Since intracranial pathologies proximate to the calotte can occur in different places, three measurements – frontal, temporoparietal and occipital – should be carried out on each side, i.e. six in total.

The principle behind CRAINSCAN is measurement of the optical density of tissue. The device contains a laser source and a neighboring photoreceiver which are both pressed to the patient's head. Near infrared light travels from the laser source through the bony skull and the uppermost layers of the brain to the photo-receiver. If the light path is obstructed by a hemorrhage, only a fraction of the irradiated light reaches the sensor.

1) Preclinical and clinical emergency medicine: Having applied CRAINSCAN at the scene and obtained a positive optical finding, the emergency physician can diagnose with a high degree of certainty the existence of an intracranial pathology proximate to the calotte. Particularly certain is the detection of intracranial hemorrhages proximate to the calotte. Rapid execution of computer tomography (CT) or, where appropriate, magnetic resonance imaging (MRI) should follow. In patients with indications for immediate treatment, this procedure could thus shorten the interval until commencement of therapy (e.g. neurosurgery), which can contribute to a significant improvement in neurological outcome.

2) Repeated optical monitoring of patients in hospital, e.g. following cranio-cerebral trauma, who have to be monitored in case of delayed intracranial hematoma. The detection can be made at the patient's bedside conveniently. In such patients CRAINSCAN is able to confirm the need of additional or advanced CT of the head.