Method for registering three-dimensional representations of an object on the object itself and device for providing navigation assistance in an object implementing said method
A registration method includes a storage of two three-dimensional representations of an object and locations of at least three reference points of the object in these two three-dimensional representations; an angular registration of the first three-dimensional representation on the object from a recording of locations of the reference points of the object in a reference frame linked to a reference ancillary fixed on the object; a surface registration of the first three-dimensional representation on the object, including a recording of locations of surface points other than the reference points on the surface of the object in the three-dimensional reference frame linked to the referencing ancillary; and a registration of the second three-dimensional representation of the object on the object itself including a surface registration of this second three-dimensional representation on the basis of the recording of the surface point locations made for the surface registration of the first three-dimensional representation.
1 . A method for three-dimensional registering three-dimensional representations of an object on the object itself, using a referencing ancillary fixed to the object, a stylus, a tip of which can be located in a three-dimensional reference frame linked to the referencing ancillary, and an instrument, a functional tip of which can be located in the three-dimensional reference frame linked to the referencing ancillary, comprising:
a memory storage of a first three-dimensional representation of the object according to a first three-dimensional imaging mode and of locations of at least three reference points of the object in this said first three-dimensional representation;
a three-dimensional angular registration, by a computing unit, of this said first three-dimensional representation on the object from a recording, using the tip of the stylus, of locations of the object's reference points in the three-dimensional reference frame linked to the referencing ancillary;
a three-dimensional surface registration, by the computing unit, of this said first three-dimensional representation on the object comprising:
extracting a surface of the object in the first three-dimensional representation,
recording the locations of a plurality of surface points other than the reference points on the surface of the object in the three-dimensional reference frame linked to the referencing ancillary, and
computing the three-dimensional surface registration from said surface point location recording;
a memory storage of a second three-dimensional representation of the object according to a second three-dimensional imaging mode, other than the first three-dimensional imaging mode, and of locations of the reference points of the object in said second three-dimensional representation;
a three-dimensional registration of this said second three-dimensional representation of the object on the object itself; and
a simultaneous display of several planar cross-sectional reconstructions of the object;
the three-dimensional registration of the second three-dimensional representation comprising a three-dimensional surface registration of this said second three-dimensional representation, by the computing unit, on the basis of the recording of the locations of surface points carried out for the surface registration of the first three-dimensional representation;
wherein the locations of the plurality of surface points other than the reference points on the surface of the object are recorded in the three-dimensional reference frame linked to the referencing ancillary using the tip of the stylus; and
wherein the display can be switched between a plurality of planar cross-sectional reconstructions of the object according to the first three-dimensional representation, a plurality of planar cross-sectional reconstructions of the object according to the second three-dimensional representation and a plurality of planar cross-sectional reconstructions of the object according to the first and second three-dimensional representations, said switching being activatable by a predetermined approach between the functional end of the instrument and a calibration pin of the referencing ancillary.
2 . The method for three-dimensional registering according to claim 1 , wherein the three-dimensional registration of the second three-dimensional representation comprises a three-dimensional angular registration, by the computing unit, of said second three-dimensional representation on the object from the recording, made for the three-dimensional angular registration of the first three-dimensional representation, of the locations of the reference points of the surface of the object in the three-dimensional reference frame linked to the referencing ancillary.
3 . The method for three-dimensional registering according to claim 1 , wherein:
the three-dimensional surface registration of the first three-dimensional representation on the object involves computing a first transition matrix between the locations of the recorded surface points and their locations on the surface of the object as extracted in the first three-dimensional representation; and
the three-dimensional surface registration of the second three-dimensional representation comprises an extraction of a surface of the object in the second three-dimensional representation and computing a second transition matrix between the locations of the surface points recorded for the surface registration of the first three-dimensional representation and their locations on the surface of the object as extracted in the second three-dimensional representation.
4 . The method for three-dimensional registering according to claim 1 , wherein the three-dimensional surface registration of the first three-dimensional representation on the object comprises recording the locations of several hundred surface points other than the reference points on the surface of the object in the three-dimensional reference frame linked to the referencing ancillary.
5 . The method for three-dimensional registering according to claim 4 , wherein the several hundred surface points comprise between 200 and 1000 surface points.
6 . The method for three-dimensional registering according to claim 5 , wherein the several hundred surface points comprise between 500 and 600 surface points.
7 . The method for three-dimensional registering according to claim 1 , comprising a prior acquisition:
of the first three-dimensional representation in the form of a volume image of the object by scanner or CT scan; and
of the second three-dimensional representation in the form of a volume image of the object by magnetic resonance.
