A kind of pedicle of vertebral arch internal fixation operation navigation system based on structured light scanningTechnical field
The present invention relates to a kind of computer assisted navigation system for pedicle of vertebral arch internal fixation operation, especially a kind of pedicle of vertebral arch internal fixation operation navigation system based on structured light scanning.
Background technology
Pedicle of vertebral arch internal fixation operation is a kind of standardization routine operation for the treatment of breast lumbar segment spinal fracture, and this operation carrys out stabilizing spine by implanting pedicle screw, can be used for treating the diseases such as lumbar spondylolisthesis, lumbar vertebra compression fracture.Because spinal cord and nervous system that pedicle of vertebral arch is contiguous are often invisible in operation, this class surgical risk is large, and difficulty is high.Clinical research shows, the screw deviation ratio of traditional pedicle of vertebral arch internal fixation operation is 28 ~ 40%, is the main reason that causes operative failure and post-operative complication.
CAOS (Computer Aided Orthopedic Surgery, also claim CAOS) be (as CT at medical image, MRI, X-ray or three-D ultrasonic etc.) guiding under, utilize navigator to follow the tracks of the position of operating theater instruments, operating theater instruments and operative site are merged mutually, and be presented in real time on computer screen, thereby increase the visuality of above-mentioned operation, help doctor to avoid important organ and tissue, improve operation precision, reduce the operation method of wound in art, also referred to as computer aided orthopedics navigating surgery.Image data in, art preoperative according to whether adopting, current airmanship can be divided into based on image and the non-navigation system based on image.
According to the difference of used image kind, be divided into again based on CT image and based on two kinds of C type arm fluoroscopy images.Take spinal operation as example, and the navigating surgery step based on CT image is: preoperative collection patient's vertebrae and implant the CT image data of navigation label, and its importing is equipped with to the computer of surgical navigational software, and rebuild vertebrae threedimensional model, carry out surgery planning; In art, reference frame is installed and light sensation is accepted positioner; With the contrast of preoperative implantation navigation label, obtain the relative position in CT image, carry out surgical navigational.This preoperative implantation navigation label has caused great misery to patient.X-ray examination navigation is directly to pass through optical positioning system and C shape arm machine imaging system in art, shows in real time the spatial relation between the dissection of x-ray image, operation tool, C shape arm machine.This method is used comparatively extensive, but in art, has a large amount of rays, and navigation is based on bidimensional image, even if use three Vc shape arm X-ray machines instead, its definition and precision be also all not as CT image, and need special-purpose saturating x-ray operation table.
Non-image dependency navigation system is suitable for anatomical structure and exposes operation fully, only need operative doctor in art, to use with the probe of infrared markers point and give me a little the characteristic point (being called " registration ") of getting anatomical structure, utilize kinesiology or anatomic marker, obtain three-dimensional multiple spot calibration, the various standard anatomical documentation Auto-generation Models that computer utilization is collected, thus determine the mutual alignment between probe and model; Dynamic benchmark is installed, to suffering from the change in location of bone in operation, is dynamically adjusted; Use is carried out navigating surgery with the operating theater instruments of infrared markers thing.In surgical navigational process, need the omnidistance infrared navigation instrument that uses by the infrared markers object location signal of following the tracks of in probe, dynamic benchmark and operating theater instruments.The operation guiding system of initiatively inducing as infrared in representative Stryker company, clinical operation Shi doctor, need manually get a little, by navigation system software, carry out a registration again, doctor is generally reflected while utilizing this system to carry out a some registration, affected by doctors experience, operate miss and some method for registering, registration accuracy is unsatisfactory, and doctor need repeatedly manually get and puts and carry out a registration.Navigation probe also can bump with dynamic benchmark sometimes, has so just changed registration relation, need re-start a registration, has extended operating time.
For solving the series of problems such as precision reduction that manually getting a little of existing in above-mentioned navigating surgery method and some registration cause, operating time lengthening, second operation, RADI, the applicant has applied for " in the pedicle of vertebral arch based on structure light image fixedly navigating surgery system and method " (publication number: CN 101862220A), this system has increased structured light scanner on aforementioned operation guiding system basis on April 15th, 2009.When work, first obtain preoperative trouble bone CT image, through three-dimensional reconstruction, obtain suffering from accordingly bone CT threedimensional model, in art, first adopt structured light scanner to scan suffering from bone, get the structural light three-dimensional image of suffering from bone place, this structural light three-dimensional image and trouble bone CT threedimensional model are carried out to surface adjustment, then in the presence of infrared navigation position finder, carry out subsequent procedures operation.Compare traditional infrared navigation system, this operation piloting method has avoided doctor manually to get point operation in the registration stage, and uses point set registration, and precision improves a lot, and doctor is simple to operate, saves operating time.
But adopt above-mentioned operation guiding system to still have weak point: after registration completes, for following the tracks of the position of dynamic benchmark and operating theater instruments, still need infrared navigation position finder to participate in, the positional information that obtains there is positional information exchange and the calibration problem with structured light scanner, cause whole system complexity to increase, cost increases, and has reduced the probability of system stability work.
Summary of the invention
The object of the invention is to propose a kind of novel pedicle of vertebral arch internal fixation operation navigation system based on structured light scanning, make it without infrared navigation position finder, participate in and not affect under the prerequisite of surgical effect, reduce to greatest extent complexity and the cost of system, and improve the stability of system.
Technical scheme of the present invention is as follows:
A pedicle of vertebral arch internal fixation operation navigation system based on structured light scanning, is characterized in that: this system comprises structured light scanner, dynamic benchmark and operating theater instruments, and the computer of the trouble bone CT threedimensional model that contains surgical navigational software and preoperative CT scan; Described structured light scanner comprises video camera and a projection grating of installing placed in the middle of two symmetrical installations, and two video cameras are connected with described computer by data wire respectively with projection grating; Described dynamic benchmark is fixed on suffers from bone place, the structural light three-dimensional image at bone place is suffered from structured light scanner collection, at least 3 not visible ray signs of conllinear are housed on dynamic benchmark, by the video camera in structured light scanner, caught, determine that the visible ray on dynamic benchmark is identified at the initial homogeneous coordinates under structure light image coordinate system; At least 3 not visible ray signs of conllinear are housed equally in described operating theater instruments, start by the video camera in structured light scanner, to be caught after surgical navigational, determine that the visible ray in operating theater instruments is identified at the initial homogeneous coordinates under structure light image coordinate system;
Surgical navigational starts after front and beginning, and described dynamic benchmark, the homogeneous coordinates of operating theater instruments under structure light image coordinate system meet following relation:
Wherein:
for the visible ray in operating theater instruments is identified at the initial homogeneous coordinates under structure light image coordinate system,
for the visible ray on dynamic benchmark is identified at the initial homogeneous coordinates under structure light image coordinate system,
for the visible ray in operating theater instruments after beginning surgical navigational is identified at the homogeneous coordinates under structure light image coordinate system,
for the visible ray on dynamic benchmark after beginning surgical navigational is identified at the homogeneous coordinates under structure light image coordinate system,
The structural light three-dimensional image at the trouble bone place that structured light scanner collects and described trouble bone CT threedimensional model carry out surface adjustment, obtain being tied to from structure light image coordinate the coordinate conversion matrix of CT image coordinate system, are designated asmeet following relation:
Wherein: Vcfor the visible ray on dynamic benchmark is identified at the homogeneous coordinates in CT image coordinate system,
Vsfor the visible ray on dynamic benchmark is identified at the homogeneous coordinates in structure light image coordinate system,
The position that visible ray after beginning surgical navigational in operating theater instruments is identified at CT image coordinate system is:
Wherein:for the visible ray in operating theater instruments after beginning surgical navigational is identified at the homogeneous coordinates in CT image coordinate system.
Technical characterictic of the present invention is also: the homogeneous coordinates between the visible ray sign in operating theater instruments distal point and operating theater instruments are designated asoperating theater instruments distal point in the position of CT image coordinate system is:
Wherein:for the homogeneous coordinates of operating theater instruments distal point in CT image coordinate system.
Visible ray on described dynamic benchmark is designated the bead that surface is covered by fluorescent material, and diameter is 3～5mm; Or the black of diameter 6～10mm is circular, centre is covered by the high bright silver circular shape concentric of diameter 3～5mm.Visible ray in described operating theater instruments is designated the bead that surface is covered by fluorescent material, and diameter is 3～5mm; Or the black of diameter 6～10mm is circular, centre is covered by the high bright silver circular shape concentric of diameter 3～5mm.
The present invention compared with prior art, has the following advantages and salience effect:
Compare operation guiding system in the past, operation guiding system of the present invention does not need additionally to adopt infrared navigation position finder to carry out real-time tracking, effectively reduced complexity, equipment cost and the space requirement to operating room of system, raising equipment is in the suitability of operating room.In art, scanning registration and real-time tracking all adopts structured light scanner to complete, visible ray sign in dynamic benchmark and operating theater instruments is carried out to real-time tracking, eliminated and introduced the coordinate conversion error that infrared navigation position finder brings, made location more accurate, improved the reliability of navigating surgery.
Accompanying drawing explanation
Fig. 1 is the pedicle of vertebral arch internal fixation operation navigation system structural principle schematic diagram based on structured light scanning of the present invention.
Fig. 2 is the structural representation of structured light scanner in the pedicle of vertebral arch internal fixation operation navigation system based on structured light scanning of the present invention.
Fig. 3 is the scaling board schematic diagram of demarcating for structured light scanner in the pedicle of vertebral arch internal fixation operation navigation system based on structured light scanning of the present invention.
Fig. 4 is the fundamental diagram of structured light scanner in the pedicle of vertebral arch internal fixation operation navigation system based on structured light scanning of the present invention.
Fig. 5 is the pedicle of vertebral arch internal fixation operation navigation system workflow diagram based on structured light scanning of the present invention.
Wherein: 1-structured light scanner; 2-dynamic benchmark; 3-operating theater instruments; 4-is equipped with the computer of surgical navigational software; 5-operating-table; 6-patient; 7-operating room; 8-projection grating; 9-the first video camera; 10-the second video camera; 11-mounting bracket; 12-data wire; 13-scaling board; 14-suffers from bone.
The specific embodiment
Below in conjunction with accompanying drawing, principle of the present invention, structure and embodiment are further described.
Fig. 1 is the pedicle of vertebral arch internal fixation operation navigation system structural principle schematic diagram based on structured light scanning of the present invention, this operation guiding system comprises: structured light scanner 1, dynamic benchmark 2 and operating theater instruments 3, and the computer 4 that the trouble bone CT threedimensional model that contains surgical navigational software and preoperative CT scan is housed.In operating room 7, have operating-table 5, patient 6 is positioned on operating-table.
Because patient's pose in art can change at any time, patient, to suffer from bone and clamp a dynamic benchmark 2, dynamic benchmark adopts normally used structure in prior art, and for example adopting publication number is the dynamic benchmark using in CN 101862220A.At least 3 not visible ray signs of conllinear are housed on dynamic benchmark 2, visible ray sign selects the material that reflectance is large to make, and generally has two types: 1) bright colored bead, and spherome surface is covered by fluorescent material, can be caught by high accuracy video camera, diameter is 3～5mm; 2) black of diameter 6～10mm is circular, and centre is that the high bright silver of diameter 3～5mm is circular.Visible ray sign on dynamic benchmark is caught by structured light scanner 1, to determine that the visible ray on dynamic benchmark is identified at the initial homogeneous coordinates under structure light image coordinate system
Fig. 2 is the structural representation of structured light scanner in the pedicle of vertebral arch internal fixation operation navigation system based on structured light scanning of the present invention, this structured light scanner comprises video camera (the first video camera 9 and the second video camera 10) and a projection grating 8 of installing placed in the middle of two symmetrical installations, described two video cameras and projection grating are fixed on mounting bracket 11, two video cameras are connected with described computer 4 by data wire respectively with projection grating, and wherein two video cameras can form a simple binocular vision system.
Use described in the present invention and first will demarcate respectively the first video camera 9 comprising and the second video camera 10 before structured light scanner 1, obtain inner parameter separately, then combine the external parameter of two video cameras, obtain the two spatial relation.In the present invention, the demarcation of video camera is adopted to method---Tsai two-step method ripe in machine vision.Demarcation to camera interior and exterior parameter, need be undertaken by scaling board, use has the scaling board of square-outside and round-inside gauge point, be illustrated in figure 3 the scaling board schematic diagram of demarcating for structured light scanner in the pedicle of vertebral arch internal fixation operation navigation system based on structured light scanning of the present invention, on scaling board 13 with 4 index points that have outer circle, these 4 index point distribution or asymmetrical distribution.
Fig. 4 is the fundamental diagram of structured light scanner 1 in the pedicle of vertebral arch internal fixation operation navigation system based on structured light scanning of the present invention.The projection grating 8 of installing placed in the middle initiatively projects the structure fringe (being called structured light) with certain specific character and suffers from bone 14 surfaces, the structure fringe of rule is subject to suffering from the modulation of bone 14 apparent heights and deforms, two video cameras absorb the reflected image of suffering from bone place simultaneously, the three-dimensional appearance data of suffering from bone surface in this image, have been comprised, so just can be by Xie Xianghe the phase demodulation method based on structure light coding obtain the phase place of modulated grating, thereby the correspondence problem that solves structure fringe and suffer from spatial point on bone place this two width image of reflected image, and the triangle by two video cameras crosses and obtains suffering from the three-dimensional coordinate information of bone surface.
