Virtual reality is a human-computer interface that simulates real environments and allows the user to face them. Such a system is like looking at three-dimensional images on a two-dimensional computer screen, similar to looking into the water from the bottom of a boat. In fact, it is as if he was inspecting his surroundings without getting wet by wearing a diving suit and diving into the water.
This system has many applications in terms of education and health in distance education and also in telemedicine . For example, in order to train surgeons before surgery, it is possible to provide a virtual environment for a physician to perform surgery on a virtual patient.
Due to the uncontrolled increase of Internet sites in the world, the competition of sites in attracting users is increasing day by day. In the meantime, sites that have more interaction with the user in addition to beautiful appearance have been more successful. A review of the top 100 Internet sites has shown that most of these sites have used advertising, 2D and 3D animation.
Think of the grid as a place through which you can walk in three-dimensional spaces, pick up objects, watch them, and cross other spaces.
فضThese spaces will be offered in a network environment based on virtual reality. In this environment, you will be able to visit the beautiful art galleries, or see inside the human brain, visit the library and easily open the desired book in the space. Read it interestingly, enter the space of the story and join the characters and events, which in fact is the promise of virtual reality in the network. The person typically uses a HMD Head Mounted Display (HMD) that has a sensor to track a person's movements and position. The sensors actually send data about a person's position and movements to the computer to update the virtual image. کردن. In this way, the person feels completely floating in this three-dimensional virtual environment. With recent advances in high-speed processors and computer graphics, PCs are now able to produce such real-world virtual environments.
Today, Virtual Reality (VR) is used by architects in various fields such as building design and interior decoration, remote control of robots (NASA), training and practice of difficult surgeries by surgeons.
virtual reality
An electronic environment that mimics reality using three-dimensional visual effects but lacks physical materiality. VR, abbreviated VR, is software-computer-generated representation of a concept or environment that is equivalent to reality for the (more visual) senses, and refers to the three-dimensional space created by the computer. In fact, virtual reality uses Advanced technology includes computers and their peripherals and various multimedia tools to create a virtual (simulated) environment. In this environment, the user interacts with virtual objects, events and happenings comparable to the real world using designed converters and special sensors, and observes dramatic and moving images so that one thinks in The real environment is located. Figure 1 shows a schematic of a virtual reality block diagram.
Virtual worlds are created using the virtual reality modeling language or VRML . This language contains instructions for making three-dimensional geometric objects. Programmers and artists in this language use geometric shapes to create complex spaces. On the 3D web, you can navigate with the browser's visual controls (arrows) or with a mouse or keyboard or information gloves or control levers.
Structure of a virtual reality system
The sensory, olfactory, tactile, olfactory, auditory, auditory, visual, auditory, auditory, visual, auditory, visual, visual, auditory, visual, visual, auditory, visual, auditory, visual Imagine a device that sends information to a person but not information about the world around them, but sends artificial information. Information about the imaginary world in such a way that one thinks it is real and deceived, and this becomes virtual reality. This is the real world created by the computer, it seems real, it feels real though it is not real, and sometimes some of the things that are in it seem impossible in the real world. Sometimes you can not see virtual reality without the help of a device. Although these systems all look very different to different applications, they all work the same way. The artificial environment is created by computer hardware software and presented to the user in a way that the user feels like a real environment. To enter this environment, some input tools (including information gloves, etc.) are needed, which control at least three senses (sight, hearing and touch) with the help of a monitor.
Figure 2 shows the complete block diagram of a VR system . In this image, a separate modeling program is used to create individual objects in a virtual environment. Application - Specific Programming Used to simulate the dynamic motion of objects in the real world according to physical laws such as gravity or inertia. Dynamics Generators is a system for tracking the position and movement of the user using the data of input devices such as Data Glove , Head tracker , etc. Renders are for displaying 3D images or sounds in real- time to the user.