8 . The method for three-dimensional registering according to claim 1 , wherein the object is a human or animal patient's head and the referencing ancillary is a device fixed to said head with a stability capable of inducing a submillimeter registration error.
9 . The method for three-dimensional registering according to claim 8 , wherein the reference points of the patient's head are non-aligned, comprising at least one nasion localization point, one naso-labial junction localization point and one external orbital rim localization point when the referencing ancillary is stably fixed to the patient's forehead.
10 . The method for three-dimensional registering according to claim 8 , wherein the device is a forehead band fixed stably to the patient's forehead.
11 . The method for three-dimensional registering according to claim 8 , wherein the device is a forehead pin fixed stably to the patient's forehead.
12 . The method for three-dimensional registering according to claim 8 , wherein the device is a buccal device clamped in the patient's mouth between their teeth.
13 . A non-transitory computer-readable medium, comprising instructions for executing the steps of a method for three-dimensional registering three-dimensional representations of an object on the object itself according to claim 1 , when said instructions are executed by a computing unit of a device for navigation assistance in the object, and when said device further comprises:
a memory for storing a first three-dimensional representation of the object according to a first three-dimensional imaging mode, locations of at least three reference points of the object in said first three-dimensional representation, a second three-dimensional representation of the object according to a second three-dimensional imaging mode other than the first three-dimensional imaging mode, and locations of the reference points of the object in said second three-dimensional representation;
a referencing ancillary designed to be attached to the object;
a stylus, manipulable by an operator, a tip of which can be located in a three-dimensional reference frame linked to the referencing ancillary;
an instrument, a functional end of which can be located in the three-dimensional reference frame linked to the referencing ancillary; and
a screen for simultaneous display of several planar cross-sectional reconstructions of the object, including at least two planar reconstructions of the same cross-section of the object obtained respectively from one and the other of the first and second three-dimensional representations.
14 . A device for navigation assistance in an object, comprising:
a memory for storing a first three-dimensional representation of the object according to a first three-dimensional imaging mode, locations of at least three reference points of the object in said first three-dimensional representation, a second three-dimensional representation of the object according to a second three-dimensional imaging mode other than the first three-dimensional imaging mode, and locations of the reference points of the object in said second three-dimensional representation;
a computing unit designed for three-dimensional registration of said first and second three-dimensional representations of the object on the object itself;
a referencing ancillary for attachment to the object;
a stylus, a tip of which can be located in a three-dimensional reference frame linked to the referencing ancillary;
an instrument, a functional end of which can be located in the three-dimensional reference frame linked to the referencing ancillary; and
a screen for simultaneous display of several planar cross-sectional reconstructions of the object, including at least two planar reconstructions of the same cross-section of the object obtained respectively from one and the other of the first and second three-dimensional representations;
wherein the computing unit is more precisely designed to perform:
a three-dimensional angular registration of the first three-dimensional representation on the object based on a recording, by interaction with the tip of the stylus when manipulated by an operator, of the locations of the object's reference points in the three-dimensional reference frame linked to the referencing ancillary;
a three-dimensional surface registration of the first three-dimensional representation on the object, comprising:
extracting a surface of the object in the first three-dimensional representation,
recording the locations of a plurality of surface points other than the reference points on the surface of the object in the three-dimensional reference frame linked to the referencing ancillary, and
computing the three-dimensional surface registration from this said surface point location recording;
the computing unit being designed so that the three-dimensional registration of the second three-dimensional representation comprises a three-dimensional surface registration of said second three-dimensional representation on the basis of the registration of locations of surface points carried out for the surface registration of the first three-dimensional representation;
wherein the recording of the locations of the plurality of surface points other than the reference points on the surface of the object in the three-dimensional reference frame linked to the referencing ancillary takes place by interaction using the tip of the stylus when it is manipulated by an operator; and
wherein the computing unit is designed to switch the display between a plurality of planar cross-sectional reconstructions of the object according to the first three-dimensional representation, a plurality of planar cross-sectional reconstructions of the object according to the second three-dimensional representation and a plurality of planar cross-sectional reconstructions of the object according to the first and second three-dimensional representations, said switching being activated by a predetermined approach between the functional end of the instrument and a calibration pin of the referencing ancillary.
15 . The device for navigation assistance in an object according to claim 14 , wherein the computing unit is further designed to locate and visually display the functional end of the instrument in each planar cross-sectional reconstruction of the object displayed by the screen.