1. A method for detecting a guiding catheter in a fluoroscopic image, comprising: detecting a plurality of guiding catheter centerline segment candidates in the fluoroscopic image; clustering the plurality of guiding catheter centerline segment candidates into a number of guiding catheter centerline segment clusters; and detecting a guiding catheter centerline connecting a guiding catheter centerline ending point in the fluoroscopic image with an image margin of the fluoroscopic image by connecting a plurality of the guiding catheter centerline segment clusters.