Each virtual reality system consists of 4 components in total:
Data
For the virtual world, all the information that defines that world. Things like shape, color of objects and how to move, sound and so on. Medical data can be completely fake or images obtained by X-ray , PET , MRI .
Powerful graphic computer with very high speed
At the center of each virtual reality device is a powerful computer. It stores data about the virtual world and directs the application software to control what is happening in the virtual world. It also takes information from the hardware and makes images and sounds. The computer is usually the generator of reality.
Application software
Software is used for the 3D virtual world that launches virtual reality and produces images, sounds and spaces and displays them. Virtual worlds are created using the virtual reality modeling language or VRML . This language contains instructions for making three-dimensional geometric objects. Programmers and artists in this language use geometric shapes to create complex spaces. VRML , pronounced VRML or Vermil , is an acronym for Virtual Reality Modeling Language.Or the language of virtual reality modeling. The language, which is the development of virtual reality and three-dimensional modeling technologies, was written in May 1994 by Mark Beski, Tons Paris and Gavin Bell. At the Professional Computer Graphics Association, they created a special effects program for the world of interactive 3D animation on the Web, driven by VRML .
Input and output tools
These tools are interfaces between the user and the computer, including:
A - Head display (HMD)
You can see and hear the virtual world with a stereo phone. The most common visual displays are virtual displays that consist of two duct displays for both eyes mounted on the user. These monitors have different viewing angle quality. Figure 3 shows the main components of an HMD .
The three main functions of an HMD system are:
1. Virtual environment display (visual impact)
2. Virtual environment sound (auditory effect)
3- Measuring the angle of the head to calculate and correct the angle of view by a tracking system computer
B - Data Glove
By taking it, you go to the virtual world and move there. Although the keyboard is a good tool for communicating with the computer, it soon became clear that it has a limiting role to play with the virtual environment. So the information glove was created by Thomas Zimmermann (the man who tried to create the virtual guitar) to make contact with the virtual world more natural. Most applications of virtual reality fall into one of three categories: simulation, Incarnation, aversion.
simulation
Simulation means pretending, solving, or imitating something. Virtual worlds are real-world reversals, such as flight simulations or driving in different environments such as physical space environment and ...
Visualization
Visualization means to visualize, to make visible, especially in the minds of virtual worlds that are easier to understand by displaying information in three-dimensional images. Like virtual representations of medical, military and educational activities
Avoidance
Avoidance means the desire to get rid of the reality of the virtual worlds that are created by the imagination of the creature, the likeness of adventure games. One of the basic characteristics of virtual reality is the sense of real presence in the simulated place and control over that simulated environment, which is mostly based on the purpose of users and the technical complexity of their environment using different tools.
The most important application of virtual reality in education - e-commerce - experimental, practical and laboratory research - industrial production architecture and the following:
Virtual stores for better use of e-commerce
Virtual universities whose classrooms and laboratories are all virtual and whose students are located in different parts of the world.
Vehicle movement simulation and driving training, piloting, simulation of various sports, etc.
Remote surgery
Libraries and information centers
Virtual Reality Multiplayer Games and Virtual Entertainment Tools (Figure 1)
In the discussion of e-learning, over the past 20 years, the educational standard has shifted from book-centered and teacher-centered to student-centered, and teaching methods have shifted to critical thinking. As a result, space is not limited to the classroom and educational information can be transferred virtually to a group in different locations. Virtual education eliminates one-way interaction between teacher and student. Because students can ask whenever they want, and the teacher can answer and teach anywhere. In the educational situation, it easily increased the student's motivation by adding a competitive-entertainment aspect.
In virtual education, the class is an interactive video conference in which everyone participates in a virtual space and interacts with each other like a real class. They can even see each other's pictures or have a graphic animation of each other. This is very effective for people with disabilities who can enter the regular classroom.
Advantages of using Virtual environments
این In this environment, the user feels more secure.
In most cases, it costs less to design and implement.
