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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_585_Библиотеки_им_академика_М_И_Перельмана.pdf
134
ab
S. Bao et al.
6.2 Virtual Surgical Instruments
Surgical simulation refers to the use of a variety of medical
image data and virtual reality technology to create a simulation environment on a computer. Surgeons use the information in the virtual environment to perform surgical planning
and training and to guide the actual operation. During the
virtual surgery process, the cutting tools and the surgical
instruments are needed for operation simulation, such as surgical scissors, hemostatic forceps, and suture. The
PHANTOM from SensAble Technologies are used to provide an excellent graphical user interface, and various kinds
of virtual surgical instruments are developed in combination
with GHOST SDK, a 3D interactive tactile environment
development kit of PHANTOM.After importing the reconstructed STL le, the 3D objects of the bile duct, artery, and
vein were obtained and combined to simulate the operation
of incision and suture.
6.2.1 Geometric Modeling
The geometric model of the liver is obtained from the previous 3D reconstruction and imported into the virtual surgical
platform through program reading. The STL model is a geometric model with a triangular set to represent the shape of
the outer contour of the object. In the tactile frame of GHOST
SDK, the model is transformed into the triangular mesh
model required by GHOST SDK by programming. In order
to speed up the calculation of collision response and to integrate the computational force feedback algorithm (developed
in-house), it is necessary to initialize the topological information of the 3D model, that is, to complete some calculation work when the program is initialized. Then the necessary
information is called directly during the movement of the
virtual surgical instruments to establish an indexed triangle
mesh.
In the indexed triangle mesh, we maintain two lists: the
vertices and triangles. Each vertex contains a 3D position, as
well as additional information about its geometric attributes
(colors and textures) and physical characteristics (hardness
and friction coefcient) to facilitate real-time extraction in
an interactive simulation. Each triangle points to its three
vertices. These vertices are listed in counterclockwise order,
and the surface normal vector should be precalculated.
Compared with triangular arrays, the use of indexed triangular mesh has the following advantages:
• Space-efcient. Its integer vertex index is much smaller
than the vertex repetition rate in a triangular array.
• Implicit adjacent topology information. Although the side
information is not directly stored, the public side can be
found by searching the triangle table.
Reference to the actual surgical instruments, geometric
modeling of surgical instruments was performed by using the
Open Graphics Library (OpenGL) software development kit
and 3D graphics software. Surgical instruments cannot be
simply constructed by basic elements supported by OpenGL,
and the use of 3DMAX improves the realism of model rendering. 3D geometries are exported into 3D Studio (3DS) format
by 3DMAX.Finally, by using OpenGL for graphics programming, the 3DS format model is generated into an OpenGL
display list and thus improve OpenGL performance (Fig.6.1)
6.2.2 Motion Modeling
Virtual surgical instruments are introduced into the reconstructed 3D object to perform various surgical procedures
including cutting, dissecting, and clamping. 3D objects in
the simulation system consist of two categories: one is 3D
objects with a tactile interface, such as virtual surgical instruments; the other is common 3D objects that constitute the
Fig. 6.1 Instruments constructed by 3D Studio MAX. (a) Scalpel; (b) Scissors
6 Virtual Surgical Instruments andSurgical Simulation
135
virtual scene, such as abdominal viscera and biliary tissue.
For the latter, the geometric transformation functions that are
available in OpenGL can be applied for coordinate transformations such as translation and rotation. A tree structure is
used to describe the hierarchical nature of the objects. The
exposed triangles of the liver and its internal vessels corre-
Fig. 6.2 Motion modelling.
