The global photographic assessment is useful for determining overall
clinical changes in a patient over time period in a standardized manner.
Global photographs are head shots taken a short distance away from the
patient and are different from the up close photographs used in the
Phototrichogram technique. A patient is usually photographed from the front, top, sides, and back to show accordingly a frontal hair line, crown, partition and vertex (center of a scalp whorl). If there are other features like patchy hair loss on a scalp, then it will be photographed, as well. This basic photographic setup gives some good, clear photographs, suitable for recording patient’s progress with their hair loss and hair growth during treatment adn can be recorded and compared in "Additional Studies" module. However, this photographic setup is not good enough for use in clinical trials and other studies where hair coverage needs to be evaluated in a consistent and quantitative manner. For clinical and research studies, global photographs are taken with a special digital photographic system, which are then also being accepted by "Additional Studies" module. It shall have the same degree of lighting with hairs beinng at the very same distance on the photograph, and the very same area of hairs is being visible in a photograph. In this way, over time multiple photographs can be taken of the same patient in exactly same way, so that photographs at a different time point of a study can be directly compared and analyzed for changes over some time span. Special Stereotactic Systems are being utilized to meet these requirements. Such system combines a device retaining patient's head in a certain set position, a camera with specifically configured set of flashes and a speical panel or ruler to measure a distance between this camera and a patient. The main task of the Stereotactic System is to create an identical reproducible conditions of a study area. There are certain restrictions to patients applicable as well. A person has to agree not to change hairstyle much, as different style may chagne how thin hairs look. Patient should aslo not to use cosmetic treatments, like having a perm (it thickens hair fibers) or use hair thickening shampoos (they coat hairs with additional protein to look thichker), etc.
For more detailed information on Stereotactic System review presentation below: