Pavan Gamage

Diagnostic radiograph based 3D bone reconstruction framework: Application to the femur

Three dimensional (3D) visualization of anatomy plays an important role in image guided orthopedic surgery and ultimately motivates minimally invasive procedures. However, direct 3D imaging modalities such as Computed Tomography (CT) are restricted to a minority of complex orthopedic procedures. Thus the diagnostics and planning of many interventions still rely on two dimensional (2D) radiographic images, where the surgeon has to mentally visualize the anatomy of interest. The purpose of this paper is to apply and validate a bi-planar 3D reconstruction methodology driven by prominent bony anatomy edges and contours identified on orthogonal radiographs. The results obtained through the proposed methodology are benchmarked against 3D CT scan data to assess the accuracy of reconstruction. The human femur has been used as the anatomy of interest throughout the paper. The novelty of this methodology is that it not only involves the outer contours of the bony anatomy in the reconstruction but also several key interior edges identifiable on radiographic images. Hence, this framework is not simply limited to long bones, but is generally applicable to a multitude of other bony anatomies as illustrated in the results section.

Intra-operative 3D pose estimation of fractured bone segments for image guided orthopedic surgery

The widespread adoption of minimally invasive surgical techniques have driven the need for 3D intra-operative image guidance. Hence the 3D pose estimation (position and orientation) performed through the registration of pre-operatively prepared 3D anatomical data to intra-operative 2D fluoroscopy images is one of the main research areas of image guided orthopedic surgery. The goal of this 2D-3D registration is to fuse highly detailed 3D information with the 2D images acquired intra-operatively to provide a real-time 3D visualization of the patients anatomy during surgery. Existing research work on fractured bone pose estimation focuses on tracking pre-operatively obtained 3D CT data through fiduciary markers implanted intra-operatively. This expensive and invasive approach is not routinely available for diagnostics, and a majority of fracture reduction procedures solely relies on xray/fluoroscopic images. The proposed concept eliminates the need to have the pre-operative CT scan of the patients injured anatomy and presents a non-invasive anatomy-based method for intra-operative pose estimation. The concept pre-operatively reconstructs a patient-specific fractured bone model utilizing two conventional x-ray images orthogonally (in anterior and lateral views) and a generic healthy 3D anatomical model. This pre-operatively reconstructed 3D model will then be utilized intra-operatively in the novel 2D–3D registration process for pose estimation. It is this registration process that is the focus of this paper. The registration is performed solely utilizing bony anatomical features extracted from fluoroscopic images without invasiveness external fiducial markers.

3D Reconstruction of Patient Specific Bone Models from 2D Radiographs for Image Guided Orthopedic Surgery

Three dimensional (3D) visualization of anatomy plays an important role in image guided orthopedic surgery and ultimately motivates minimally invasive procedures. However, direct 3D imaging modalities such as Computed Tomography (CT) are restricted to a minority of complex orthopedic procedures. Thus the diagnostics and planning of many interventions still rely on two dimensional (2D) radiographic images, where the surgeon has to mentally visualize the anatomy of interest. The purpose of this paper is to apply and validate a bi-planar 3D reconstruction methodology driven by prominent bony anatomy edges and contours identified on orthogonal radiographs. The results obtained through the proposed methodology are benchmarked against 3D CT scan data to assess the accuracy of reconstruction. The human femur has been used as the anatomy of interest throughout the paper. The novelty of this methodology is that it not only involves the outer contours of the bony anatomy in the reconstruction but also several key interior edges identifiable on radiographic images. Hence, this framework is not simply limited to long bones, but is generally applicable to a multitude of other bony anatomies as illustrated in the results section.

A real time vision system for defect inspection in a cast extrusion manufacturing process

The cast extrusion manufacturing process is the initial step which enables the creation of the raw materials, such as clear polypropylene film, needed for the flexible packaging manufacturing process. The current methodology of controlling extrusion related defect occurrences is attempted by a combination of statistical sampling and human inspection. However, the defects are small in size and hard to visualise in a clear thin film 3 m in width moving at a speed of 50 m/min. This resulted in poor product quality and high return ratio from customers. To the best of our knowledge, there is no system available that can automatically and accurately detect such defects. This research investigates possible defect detection methodologies and has subsequently proposed a system that is capable of real time monitoring of defects on the cast extrusion manufacturing process.

Pose estimation of femur fracture segments for image guided orthopedic surgery

The widespread adoption of minimally invasive surgical techniques has driven the need for three dimensional (3D) intra-operative image guidance. Hence the pose estimation (position and orientation) performed through the registration of pre-operatively prepared 3D anatomical data to intra-operative two dimensional (2D) fluoroscopy images is one of the main research areas of image guided orthopedic surgery. This paper proposes a non-invasive anatomy-based method for intraoperative pose estimation. The registration is performed solely utilizing bony anatomical features extracted from bi-planar fluoroscopic images (frontal and lateral) without invasive external fiducial markers. The novelty of the proposed methodology is involved in the anatomical features utilized, which are unproblematic and robust to extract and facilitate near real-time pose estimation.