(a) Simulated liver; (b)
hepatic vein incision; (c)
Suture of hepatic veins
a
a
spond to the leaf nodes of the tree. These triangles specify
the geometrical properties of leaf nodes and their direction
and proportion relative to the parent node. Any transformation applied to the parent node will automatically affect its
leaf nodes. The motion of all objects is constrained and controlled in this way (Fig.6.2).
b
b
136
S. Bao et al.
Fig. 6.2 (continued)
c
The PHANTOM interface corresponding to the virtual
surgical instruments is a particular type of 3D object. In the
servo loop, the status information of the PHANTOM device
(such as position and orientation) can be queried by the callback function. The orientation of the PHANTOM stylus is
described by a 4×4 homogeneous coordinate transformation
matrix.
In addition, the motion modeling of virtual surgical
instruments also needs graphics and PHANTOM correction.
In the 3D simulation, the view of the virtual camera and
workspace of PHANOM should be aligned to immerse the
user who participates in the virtual surgery. Therefore, the
workspace of PHANTOM needs to be centered on the Z-axis
of the visual body. PHANTOM’s workspace should be
located between the clipping planes of the observation cone
so that objects of interest can appear on the screen. This is
achieved by placing the PHANTOM workspace in the center
of the virtual camera and moving it along Z-axis. In order to
be able to move the surgical instruments within the screen
area to the graphical objects mapped to PHANTOM. It is
also necessary to calculate the scaling factor of the
PHANTOM working scope.
6.2.3 Physical Modeling
Collision detection has been the focus and one of the fundamental problems in surgical simulation. Only when surgical
instruments collide with human tissues, is it necessary to
perform cutting and suturing procedures. Since the model of
organs and tissues is required to be as elaborate as possible,
the number of triangles generally reaches 10,000 to 100,000.
In order to improve the detection efciency, a point-to-body
collision detection method is used. The particles represent
the moving virtual surgical instrument, and triangles represent the static organ and tissues.
The virtual surgical instrument (PHANTOM lever) is in
contact with the virtual object only at the tip of the stylus,
and from this point, the force is fed back to the user’s hand
through the operating lever. The specic description is as follows: judge whether the tip of the stylus passes through the
object in the scenario according to the motion information of
the PHANTOM handle. If intersection is determined, the
feedback force can be further calculated based on the point
of intersection with the object. The movement of the handle
is usually small, relative to the frequency of the tactile feed-
New position
6 Virtual Surgical Instruments andSurgical Simulation
137
Original position
Surface
Grid-based operation
Fig. 6.3 Grid-based needle operation
back, which means that each frame only needs to check a
relatively small spatial area. In the accurate collision detection phase, the built-in algorithm of the development kit can
be used to determine whether the tip of the surgical instrument has collided. For specic collision information (such as
the triangle index of the collision and its vertex), the calculation is simplied by the method of vertex/triangle collision.
In the actual operation, surgeons usually adopt a variety
of surgical instruments for collaborative operation, and
hence the collision detection between surgical instruments is
essential. Since the model of various surgical instruments are
relatively simple, and they do not deform during operation.
In order to improve the authenticity of such detection, a free
3D collision detection library (ColDet) is used to achieve
body-to-body collision detection (Fig.6.3).
When the surgeon manipulates the surgical instrument to
interact with the 3D object surface, a reaction force is felt at
collision. PHANTOM’s particle-spring-damper force feedback model can be used for liver physics simulation. Springs
and dampers are attached to the surface of the soft tissue. In
a virtual environment, a vertex of a virtual surgical instrument model will undergo elastic deformation once it collides
with the surface. By obtaining a vector of the original position and the new position of a vertex of the instrument model,
the intersection contact point (SCP) of the soft tissue surface
can be obtained, and the length of the spring stretching can
also be obtained to calculate the surface elasticity (Fig.6.4).
Foreign virtual surgery systems are expensive. However,
there is no medical image processing and virtual surgery system for abdominal and thoracic surgery in China, and no
simulation environment is provided. The simulation system
has only partial functionality for force feedback and does not
provide a realistic simulation of the operating environment.
Also, the production of viscera and visceral surgical software
involves a considerable amount of data and calculations. The
damping
Fig. 6.4 Diagram of force feedback model
spring
methods to achieve the rapid reconstruction, arbitrary cutting, soft tissue deformation, and the software development
and hardware conguration of human–computer interaction
of the existing methods remain as problems to be solved.
