Medical system for use in interventional radiology

A medical system for use in interventional radiology, adapted to be coupled to a navigation system, comprising:

• a needle to be inserted into a patient's body toward a target, said needle comprising a distal tip and a proximal stop;
• a needle guide, the needle being able to slide within said guide along a longitudinal axis thereof, said needle guide comprising a tracker for navigating the needle guide with respect to a 3D medical image of a patient, an axis of the needle being indirectly navigated relative to the 3D medical image through the needle guide;
• a processor configured to
• detect a contact between the needle guide and the proximal stop as the needle guide is slid along the needle in the proximal direction while the needle remains fixed relative to the patient's body;
• determine, from navigation data of the needle guide when said needle guide is in contact with the proximal stop of the needle and from a length of said needle, a position of the distal needle tip with respect to the 3D medical image;
• and
• memorize an orientation and position of the needle when the guide is adjacent to the patient's skin;
• compute a curvilinear distance from the position of the needle guide adjacent to the patient's skin to the position of the needle guide in contact with the needle stop using a circular arc model by taking into account the localization data of the needle guide when the needle guide is adjacent to the patient's skin and when the needle guide is in contact with the needle stop;
• and
• user interface coupled to said processor and configured to display, on at least one image of the patient, a representation of the needle and a point on said representation of the needle to represent the needle tip in said memorized orientation and position.

A method for determining a position of a needle tip in a 3D medical image of a patient in interventional radiology, comprising:

• providing a needle having a distal tip and a proximal stop and a needle guide, the needle being able to slide within the needle guide along a longitudinal axis thereof;
• inserting the needle into the patient's body toward a target;
• navigating the needle guide with respect to the 3D medical image, an axis of the needle being indirectly navigated relative to the 3D medical image through the needle guide;
• detecting a contact between the needle guide and the proximal stop as the needle guide is slid along the needle in the proximal direction while the needle remains fixed relative to the patient's body;
• determining, from navigation data of the needle guide when said needle guide is in contact with the proximal stop of the needle and from a length of said needle, a position of the distal needle tip with respect to the 3D medical image;
• and
• displaying, on at least one image of the patient, a representation of the needle and a point on said representation of the needle to represent the needle tip in said determined position.