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Near infrared imaging systems are increasingly being used to monitor the localised haemodynamic response to functional activation via the resulting spatially and temporally varying optical changes specific to cortical layers of the brain. These types of evoked physiological signals are difficult to simulate using the existing homogenous optical phantoms. Our group in UCL has developed a novel solid dynamic tissue equivalent phantom that enables spatially localised and temporally varying tissue properties to be reproduced. This dynamic test phantom consists of a modified layer of liquid crystal display (LCD), which enables flexible and rapid changes in attenuation across different regions of the phantom, sandwiched between two layers of an epoxy resin based tissue equivalent phantom material (providing homogeneous and well characterised optical properties). By switching the voltage applied to different pixels in the graphical display it is possible to produce highly localised and dynamic real time attenuation changes which can be used to simulate the changes often observed during evoked physiological functional response.
For further information please refer to:
Koh P.H., Elwell C.E., Delpy D.T., "Development Of A Dynamic Test Phantom For Optical Topography," Advances in Experimental Medicine and Biology (2009) 645:142-146 [URL] [PDF]