SU-GG-J-13: A New Self-Consistent Inverse Deformation Field Generator and Its Applications

Abstract

Purpose: To provide a tool to map image intensity, dose, and contours back‐and‐forth consistently between two images.Method and Materials: A new concept, a self‐consistent Inverse Displacement Vector Field (IDVF) is defined and an algorithm to generate the IDVF is implemented. A deformable image registration (DIR) algorithm was chosen to generate a DVFA‐B between reference image A and study image B . The same DIR algorithm is also used to generate DVFB‐A and our IDVF generator is used to create IDVFB‐A, which is consistent with DVFA‐B. To test whether DVFB‐A or IDVFB‐A better maps information from A‐B back to A for a lung 4D CT dataset, an arbitrary set of points SA is chosen and are warped to SB by using DVFA‐B. DVFB‐A is used to warp SB back to A to get S A D . Similarly, IDVFB‐A is used to warp SB back to A to get S A I . For each point in S A D (or S A I ), we know its original point in SA . Hence, one can calculate the Euclidean distance between each point in S A D (or S A I ) and its original point in SA to quantify the error in the back‐and‐forth image warping. Similarly, dose on A is warped to B and back to A . Results: The IDVF warped points from study back to reference with maximum error about 10 times smaller than using DVFB‐A. Similarly, the IDVFB‐A dose maximum warping error is about 2 times smaller than using DVFB‐A. Conclusion: This work shows that it is possible to generate self‐consistent IDVF with small mapping error. This IDVF is useful to warp contours and dose for IGART. (Work supported by NIH P01CA116602).