c o m p u t e r m e t h o d s a n d p r o g r a m s i n b i o m e d i c i n e 1 1 3 ( 2 0 1 4 ) 674–681
journal homepage: www.intl.elsevierhealth.com/journals/cmpb
Evaluation of a haptics-based virtual reality temporal bone simulator for anatomy and surgery training Te-Yung Fang a,b,1 , Pa-Chun Wang a,b,c,d,1 , Chih-Hsien Liu a , Mu-Chun Su e , Shih-Ching Yeh e,∗ a
Department of Otolaryngology, Cathay General Hospital, Taipei, Taiwan Fu Jen Catholic University School of Medicine, New Taipei City, Taiwan c Department of Public Health, China Medical University, Taichung, Taiwan d School of Medicine, Taipei Medical University, Taipei, Taiwan e Department of Computer Science and Information Engineering, National Central University, Taoyuan, Taiwan b
a r t i c l e
i n f o
a b s t r a c t
Article history:
Introduction: Virtual reality simulation training may improve knowledge of anatomy and
Received 31 August 2013
surgical skills. We evaluated a 3-dimensional, haptic, virtual reality temporal bone simulator
Received in revised form
for dissection training.
4 November 2013
Methods: The subjects were 7 otolaryngology residents (3 training sessions each) and 7
Accepted 8 November 2013
medical students (1 training session each). The virtual reality temporal bone simulation station included a computer with software that was linked to a force-feedback hand stylus,
Keywords:
and the system recorded performance and collisions with vital anatomic structures. Sub-
Medical education
jects performed virtual reality dissections and completed questionnaires after the training
Virtual environment
sessions.
Haptics
Results: Residents and students had favorable responses to most questions of the technol-
Otolaryngology
ogy acceptance model (TAM) questionnaire. The average TAM scores were above neutral
Anatomic dissection
for residents and medical students in all domains, and the average TAM score for resi-
Surgical technique
dents was significantly higher for the usefulness domain and lower for the playful domain than students. The average satisfaction questionnaire for residents showed that residents had greater overall satisfaction with cadaver temporal bone dissection training than training with the virtual reality simulator or plastic temporal bone. For medical students, the average comprehension score was significantly increased from before to after training for all anatomic structures. Medical students had significantly more collisions with the dura than residents. The residents had similar mean performance scores after the first and third training sessions for all dissection procedures. Discussion: The virtual reality temporal bone simulator provided satisfactory training for otolaryngology residents and medical students. © 2013 Published by Elsevier Ireland Ltd.
∗
Corresponding author at: Department of Computer Science and Information Engineering, National Central University, No. 300, Jhongda Rd., Jhongli City, Taoyuan County 32001, Taiwan. Tel.: +886 3 4227151x35216; fax: +886 3 4222681. E-mail address: [email protected] (S.-C. Yeh). 1 Te-Yung Fang and Pa-Chun Wang are the joint first authors. 0169-2607/$ – see front matter © 2013 Published by Elsevier Ireland Ltd. http://dx.doi.org/10.1016/j.cmpb.2013.11.005
c o m p u t e r m e t h o d s a n d p r o g r a m s i n b i o m e d i c i n e 1 1 3 ( 2 0 1 4 ) 674–681
1.
675
Introduction
During the past century, there have been major improvements in patient safety and health care quality and increased complexity of available technical services. Therefore, the informal clinical training that uses the “see one, do one, teach one” [1] approach may no longer be adequate. Simulation is being used in medical education for multiple specialties including emergency medicine, pediatrics, anesthesiology, obstetrics and gynecology, and surgery. Development of medical skills may be better with simulation than traditional clinical education [2]. The temporal bone is the most intricate and complex structure encountered by otolaryngologists. It is necessary to know the 3-dimensional anatomy of the temporal bone to understand the pathophysiology and treatment of otologic disorders, and otolaryngologists have used cadaver temporal bone dissection to learn temporal bone anatomy and improve surgical skills, hand-eye coordination, and fine motor skills [3]. Although temporal bone laboratories and dissection courses are available for resident training, they may be inaccessible to otolaryngology residents because of geographic distance, scheduling difficulties, and high cost. Furthermore, it may be difficult to obtain cadaver temporal bones in some countries because of cultural and religious practices or legal restrictions. Alternatives to cadaver temporal bone dissection include plastic and virtual reality temporal bone simulators. The virtual reality temporal bone simulator is a computer screenbased simulation, analogous to a video game. The trainee interacts with a 3-dimensional temporal bone using a haptic (tactile) interface. The 3-dimensional images are created with volume rendering techniques using high resolution computed tomography scans of cadaver temporal bones. The haptic feedback device, also used in simulation for dental implant surgery [4], may detect contact between the virtual surgical burr and the volume rendered data and calculates the force feedback to the tools. Bone erosion is simulated by decreasing the density of voxels [5–10]. The availability of temporal bone simulation has increased because of advances in computer technology and lower costs. Simulation may be used economically in the early stages of learning temporal bone anatomy and surgery, and residents may use the virtual reality temporal bone simulator before participating in cadaver temporal bone dissections. In addition, medical students may use the temporal bone simulator to learn temporal bone anatomy. We hypothesized that the virtual reality temporal bone simulator may improve the learning experience of otolaryngology residents and medical students. The purpose of the present study was to evaluate the technology acceptance, satisfaction and skill development with this system.
2.
Materials and methods
2.1.
Subjects
The subjects recruited were 7 otolaryngology residents in their second through fifth year of postgraduate training and 7
Fig. 1 – The virtual reality temporal bone simulation station, including a computer screen, specialized software, and hand stylus. Subjects followed the software tutorial description and used the virtual drill to perform surgical procedures.
voluntary medical students in their fifth through seventh year of medical school at the Cathay General Hospital. All the residents had the experiences of the plastic and cadaver temporal bone dissections (one to two times for both) before performing the virtual reality temporal bone simulation. The study was approved by the Cathay General Hospital Institutional Review Board committee.
2.2.
Virtual reality temporal bone simulation
The virtual reality temporal bone simulation station included a computer with software linked to a force-feedback hand stylus (Visible Ear Simulator, Alexandra Institute, Aarhus, Denmark and ENT Department, Rigshospitalet, Copenhagen, Denmark). The software provided real-time simulation of temporal bone surgery and an interactive, 3-dimensional representation of the temporal bone with specialized red and blue eyeglasses (Anaglyph 3D glasses, Rainbow Symphony Inc., Reseda, CA). The system used volumetric, high-resolution images of the temporal bone, and the colors of vital structures were similar to the colors in vivo. The system enabled users to adjust bone transparency and vital structure opacity to explore spatial relations of the sinus, middle and posterior fossa, facial nerve, and inner ear. The simulated drill included a hand stylus and specialized software (PHANTOM OMNI Haptic Device, Geomagic Sensable Group, Wilmington, MA) and allowed users to feel the change in pressure while drilling and to see changes in tissue as the drill cut through the simulated temporal bone (Fig. 1). Users could change the temporal bone orientation, magnification, drill size, and drill type. The software enabled measurement of performance for the important steps of temporal bone dissection, providing
676
c o m p u t e r m e t h o d s a n d p r o g r a m s i n b i o m e d i c i n e 1 1 3 ( 2 0 1 4 ) 674–681
Fig. 2 – Summary of the study protocol to evaluate the virtual reality temporal bone simulator.
an objective evaluation for the users. Performance scores included the volume of reference bone removed; collisions with the dura, facial nerve, inner ear, stapes, malleus, and incus; and time to perform the procedure.
2.3.
Procedure
Before the virtual reality dissection sessions, all subjects participated in a standardized session to become familiar with the system, including interface orientation and hands-on experience with introductory tasks (Fig. 2). Subsequently, the subjects performed the virtual reality dissections (residents, 3 sessions at 1-week intervals; medical students, 1 session after learning the anatomy from adjusting the visual settings to explore spatial relations of the vital structures) and followed the stepwise tutorial description for dissection tasks provided on the computer screen. The dissection tasks performed in sequence by each subject included an initial surface cut, saucerization of mastoid cavity, antrum opening, tegmen exposure, sigmoid and sinodural angle exposure, atticotomy, mastoid tip opening, posterior canal wall thinning, posterior tympanotomy, semicircular canal (lateral, posterior, and superior) outlining with a blue line, endolymphatic sac exposure, cochleostomy, and radical mastoidectomy.
2.4.
