Fahrig R, "Diaphragm Tracking in Cardiac C-Arm Projection Data

Abstract. Long acquisition times of several seconds lead to image ar-tifacts in cardiac C-arm CT. These artifacts are mostly caused by res-piratory motion. In order to improve image quality, it is important to accurately estimate the breathing motion that occurred during image acquisition. It has been shown that diaphragm motion is correlated to the respiration-induced motion of the heart. We describe the develop-ment of a method that is able to accurately track the contour of the diaphragm in projection space. Therefore, the contour is modelled as a 2-D quadratic curve. In order to provide robust and stable tracking, ad-ditional constraints based on prior knowledge of the projection geometry and human anatomy are introduced. Results show that the tracking is very accurate. A mean model error per pixel of 0:93 0:44 pixels was observed. The diaphragm top is tracked with an even lower error of only 0:62 0:60 pixels.