Measurements between anatomical landmarks on X-ray radiographs are useful for diagnosis and treatment planning in fields such as orthopedics and orthodontics. Direct measurement on single radiographic images, however, does not truly reflect spatial relationships, as depth information is lost.
We used stereo images from a low dose X-ray machine employing linear slot-scanning radiography (LSSR) to estimate coordinates of 3D bony landmarks from 2D images. LSSR consists of a linearly moving focal spot that emits a very narrow fan-beam through a narrow slot. Object magnification therefore occurs along the slot direction (X-direction in Fig. 1) but is negligible in the scan direction.
The aim of the study was to develop an algorithm to determine 3D coordinates of landmarks from radiographic images for measurement, while accounting for the magnification along the slot direction of the imaging system.
Stereophotogrammetry (SPG) is a 3D point localization technique using...