Hitachi Ltd's Advanced Research Laboratory has prototyped a portable photo-topography equipment, which weighs only 1 kg. As using this equipment allows easy measurement of brain activities in daily life, "Not just for medical applications, photo-topography technology will be more familiar to us. For example, this technology may be useful for health care application with observing a trend in everyday measurements," said Hitachi. The company also explains about some other application fields such as psychology, marketing and education.
Photo-topography method is a method that measures a change of blood volume in a brain associated with brain activities by radiating weak near-infrared ray from above scalp skin. The photo-topography equipment launched by Hitachi Medical Corp. for medical use in 2001 was so heavy itself that the equipment was not adequate to measure daily brain activities.
The photo-topography equipment is lightweight, with a measurement device that attaches to the head that weighs roughly 400 g and a main unit that attaches to the wrist, for example, which weighs roughly 630 g. In a measurement device, 8 pairs of small plane emission laser devices and photodiodes are mounted. A personal computer connected to a wireless LAN is used for displaying and analyzing data. Miniaturization and weight saving are achieved by these developments and by limiting a measurement region to the prefrontal cortex.
The measurement device and the equipment body can be operated for 3 hours with the built-in secondary battery. To save electric consumption, 8 light sources emit lights with time difference. In addition, to remove noise, the light source blinks at 1 kHz and only signals synchronized to the blinking light will be detected.
As one personal computer can control 24 equipments and display the data from them, this equipment can be used for measurements of brain activities during group activities and group communications. The timing of practical implementation of this photo-topography system has not yet been determined.