. It is flexible and can be easily changed based on conditions and goals.
It has real users and tremendous potential so that users can experience a life-like model or walk in a safe environment and at the same time have control over that environment. In fact, this may not be possible.
Virtual reality methods
Simulation-based method
The first method of VR implementation is based on simulation. For example, creating a situation in which the driver thinks his car is moving (via audio, visual, and motor inputs). A visit is needed. A navigation system is the interface between the simulator and the driver. A comprehensive data management system and subsystem synchronization are also used.
Image-based method
In this way, people see virtual environments in the form of a real video. The system can manage two groups of users: one participant is distributed in 3D virtual environments in which the user chooses the type of presence according to the capabilities of the system. This method has already created a good environmental interaction between humans and computers. The same technology is often used in VR medical applications, which we will discuss in the following sections.
Facing the projector
Real-environment modeling plays a vital role in real-world applications. Structural modeling, aircraft simulation, the use of image-based VR systems in computer graphics, and computer visual communities are on the rise because of the simplicity of the modeling process.
DESKTOP based
This method uses interactive 3D graphics. Experience shows that 3D images and interactive graphics can take the user into the 3D world. So the goal is actually to create psychological and emotional immersion. One drawback of this method is the lack of vision of peripherals in desktop displays. So that the user is not aware of his virtual space.
Virtual body and organs
In surgical planning, surgeons actually deal with a simulated model of patient information. In surgical training, a very accurate and detailed data is required for an accurate and realistic simulation . Patient information used in VR may be collected from a variety of sources, including:
CT-Scan computed tomography
باMagnetic resonance imaging by MRI
Ultrasound
PET (physiological Imaging )
And ...
After collecting images and information with computer graphic techniques, modeling and rendering are transformed into simulated three-dimensional images of the human body.
Technology volumetric images (Volume Imaging Technologies)
In this technology, a set of data including Voxels is obtained from various techniques of CT , MRI , MRA , ultrasound or PET , SPET , FMRI .
One of the skills that surgeons acquire is 3D visualization from 2D images. In fact, this technique performs the surgeon's work in visualization and provides a three-dimensional visualization of the organ from CT slides and so on. In addition to this advantage, the various images of the source of the combine. As a result, information can be obtained simultaneously from, for example, X-rays of the bones and blood vessels, MRI of an organ.
FaceSurface Rendering Method
Surface rendering actually converts volumes into primary components (geometric features), which is actually based on some kind of iso-contouring template . Thresholding isocentering is the threshold at which data information is required. The presence of noise causes blurring of the boundaries of the areas in the image, which in turn causes the loss of some information compared to the original data. Figure 5 shows the images obtained by this method.
Virtual Reality Applications in Medicine
Imaging, virtual endoscopy, bronchoscopy, and colonoscopy are some of the applications of virtual reality in medicine.
To better understand the difference between classical and virtual endoscopy, a brief description of classical endoscopy is first given. Classical endoscopy is the insertion of an optical system into the patient's organ (colon, stomach, intestine, sinus, etc.) for examination.
Advantage: Create a clear image of the tissue surface for detection
Disadvantages: Possibility of tissue surface injury, semi invasive
Impossibility to pass through the walls of the colon
However, in virtual endoscopy or virtual endoscopy, it is completely non-invasive and the patient is not harmed.
Virtual endoscopy steps:
3D imaging of the target organ ( CT, MRI , etc.)
image preprocessing (registration ) , interpolation ( next three)
Three-dimensional image segmentation to create an anatomical model (segmentation)
Calculate the 3D camera-target path for automatic or manual selection of the observation path
Place repeated views on the track
View in order to produce animation
Suitable for large organs: such as the cardiovascular system, major joints, kidney system, spinal cord
The first VR system for colonoscopy was used in 1995.