6.3 Surgical Simulation
With the interdisciplinary integration and rapid development
of computer technology, image processing technology, medical physics, and medicine; the methods of surgical diagnosis
and treatment are undergoing rapid changes. The computedaided surgery system and the simulation surgery system
devised in recent years are the results of the rapid development and application of information science in the medical
eld. Simulated surgery refers to the application of virtual
human research results on the “virtual human” surgery by
using simulated surgical instruments (scalpels, hemostats) in
the virtual surgery environment. Surgeons can use these
advanced technical means as the preoperative, intraoperative, and postoperative auxiliary support for real surgery to
make the surgery safer, more reliable, more accurate, and
less invasive.
Current research on simulation surgery mainly focuses on
neurosurgery, plastic surgery, and orthopedics; especially in
intraoperative navigation, which combines virtual reality
with augmented reality; and even the successful application
of surgical robots in clinical practice. However, there are few
clinical reports in the eld of hepatobiliary and pancreatic
surgery, which are limited to the preoperative study or evaluation of liver surgery. For example, Bro-Nielsen etal. used
liver data from the VHP male dataset to study the reconstruction of the liver and simulate the surgical plane of the liver by
nite element method (Bro-Nielsen et al. 1996). They
believed that the 3D reconstruction of the liver contributes to
the understanding of the liver anatomy, and it is possible to
realize the preoperative planning, training, and teaching of
138
S. Bao et al.
liver surgery. Wigmore etal. used 3D models reconstructed
from computed tomography angioportography (CTAP)
images in clearly displaying the hepatic and portal veins.
Twenty-seven patients undergoing hepatobiliary surgery
were retrospectively studied. By comparing tumor volume,
total liver volume, and functional liver volume to body
weight, it was found that functional liver volume was
strongly correlated to body weight, and the risk of postoperative liver failure could be well predicted (Wigmore et al.
2001).
At present, liver surgery remains one of the most chal-
lenging operations, mainly because of the complexity and
variability of the internal organ structure. Therefore, the
establishment of the liver surgery program often depends on
the operator’s precise understanding of the 3D spatial relationship between the intrahepatic vascular biliary tree and
the lesion. However, anatomical variation and deformity,
tumor extrusion inltration, and previous liver resection can
cause changes in the spatial relationship of the intrahepatic
biliary vascular tree; so, it is often challenging to develop
accurate surgical plans. It is also difcult to accurately determine the variation type, branch direction, location, size, and
geometry of the lesion and the spatial relationship between
the lesion and the surrounding ductal system by observing
the traditional 2D image. Moreover, since visible light cannot penetrate human tissues and the internal structures that
have not yet been cut cannot be seen and felt, it is difcult to
obtain the spatial information of the individual anatomical
structure of the patient’s liver. Due to the lack of a quantitative description of the tissues involved in the operation, intraoperative exploration combined with traditional 2D images
cannot adequately meet the needs of liver surgery. Doctors
can only rely on experience to plan for liver surgery blindly,
which inevitably leads to inaccuracy in the location of the
operation space. Moreover, it is impossible to accurately formulate the operation path and avoid the risks of surgery,
which will undoubtedly affect the quality, increase trauma,
and prolong the duration of surgery. Meanwhile, because 2D
images cannot accurately calculate the liver volume, and for
patients with varying degrees of liver cirrhosis, it is difcult
to choose between preserving enough residual liver volume
and completely removing the lesion. The rapid development
of modern medical image technology and computer technology, especially the appearance of 3D image visualization
reconstruction technology, provides an opportunity to solve
the above problems. 3D image visualization reconstruction
technology is called non-injurious stereoscopic anatomy
technology. Its principle is to use computer image processing
technology to analyze and process traditional 2D slice
images, to realize 3D reconstruction and display of the segmentation and extraction of human organs, soft tissues, and
lesions, to simplify the cognitive process of the human brain
on 2D images, to further intuitively and accurately display
the full range of stereo information of the liver and its piping
systems and lesions. The 3D image visualization reconstruction technology can assist the physician to analyze the lesions
and other areas of interest qualitatively and quantitatively,
which signicantly improves the accuracy and reliability of
medical diagnosis. It can provide accurate, individualized
anatomical information for the design of the surgical plan, so
it has a more signicant clinical application value than traditional two-dimensional tomography.
