1. A method for registering an ultrasound image acquired using an ultrasound probe to a fluoroscopic image acquired using a fluoroscopic image acquisition device, comprising: detecting a 2D location of the ultrasound probe in the fluoroscopic image using a trained machine learning based probe detector that extracts features from image patches of the fluoroscopic image, determines a probability score for each image patch, and selects the image patch having the highest probability score as the 2D location of the ultrasound probe; estimating an initial machine learning based 3D pose of the ultrasound probe based on the detected 2D location of the ultrasound probe in the fluoroscopic image by initializing pose estimation using X and Y coordinates estimated from the detected 2D location of the ultrasound probe, estimating a 3D position of the ultrasound probe including X, Y, and Z coordinates based on the X and Y coordinates estimated from the detected 2D location by applying a trained machine learning based position classifier to the fluoroscopic image, and estimating a 3D position and orientation of the ultrasound probe including X, Y, and Z coordinates and a roll, pitch, and yaw based on the 3D position estimating using the trained machine learning based position classifier by applying a trained machine learning based position and orientation classifier to the fluoroscopic image; iteratively refining the estimated initial machine learning based 3D pose of the ultrasound probe using 2D/3D registration based on the ultrasound and the fluoroscopic image to estimate a final 3D pose of the ultrasound probe; mapping the ultrasound image to a 3D coordinate system of the fluoroscopic image acquisition device based on the estimated final 3D pose of the ultrasound probe; estimating a patient specific physiological model of an anatomical structure in the ultrasound image; and projecting the patient specific physiological model of the anatomical structure into the fluoroscopic image using a projection matrix associated with the fluoroscopic image.