User:Surbhi crpf/sandbox

Computerised cephalometrics is the process of entering cephalometric data in digital format into a computer for cephalometric analysis. Digitization (of radiographs) is the conversion of landmarks on a radiograph or tracing to numerical values on a two- (or three-) dimensional coordinate system, usually for the purpose of computerized cephalometric analysis. The process allows for automatic measurement of landmark relationships. Depending on the software and hardware available, the incorporation of data can be performed by digitizing points on a tracing, by scanning a tracing or a conventional radiograph, or by originally obtaining computerized radiographic images that are already in digital format, instead of conventional radiographs. Computerized cephalometrics offers the advantages of instant analysis; readily available race-, sex- and age-related norms for comparison; as well as ease of soft tissue change and surgical predictions.

Digitization
Computer processing of cephalometric radiographs uses a digitizer. Digitization refers to the process of expressing analog information in a digital form. A digitizer is a computer input device which converts analog information into an electronic equivalent in the computer’s memory. In this treatise and its application to computerized cephalometrics, digitization refers to the resolving of headfilm landmarks into two numeric or digital entities – the X and Y coordinate. 3D analysis would have third quantity - Z coordinate.

Classification of Analyses
The basic elements of analysis are angles and distances. Measurements (in degrees or millimetres) may be treated as absolute or relative, or they may be related to each other to express proportional correlations. The various analyses may be grouped into the following: These in turn may be grouped according to the following concepts on which normal values have been based:
 * 1) Angular – dealing with angles,
 * 2) Linear – dealing with distances and lengths,
 * 3) Coordinate – involving the Cartesian (X, Y) or even 3-D planes,
 * 4) Arcial – involving the construction of arcs to perform relational analyses.
 * 1) Mononormative analyses: averages serve as the norms for these and may be arithmetical (average figures) or geometrical (average tracings). E.g. Bolton Standards.
 * 2) Multinormative:  for these a whole series of norms are used, with age and sex taken into account, e.g. Bolton Standards.
 * 3) Correlative: used to assess individual variations of facial structure to establish their mutual relationships, e.g. Sassouni’s arcial analysis.