Outcome measures
After the subjects completed dissection sessions with the virtual reality temporal bone simulator, they completed questionnaires that were designed for the study. (1) The technology acceptance model (TAM) questionnaire evaluated how users accepted and used new technology. The TAM suggested that the system design characteristics may directly affect 3 main factors: “perceived ease of use,” “perceived usefulness,” and “attitude toward using the system”; these main factors may determine whether the user will use or reject the system [11]. The TAM questionnaire included 44 items to evaluate 7 domains: awareness, presence, usefulness, playfulness, ease of use, attitude, and intention to use (Tables 1 and 2). The items were rated on a 5-point Likert
scale (1, very untrue; 2, unture; 3, neutral; 4, true; 5, very true). The TAM questionnaire was completed by all participants upon completion of the virtual reality training; however, medical students did not answer TAM questions 19–22 because these questions evaluated the application of learned skills to cadaver dissection and surgery. (2) The satisfaction questionnaire for otolaryngology residents included 10 items to assess skill development, learning effect, appropriateness for individual needs, environment, and overall satisfaction with different training methods (virtual reality simulator, plastic bone, and cadaver bone) (Table 3). The satisfaction questionnaire was completed after the virtual reality training by the otolaryngology residents and not the medical students. Residents also were interviewed for qualitative comments about the simulator training. (3) The medical student questionnaire evaluated comprehension of anatomy and not surgical skills (Table 4). Although the medical students performed the surgical dissection tasks with the virtual reality temporal bone simulator, the main goal of medical students was to learn temporal bone anatomy. The medical student questionnaire was designed to evaluate knowledge improvement of temporal bone anatomy, dissection procedure understanding, and interest in otology after using the simulator. The comprehension for 5 anatomic structures (tegmen, sigmoid sinus, facial nerve, semicircular canals, ossicles) was rated on a 3-point Likert scale (1, not clear; 2, probably understood; 3, very well understood). The medical student questionnaire was completed by the medical students before and after the virtual reality session, and it was not completed by the otolaryngology residents. Medical students also were interviewed about their interest in otology and usefulness of the simulator training. The virtual reality temporal bone simulator recorded technical errors by determining the number of collisions by each subject with 6 vital anatomic structures (Table 5). Performance scores recorded for otolaryngology residents during each training session were based on the percentage of the volume of reference bone removed, which was from the built-in performance metrics, during 15 key steps of temporal bone dissection (Table 6). The time to complete the dissection
c o m p u t e r m e t h o d s a n d p r o g r a m s i n b i o m e d i c i n e 1 1 3 ( 2 0 1 4 ) 674–681
training session was not analyzed because the participants were allowed to divide the training sessions for convenience.
2.5.
Statistical analysis
Table 1 – Evaluation of the virtual reality temporal bone simulator with the technology acceptance model questionnaire in otolaryngology residents and medical students.a TAM questionnaire item
Data were analyzed with spreadsheet software (Microsoft Excel 2010, Microsoft Corp., Redmond, WA). Residents and medical students were compared with t-test. Satisfaction of residents with the 3 types of temporal bone dissection training was evaluated with 1-way analysis of variance. Statistical significance was defined by P < 0.05.
3.
Results
In all 14 participants (7 otolaryngology residents and 7 medical students), there were favorable responses predominating for all questions (and questions TAM 19–22, which were not answered by medical students) (Table 1). The average TAM score for residents was significantly higher for the usefulness domain and lower for the playful domain than medical students (Table 2). The average satisfaction questionnaire for residents showed that residents had greater overall satisfaction with cadaver temporal bone dissection training more than training with the virtual reality simulator or plastic temporal bone (Table 3). When comparing between the virtual reality simulator and plastic temporal bone, the plastic temporal bone was rated better in sense of reality, and the simulator was rated better in learning anatomy (Table 3). All residents agreed that simulator training could improve efficiency, increase confidence level, increase carefulness near vital structures (because of the warning pop-out in the simulator), and decrease mistakes during subsequent cadaver dissection training. All medical students agreed that they had improved comprehension of temporal bone anatomy from before to after the simulation training, and average comprehension score was significantly increased from before to after training for all anatomic structures (Table 4). All students stated that the simulator training increased their interest in otology, but they could not become proficient with temporal bone dissection procedures with only 1 simulator training session. The average performance scores were similar between the first simulation training session for residents and the single simulation session for medical students (data not shown). However, medical students had significantly more collisions with the dura than residents (Table 5). The medical students also had more collisions with the facial nerve and the labyrinth than the residents even though there was no significant difference. The residents had similar mean performance score after the first and third training sessions for all dissection procedures (Table 6).
4.
Discussion
The present results showed that the virtual reality temporal bone simulator provided satisfactory training for otolaryngology residents and medical students. Average TAM scores were above neutral for residents and medical students in all
677
A. Awareness TAM 1 The images display the drilled and undrilled bone. TAM 2 The images show the correct spot and the correct depth of the drilled bone. TAM 3 The tutor window demonstrates the current step and the unfinished steps. TAM 4 The warning system reminds me about the important structures. TAM 5 The build-in performance scores help me know my performance. TAM 6 The build-in performance scores remind me to avoid the important structures. TAM 7 The haptic force-feedback system helps me know whether the drill touches the target location. TAM 8 The haptic force-feedback system helps me know the strength of drilling bones. B. Presence TAM 9 The function of opacity adjustment of the important structures helps me know the temporal bone anatomy. TAM 10 The presentation of the virtual drill helps me know how to apply the drill with the correct direction. TAM 11 There is no lag time between motion of my hands and the virtual drill on the screen. TAM 12 The 3D images help to perceive the correct location of the drills. TAM 13 The 3D images demonstrate the target location of drilling on the temporal bone. TAM 14 The 3D images show the distance between the drill tip and the target location on the temporal bone. C. Usefulness TAM 15 The simulator helps to learn the dissection procedures. TAM 16 The simulator helps to learn the temporal bone anatomy. TAM 17 The simulator helps to learn how to select the drills during the dissection. TAM 18 The simulator helps to learn the manipulation of the drills. TAM 19 What I have learned from the simulator can be applied to the cadaver temporal bone dissection. TAM 20 What I have learned from the simulator can improve the efficiency of cadaver temporal bone dissection. TAM 21 What I have learned from the simulator can increase my confidence when performing cadaver temporal bone dissection. TAM 22 What I have learned from the simulator can be applied to surgery on patients. D. Playfulness TAM 23 I feel time pass quickly when using this simulation. TAM 24 I usually forget the goals of training because of being engrossed in playing the simulator. TAM 25 I feel happy when using this simulation.
Score 4.0 ± 0.6 3.6 ± 0.6 3.9 ± 0.5 4.2 ± 0.7 3.9 ± 0.8 3.7 ± 0.7 3.9 ± 0.7 3.4 ± 0.9
4.1 ± 0.7
3.4 ± 0.7
4.1 ± 0.5 3.6 ± 0.7 4.0 ± 0.6 3.5 ± 0.7
4.2 ± 0.6 4.3 ± 0.6 3.6 ± 0.6 3.6 ± 0.5 4.3 ± 0.5
4.1 ± 0.4
4.1 ± 0.4
4.1 ± 0.0
3.5 ± 1.0 3.3 ± 0.9 3.6 ± 1.1
678
c o m p u t e r m e t h o d s a n d p r o g r a m s i n b i o m e d i c i n e 1 1 3 ( 2 0 1 4 ) 674–681
Table 1 (Continued) TAM questionnaire item TAM 26 This temporal bone dissection simulation is interesting. E. Ease of use TAM 27 Learning how to operate this simulation is easy. TAM 28 I can use this simulation with ease. TAM 29 I can use this simulation comfortably. TAM 30 I still can use this simulation if nobody teaches me how to use it. TAM 31 This simulation takes me a long time to learn the operation.b TAM 32 I need to concentrate during use of the simulation. TAM 33 The message in the simulation helps me finish every step smoothly. TAM 34 The design of the simulation helps me complete temporal bone dissection smoothly. F. Attitude TAM 35 I have a positive attitude about the simulation. TAM 36 The simulation is a good method of learning temporal bone dissection. TAM 37 I like the idea of “virtual temporal bone dissection.” TAM 38 Using this simulation gives me a lot of fun. TAM 39 Overall, I take pleasure in using the simulation. G. Intention to use TAM 40 The simulation makes me have strong will to learn temporal bone dissection. TAM 41 The simulation encourages me to perfect the temporal bone dissection. TAM 42 The simulation encourages me to comprehend temporal bone anatomy more. TAM 43 I wish I could keep practicing the temporal bone dissection on this simulation. TAM 44 I will recommend this simulation to other doctors or students. a
b
Score 3.9 ± 0.9
Table 2 – Summary of the technology acceptance model questionnaire for residents and students who used the virtual reality temporal bone simulator.a TAM questionnaire domain
Residents
3.8 ± 1.0 3.9 ± 0.8 3.8 ± 0.8 4.0 ± 0.8 3.2 ± 0.8 3.6 ± 0.6
Awareness Presence Usefulness Playful Ease of use Attitude Intention to use a
4.0 ± 0.4 4.0 ± 0.4
3.9 ± 0.7 4.1 ± 0.8 3.9 ± 0.6 3.6 ± 0.6 3.7 ± 0.7
4.0 ± 0.8 3.9 ± 0.6 4.1 ± 0.4 3.8 ± 0.7 3.8 ± 0.6
N = 7 otolaryngology residents and 7 medical students. Medical students did not answer TAM questions 19–22 because these questions evaluated the application of learned skills to cadaver dissection and surgery. Data reported as mean ± SD for all subjects combined. TAM questionnaire rating (Likert scale): 1, very untrue; 2, untrue; 3, neutral; 4, true; 5, very true. TAM, technology acceptance model; 3D, 3-dimensional. Reverse item.
