Evaluation of 2D and 3D ultrasound tracking algorithms and impact on ultrasound‐guided liver radiotherapy margins by De Luca, V, Banerjee, J, Hallack, A, Kondo, S, Makhinya, M, Nouri, D, Royer, L, Cifor, A, Dardenne, G, Goksel, O, Gooding, M, Klink, C, Krupa, A, Le Bras, A, Marchal, M, Moelker, A, Niessen, W, Papiez, B, Rothberg, A, Schnabel, J, Van Walsum, T, Harris, E, Bell, L, Tanner, C