On the other hand, although the emergence of the 3D digital model of the liver has dramatically deepened the surgeon’s understanding of liver anatomy as well as the spatial
relationship between lesions and intrahepatic ducts, pancreas
and peripancreatic tissues, the clinical expectation of hepatobiliary and pancreatic surgery is to develop a comprehensive
simulation system suitable for clinical needs. Hepatobiliary
and pancreatic surgeons can use it to practice repeatedly,
familiarize themselves with the surgical procedures, improve
surgical skills, and shorten time to competency. It can also be
used to carry out new operations and to learn from the old
and improve the operation, reduce the trauma of the operation, preserve the function of the liver, and improve patients’
quality of life after the operation.
The surgical simulation system requires that the target
object model and the simulated surgical instrument must
have both high-quality realistic visual images, and real-time
interaction of high-resolution, Life-like haptic feedback
(force feedback). The visual feedback refers to observing the
realistic virtual environment through the display and the
real-time deformation of the simulated body under the operation of the interactive device; the tactile feedback means
that the operator perceives the physical characteristics of the
simulated body through the interactive device. Fidelity refers
to the degree of the recreation of the whole structure and
behavior of the simulation object and the capacity of the system simulation object. In the visual simulation surgery system, in order to ensure a real-time experience from the
simulation process, the graphics refresh frequency of no less
than 30Hz is required, and the force feedback refresh frequency is not less than 1000Hz. Tactile feedback is a twoway exchange of information with the user, while the visual
feedback is one way. When the user exerts an external force
on the virtual model, the data is transmitted to the interface
controller. The master computer calls the graph drawing software to change the virtual environment and relay the positional and tactile feedback information to the user. Any
virtual reality system is restricted by its temporal and structural authenticity, which is mainly determined by its hardware structure and software composition.
6 Virtual Surgical Instruments andSurgical Simulation
139
6.3.1 The Hardware System
Hardware devices include the main computer graphics workstation, display device, and the PHANTOM Force feedback
device. The computing requirements to run the PHANTOM
device are a computer with at least a 2 core 2GHz processor,
2GB available RAM, 512MB Hard drive, and a high-speed
connection (IEEE 1394a rewire). it mainly completes the
tasks of simulation calculation and graphics rendering. Of
the two tasks, the simulation calculation involves the display
of virtual environment, collision detection, force feedback
calculation, and tactile interaction. The display equipment
mainly completes visual feedback between the operator and
the virtual environment. The PHANTOM Force feedback
device is an essential tool for users to interact with simulation systems. Through PHANTOM, the space position and
motion direction of “surgical instruments” (force feedback
device joystick) controlled by the operator can be input into
the system. At the same time, after the host computer completes collision detection and forces feedback calculation,
tactile feedback is provided to the operator by PHANTOM,
so that the surgeon can perceive the delicate features of the
object and the resistance of the object to the force. The product “PHANTOM” with a 3D force feedback function developed by SensAble Company, is used as a tactile interactive
device, and the model is PHANTOM Desktop. The
PHANTOM product, developed at the Massachusetts
Institute of Technology in the United States, has led several
patents. Among them, PHANTOM Desktop provides a real-
istic 3D force feedback function for users with its rst-class
design.
