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7 Serious Game for Laparoscopic Suturing Training

The aim of the developed serious game is to teach to surgeons the laparoscopic suture technique in minimally invasive surgery. An assessment module in the game were also provided to evaluate surgeon performance during the training phase.

To execute the surgical procedure two clamps are provided in the virtual environment. They are controlled by two haptic interfaces and should be used in order to pick the needle and execute the suture like in the real world.

After playing the serious game simulation the user should:

• acquire a good eye-hand coordination, that is very important in laparoscopic surgery;

• improve the ability to manipulate the surgical instruments;

• learn the techniques for performing the suture node.

Table 1. Parameters used to assess the player's performance

Parameter

Description

Duration time

It is the time elapsed between the first contact of the needle with the tissue and the completion of the node. Less time the surgeon spends to complete the procedure and greater is the evaluated skill.

Accuracy error

This parameter describes the maximum distance between the ideal point (indicated by a marker) and the real point of entry of the needle into the tissue. Smaller is the error and higher is the quality of the node.

Force peak

This number is the value of the maximum force used during the simulation in order to pierce the tissue by means of the needle.

Tissue damage

This value represents the sum of the forces applied to the tissue over the threshold of breakage of the tissue.

Angle of entry

This parameter is the difference between the normal to the surface and the tangent at the point of the needle entry.

Overall score

This parameter is determined by the average of all previous specified parameters.

Needle total distance

This value represents the total distance traveled from the needle in order to complete the task. Shorter is this distance and greater is evaluated the skill of the surgeon. Anyway this parameter is not included in the calculation of the quality assessment of the suture task.

Before developing the serious game some requirements were defined. These guided the entire development process and are:

• Simulation: the system should simulate as much as possible the real appearance and behavior of a real human tissue and suture thread;

• Configuration: the size of the tissue, the number of elements of the thread, the number and position of the fiducial points on the tissue and the time duration of the simulation must be specified before starting the simulation. These parameters are all stored in an XML configuration file;

• Haptic device surgical forceps interaction: the user must to be able to move the virtual surgical forceps by means of the haptic device;

• Skill evaluation: the game must implement algorithms for measuring the skill

of the user during the execution of the surgical procedure.

In the assessment of a suturing procedure it is necessary to consider some parameters that should be evaluated. These parameters are not extracted from the medical literature, which does not specify any quantitative metrics for evaluating the performance of this task, but were expressly defined for this serious game.

Some numerical indicators can be achieved by the physically-based virtual simulation. The Table 1 summarize the parameters used to assess the player's performance.

The software architecture of the serious game has been developed using the architectural pattern Model-View-Controller (MVC), whose use is not limited to the development of web applications, but also to virtual simulators [23].

The model manages the behavior and objects of the virtual environment, responds to requests for information about its state and responds to instructions to change state (Fig.4).

Fig. 4. Model-View-Controller pattern representation

The view renders the model into a form suitable for interaction and is managed by OGRE 3D graphical engine.

The controller accepts input from the user and instructs the model to perform actions based on that input. There are two subcontrollers:

• The controller of the physical simulation that applies the laws of the physics to the elements of the model (by changing the position, velocity and acceleration of the objects) and handles the collision detection between objects in the scene. This controller is implemented by the PhysX library.

• The controller of the haptic simulation that allows the communication between the model and the haptic device. This controller returns the forces, but is not responsible for the calculation of these that are computed by the controller of the physical simulation.

In Fig. 5 is shown the monitor of a pc with the serious game interface loaded and the two Novint Falcon haptic devices.

Fig. 5. The serious game using two Novint Falcon haptic devices

 
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