3D pose estimation of femur fracture segments for vision guided robotic orthopaedic surgery

The widespread adoption of minimally invasive surgical techniques has driven the need for three dimensional (3D) intra-operative image guidance. Hence the pose estimation (position and orientation) performed through the registration of pre-operatively prepared 3D anatomical data to intra-operative two dimensional (2D) fluoroscopic images is one of the main research areas of image guided orthopaedic surgery. This paper proposes a non-invasive anatomy-based method for intra-operative pose estimation. The registration is performed solely utilising bony anatomical features extracted from bi-planar fluoroscopic images (frontal and lateral) without invasive external fiducial markers. The novelty of the proposed methodology is involved in the anatomical features utilised, which are unproblematic and robust to extract and facilitate near real-time pose estimation. The results section highlights the implementation of the proposed methodology into a vision guided robotic fracture reduction phantom study.

Radiograph Based Patient-Specific Customization of a Generic Femur

Three dimensional (3D) visualization of anatomy plays an important role in image guided orthopedic surgery and ultimately motivates minimally invasive procedures. However, direct 3D imaging modalities such as computed tomography (CT) are restricted to a minority of complex orthopedic procedures. Thus the diagnostics and planning of many interventions still rely on two dimensional (2D) radiographic images, where the surgeon has to mentally visualizing the anatomy of interest. Therefore, a crucial enhancement to the current orthopedic imaging practice would be to facilitate pre and intra-operatively 3D visualization by providing a compelling alternative to direct 3D imaging modalities. This paper presents a new concept for the pre-operative reconstruction of intact 3D bony anatomy and is proposed as a substitute to CT scanning for certain procedures. The human femur has been used as the anatomy of interest throughout the paper. The proposed methodology is based on two conventional orthogonal (anterior and lateral) 2D radiographic images and a supporting database of 3D intact anatomical surface models. Firstly, a search over the database finds the closest match to the patients bone. The best matched healthy bone is then customized through a non-rigid registration to match the shape of the patient-specific anatomy. It is this shape customization that is the focus of the paper. This process is used as the precursor to reconstruct a fractured bone model to be used intra-operatively for pose estimation (tracking).

Computer assisted 3D pre-operative planning tool for femur fracture orthopedic surgery

Femur shaft fractures are caused by high impact injuries and can affect gait functionality if not treated correctly. Until recently, the pre-operative planning for femur fractures has relied on two-dimensional (2D) radiographs, light boxes, tracing paper, and transparent bone templates. The recent availability of digital radiographic equipment has to some extent improved the workflow for preoperative planning. Nevertheless, imaging is still in 2D X-rays and planning/simulation tools to support fragment manipulation and implant selection are still not available. Direct three-dimensional (3D) imaging modalities such as Computed Tomography (CT) are also still restricted to a minority of complex orthopedic procedures. This paper proposes a software tool which allows orthopedic surgeons to visualize, diagnose, plan and simulate femur shaft fracture reduction procedures in 3D. The tool utilizes frontal and lateral 2D radiographs to model the fracture surface, separate a generic bone into the two fractured fragments, identify the pose of each fragment, and automatically customize the shape of the bone. The use of 3D imaging allows full spatial inspection of the fracture providing different views through the manipulation of the interactively reconstructed 3D model, and ultimately better pre-operative planning.

Diagnostic radiograph based 3D bone reconstruction framework: application to osteotomy surgical planning

Pre-operative planning in orthopedic surgery is essential to identify the optimal surgical considerations for each patient-specific case. The planning for osteotomy is presently conducted through two-dimensional (2D) radiographs, where the surgeon has to mentally visualize the bone deformity. This is due to direct three-dimensional (3D) imaging modalities such as Computed Tomography (CT) still being restricted to a minority of complex orthopedic procedures. This paper presents a novel 3D bone reconstruct technique, through bi-planar 2D radiographic images. The reconstruction will be pertinent to osteotomy surgical diagnostics and planning. The framework utilizes a generic 3D model of the bone of interest to obtain the anatomical topology information. A 2D non-rigid registration is performed between the projected contours of this generic 3D model and extracted edges of the X-ray image to identify the planar customization required. Subsequently a free-form deformation based manipulation is conducted to customize the overall 3D bone shape.

Patient-Specific Customization of a Generic Femur Model Using Orthogonal 2D Radiographs

Visualization of the patient-specific fractured bone in three dimensions (3D) plays an important role in image guided orthopedic surgery. Existing research often focuses on intra-operative registration of the patientspsila anatomy with pre-operatively obtained 3D volumetric data (e.g. CT scans) utilizing fiduciary markers. This expensive and invasive approach is not routinely available for diagnostics, and a majority of fracture reduction procedures currently solely relies on two dimensional (2D) x-ray/fluoroscopic images. This paper presents a new concept for the construction of a 3D model of a fractured human femur that eliminates the need to have the preoperative CT scan of the patientpsilas injured anatomy. It is based on two conventional orthogonal (in anterior and lateral views) 2D radiographic images and a supporting database of 3D intact (healthy) femurs. A search over the database initially finds the closest match to the patientpsilas femur. This best match is then customized through a non-rigid registration to the shape of the patientpsilas femur. Once the customization is complete a novel 2D-3D registration process separates the bone into the proximal and distal segments and identifies the pose (position and orientation) of each fragment.