domains (Table 2), and medical students had improved comprehension of anatomy after training (Table 4). The present virtual reality system provided all 10 features of effective learning for simulation-based medical education, including (1) a mechanism for repetitive practice; (2) the ability to integrate the system into a curriculum; (3) the potential to change the degree of difficulty; (4) the potential to include clinical variation; (5) practice in a controlled environment; (6) individualized, active learning; (7) adaptability to multiple learning strategies; (8) measurable outcomes; (9) feedback during the experience; and (10) validity of the simulation as an approximation of clinical practice [12,13]. This type of simulation training may improve health care education [14],
b
P≤b
TAM score
3.8 3.8 4.1 3.2 3.9 3.9 4.1
± ± ± ± ± ± ±
0.4 0.5 0.3 0.8 0.3 0.3 0.4
Students 3.8 3.7 3.8 3.9 3.7 3.8 3.8
± ± ± ± ± ± ±
0.5 0.4 0.2 0.6 0.7 0.8 0.7
NS NS 0.03 0.04 NS NS NS
N = 7 residents and 7 students. Data presented as mean ± SD. TAM, technology acceptance model. TAM questionnaire rating (Likert scale): 1, very untrue; 2, untrue; 3, neutral; 4, true; 5, very true. NS, not significant; P > 0.05
practice, patient safety, and surgical training [15–17]. The skills obtained from medical simulation laboratories may be transferred directly to clinical situations such as difficult obstetric deliveries [18], laparoscopic surgery [19], and bronchoscopy [20]. The software for the virtual reality system used in the present study was available without charge for download from the Internet [21,22]. The effect of the built-in learning and performance metrics had not been assessed to date. Other virtual reality temporal bone simulators are commercially available (VOXEL-MAN TempoSurg Simulator, VOXEL-MAN Group, Hamburg, Germany; Mediseus Surgical Drilling Simulator, Medic Vision, Melbourne, Victoria, Australia) that may differentiate between levels of trainee experience [23,24]. The TAM questionnaire showed that both residents and medical students scored the temporal bone simulator positively in all domains (Table 2). There was consensus among residents that the simulator could improve understanding of 3-dimensional anatomic relations and surgical steps; increase drilling skills and efficiency; decrease injuries; increase confidence; and provide preparation for cadaver temporal bone training. The satisfaction evaluation showed that simulator training was similar to plastic temporal bone training. The simulator included user-controlled transparency, shadowing, tinting, and visibility functions for all relevant anatomic structures, which made simulator training more satisfactory than plastic temporal bone training for learning anatomy (Table 3). However, simulator training may not be a satisfactory substitute for cadaver temporal bone training, which may provide irreplaceable and invaluable experience with anatomic variation (Table 3). The performance measures with virtual reality simulator systems may provide trainees immediate feedback and may help trainers differentiate levels of proficiency. Systems with adequate sensitivity may be integrated into surgical curricula to assess training results. However, the present study did not distinguish the performance level between the residents in the first training session and medical students (data not shown). Since performance scores were calculated based on percentage of reference bone volume removed; it is speculated that students, who were not familiar with the dissection
679
c o m p u t e r m e t h o d s a n d p r o g r a m s i n b i o m e d i c i n e 1 1 3 ( 2 0 1 4 ) 674–681
Table 3 – Comparison of satisfaction of otolaryngology residents with different training methods for temporal bone dissection.a Satisfaction questionnaire item
Temporal bone Simulator
Learning anatomy Learning anatomic variants Learning procedures Drilling skills Sense of reality Meet individualized requirements Meet individualized level Comfortable environment Transfer to real surgery Overall satisfaction a b c
4.4 3.3 4.1 3.4 3.0 4.3 3.6 4.3 3.6 4.3
± ± ± ± ± ± ± ± ± ±
0.5 0.5 0.4 0.5 0.0 0.5 0.5 0.8 0.5 0.5
Plastic
P≤b
Cadaver
± ± ± ± ± ± ± ± ± ±
0.006 NS NS NS 0.014 NS NS NS NS NS
4.6 4.6 4.3 4.6 4.6 4.6 4.9 4.3 4.9 4.9
3.6 3.6 3.9 3.7 3.7 4.1 3.6 4.0 3.6 4.4
0.5 0.8 0.7 0.8 0.8 0.7 0.5 0.8 0.5 0.5
± ± ± ± ± ± ± ± ± ±
P≤c
0.5 0.5 0.5 0.5 0.5 0.5 0.4 0.5 0.4 0.4
NS 0.002 NS 0.006 0.001 NS 0.001 NS 0.001 0.015
N = 7 otolaryngology residents. Satisfaction scale: 1, very dissatisfied; 2, dissatisfied; 3, neutral; 4, satisfied; 5, very satisfied. Comparison between virtual reality simulator and plastic temporal bone. NS, not significant; P > 0.05 Comparison between virtual reality simulator and cadaver temporal bone. NS, not significant; P > 0.05
procedures, might have removed more bone but injured many vital structures as well. Even though the changes of performance were not statistically significant for residents after 3 training sessions (Table 6), we did observe some improvement in scores from this small group of trainees. Nevertheless, the system distinguished between residents and medical students with lower collisions among residents (Table 5), probably because of better anatomic knowledge and surgical experience among the residents. The residents were more aware of the risk to anatomic structures and may have used more caution, but the students may have been unaware of the potential for injury to the anatomic structures. Therefore, the present system may potentially distinguish between experienced and inexperienced surgeons. Limitations of the present virtual reality temporal bone simulator include the availability of images for just 1 normal human specimen. This may be adequate for basic medical student training, but residents may need a higher level of training with more variations of anatomy and pathology. In addition, the performance score may not distinguish different levels of surgical training (Table 6), and the trainer may need a more sensitive scoring system or use the combination results of performance scores and collision numbers to evaluate different levels of experience. Furthermore, the training simulator may emphasize the final results, and additional features may be needed to train and evaluate earlier steps for safety and proficiency. The simulation training may increase the risk of overconfidence; a good outcome in the simulation may not guarantee good performance in live surgery, which requires skills, preoperative medical decision making and planning, good team communication, appropriate response to blood in the surgical field or unexpected anatomy, and surgical judgment under pressure. Despite these limitations, the present study showed that virtual reality simulation training for residents and medical students may increase knowledge of anatomy and may be useful before cadaver temporal bone dissection training. The virtual reality system has the advantages of minimal setup, no cleanup, minimal cost, and high daily accessibility and convenience without constraints of clinical schedules. Residents may perform some steps of simulated temporal bone
Table 4 – Comprehension of temporal bone anatomy by medical students before and after using the virtual reality temporal bone simulator.a Anatomic structure
Comprehension score Before
Tegmen Sigmoid sinus Facial nerve Semicircular canal Ossicles a
b
1.6 1.4 2.0 1.6 2.0
± ± ± ± ±
0.8 0.5 0.6 0.5 0.6
P≤b
After 2.0 2.3 2.4 2.4 2.6
± ± ± ± ±
0.6 0.5 0.5 0.5 0.5
0.04 0.0005 0.04 0.0005 0.02
N = 7 medical students. Data presented as mean ± SD. Comprehension score: 1, not clear; 2, probably understood; 3 very well understood. NS, not significant; P > 0.05.
dissection during brief periods. The safe, consistent, predictable, and reproducible materials may decrease time needed for direct supervision. In addition, the built-in performance measures for key steps of temporal bone dissection may provide immediate feedback to the trainee. Therefore, the virtual reality simulator may provide an effective, efficient, and economical training program during early stages of
Table 5 – Collisions with vital structures during training with the virtual reality temporal bone simulator by otolaryngology residents and medical students.a Anatomic structure
Residentsc Dura Facial nerve Labyrinth Stapes Malleus Incus a
b c
P≤b
Collision score
8 18 10 2 0.3 1
± ± ± ± ± ±
12 17 7 1 0.5 2
Students 37 27 31 1 1 2
± ± ± ± ± ±
39 21 35 2 1 3
0.05 NS NS NS NS NS
N = 7 residents and 7 students. Data reported as the average number of collisions for each anatomic region (mean ± SD). NS, not significant; P > 0.05. After the first training session.