The structure fringe of the structured light scanner projection adopting in the present invention carries out according to time order and function order, comprises several structure fringe images, projection process approximately 20 seconds.By separating phase and phase expansion process, can obtain respectively phase main value and the phase cycle information of structure fringe, stack phase main value and phase cycle get final product to such an extent that suffer from the absolute phase information of grating after surperficial each point deformation of bone 14, again in conjunction with outer polar curve geometrical principle, mate the point on the structure fringe image of two video cameras projection, inside and outside parameter and the spatial relation of two video cameras that the imagery exploitation after coupling has been calibrated, calculate the three-dimensional coordinate of suffering from bone surface each point, thereby reconstruct the structural light three-dimensional image of suffering from bone surface.Separate in the present invention phase method based on to the insensitive multifrequency heterodyne system of surround lighting principle.
Often carry out primary structure photoscanning and can not completely obtain the structural light three-dimensional image of trouble bone surface to be measured, need to carry out various visual angles scanning, the structural light three-dimensional image joint preferably Multiple-Scan being obtained respectively forms an integral body, forms complete trouble bone surface structural light three-dimensional image.In carrying out structured light scanning process, owing to existing light to disturb in environment, as dynamic benchmark or to suffer from bone surface point reflection light excessively strong, can be thought by mistake be that visible ray on dynamic benchmark identifies by structured light scanner, therefore after having scanned, need to check structural light three-dimensional image, the data of identification error are deleted from structural light three-dimensional image.
In pedicle of vertebral arch internal fixation operation navigation system based on structured light scanning of the present invention, each ingredient is established coordinate system separately, and wherein structured light scanner 1 is established structure light image coordinate system; Dynamic benchmark 2 is fixed on trouble bone place and for being rigidly connected, represents patient coordinate system; Visible ray sign in operating theater instruments 3 is established operating theater instruments coordinate system, and any point coordinate on this coordinate system menisectomy apparatus is also constant; In computer 4, preserve and suffer from bone CT threedimensional model establishment CT image coordinate system (being also navigation picture coordinate system).Utilize computer to try to achieve the transformation relation between operating theater instruments coordinate system and CT image coordinate system, operating theater instruments distal point and the relative position of suffering from bone CT threedimensional model are shown on computers in real time.
The operating theater instruments 3 adopting in the present invention is common therapy apparatus, adheres at least 3 not visible ray signs of conllinear on it, and visible ray sign adopts same-type with the visible ray sign on dynamic benchmark; Visible ray sign in operating theater instruments is caught by structured light scanner 1, to determine that the visible ray in operating theater instruments is identified at the initial homogeneous coordinates under structure light image coordinate system
Operating theater instruments is demarcated, obtain operating theater instruments axis and the coordinate of operating theater instruments distal point under operating theater instruments coordinate system.In the present invention, the scaling method of operating theater instruments is: operating theater instruments is axially inserted in general calibration platform, adjust height and the operating theater instruments height of structured light scanner, make the visible ray sign in operating theater instruments be arranged in two camera coverages, keep calibrating table position motionless, rotary operation apparatus is to diverse location, by two video cameras, visible ray sign is gathered respectively, by image matching, draw the spatial axis of operating theater instruments; The distal point of operating theater instruments is demarcated and is demarcated similar with axis.
Fig. 5 is the pedicle of vertebral arch internal fixation operation navigation system workflow diagram based on structured light scanning of the present invention, is mainly divided into three steps:
The first step: preoperative patient is carried out to CT scan, obtain the CT view data that it suffers from bone, obtain suffering from bone CT three-dimensional modeling data through CT three-dimensional reconstruction.
In the present invention, the concrete grammar of CT three-dimensional reconstruction is: the CT image of DICOM form is imported to the computer 4 that surgical navigational software is housed, set based on experience value gray threshold, for vertebrae, gray threshold is set as 190 ~ 210, according to the method for contour surface, isolate skeleton and soft tissue, reconstruction obtains suffering from bone CT threedimensional model, is kept in the computer that surgical navigational software is housed, and shows.Doctor can determine according to the form of this trouble bone CT threedimensional model showing in computer position and the angle of operation technique, complete preoperative planning---according to the position of the definite implantation of patient's situation pedicle nail, the degree of depth, angle etc., and the enterprising row labels of trouble bone CT threedimensional model showing on computers, to carry out reference in art, now also can on trouble bone CT threedimensional model, draw a circle to approve the region of carrying out surface adjustment with structure light image, generally get spinous process and near bone surface thereof.
