Workflow based Slicer IGT Module : Tutorial

Andinet Enquobahrie, PhDKitware Inc

December, 2008

Purpose of the module

• Provide a generic workflow based wizard to be used as a framework for IGT applications development.

• Identify the major steps in IGT procedure and translate these steps into wizard interfaces.

Download and Build Instructions

1. Download the module source code – http://www.na-mic.org/Wiki/index.php/Image:SlicerIGTModule.tgz

2. Specify your Slicer3 build directory during CMake configuration

3. Build the module

If you have successfully build the module, then in the module subdirectory of your build, you should get a shared library for SlicerIGT module ( "IGT.dll" for windows or "libIGT.so" for Unix build.

How to load SlicerIGTModule to Slicer

1. Start slicer2. Click on "Application Settings" in View menu and then click

on "Module settings" 3. Add the path to your SlicerIGTModule plugin4. Restart slicer and verify “Image Guided Therapy Module”

exists in the modules list

Load required Data for the IGT application

• Three types of data can be loaded 1. Preoperative Image Data2. Model Data for Surgical Tools3. Calibration Data

Preoperative Image Data – Using Volumes Module

Use Fiducials Module – Generate fiducials image coordinates for registration

SlicerIGT Module Interface

Interface Design

• Five major steps1. Initialization2. Loading preoperative data3. Calibration4. Registration5. Intrapoperative procedure

• Designed using KWWidgets wizard

Step 1/5 Initialization

Initialization step includes establishing communication with• Navigation system and/or tracking device• Endoscope• External tracking software

– For example, setup communication with IGSTK using OpenIGT link

• Robot control computer if a robot is used in the surgical procedure.

Initialization Interface

Step 2/5 Loading Preoperative Data

Preoperative data includes• Images ( such as CT, MRI data )• Models • Surgical planning ( developed preoperatively )

Preoperative Data Loading Interface

Select Image Data loaded using Volumes Module

Step 3/5 Calibration

• This step includes– Calibration of camera (Endoscope) and probe– Calibration of tracker tools

• For example, Pivot calibrations

– Calibration of robot tools

• Two options are available– Load precomputed calibration data– Run calibration algorithm

Calibration Interface

Step 4/5 Registration

In this step, transformations between different coordinate systems are established• Register preoperative image with the

navigation system’s reference frame ( i.e. Patient-Image registration )

• If robot is available, register robot coordinate system with the navigation system reference frame.

Registration Interface

Select fiducial coordinates from the list of fiducials marked in Fiducals module

Step 5/5 Intraoperative procedure

During the procedure– Start Tracking – If robot is available, transmit commands to robot

to get it to the right mode– Gather pose information of tracker/surgical tools

and update the display

Intraoperative Procedure Interface

Summary

• Workflow based design streamlines application development

• IGT application developers fill in the SlicerIGT module steps with implementations specific to their application