680
c o m p u t e r m e t h o d s a n d p r o g r a m s i n b i o m e d i c i n e 1 1 3 ( 2 0 1 4 ) 674–681
Table 6 – Performance scores of first and third training sessions of otolaryngology residents with the virtual reality temporal bone simulator.a Procedure First score (%) Initial surface cut Saucerization Antrum opening Tegmen exposure Sigmoid and sinodural angle exposure Atticotomy Mastoid tip opening Posterior canal wall thinning Posterior tympanotomy Semicircular canal outlining with blue line Lateral Posterior Superior Endolymphatic sac exposure Cochleostomy Radical mastoidectomy a b
P≤b
Training session Third score (%)
65 93 88 91 90 92 87 88 91
± ± ± ± ± ± ± ± ±
15 8 7 6 7 4 8 7 5
73 90 93 94 93 94 91 92 92
± ± ± ± ± ± ± ± ±
16 14 4 3 2 2 5 4 4
NS NS NS NS NS NS NS NS NS
91 92 90 91 91 88
± ± ± ± ± ±
5 5 5 6 5 8
92 92 91 92 91 87
± ± ± ± ± ±
4 4 4 4 3 3
NS NS NS NS NS NS
N = 7 residents. Data presented as mean ± SD. Performance scores: the percentage of volume of reference bone removed. NS, not significant; P > 0.05.
learning and may decrease the dependency on cadaver temporal bone or live surgery to achieve the necessary competency. The incorporation of this simulator in surgical curricula may improve complex anatomic knowledge, surgical skills, and confidence, especially in programs that have limited access to human cadaver temporal bone specimens.
Acknowledgement The authors thank Ms. Li-Ju Chuang for data management in reporting outcomes. This study was supported by the joint research fund (project number: 101 CGH-NCU-A4) of Cathay General Hospital and National Central University of Taiwan.
references
[1] W.S. Halsted, The training of the surgeon, Bull. Johns Hopkins Hosp. 15 (1904) 267–275. [2] W.C. McGaghie, S.B. Issenberg, E.R. Cohen, J.H. Barsuk, D.B. Wayne, Does simulation-based medical education with deliberate practice yield better results than traditional clinical education? A meta-analytic comparative review of the evidence, Acad. Med. 86 (2011) 706–711. [3] E.A. Duckworth, F.E. Silva, J.P. Chandler, H.H. Batjer, J.C. Zhao, Temporal bone dissection for neurosurgery residents: identifying the essential concepts and fundamental techniques for success, Surg. Neurol. 69 (2008) 93–98. [4] F. Zheng, W.F. Lu, Y.S. Wong, K.W. Foong, An analytical drilling force model and GPU-accelerated haptics-based simulation framework of the pilot drilling procedure for micro-implants surgery training, Comput. Methods Programs Biomed. 108 (2012) 1170-1184. [5] T. Harada, S. Ishii, N. Tayama, Three-dimensional reconstruction of the temporal bone from histologic sections, Arch. Otolaryngol. Head Neck Surg. 114 (1988) 1139–1142.
[6] R.B. Kuppersmith, R. Johnston, D. Moreau, R.B. Loftin, H. Jenkins, Building a virtual reality temporal bone dissection simulator, Stud. Health Technol. Inform. 39 (1997) 180–186. [7] D. Stredney, G.J. Wiet, J. Bryan, D. Sessanna, J. Murakami, P. Schmalbrock, K. Powell, B. Welling, Temporal bone dissection simulation – an update, Stud. Health Technol. Inform. 85 (2002) 507–513. [8] G.J. Wiet, D. Stredney, D. Sessanna, J.A. Bryan, D.B. Welling, P. Schmalbrock, Virtual temporal bone dissection: an interactive surgical simulator, Otolaryngol. Head Neck Surg. 127 (2002) 79–83. [9] G.J. Wiet, P. Schmalbrock, K. Powell, D. Stredney, Use of ultra-high-resolution data for temporal bone dissection simulation, Otolaryngol. Head Neck Surg. 133 (2005) 911–915. [10] M. Agus, A. Giachetti, E. Gobetti, G. Zanetti, A. Zorcolo, Tracking the movement of surgical tools in a virtual temporal bone dissection simulator, in: N. Ayache, H. Delingette (Eds.), Surgery Simulation and Soft Tissue Modeling, vol. 2673, Springer, New York, Berlin, Heidelberg, 2003, pp. 100–107. [11] F.D. Davis, Perceived usefulness, perceived ease of use, and user acceptance of information technology, MIS Quart. 13 (1989) 319–340. [12] S.B. Issenberg, W.C. McGaghie, E.R. Petrusa, D. Lee Gordon, R.J. Scalese, Features and uses of high-fidelity medical simulations that lead to effective learning: a BEME systematic review, Med. Teach. 27 (2005) 10–28. [13] W.C. McGaghie, S.B. Issenberg, E.R. Petrusa, R.J. Scalese, Effect of practice on standardised learning outcomes in simulation-based medical education, Med. Educ. 40 (2006) 792–797. [14] L.F. Bastos, W. van Meurs, D. Ayres-de-Campos, A model for educational simulation of the evolution of uterine contractions during labor, Comput. Methods Programs Biomed. 107 (2012) 242–247. [15] B. Wheeler, P.C. Doyle, S. Chandarana, S. Agrawal, M. Husein, H.M. Ladak, Interactive computer-based simulator for training in blade navigation and targeting in myringotomy, Comput. Methods Programs Biomed. 98 (2010) 130–139. [16] R. Buttin, F. Zara, B. Shariat, T. Redarce, G. Grangé, Biomechanical simulation of the fetal descent without
c o m p u t e r m e t h o d s a n d p r o g r a m s i n b i o m e d i c i n e 1 1 3 ( 2 0 1 4 ) 674–681
imposed theoretical trajectory, Comput. Methods Programs Biomed. 111 (2013) 389–401. [17] V. Luboz, Y. Zhang, S. Johnson, Y. Song, C. Kilkenny, C. Hunt, H. Woolnough, S. Guediri, J. Zhai, T. Odetoyinbo, P. Littler, A. Fisher, C. Hughes, N. Chalmers, D. Kessel, P.J. Clough, J. Ward, R. Phillips, T. How, A. Bulpitt, N.W. John, F. Bello, D. Gould, ImaGiNe Seldinger: first simulator for Seldinger technique and angiography training, Comput. Methods Programs Biomed. 111 (2013) 419–434. [18] T.J. Draycott, J.F. Crofts, J.P. Ash, L.V. Wilson, E. Yard, T. Sibanda, A. Whitelaw, Improving neonatal outcome through practical shoulder dystocia training, Obstet. Gynecol. 112 (2008) 14–20. [19] N.E. Seymour, A.G. Gallagher, S.A. Roman, M.K. O’Brien, V.K. Bansal, D.K. Andersen, R.M. Satava, Virtual reality training improves operating room performance: results of a randomized, double-blinded study, Ann. Surg. 236 (2002) 458–463.