Moreover, the device’s universal design makes it compatible with operating systems running on ordinary microcomputers. This interactive device is different from the previous
tactile device. Its portable design and compact base bring
exibility for users and avoids the disadvantages of the traditional device, such as large volume, skeleton mechanical
structure, noise, and joystick vibration in the tactile device.
In terms of design, due to sufcient consideration of the general working application environment, this type of equipment is connected to the computer through extended parallel
port (EPP) and is equipped with a general 110/220v AC
power supply (Fig.6.5).
The accepted criteria for measuring the quality of a tactile feedback device are low inertia, low lag, high reverse
drive capability, extensive force range, high mechanical
signal bandwidth, and suitable workspace. PHANTOM
Desktop is a 6-DOF force feedback manipulator with joint
coordinates, which can send instruction information to six
directions of rotation and can also feedback the force information to X, Y, and Z directions. In other words, the user
can perceive and manipulate the 3D simulation body built
in the virtual environment through the joystick or nger
sleeve of the PHANTOM end, and feedback tactile information to users. Its fundamental performance indicators
and relevant parameters are shown in Table6.1, which can
fully meet the needs of tactile interaction in virtual abdominal surgery.
a b c
Fig. 6.5 The hardware system of surgery simulation. (a) Computer host; (b) display of the simulation system; (c) PHANTOM (the force feedback
device)
Table 6.1 Parameters of PHANTOM
Resolution Maximum force Rigidity Force feedback Stylus inertia Degree of freedom
0.023mm 7.9N 3.16N/mm x, y, z 45g x, y, z, yaw, pitch, roll
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S. Bao et al.
6.3.2 Software System
The software system is the core of the surgical simulation
system. Through this system, various types of surgical simulations are available, and feedback can be provided according to the simulation results. All calculations related to visual
and tactile feedback can be completed by the software system. By using a tactile development kit that is compatible
with PHANTOM (Fig.6.6), a virtual tactile environment can
be easily established. The software development environment is the Visual C ++ platform. The design languages and
the development kit of the virtual environment mainly
include OpenGL, GHOST, and OpenHaptics SDKs.
6.3.2.1 FreeForm Modeling System
FreeForm Modeling System is a force feedback virtual reality system developed by SensAble Technologies, Inc. The
system can be used in conjunction with PHANTOM.Although
the FreeForm system is powerful and can simulate the virtual
liver surgery after research, it still has some certain
drawbacks:
• Virtual liver surgery requires not only surgical tools but
also instruments such as surgical scissors, vascular forceps, sutures, which are currently not available in the
FreeForm system.
• FreeForm is not a native virtual surgery system, and its
expansibility is limited. Its interface and related functions
need to be improved. Professor Fang’s research group has
independently built a virtual reality software solution.
6.3.2.2 Open Graphics Library
A virtual surgical instrument with high delity is designed in
the system, this “virtual instrument” can then be manipulated
through the PHANTOM handle to simulate the surgical processes, such as liver cutting. Real-time force feedback can be
Fig. 6.6 The liver is being cut with PHANTOM
generated by real-time cutting and suture of the liver, and the
force can be felt concurrently. The Open Graphics Library
(OpenGL) is strictly dened as “a software interface to
graphics hardware.” In essence, it is a fully portable and fast
3D graphics and modeling library. OpenGL is a software
interface that uses specialized graphics processing hardware
to support users’ graphics and image manipulation for highquality 3D objects. OpenGL sets patterns, determines the
graph element, and describes other OpenGL operations by
transferring instruction in the form of functions or procedure
calls. The primary work used to create graphics is to organize
a nite number of polygons whose objects are composed of
vertices in three dimensions. It consists of hundreds of procedures and functions that developers can use to build 3D
models and interact in 3D real time. Most OpenGL systems
require at least one frame buffer in the graphics hardware
system. OpenGL’s graphics functions do not require developers to write 3D object model data into a xed data format.
In this way, developers can not only use their data but also
use data sources in other different formats, such as les in
3DS format. This exibility dramatically saves development
time and improves the developmental benets of the
software.
