[Insight-users] Influence of background on Registration metric &Choice of transform VersorRigid3DTransform /QuaternionRigidTransform / Euler3DTransform

[Miller, James V (Research)]

You can use a mask to limit the metric to be calculated only on the foreground of the fixed image.
See ImageToImageMetric::SetFixedImageMask()
 
Jim

	-----Original Message----- 
	From: insight-users-bounces+millerjv=crd.ge.com at itk.org on behalf of Axel Martinez Möller 
	Sent: Wed 12/14/2005 12:14 PM 
	To: insight-users at itk.org 
	Cc: 
	Subject: [Insight-users] Influence of background on Registration metric &Choice of transform VersorRigid3DTransform /QuaternionRigidTransform / Euler3DTransform
	
	


	 Hi all,
	
	 I am doing a 3D image registration between a PET and a CT image, both of
	size 128x128x47 voxels, each voxel being 5x5x3 mm. I have encountered two
	issues:
	
	1) Approximately 60 to 80% of my images is background (the patient occupies
	only a small part in the center of the field of view). I am afraid that this
	is having a bad influence on the registration: there are more voxels to
	interpolate, and the sampling for the metric takes into account much voxels
	which are irrelevant. Are my assumptions right? If so, do you know how to
	remove the influence of the background?
	
	2) Until now I have tested only the TranslationTransform, until I managed to
	tune the parameters and make it work. I want to switch now to a translation
	+ rotation transform. Going through the manual I am quite confused about the
	3 transforms which refer all to a 3D rigid registration:
	*VersorRigid3DTransform
	*QuaternionRigidTransform
	*Euler3DTransform
	My first tests were a bit frustrating. Can you give me some advice? Which
	combination Transform / Optimizer should perform better? Which should be
	avoided?
	
	 Thanks,
	
	  Axel
	
	_______________________________________________
	Insight-users mailing list
	Insight-users at itk.org
	http://www.itk.org/mailman/listinfo/insight-users