681
[20] M.G. Blum, T.W. Powers, S. Sundaresan, Bronchoscopy simulator effectively prepares junior residents to competently perform basic clinical bronchoscopy, Ann. Thorac. Surg. 78 (2004) 287–291. [21] VES Visible Ear Simulator, Available from: http://www.daimi.au.dk/∼trier/VES blog/?page id=11 (accessed 05.04.13). [22] M.S. Sorensen, J. Mosegaard, P. Trier, The visible ear simulator: a public PC application for GPU-accelerated haptic 3D simulation of ear surgery based on the visible ear data, Otol. Neurotol. 30 (2009) 484–487. [23] S. Khemani, A. Arora, A. Singh, N. Tolley, A. Darzi, Objective skills assessment and construct validation of a virtual reality temporal bone simulator, Otol. Neurotol. 33 (2012) 1225–1231. [24] Y.C. Zhao, G. Kennedy, R. Hall, S. O’Leary, Differentiating levels of surgical experience on a virtual reality temporal bone simulator, Otolaryngol. Head Neck Surg. 143 (5 Suppl. 3) (2010) S30–S35.
journal homepage: www.intl.elsevierhealth.com/journals/cmpb
Evaluation of a haptics-based virtual reality temporal bone simulator for anatomy and surgery training Te-Yung Fang a,b,1 , Pa-Chun Wang a,b,c,d,1 , Chih-Hsien Liu a , Mu-Chun Su e , Shih-Ching Yeh e,∗ a
Department of Otolaryngology, Cathay General Hospital, Taipei, Taiwan Fu Jen Catholic University School of Medicine, New Taipei City, Taiwan c Department of Public Health, China Medical University, Taichung, Taiwan d School of Medicine, Taipei Medical University, Taipei, Taiwan e Department of Computer Science and Information Engineering, National Central University, Taoyuan, Taiwan b
a r t i c l e
i n f o
a b s t r a c t
Article history:
Introduction: Virtual reality simulation training may improve knowledge of anatomy and
Received 31 August 2013
surgical skills. We evaluated a 3-dimensional, haptic, virtual reality temporal bone simulator
Received in revised form
for dissection training.
4 November 2013
Methods: The subjects were 7 otolaryngology residents (3 training sessions each) and 7
Accepted 8 November 2013
medical students (1 training session each). The virtual reality temporal bone simulation station included a computer with software that was linked to a force-feedback hand stylus,
Keywords:
and the system recorded performance and collisions with vital anatomic structures. Sub-
Medical education
jects performed virtual reality dissections and completed questionnaires after the training
Virtual environment
sessions.
Haptics
Results: Residents and students had favorable responses to most questions of the technol-
Otolaryngology
ogy acceptance model (TAM) questionnaire. The average TAM scores were above neutral
Anatomic dissection
for residents and medical students in all domains, and the average TAM score for resi-
Surgical technique
dents was significantly higher for the usefulness domain and lower for the playful domain than students. The average satisfaction questionnaire for residents showed that residents had greater overall satisfaction with cadaver temporal bone dissection training than training with the virtual reality simulator or plastic temporal bone. For medical students, the average comprehension score was significantly increased from before to after training for all anatomic structures. Medical students had significantly more collisions with the dura than residents. The residents had similar mean performance scores after the first and third training sessions for all dissection procedures. Discussion: The virtual reality temporal bone simulator provided satisfactory training for otolaryngology residents and medical students. © 2013 Published by Elsevier Ireland Ltd.
∗
Corresponding author at: Department of Computer Science and Information Engineering, National Central University, No. 300, Jhongda Rd., Jhongli City, Taoyuan County 32001, Taiwan. Tel.: +886 3 4227151x35216; fax: +886 3 4222681. E-mail address: [email protected] (S.-C. Yeh). 1 Te-Yung Fang and Pa-Chun Wang are the joint first authors. 0169-2607/$ – see front matter © 2013 Published by Elsevier Ireland Ltd. http://dx.doi.org/10.1016/j.cmpb.2013.11.005
c o m p u t e r m e t h o d s a n d p r o g r a m s i n b i o m e d i c i n e 1 1 3 ( 2 0 1 4 ) 674–681
1.
675
Introduction
During the past century, there have been major improvements in patient safety and health care quality and increased complexity of available technical services. Therefore, the informal clinical training that uses the “see one, do one, teach one” [1] approach may no longer be adequate. Simulation is being used in medical education for multiple specialties including emergency medicine, pediatrics, anesthesiology, obstetrics and gynecology, and surgery. Development of medical skills may be better with simulation than traditional clinical education [2]. The temporal bone is the most intricate and complex structure encountered by otolaryngologists. It is necessary to know the 3-dimensional anatomy of the temporal bone to understand the pathophysiology and treatment of otologic disorders, and otolaryngologists have used cadaver temporal bone dissection to learn temporal bone anatomy and improve surgical skills, hand-eye coordination, and fine motor skills [3]. Although temporal bone laboratories and dissection courses are available for resident training, they may be inaccessible to otolaryngology residents because of geographic distance, scheduling difficulties, and high cost. Furthermore, it may be difficult to obtain cadaver temporal bones in some countries because of cultural and religious practices or legal restrictions. Alternatives to cadaver temporal bone dissection include plastic and virtual reality temporal bone simulators. The virtual reality temporal bone simulator is a computer screenbased simulation, analogous to a video game. The trainee interacts with a 3-dimensional temporal bone using a haptic (tactile) interface. The 3-dimensional images are created with volume rendering techniques using high resolution computed tomography scans of cadaver temporal bones. The haptic feedback device, also used in simulation for dental implant surgery [4], may detect contact between the virtual surgical burr and the volume rendered data and calculates the force feedback to the tools. Bone erosion is simulated by decreasing the density of voxels [5–10]. The availability of temporal bone simulation has increased because of advances in computer technology and lower costs. Simulation may be used economically in the early stages of learning temporal bone anatomy and surgery, and residents may use the virtual reality temporal bone simulator before participating in cadaver temporal bone dissections. In addition, medical students may use the temporal bone simulator to learn temporal bone anatomy. We hypothesized that the virtual reality temporal bone simulator may improve the learning experience of otolaryngology residents and medical students. The purpose of the present study was to evaluate the technology acceptance, satisfaction and skill development with this system.
2.
Materials and methods
2.1.
Subjects
The subjects recruited were 7 otolaryngology residents in their second through fifth year of postgraduate training and 7
Fig. 1 – The virtual reality temporal bone simulation station, including a computer screen, specialized software, and hand stylus. Subjects followed the software tutorial description and used the virtual drill to perform surgical procedures.
voluntary medical students in their fifth through seventh year of medical school at the Cathay General Hospital. All the residents had the experiences of the plastic and cadaver temporal bone dissections (one to two times for both) before performing the virtual reality temporal bone simulation. The study was approved by the Cathay General Hospital Institutional Review Board committee.
2.2.
Virtual reality temporal bone simulation
The virtual reality temporal bone simulation station included a computer with software linked to a force-feedback hand stylus (Visible Ear Simulator, Alexandra Institute, Aarhus, Denmark and ENT Department, Rigshospitalet, Copenhagen, Denmark). The software provided real-time simulation of temporal bone surgery and an interactive, 3-dimensional representation of the temporal bone with specialized red and blue eyeglasses (Anaglyph 3D glasses, Rainbow Symphony Inc., Reseda, CA). The system used volumetric, high-resolution images of the temporal bone, and the colors of vital structures were similar to the colors in vivo. The system enabled users to adjust bone transparency and vital structure opacity to explore spatial relations of the sinus, middle and posterior fossa, facial nerve, and inner ear. The simulated drill included a hand stylus and specialized software (PHANTOM OMNI Haptic Device, Geomagic Sensable Group, Wilmington, MA) and allowed users to feel the change in pressure while drilling and to see changes in tissue as the drill cut through the simulated temporal bone (Fig. 1). Users could change the temporal bone orientation, magnification, drill size, and drill type. The software enabled measurement of performance for the important steps of temporal bone dissection, providing
676
c o m p u t e r m e t h o d s a n d p r o g r a m s i n b i o m e d i c i n e 1 1 3 ( 2 0 1 4 ) 674–681
Fig. 2 – Summary of the study protocol to evaluate the virtual reality temporal bone simulator.
an objective evaluation for the users. Performance scores included the volume of reference bone removed; collisions with the dura, facial nerve, inner ear, stapes, malleus, and incus; and time to perform the procedure.
2.3.
Procedure
Before the virtual reality dissection sessions, all subjects participated in a standardized session to become familiar with the system, including interface orientation and hands-on experience with introductory tasks (Fig. 2). Subsequently, the subjects performed the virtual reality dissections (residents, 3 sessions at 1-week intervals; medical students, 1 session after learning the anatomy from adjusting the visual settings to explore spatial relations of the vital structures) and followed the stepwise tutorial description for dissection tasks provided on the computer screen. The dissection tasks performed in sequence by each subject included an initial surface cut, saucerization of mastoid cavity, antrum opening, tegmen exposure, sigmoid and sinodural angle exposure, atticotomy, mastoid tip opening, posterior canal wall thinning, posterior tympanotomy, semicircular canal (lateral, posterior, and superior) outlining with a blue line, endolymphatic sac exposure, cochleostomy, and radical mastoidectomy.
2.4.