6.3.2.3 Tactile Development Kit
General haptics open software toolkit SDK (GHOST SDK)
is an object-oriented C++ toolkit, which allows users to
dene the geometry, physical properties, and tactile effects
of emulators according to their needs. OpenHaptics is the
successor to the GHOST SDK. Virtual instruments developed with OpenHaptics are all oriented to PHANTOM force
feedback devices, and their programs function well. The
OpenHaptics development kit utilizes the OpenGL API,
which is very familiar to graphics developers. With the
OpenHaptics development kit, developers can use existing
OpenGL code to develop special geometric applications, or
they can use OpenHaptics commands to set tactile properties
of materials, such as friction and hardness. Its extensible
architecture allows developers to add support for new shape
types. It is also possible to integrate other library les such as
physics/kinematics and collision detection engines. The
OpenHaptics development kit supports devices ranging from
low-cost PHANTOM Omni to larger PHANTOM Premium
haptic devices. Software developers can use the SensAble
OpenHaptics development kit to add tactile and accurate 3D
navigation features in a wide range of areas.
The visual simulation surgery system uploads the liver
and its internal conduit model reconstructed by MI-3DVS
abdominal 3D reconstruction software into the FreeForm
Modeling System and uses virtual cutting software and
PHANTOM force feedback devices to manipulate virtual
surgical instruments to cut, clamp and stitch the liver
model. The Visual simulation surgery system is not only an
6 Virtual Surgical Instruments andSurgical Simulation
141
excellent liver simulation surgery environment system with
immersion, interaction, and force feedback, but also a system that can easily realize the simulation research of all
kinds of surgery in other organs of hepatobiliary and pancreatic surgery. At present, this system is being commercialized step by step and has been applied preliminarily in
the clinic.
6.3.3 Development andApplication
ofVirtual Surgical Instruments
The above-reconstructed model is introduced into the
SensAble’s FreeForm 3D Modeling System for necessary
modication such as denoising, smoothing, automatic spatial
registration, and color matching. The reconstructed image is
realistic in shape, and the operator can combine, rotate, set
the transparent or opaque display of multiple models, or hide
any organs and blood vessels for observation. The smoothed
model is observable, and the morphological and spatial anatomical relationship is the same as the real human body. It
can meet the requirements of the next auxiliary diagnosis
and simulation surgery.
Surgical simulation is implemented in a virtual surgical
instrument simulation system (software copyright 105,978).
The virtual surgical instrument simulation system consists of
hardware and software systems. The virtual surgical platform is constructed by using the hardware of the main workstation and force feedback equipment, and the GHOST SDK
software development kit used to develop the virtual surgery
platform. A complete range of simulated surgical instruments (Fig.6.7) was made, including scalpel, surgical scissors, hemostatic forceps, needle holder, surgical needle,
suture, retractor, bile duct probe, skin forceps, electric knife,
ultrasonic knife, and drainage tube.
6.3.4 Signicance ofLiver Virtual Simulation
Surgery
The Liver Visualization Simulation Surgery System is a virtual environment system for hepatectomy based on the selfdeveloped 3D system of abdominal medical images
(MI-3DVS) combined with the FreeForm Modeling System.
It mainly aims at liver tumor resection simulation, using a
computer and other techniques to analyze and process twodimensional medical image data; and to provide realistic
medical images and simulated surgical process and results. It
can be used to simulate similar resections of other organs,
such as biliary tract, pancreas, spleen, and other diseases.
The results are preliminary, and there is still a lot of work to
be done, such as adding a measurement module to measure
the volume of the liver and the excised liver, as well as the
size and length of the hepatic duct structure; adding a liver
function evaluation module to evaluate postoperative liver
function, the risk of operation, and the quality of life according to the parameters of the liver function examination; adding the evaluation module of surgical skills to provide a
comprehensive evaluation of the skills, process, and the
result of the virtual operation.
