One example method to determine a position of a probe in a surgical site with a plurality of reference structures may include receiving a three-dimensional image of the surgical site generated before the probe enters the surgical site and receiving a first two-dimensional image generated by the probe from a position within the surgical site. The three-dimensional image is associated with a first coordinate system, and the first two-dimensional image is associated with a second coordinate system. The method also includes acquiring registration to the plurality of reference structures based on the first two-dimensional image to obtain a permissible set of probe pose parameters, extracting a second two-dimensional image based on the permissible set of probe pose parameters from the three-dimensional image, and computing a correlation between the first two-dimensional image and the extracted second two-dimensional image to map the position of the probe represented by the second coordinate system to a position represented by the first coordinate system with respect to the three-dimensional image.一種以複數個參考結構判定一手術部位中一探針之一位置之例示方法可包含：接收該探針進入該手術部位前所產生的該手術部位之一三維影像；以及接收該探針從該手術部位中一位置產生的一第一二維影像。該三維影像係與一第一座標系統相關聯，而該第一二維影像係與一第二座標系統相關聯。該方法亦包含：基於該第一二維影像，取得該複數個參考結構的定位，進而獲得一組容許的探針姿態參數；基於該組容許的探針姿態參數，從該三維影像擷取一第二二維影像；以及計算該第一二維影像與所擷取的該第二二維影像之間的相關性，進而將該第二座標系統所表示的該探針之該位置映射至有關該三維影像之該第一座標系統所表示的一位置。