Outcome measures
After the subjects completed dissection sessions with the virtual reality temporal bone simulator, they completed questionnaires that were designed for the study. (1) The technology acceptance model (TAM) questionnaire evaluated how users accepted and used new technology. The TAM suggested that the system design characteristics may directly affect 3 main factors: “perceived ease of use,” “perceived usefulness,” and “attitude toward using the system”; these main factors may determine whether the user will use or reject the system [11]. The TAM questionnaire included 44 items to evaluate 7 domains: awareness, presence, usefulness, playfulness, ease of use, attitude, and intention to use (Tables 1 and 2). The items were rated on a 5-point Likert
scale (1, very untrue; 2, unture; 3, neutral; 4, true; 5, very true). The TAM questionnaire was completed by all participants upon completion of the virtual reality training; however, medical students did not answer TAM questions 19–22 because these questions evaluated the application of learned skills to cadaver dissection and surgery. (2) The satisfaction questionnaire for otolaryngology residents included 10 items to assess skill development, learning effect, appropriateness for individual needs, environment, and overall satisfaction with different training methods (virtual reality simulator, plastic bone, and cadaver bone) (Table 3). The satisfaction questionnaire was completed after the virtual reality training by the otolaryngology residents and not the medical students. Residents also were interviewed for qualitative comments about the simulator training. (3) The medical student questionnaire evaluated comprehension of anatomy and not surgical skills (Table 4). Although the medical students performed the surgical dissection tasks with the virtual reality temporal bone simulator, the main goal of medical students was to learn temporal bone anatomy. The medical student questionnaire was designed to evaluate knowledge improvement of temporal bone anatomy, dissection procedure understanding, and interest in otology after using the simulator. The comprehension for 5 anatomic structures (tegmen, sigmoid sinus, facial nerve, semicircular canals, ossicles) was rated on a 3-point Likert scale (1, not clear; 2, probably understood; 3, very well understood). The medical student questionnaire was completed by the medical students before and after the virtual reality session, and it was not completed by the otolaryngology residents. Medical students also were interviewed about their interest in otology and usefulness of the simulator training. The virtual reality temporal bone simulator recorded technical errors by determining the number of collisions by each subject with 6 vital anatomic structures (Table 5). Performance scores recorded for otolaryngology residents during each training session were based on the percentage of the volume of reference bone removed, which was from the built-in performance metrics, during 15 key steps of temporal bone dissection (Table 6). The time to complete the dissection
c o m p u t e r m e t h o d s a n d p r o g r a m s i n b i o m e d i c i n e 1 1 3 ( 2 0 1 4 ) 674–681
training session was not analyzed because the participants were allowed to divide the training sessions for convenience.
2.5.
Statistical analysis
Table 1 – Evaluation of the virtual reality temporal bone simulator with the technology acceptance model questionnaire in otolaryngology residents and medical students.a TAM questionnaire item
Data were analyzed with spreadsheet software (Microsoft Excel 2010, Microsoft Corp., Redmond, WA). Residents and medical students were compared with t-test. Satisfaction of residents with the 3 types of temporal bone dissection training was evaluated with 1-way analysis of variance. Statistical significance was defined by P < 0.05.
3.
Results
In all 14 participants (7 otolaryngology residents and 7 medical students), there were favorable responses predominating for all questions (and questions TAM 19–22, which were not answered by medical students) (Table 1). The average TAM score for residents was significantly higher for the usefulness domain and lower for the playful domain than medical students (Table 2). The average satisfaction questionnaire for residents showed that residents had greater overall satisfaction with cadaver temporal bone dissection training more than training with the virtual reality simulator or plastic temporal bone (Table 3). When comparing between the virtual reality simulator and plastic temporal bone, the plastic temporal bone was rated better in sense of reality, and the simulator was rated better in learning anatomy (Table 3). All residents agreed that simulator training could improve efficiency, increase confidence level, increase carefulness near vital structures (because of the warning pop-out in the simulator), and decrease mistakes during subsequent cadaver dissection training. All medical students agreed that they had improved comprehension of temporal bone anatomy from before to after the simulation training, and average comprehension score was significantly increased from before to after training for all anatomic structures (Table 4). All students stated that the simulator training increased their interest in otology, but they could not become proficient with temporal bone dissection procedures with only 1 simulator training session. The average performance scores were similar between the first simulation training session for residents and the single simulation session for medical students (data not shown). However, medical students had significantly more collisions with the dura than residents (Table 5). The medical students also had more collisions with the facial nerve and the labyrinth than the residents even though there was no significant difference. The residents had similar mean performance score after the first and third training sessions for all dissection procedures (Table 6).
4.
Discussion
The present results showed that the virtual reality temporal bone simulator provided satisfactory training for otolaryngology residents and medical students. Average TAM scores were above neutral for residents and medical students in all
677
A. Awareness TAM 1 The images display the drilled and undrilled bone. TAM 2 The images show the correct spot and the correct depth of the drilled bone. TAM 3 The tutor window demonstrates the current step and the unfinished steps. TAM 4 The warning system reminds me about the important structures. TAM 5 The build-in performance scores help me know my performance. TAM 6 The build-in performance scores remind me to avoid the important structures. TAM 7 The haptic force-feedback system helps me know whether the drill touches the target location. TAM 8 The haptic force-feedback system helps me know the strength of drilling bones. B. Presence TAM 9 The function of opacity adjustment of the important structures helps me know the temporal bone anatomy. TAM 10 The presentation of the virtual drill helps me know how to apply the drill with the correct direction. TAM 11 There is no lag time between motion of my hands and the virtual drill on the screen. TAM 12 The 3D images help to perceive the correct location of the drills. TAM 13 The 3D images demonstrate the target location of drilling on the temporal bone. TAM 14 The 3D images show the distance between the drill tip and the target location on the temporal bone. C. Usefulness TAM 15 The simulator helps to learn the dissection procedures. TAM 16 The simulator helps to learn the temporal bone anatomy. TAM 17 The simulator helps to learn how to select the drills during the dissection. TAM 18 The simulator helps to learn the manipulation of the drills. TAM 19 What I have learned from the simulator can be applied to the cadaver temporal bone dissection. TAM 20 What I have learned from the simulator can improve the efficiency of cadaver temporal bone dissection. TAM 21 What I have learned from the simulator can increase my confidence when performing cadaver temporal bone dissection. TAM 22 What I have learned from the simulator can be applied to surgery on patients. D. Playfulness TAM 23 I feel time pass quickly when using this simulation. TAM 24 I usually forget the goals of training because of being engrossed in playing the simulator. TAM 25 I feel happy when using this simulation.
Score 4.0 ± 0.6 3.6 ± 0.6 3.9 ± 0.5 4.2 ± 0.7 3.9 ± 0.8 3.7 ± 0.7 3.9 ± 0.7 3.4 ± 0.9
4.1 ± 0.7
3.4 ± 0.7
4.1 ± 0.5 3.6 ± 0.7 4.0 ± 0.6 3.5 ± 0.7
4.2 ± 0.6 4.3 ± 0.6 3.6 ± 0.6 3.6 ± 0.5 4.3 ± 0.5
4.1 ± 0.4
4.1 ± 0.4
4.1 ± 0.0
3.5 ± 1.0 3.3 ± 0.9 3.6 ± 1.1
678
c o m p u t e r m e t h o d s a n d p r o g r a m s i n b i o m e d i c i n e 1 1 3 ( 2 0 1 4 ) 674–681
Table 1 (Continued) TAM questionnaire item TAM 26 This temporal bone dissection simulation is interesting. E. Ease of use TAM 27 Learning how to operate this simulation is easy. TAM 28 I can use this simulation with ease. TAM 29 I can use this simulation comfortably. TAM 30 I still can use this simulation if nobody teaches me how to use it. TAM 31 This simulation takes me a long time to learn the operation.b TAM 32 I need to concentrate during use of the simulation. TAM 33 The message in the simulation helps me finish every step smoothly. TAM 34 The design of the simulation helps me complete temporal bone dissection smoothly. F. Attitude TAM 35 I have a positive attitude about the simulation. TAM 36 The simulation is a good method of learning temporal bone dissection. TAM 37 I like the idea of “virtual temporal bone dissection.” TAM 38 Using this simulation gives me a lot of fun. TAM 39 Overall, I take pleasure in using the simulation. G. Intention to use TAM 40 The simulation makes me have strong will to learn temporal bone dissection. TAM 41 The simulation encourages me to perfect the temporal bone dissection. TAM 42 The simulation encourages me to comprehend temporal bone anatomy more. TAM 43 I wish I could keep practicing the temporal bone dissection on this simulation. TAM 44 I will recommend this simulation to other doctors or students. a
b
Score 3.9 ± 0.9
Table 2 – Summary of the technology acceptance model questionnaire for residents and students who used the virtual reality temporal bone simulator.a TAM questionnaire domain
Residents
3.8 ± 1.0 3.9 ± 0.8 3.8 ± 0.8 4.0 ± 0.8 3.2 ± 0.8 3.6 ± 0.6
Awareness Presence Usefulness Playful Ease of use Attitude Intention to use a
4.0 ± 0.4 4.0 ± 0.4
3.9 ± 0.7 4.1 ± 0.8 3.9 ± 0.6 3.6 ± 0.6 3.7 ± 0.7
4.0 ± 0.8 3.9 ± 0.6 4.1 ± 0.4 3.8 ± 0.7 3.8 ± 0.6
N = 7 otolaryngology residents and 7 medical students. Medical students did not answer TAM questions 19–22 because these questions evaluated the application of learned skills to cadaver dissection and surgery. Data reported as mean ± SD for all subjects combined. TAM questionnaire rating (Likert scale): 1, very untrue; 2, untrue; 3, neutral; 4, true; 5, very true. TAM, technology acceptance model; 3D, 3-dimensional. Reverse item.
