http://www.digitaljournal.com/life/health/lasers-used-to-detect-brain-tumors/article/442564

Lasers used to detect brain tumors

Posted Sep 1, 2015 by Tim Sandle
Brain surgeons in Britain have used lasers to detect a tumor during a surgical procedure. This was the first use of the procedure in Europe.
The Human Brain
Brain preserved in formaldehyde.
By Gaetan Lee (CC BY 2.0)
The person who underwent the technique was a young man called Reuben Hill, aged 22. The non-invasive technique was deployed in London. The method looks for levels of light reflected off tissue. The pattern of reflection helps to determine if the tissue is cancerous or healthy.
Having identified a tumor, the surgeons proceeded to perform an operation. According to The Daily Mail newspaper "in a poignant moment captured on film, the doctors woke Mr Hill during the surgery and asked him to sing - to check they hadn't damaged key areas of the brain." The singing was no doubt of good quality, given that Mr. Hill is a member of his university's choir.
The procedure took place at Charing Cross Hospital. The method had previously been tested at a hospital in Montreal, Canada. The procedure works through the following steps:
A device generates a near-infrared laser probe
The generated beam of light is directed at the exposed brain.
The light-beam causes molecules in the cells to vibrate.
Fiber optics in the probe proceed to collect the scattered light that bounces off the tissue.
The light is analyzed using Raman spectroscopy.
A spectrometer measures the frequency of vibrations.
Healthy and abnormal tissue have a slightly different "signature", enabling surgeons to detect the presence of a tumor.
The laser scanning is a step forward from current methods. This is through biopsies, where sections of tissue are removed during surgery and then sent for analysis to determine if they are cancerous. This can take up to 40 minutes at a time.