Fig. 1.

Method processing algorithm subdivided into annotation, training, and output steps. Annotation step: the mask of the cryo-balloon marker mask^marker is obtained from the original XR image to be processed by the U-net^marker; the mask of the cryo-balloon catheter shaft centerline mask^{shaft ctrl} is obtained from the original XR image and its corresponding mask^marker to be processed by the U-net^shaft. Training step: U-net^marker is trained on the image sample consisting of original XR image and its corresponding mask^marker as ground truth; U-net^shaft is trained on the image sample consisting of original XR image and its corresponding mask^marker as inputs and mask^{shaft ctrl} as ground truth. Output step: mask^marker and mask^shaft are predicted by the U-net^marker and U-net^shaft correspondingly as images containing contours of specific pixel values against background