Method for determining the position of an organ

A method for determining the position of a patient's organ with respect to at least two imaging devices, including the following steps:

• making at least one 3D first image of an organ of a patient having a first coordinate system and of a surface of the organ or skin region with a first imaging device while the patient is in a pre-operation site without fixing any mark to the patient;
• placing the patient in an operation site having a second coordinate system;
• determining a first position of a second imaging device with respect to the second coordinate system of the operation site;
• making a second image with said second imaging device, the second image corresponding to a cloud of points of the surface of the organ or skin region;
• matching the at least one 3D first image and the second image where the at least one 3D first image is located with respect to the first coordinate system of the patient;
• and
• providing a third device having a third coordinate system in the operation site and determining a first position of the third device with respect to the second image of the second imaging device, whereby the third coordinate system of the third device is positioned with respect to the second image of the second imaging device and thereby with respect to the at least one 3D first image from the first imaging device.