The Liver Visual Simulation Surgery System has the
advantages of interoperability, intervention, arbitrariness,
and repeatability. It can simulate the cutting process in
advance without performing surgery and predict complex
and dangerous situations that are expected to occur in actual
surgery. For example, when the segmentation level involves
important blood vessels or bile ducts in the liver, or there a
risk of injury. Under these circumstances, the corresponding
adjustment should be adopted. By comparing the advantages
and disadvantages of various programs through the simulation of different surgical programs, a reasonable individualized surgical plan is formulated, and necessary preventive
measures can be taken in advance. The system not only helps
to preserve the integrity of residual hepatic vessels and necessary important structures, minimize the incidence of postoperative complications, and increase the success rate of
surgery: but also can accurately measure the total volume of
liver, the volume of lesion, the volume of functional liver, the
volume of the resection and residual liver; thus predicting the
risk of postoperative liver failure.
Currently, the liver visualization simulation surgery system only simulates the rough process of liver surgery.
However, it has reected the characteristics of liver surgery,
such as preoperative liver resection line, separation of liver
tissue, cutting of hepatic vessels, and removal of hepatobiliary tumors and diseased liver. Of course, there are still many
vital technical challenges to be solved:
• The recognition of liver internal pipeline structure in liver
image is called image segmentation. Due to the unobvi-
ous boundary between various duct structures, hepatobili-
ary tumors, and liver parenchyma in some CT images, the
angiography can only make individual structures stand
out, and the images cannot clearly show all four liver
tubes (especially intrahepatic bile ducts) and the adjacent
relationship between the tumor and the internal structure
of the liver. Thus, utterly automatic segmentation by the
software is impossible, and manual intervention is
required. Even the effect of manual intervention is not
completely satisfactory.
• The structure of the liver varies. How to apply specic
data and a virtual “standard liver” model with image
fusion technology to reect the specicity and individual-
ity of the liver; so as to achieve the preoperative planning
of specic patients with hepatobiliary tumor, preoperative
targeted training, and further improve the surgical plan,
increase the success rate of actual surgery and reduce the
complications of surgery; remains a problem.
142
ab c
S. Bao et al.
d
e
f
Fig. 6.7 Simulated surgical instruments. (a) Simulated scalpel handle;
(b) simulated stone forceps; (c) simulated surgical scissors; (d) simulation of needle holder and suture operation; (e) simulated laparoscopic
instruments; (f) simulated electric knife; (g) simulated surgical suture
needle; (h) simulated tissue forceps; (i) simulated operating scalpel
6 Virtual Surgical Instruments andSurgical Simulation
143
g
i
h
Fig. 6.7 (continued)
• The liver is a highly active organ in the human body. How
to combine virtual reality with augmented reality remains
a problem. It means valid linking of the “virtual liver”
established by the patient’s actual CT scan data, the
patient’s human body and the surgical instruments in the
laparoscopic surgery or the surgical robot operation; to
navigate surgery, reduce injury, improve the success rate,
and reduce the complications of the operation.
• How to realistically reproduce the scenes and feelings of
an actual operation in a virtual operation, is a question
that needs to be solved, including vascular injury bleeding, soft tissue deformation, different sensations when the
separation of different tissues occur, and a series of force
feedback issues such as the different force required to cut
different tissues. Clearly, this is a highly technical problem, which needs further research.
6.4 Application of3D Visualization
Virtual Simulation Surgery inBiliary
Surgery
The development of modern science and technology is
increasingly reecting the intersection and connectedness of
multiple disciplines. Virtual reality (VR) is a high-tech concept developed in recent years. It is an interdisciplinary, integrated technology involving elds such as computer graphics,
human–computer interaction technology, sensing technology, articial intelligence, and cognitive science. It uses the
computer to form sensations such as realistic threedimensional visual, auditory and tactile perception, enabling
people to experience and communicate with the virtual world
through appropriate devices. In the past 10 years, virtual
reality technology has exerted an increasingly important