When the pleural cavity is opened during the surgery portion of pleural photodynamic therapy (PDT) of malignant
mesothelioma, the pleural volume will deform. This impacts the delivered dose when using highly conformal treatment
techniques. To track the anatomical changes and contour the lung and chest cavity, an infrared camera–based navigation
system (NDI) is used during PDT. In the same patient, a series of computed tomography (CT) scans of the lungs are also
acquired before the surgery. The reconstructed three-dimensional contours from both NDI and CTs are imported into
COMSOL Multiphysics software, where a finite element-based (FEM) deformable image registration is obtained. The
CT contour is registered to the corresponding NDI contour by overlapping the center of masses and aligning their
orientations. The NDI contour is considered as the reference contour, and the CT contour is used as the target one, which
will be deformed. Deformed Geometry model is applied in COMSOL to obtain a deformed target contour. The distortion
of the volume at X, Y and Z is mapped to illustrate the transformation of the target contour. The initial assessment shows
that FEM-based image deformable registration can fuse images acquired by different modalities. It provides insights into
the deformation of anatomical structures along X, Y and Z-axes. The deformed contour has good matches to the
reference contour after the dynamic matching process. The resulting three-dimensional deformation map can be used to
obtain the locations of other critical anatomic structures, e.g., heart, during surgery.
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