Advantages:
No movement limit for the endoscope
Completely non-invasive
No need for hospitalization
Disadvantages:
Current virtual endoscopic techniques do not allow the image to be reconstructed from the surface of the organ tissue.
medical education
The main application of virtual reality in medicine is its use to actively teach anatomy and physiology to medical students. Using this system, students can learn effectively and optimally in a simulated and three-dimensional environment.
Surgical training and assessment assistant
Using the surgical training system, surgery can be performed on the patient thousands of times to maximize the surgeon's skill. In this system, by simulating the surgical environment, it is possible to repeat thousands of surgeries during consecutive and long hours. Among the fields of surgical training in which VR has many applications:
laparoscopic surgery Laparoscopic surgery
heart catheterization simulation Kattrasyvn heart
open surgery Open surgery
Psychiatry
One of the important applications of virtual reality is in the field of psychiatry. In psychiatry, virtual reality is a method of treating mental disorders. One of these is the treatment of phobia. A phobia is a severe fear of a particular object or situation. The patient, knowing that this fear is not real,
He is constantly suffering from anxiety that disrupts his normal life. This fear can include fear of the outdoors, ghosts, suffocation, blood, altitude, water, or other things. In traditional therapy, the doctor puts the patient in a position of fear by talking to them.
In the new treatment, using virtual reality, the environment that the patient is afraid of is simulated, and the patient, knowing that this environment is not real, tries to adapt to it by being in it, and fear Destroy yourself. In addition to treating fear, virtual reality has been used to treat other mental disorders such as autism (autism) and even cases of schizophrenia, and satisfactory results have been obtained. It is also noteworthy that in medical science, in addition to discussing treatment, virtual reality is also used in educational and research fields such as surgery simulation.
Telemedicine
Undoubtedly, Virtual Reality can be considered as one of the most valuable achievements of the evolution of communication communication interfaces , which is characterized by the complete immersion of human sensory-motor dimensions in an experience. It is a virtual communication. A Virtual Environment شی is a dynamic and processed visual representation, often reinforced by other non-visual stimuli (such as hearing and touch), thus instilling in the interactor a sense of interaction with the components of an unreal three-dimensional environment in the present. Does.
Possessing this unique capability, virtual reality has emerged in recent years as an efficient and valuable tool in telemedicine technology, because the processing and transmission of medical information is at the heart of this technology. Virtual reality in telemedicine, as an advanced level of communication, allows intuitive interaction with relevant information, in parallel, in the form of a flexible virtual environment, enhances the feeling of physical presence during the interaction competently.
Applications of virtual reality in medicine include remote surgery, preparation and simulation of different stages of a surgery, training and treatment of remote patients, rehabilitation and skills development in assistants, and even the design and architecture of medical facilities and Rehabilitation, he noted. This article will review recent research on the application of virtual reality in telemedicine, and will list the pros and cons of this issue.
Surgical planning
It is usually performed manually with minimal injuries or with special robots such as Da Vinci. First, valves are created by the surgeon and the surgical instrument and camera are sent into the patient's body. When these valves are opened, they can no longer be moved because otherwise they will not be different from the open surgical method. Therefore, choosing the location of these valves is very important in terms of proper access to the tumor and the possibility of removing it.
This procedure has been sensory until now, and the doctor observes the patient's CT scan results to determine where to make the hole. Because the anatomy of different people is different and a general rule cannot be made for it, a method has been devised that virtually shows the physician what he or she will see if it enters a patient through a hypothetical hole. The previous methods were not interesting to doctors for two reasons: the angle at which the imaging system touches the target points changes the accuracy of the images, and it is very difficult to move with the robot. In the new method (augmented reality), markers are installed on the patient's body that the position of these markers in CT-scan imagesIs visible . Now, instead of touching the signs with a robot, the surgeon moves with his camera and outside the patient's body, and the movement and position of the camera are calculated using the principles of computer vision, and the three-dimensional space inside the patient's body is reconstructed from the camera's point of view. Be. The reconstructed space is then matched to the available CT scan images to virtually show the doctor what he or she will see from anywhere he or she enters the body. Of course, in all cases it is assumed that the patient was completely stable.
