Unstable registration results

[BigPandaCPU]

Hi @fabio86d ，I tested the Register_femoral_implant.py, I find that the registation results unstable.

I generated DRR image at initial pose [30(degree), 0, 0, 11.84455, 57.40224, -818.1117], named as SC_g1_037, use it as a fixed image. Then use Register_femoral_implant.py to registration. The optimal pose at different times as below.(The offset pose are set to [0, 0, 0, 0, 0,0])

Found optimal pose: [ 17.72911351 0. 2.52833828 11.84455 57.40224 -818.1117 ] #first time

Found optimal pose: [ -3.17360494 0. 2.74304042 11.84455 57.40224 -818.1117 ] #second time

Found optimal pose: [ 14.85806329 0. 4.8200415 11.84455 57.40224 -818.1117 ] #Third time

I run it three times and get three different results.
Maybe the Optimizer Method is not good.