Second step: be furnished with operation guiding system of the present invention in operating room, first enter scan pattern after this structured light scanner and operating theater instruments initial alignment are completed.Doctor separates and is preoperatively suffering from selected trouble bony site on bone CT threedimensional model, fixed placement dynamic benchmark 2, and all visible rays on dynamic benchmark 2 are identified to two video cameras in structured light scanner, then utilize trouble bone and the dynamic benchmark 2 that 1 pair of structured light scanner exposes to scan, the structural light three-dimensional image that shows trouble bony site on the computer 4 of surgical navigational software is being housed, visible ray sign on dynamic benchmark 2 also can be caught by structured light scanner 1, be simultaneously displayed in the structural light three-dimensional image of suffering from bony site, as the initial reference position of suffering from bone.By the computer that surgical navigational software is housed, the some cloud of this two width image construction of structural light three-dimensional image in preoperative trouble bone CT threedimensional model and art is carried out to surface adjustment, calculate the respectively affiliated coordinate system of above-mentioned two width images---be the initial mapping relation of CT image coordinate system and structure light image coordinate system, obtain being tied to from structure light image coordinate the coordinate conversion matrix of CT image coordinate system
Position by the center of certain visible ray sign on dynamic benchmark in CT image coordinate system and structure light image coordinate system is denoted as respectively homogeneous coordinates Vcand Vs:
In the present invention, the surface adjustment method that trouble bone CT threedimensional model and structural light three-dimensional image adopt is: it is right that doctor chooses 3～5 points at the corresponding position (the corresponding bone same position of suffering from) of trouble bone CT threedimensional model and structural light three-dimensional image respectively, structural light three-dimensional image and trouble bone CT threedimensional model are carried out to just registration, and guarantee that the initial position of putting cloud on above-mentioned two width images differs not too large, obtain the preliminary spatial alternation matrix that structure light image coordinate is tied to CT image coordinate system, by closest approach iterative algorithm (ICP), carry out smart registration again, the mapping relations that calculate under above-mentioned two width image initial states (are coordinate conversion matrix).In registration process of the present invention, step-up error threshold value is 0.3mm, is limited to 100 times on iterations, and the smart registration time is no more than 3 seconds.
The 3rd step: after scan pattern finishes, enter tracing mode, start surgical navigational.Projection grating 8 on closing structure photoscanner 1, the visible ray sign of installing in technique of binocular stereoscopic vision real-time tracking dynamic benchmark 2 and operating theater instruments 3 for two video cameras of having demarcated still opening (the first video camera 9 and the second video camera 10).Because the visible ray in operating theater instruments 3 is identified at the relative position process demarcation in advance in operating theater instruments, therefore can be identified at by the visible ray in operating theater instruments the position in structure light image coordinate system, determine operating theater instruments coordinate system, and utilize coordinate transformation method to obtain the orientation of operating theater instruments 3 in CT image coordinate system.Like this, doctor just can see operating theater instruments distal point and the relative position of suffering from bone on the computer that surgical navigational software is housed, thereby performs a surgical operation.
The present invention is based on second step and the 3rd step in the pedicle of vertebral arch internal fixation operation navigation system workflow diagram of structured light scanning and all use two video cameras in structured light scanner, so the coordinate system of structure light image coordinate system and video camera is identical, avoided by infrared navigation position finder, being participated in following the tracks of and the Coordinate Conversion loss of significance of generation in homogeneous system.
The initial homogeneous coordinates that visible ray on dynamic benchmark is identified under structure light image coordinate system are denoted ashomogeneous coordinates after beginning surgical navigational under structure light image coordinate system are denoted asthe initial homogeneous coordinates that visible ray in operating theater instruments is identified under structure light image coordinate system are denoted asstart after surgical navigational, the homogeneous coordinates that the visible ray in operating theater instruments is identified under patient coordinate system (being determined by dynamic benchmark) are denoted ashomogeneous coordinates under structure light image coordinate system are denoted assurgical navigational starts after front and beginning, and described dynamic benchmark, the homogeneous coordinates of operating theater instruments under structure light image coordinate system meet following relation:
The position that visible ray after starting surgical navigational in operating theater instruments is identified at CT image coordinate system is:
Wherein:for the visible ray in operating theater instruments after beginning surgical navigational is identified at the homogeneous coordinates in CT image coordinate system.
Because operating theater instruments is in advance through demarcating, established operating theater instruments coordinate system.If the homogeneous coordinates between operating theater instruments distal point and a certain visible ray identification point arethe homogeneous coordinates of operating theater instruments distal point in CT image coordinate system are designated asmeet following relation:
By coordinate transformation relation, can determine that in operating theater instruments, any point is relatively suffered from the dynamic coordinate of bone CT threedimensional model and the axial location of operating theater instruments in CT image coordinate system, thereby realize surgical navigational.