domains (Table 2), and medical students had improved comprehension of anatomy after training (Table 4). The present virtual reality system provided all 10 features of effective learning for simulation-based medical education, including (1) a mechanism for repetitive practice; (2) the ability to integrate the system into a curriculum; (3) the potential to change the degree of difficulty; (4) the potential to include clinical variation; (5) practice in a controlled environment; (6) individualized, active learning; (7) adaptability to multiple learning strategies; (8) measurable outcomes; (9) feedback during the experience; and (10) validity of the simulation as an approximation of clinical practice [12,13]. This type of simulation training may improve health care education [14],
b
P≤b
TAM score
3.8 3.8 4.1 3.2 3.9 3.9 4.1
± ± ± ± ± ± ±
0.4 0.5 0.3 0.8 0.3 0.3 0.4
Students 3.8 3.7 3.8 3.9 3.7 3.8 3.8
± ± ± ± ± ± ±
0.5 0.4 0.2 0.6 0.7 0.8 0.7
NS NS 0.03 0.04 NS NS NS
N = 7 residents and 7 students. Data presented as mean ± SD. TAM, technology acceptance model. TAM questionnaire rating (Likert scale): 1, very untrue; 2, untrue; 3, neutral; 4, true; 5, very true. NS, not significant; P > 0.05
practice, patient safety, and surgical training [15–17]. The skills obtained from medical simulation laboratories may be transferred directly to clinical situations such as difficult obstetric deliveries [18], laparoscopic surgery [19], and bronchoscopy [20]. The software for the virtual reality system used in the present study was available without charge for download from the Internet [21,22]. The effect of the built-in learning and performance metrics had not been assessed to date. Other virtual reality temporal bone simulators are commercially available (VOXEL-MAN TempoSurg Simulator, VOXEL-MAN Group, Hamburg, Germany; Mediseus Surgical Drilling Simulator, Medic Vision, Melbourne, Victoria, Australia) that may differentiate between levels of trainee experience [23,24]. The TAM questionnaire showed that both residents and medical students scored the temporal bone simulator positively in all domains (Table 2). There was consensus among residents that the simulator could improve understanding of 3-dimensional anatomic relations and surgical steps; increase drilling skills and efficiency; decrease injuries; increase confidence; and provide preparation for cadaver temporal bone training. The satisfaction evaluation showed that simulator training was similar to plastic temporal bone training. The simulator included user-controlled transparency, shadowing, tinting, and visibility functions for all relevant anatomic structures, which made simulator training more satisfactory than plastic temporal bone training for learning anatomy (Table 3). However, simulator training may not be a satisfactory substitute for cadaver temporal bone training, which may provide irreplaceable and invaluable experience with anatomic variation (Table 3). The performance measures with virtual reality simulator systems may provide trainees immediate feedback and may help trainers differentiate levels of proficiency. Systems with adequate sensitivity may be integrated into surgical curricula to assess training results. However, the present study did not distinguish the performance level between the residents in the first training session and medical students (data not shown). Since performance scores were calculated based on percentage of reference bone volume removed; it is speculated that students, who were not familiar with the dissection
679
c o m p u t e r m e t h o d s a n d p r o g r a m s i n b i o m e d i c i n e 1 1 3 ( 2 0 1 4 ) 674–681
Table 3 – Comparison of satisfaction of otolaryngology residents with different training methods for temporal bone dissection.a Satisfaction questionnaire item
Temporal bone Simulator
Learning anatomy Learning anatomic variants Learning procedures Drilling skills Sense of reality Meet individualized requirements Meet individualized level Comfortable environment Transfer to real surgery Overall satisfaction a b c
4.4 3.3 4.1 3.4 3.0 4.3 3.6 4.3 3.6 4.3
± ± ± ± ± ± ± ± ± ±
0.5 0.5 0.4 0.5 0.0 0.5 0.5 0.8 0.5 0.5
Plastic
P≤b
Cadaver
± ± ± ± ± ± ± ± ± ±
0.006 NS NS NS 0.014 NS NS NS NS NS
4.6 4.6 4.3 4.6 4.6 4.6 4.9 4.3 4.9 4.9
3.6 3.6 3.9 3.7 3.7 4.1 3.6 4.0 3.6 4.4
0.5 0.8 0.7 0.8 0.8 0.7 0.5 0.8 0.5 0.5
± ± ± ± ± ± ± ± ± ±
P≤c
0.5 0.5 0.5 0.5 0.5 0.5 0.4 0.5 0.4 0.4
NS 0.002 NS 0.006 0.001 NS 0.001 NS 0.001 0.015
N = 7 otolaryngology residents. Satisfaction scale: 1, very dissatisfied; 2, dissatisfied; 3, neutral; 4, satisfied; 5, very satisfied. Comparison between virtual reality simulator and plastic temporal bone. NS, not significant; P > 0.05 Comparison between virtual reality simulator and cadaver temporal bone. NS, not significant; P > 0.05
procedures, might have removed more bone but injured many vital structures as well. Even though the changes of performance were not statistically significant for residents after 3 training sessions (Table 6), we did observe some improvement in scores from this small group of trainees. Nevertheless, the system distinguished between residents and medical students with lower collisions among residents (Table 5), probably because of better anatomic knowledge and surgical experience among the residents. The residents were more aware of the risk to anatomic structures and may have used more caution, but the students may have been unaware of the potential for injury to the anatomic structures. Therefore, the present system may potentially distinguish between experienced and inexperienced surgeons. Limitations of the present virtual reality temporal bone simulator include the availability of images for just 1 normal human specimen. This may be adequate for basic medical student training, but residents may need a higher level of training with more variations of anatomy and pathology. In addition, the performance score may not distinguish different levels of surgical training (Table 6), and the trainer may need a more sensitive scoring system or use the combination results of performance scores and collision numbers to evaluate different levels of experience. Furthermore, the training simulator may emphasize the final results, and additional features may be needed to train and evaluate earlier steps for safety and proficiency. The simulation training may increase the risk of overconfidence; a good outcome in the simulation may not guarantee good performance in live surgery, which requires skills, preoperative medical decision making and planning, good team communication, appropriate response to blood in the surgical field or unexpected anatomy, and surgical judgment under pressure. Despite these limitations, the present study showed that virtual reality simulation training for residents and medical students may increase knowledge of anatomy and may be useful before cadaver temporal bone dissection training. The virtual reality system has the advantages of minimal setup, no cleanup, minimal cost, and high daily accessibility and convenience without constraints of clinical schedules. Residents may perform some steps of simulated temporal bone
Table 4 – Comprehension of temporal bone anatomy by medical students before and after using the virtual reality temporal bone simulator.a Anatomic structure
Comprehension score Before
Tegmen Sigmoid sinus Facial nerve Semicircular canal Ossicles a
b
1.6 1.4 2.0 1.6 2.0
± ± ± ± ±
0.8 0.5 0.6 0.5 0.6
P≤b
After 2.0 2.3 2.4 2.4 2.6
± ± ± ± ±
0.6 0.5 0.5 0.5 0.5
0.04 0.0005 0.04 0.0005 0.02
N = 7 medical students. Data presented as mean ± SD. Comprehension score: 1, not clear; 2, probably understood; 3 very well understood. NS, not significant; P > 0.05.
dissection during brief periods. The safe, consistent, predictable, and reproducible materials may decrease time needed for direct supervision. In addition, the built-in performance measures for key steps of temporal bone dissection may provide immediate feedback to the trainee. Therefore, the virtual reality simulator may provide an effective, efficient, and economical training program during early stages of
Table 5 – Collisions with vital structures during training with the virtual reality temporal bone simulator by otolaryngology residents and medical students.a Anatomic structure
Residentsc Dura Facial nerve Labyrinth Stapes Malleus Incus a
b c
P≤b
Collision score
8 18 10 2 0.3 1
± ± ± ± ± ±
12 17 7 1 0.5 2
Students 37 27 31 1 1 2
± ± ± ± ± ±
39 21 35 2 1 3
0.05 NS NS NS NS NS
N = 7 residents and 7 students. Data reported as the average number of collisions for each anatomic region (mean ± SD). NS, not significant; P > 0.05. After the first training session.
