer. 

PhD student Alicia Cavan says because radiation damages healthy cells as well as cancerous cells, it is important to accurately measure radiation doses for patients.

``There are definitely benefits to New Zealand for having this kind of ongoing research here, as it keeps us part of the global research and developments towards cancer treatments.

``For conventional radiation treatments the measurement tools we have are effective to measure the radiation doses. However, there are many research areas developing newer techniques for radiation therapy which push the limits of what we can measure with the existing tools.

``For this reason research must also be ongoing into radiation detectors so that the new treatment techniques can be safely and effectively applied to clinical situations to control cancer.

``The detector I am developing is based on an optical technique called digital holographic interferometry which uses a laser and a camera to measure very small changes in the temperature of a water sample when it is irradiated.

``This relates directly to the dose received by a patient and we are applying this treatment technique to proton radiation therapy.  Normal radiation therapy uses high energy beams of x-rays or electrons, but this can cause a lot of tissue damage to the surrounding healthy tissues.

``A proton beam has the unique property that it delivers a lower dose until a certain depth and then a steep peak in the dose (Bragg peak), so treatments can be tailored to much more preferentially treat a tumour.

``However, because this peak dose is really steep it is necessary to accurately measure the location and the amount of dose in the peak. There is no perfect detector for this at this stage. Currently there are no proton beams in Australia or New Zealand because it is still a highly experimental developing technique, and there are only a limited number of centres worldwide that offer this.

``Having New Zealand research ongoing into techniques such as these allows New Zealand to be a part of international research that is at the forefront of cancer research worldwide and increases the knowledge base for when it becomes feasible to implement treatment techniques such as this here.’’

In preliminary measurements in collaboration with the University of Washington Proton Research Centre in Seattle, the UC prototype detector was able to resolve the Bragg Peak of the proton beam, without some of the limitations of other detectors.

Cavan is studying towards her PhD and next year will continue her clinical training as a medical physics registrar at Christchurch Hospital, which will lead to her becoming a qualified medical physicist.

Cavan recently returned from a University of Washington study trip and has returned from a conference where she presented her results to the American Association of Medical Physicists.

Alicia Cavan.


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