Real-time VR Simulation of Laparoscopic Cholecystectomy based on
Parallel Position-based Dynamics in GPU
Junjun Pan
†
*
State Key Lab of VR Tech & Syst
Beihang University
Peng Cheng Lab
Leiyu Zhang
†
State Key Lab of VR Tech & Syst
Beihang University
Peng Yu
†
State Key Lab of VR Tech & Syst
Beihang University
Yang Shen
Faculty of Education
Beijing Normal University
Haipeng Wang
Beijing Aerospace General Hospital
Haimin Hao
Beihang University
Peng Cheng Lab
Hong Qin
*
Department of Computer Science
Stony Brook University
ABSTRACT
In recent years, virtual reality (VR) based training has greatly
changed surgeons learning mode. It can simulate the surgery from
the visual, auditory, and tactile aspects. VR medical simulator can
greatly reduce the risk of the real patient and the cost of hospitals.
Laparoscopic cholecystectomy is one of the typical representatives
in minimal invasive surgery (MIS). Due to the large incidence of
cholecystectomy, the application of its VR-based simulation is vi-
tal and necessary for the residents’ surgical training. In this paper,
we present a VR simulation framework based on position-based
dynamics (PBD) for cholecystectomy. To further accelerate the
deformation of organs, PBD constraints are solved in parallel by a
graph coloring algorithm. We introduce a bio-thermal conduction
model to improve the realism of the fat tissue electrocautery. Finally,
we design a hybrid multi-model connection method to handle the
interaction and simulation of the liver-gallbladder separation. This
simulation system has been applied to laparoscopic cholecystectomy
training in several hospitals. From the experimental results, users
can operate in real-time with high stability and fidelity. The simu-
lator is also evaluated by a number of digestive surgeons through
preliminary studies. They believed that the system can offer great
help to the improvement of surgical skills.
Index Terms:
Human-centered computing—Human computer
interaction—Interactive systems and tools—User interface program-
ming; Computer systems organization—Real-time systems—Real-
time system architecture
1I
NTRODUCTION AND MOTIVATION
As one of the modern minimally invasive procedures, laparoscopic
surgery has become popular primarily because of its small wounds
and rapid recovery. For instance, nearly 15 million laparoscopic
procedures are performed globally annually [21]. Laparoscopic c-
holecystectomy (LC) is one of the typical representatives. However,
in reality the number of laparoscopic surgeons cannot meet the huge
demand in clinic. One reason is that the learning curve of laparo-
scopic surgery is very long. In the narrow operation space, mistakes
may easily occur if surgeons do not handle procedures properly. It
usually takes about ten years to became a laparoscopic surgeon for
resident. Traditional training approaches of laparoscopic surgeries
are usually on animals or corpses, which could give rise to negative
effects, such as high cost, low practice opportunities, and related
*
Corresponding authors: pan junjun@buaa.edu.cn,
qin@cs.stonybrook.edu.
†
These authors contributed equally to this work.
ethical issues. These problems have become bottleneck for the de-
velopment of laparoscopic surgery skill training. The advent of VR
surgical simulator has changed this situation. It not only reconstructs
the real surgical environment and procedures, but also can be reused
for a variety of designed training tasks. Therefore, many institutions
and commercial companies, such as Lap Mentor [24], LapVR CAE
Healthcare Interventional Simulator [8], and the LapSim Surgical
Science Simulator [23] have carried out research and development
on VR medical simulators. Whereas, to our knowledge, there is no
paper that elaborates the whole laparoscopic cholecystectomy proce-
dure and the development details. This paper presents a framework
of virtual laparoscopic cholecystectomy. For the deformation of soft
tissue, we propose the algorithm to parallelize position-based dynam-
ics (PBD) through graph coloring. To simulate electrocautery, we
introduce the bio-thermal conduction model to modify the topology
of gallbladder fat tissue. For the separation of liver and gallbladder,
a hybrid multi-model connectivity method is designed to handle the
interactions and visual rendering. Compared with the work of Kim
et al. [11], the experimental results confirms that our technique is
more efficient in soft tissue deformation. Finally, a questionnaire is
designed to evaluate the utility experience of our system by digestive
surgeons.
The simulator (Fig. 1) hardware consists of a touch screen, two
surgical instrument handles, a foot pedal, a Bluetooth mouse, and
a computer with two haptic devices. We choose Geomagic Touch
(Phantom Omni, Sensible) as the haptic feedback device of our
simulator. It could offer 6 degree-of-freedom (DOF) input data with
a resolution of 0.009 mm in 3D space, and up to 3.3N3DOF
force output [25]. The software is developed with OpenHaptics,
GLSL, CUDA, and C++. The anatomy models are obtained from
the human anatomy database [9], which contains the gallbladder,
liver, abdominal wall, bile duct, and cystic duct/artery.
Fig. 2 illustrates the software architecture of our system, which
includes two phases: offline and online. The offline phase consist-
s of loading the geometric model, initializing the physical model
(creating stretching constraints and volume constraints), and color-
ing the physical model using the graph algorithm. For the online
phase, the system first detects collision based on the data sent by the
force feedback device, then calculates the potential distribution of
the model and solves the constraints in parallel for the soft tissue
deformation, and finally updates the model texture and shape in a
graphic and tactile manner. In technical essence, there are three
innovative contributions:
•
We propose a deformation model of soft tissue based on graph
coloring parallel acceleration, within the position-based dy-
namics (PBD) framework.
•
The laws of thermodynamics is employed in the electrocautery
simulation. A bio-thermal conduction model is presented to
improve the realism of fat tissue burning.
548
2020 IEEE Conference on Virtual Reality and 3D User Interfaces (VR)
2642-5254/20/$31.00 ©2020 IEEE
DOI 10.1109/VR46266.2020.00-28