680
c o m p u t e r m e t h o d s a n d p r o g r a m s i n b i o m e d i c i n e 1 1 3 ( 2 0 1 4 ) 674–681
Table 6 – Performance scores of first and third training sessions of otolaryngology residents with the virtual reality temporal bone simulator.a Procedure First score (%) Initial surface cut Saucerization Antrum opening Tegmen exposure Sigmoid and sinodural angle exposure Atticotomy Mastoid tip opening Posterior canal wall thinning Posterior tympanotomy Semicircular canal outlining with blue line Lateral Posterior Superior Endolymphatic sac exposure Cochleostomy Radical mastoidectomy a b
P≤b
Training session Third score (%)
65 93 88 91 90 92 87 88 91
± ± ± ± ± ± ± ± ±
15 8 7 6 7 4 8 7 5
73 90 93 94 93 94 91 92 92
± ± ± ± ± ± ± ± ±
16 14 4 3 2 2 5 4 4
NS NS NS NS NS NS NS NS NS
91 92 90 91 91 88
± ± ± ± ± ±
5 5 5 6 5 8
92 92 91 92 91 87
± ± ± ± ± ±
4 4 4 4 3 3
NS NS NS NS NS NS
N = 7 residents. Data presented as mean ± SD. Performance scores: the percentage of volume of reference bone removed. NS, not significant; P > 0.05.
learning and may decrease the dependency on cadaver temporal bone or live surgery to achieve the necessary competency. The incorporation of this simulator in surgical curricula may improve complex anatomic knowledge, surgical skills, and confidence, especially in programs that have limited access to human cadaver temporal bone specimens.
Acknowledgement The authors thank Ms. Li-Ju Chuang for data management in reporting outcomes. This study was supported by the joint research fund (project number: 101 CGH-NCU-A4) of Cathay General Hospital and National Central University of Taiwan.
references
[1] W.S. Halsted, The training of the surgeon, Bull. Johns Hopkins Hosp. 15 (1904) 267–275. [2] W.C. McGaghie, S.B. Issenberg, E.R. Cohen, J.H. Barsuk, D.B. Wayne, Does simulation-based medical education with deliberate practice yield better results than traditional clinical education? A meta-analytic comparative review of the evidence, Acad. Med. 86 (2011) 706–711. [3] E.A. Duckworth, F.E. Silva, J.P. Chandler, H.H. Batjer, J.C. Zhao, Temporal bone dissection for neurosurgery residents: identifying the essential concepts and fundamental techniques for success, Surg. Neurol. 69 (2008) 93–98. [4] F. Zheng, W.F. Lu, Y.S. Wong, K.W. Foong, An analytical drilling force model and GPU-accelerated haptics-based simulation framework of the pilot drilling procedure for micro-implants surgery training, Comput. Methods Programs Biomed. 108 (2012) 1170-1184. [5] T. Harada, S. Ishii, N. Tayama, Three-dimensional reconstruction of the temporal bone from histologic sections, Arch. Otolaryngol. Head Neck Surg. 114 (1988) 1139–1142.
[6] R.B. Kuppersmith, R. Johnston, D. Moreau, R.B. Loftin, H. Jenkins, Building a virtual reality temporal bone dissection simulator, Stud. Health Technol. Inform. 39 (1997) 180–186. [7] D. Stredney, G.J. Wiet, J. Bryan, D. Sessanna, J. Murakami, P. Schmalbrock, K. Powell, B. Welling, Temporal bone dissection simulation – an update, Stud. Health Technol. Inform. 85 (2002) 507–513. [8] G.J. Wiet, D. Stredney, D. Sessanna, J.A. Bryan, D.B. Welling, P. Schmalbrock, Virtual temporal bone dissection: an interactive surgical simulator, Otolaryngol. Head Neck Surg. 127 (2002) 79–83. [9] G.J. Wiet, P. Schmalbrock, K. Powell, D. Stredney, Use of ultra-high-resolution data for temporal bone dissection simulation, Otolaryngol. Head Neck Surg. 133 (2005) 911–915. [10] M. Agus, A. Giachetti, E. Gobetti, G. Zanetti, A. Zorcolo, Tracking the movement of surgical tools in a virtual temporal bone dissection simulator, in: N. Ayache, H. Delingette (Eds.), Surgery Simulation and Soft Tissue Modeling, vol. 2673, Springer, New York, Berlin, Heidelberg, 2003, pp. 100–107. [11] F.D. Davis, Perceived usefulness, perceived ease of use, and user acceptance of information technology, MIS Quart. 13 (1989) 319–340. [12] S.B. Issenberg, W.C. McGaghie, E.R. Petrusa, D. Lee Gordon, R.J. Scalese, Features and uses of high-fidelity medical simulations that lead to effective learning: a BEME systematic review, Med. Teach. 27 (2005) 10–28. [13] W.C. McGaghie, S.B. Issenberg, E.R. Petrusa, R.J. Scalese, Effect of practice on standardised learning outcomes in simulation-based medical education, Med. Educ. 40 (2006) 792–797. [14] L.F. Bastos, W. van Meurs, D. Ayres-de-Campos, A model for educational simulation of the evolution of uterine contractions during labor, Comput. Methods Programs Biomed. 107 (2012) 242–247. [15] B. Wheeler, P.C. Doyle, S. Chandarana, S. Agrawal, M. Husein, H.M. Ladak, Interactive computer-based simulator for training in blade navigation and targeting in myringotomy, Comput. Methods Programs Biomed. 98 (2010) 130–139. [16] R. Buttin, F. Zara, B. Shariat, T. Redarce, G. Grangé, Biomechanical simulation of the fetal descent without
c o m p u t e r m e t h o d s a n d p r o g r a m s i n b i o m e d i c i n e 1 1 3 ( 2 0 1 4 ) 674–681
imposed theoretical trajectory, Comput. Methods Programs Biomed. 111 (2013) 389–401. [17] V. Luboz, Y. Zhang, S. Johnson, Y. Song, C. Kilkenny, C. Hunt, H. Woolnough, S. Guediri, J. Zhai, T. Odetoyinbo, P. Littler, A. Fisher, C. Hughes, N. Chalmers, D. Kessel, P.J. Clough, J. Ward, R. Phillips, T. How, A. Bulpitt, N.W. John, F. Bello, D. Gould, ImaGiNe Seldinger: first simulator for Seldinger technique and angiography training, Comput. Methods Programs Biomed. 111 (2013) 419–434. [18] T.J. Draycott, J.F. Crofts, J.P. Ash, L.V. Wilson, E. Yard, T. Sibanda, A. Whitelaw, Improving neonatal outcome through practical shoulder dystocia training, Obstet. Gynecol. 112 (2008) 14–20. [19] N.E. Seymour, A.G. Gallagher, S.A. Roman, M.K. O’Brien, V.K. Bansal, D.K. Andersen, R.M. Satava, Virtual reality training improves operating room performance: results of a randomized, double-blinded study, Ann. Surg. 236 (2002) 458–463.
681
[20] M.G. Blum, T.W. Powers, S. Sundaresan, Bronchoscopy simulator effectively prepares junior residents to competently perform basic clinical bronchoscopy, Ann. Thorac. Surg. 78 (2004) 287–291. [21] VES Visible Ear Simulator, Available from: http://www.daimi.au.dk/∼trier/VES blog/?page id=11 (accessed 05.04.13). [22] M.S. Sorensen, J. Mosegaard, P. Trier, The visible ear simulator: a public PC application for GPU-accelerated haptic 3D simulation of ear surgery based on the visible ear data, Otol. Neurotol. 30 (2009) 484–487. [23] S. Khemani, A. Arora, A. Singh, N. Tolley, A. Darzi, Objective skills assessment and construct validation of a virtual reality temporal bone simulator, Otol. Neurotol. 33 (2012) 1225–1231. [24] Y.C. Zhao, G. Kennedy, R. Hall, S. O’Leary, Differentiating levels of surgical experience on a virtual reality temporal bone simulator, Otolaryngol. Head Neck Surg. 143 (5 Suppl. 3) (2010) S30–S35.
