Figure 5.

Sensitivity to the number of vertebrae included in single-stage registration evaluated in 61 clinical radiographs. (a) Examples show n₁ = 1, 3, and 5 vertebrae, each with a 50 mm binary volume mask. (b) Failure rate and maximum PDE measured as a function of n₁. The observation that smaller mask size reduced the max PDE motivated development of the msLevelCheck method to provide both robust global registration (via the initial stages) and more accurate registration local to each vertebra (via the end stages).