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<P class=EC_EC_MsoNormal>Greetings, </P>
<P class=EC_EC_MsoNormal> </P>
<P class=EC_EC_MsoNormal>I am sorry for the repost but I forgot to include a subject line previously. </P>
<P class=EC_EC_MsoNormal> </P>
<P class=EC_EC_MsoNormal>I am new to ITK and am trying to use the registration algorithms to register two 3D x-ray image datasets. The problem is that all the images have very low contrast and the intensity-based algorithms fail when used with the mean square metric (I also tried mutual information with no success). I need to perform a rigid registration and am hoping someone with more experience could suggest a metric which would be appropriate for use with low contrast images. </P>
<P class=EC_EC_MsoNormal> </P>
<P class=EC_EC_MsoNormal>Alternatively, I am open to the idea of using control points which the user would input. I am most interested in the actual values of translation, rotation and scaling required for the registration than in the final registered datasets themselves. The reason is that we are investigating the use of those images in patient positioning prior to radiation delivery. Can someone please point me in the right direction as to whether this is possible using ITK? It is probably obvious that I am very new at this and I would appreciate any help and/or pointers. Thank you. </P>
<P class=EC_EC_MsoNormal> </P>
<P class=EC_EC_MsoNormal>Vik</P>
<P class=EC_EC_MsoNormal> </P></DIV></BLOCKQUOTE><BR>
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