With the opening of a new quasi-real center for brain surgery training and practice at Western Hospital in Toronto, Canada, brain surgery patients in the country are expected to receive better services and care.
The center is a breakthrough in brain surgery training and patient care that allows physicians to perform more complex surgeries on virtual simulated brain glands (tumors) based on each patient's specific needs.
This technology paves the way for a significant leap forward in surgical training and practice, as well as patient care and safety. The goal is to reduce the risk of complications and complications from surgery, shorten recovery time, and increase the speed of operating room surgery.
Canada's first neurosurgery center opened in September 2010 at the Montreal Institute of Neurology and McGill University Hospital.
Dentistry - Oral and Maxillofacial Surgery
Virtual reality in dentistry ( virtual dentistry) is one of the practical manifestations of applying specialized dental concepts in computer. The most important purpose of using virtual reality and such software is to create an environment similar to the real similarities as much as possible so that you can experience everything and feel it closely before facing the realities. Common applications in dentistry include:
Digital imaging of teeth
Provide a dental implant plan before surgery
Designing a virtual environment to perform dental surgery processes and ...
The principle of operation is that the patient is placed on a chair in a special position, so as not to prevent the movement of a device called Cat Scan . The scanner scans the patient's location and, like a panoramic X-ray , captures the patient's teeth in high resolution. These images will be the basis of the dentist's work in examining the surgical process in a virtual environment.
In the process of performing endodontic procedures in dental volumetric models capable of deformation (Deformation) , pitting (Drilling) for cutting Cutting materials in the simulated virtual environment training is necessary.
Oral and maxillofacial surgeries also deal directly with the anatomy of the bones involved, and as mentioned at the beginning of the discussion, three-dimensional anatomical shapes will greatly aid in better diagnosis and examination. In examples of these virtual environments, it is possible to really feel objects and the oral environment, in addition to being able to hold probes and handpieces and work with them.
special benefits
Patient participation in the process of taking all necessary measures and assisting in decision making, especially in cosmetic surgeries
Speed of surgery by the surgeon through practice and practice before the operation
Rehabilitation treatments
Virtual reality simulation is different from other computer simulations; Because it requires special interactive tools that convey vision, hearing and feeling in the simulated world to the user. These tools save users' voice and movement and send them to the simulation program.
To see in the virtual world, the user installs a display on his head that has screens in front of his eyes. The display also has a motion tracker that monitors the location of the user's head and the direction he or she is looking. Using this information, the computer calculates the virtual world images with a slight difference from each eye and displays them on the screen.
In order for these images not to look paused and irregular, the computer must create at least ten new images per second. Virtual reality scenes should be relatively simple so that the computer can update them quickly. Due to this simplicity and other disadvantages of monitors, virtual reality users can easily distinguish simulation from reality. The user hears sounds through the phone in the virtual world. It can also be used to update audio signals using information obtained through motion trackers.
When an audio source in cyberspace is not directly in front of or behind the user, the computer sends the sound in such a way that it reaches one ear sooner than the other; This way, the sound will be a little louder or slower. However, there are still scientific and engineering challenges that must be overcome to make sounds sound completely natural.
Touch simulation is the least developed and the most challenging part of the job. Using a glove and a motion tracker, the computer now detects the user's hand position and measures finger movements. In the virtual world, the user can move objects, but can not feel them. It is technically difficult to produce the sensation that occurs when tapping a hard surface, picking up an object, or moving fingers on a tissue. The sense of touch must be coordinated with the user's sight and hearing. The most common use of VR in rehabilitation is to treat various phobias (fears) such as fear of heights, flying, animals, etc.
The treatment method is to put the patient in a stressful situation for him in the virtual environment and to control the stress, start working with a low stressful situation and gradually add more situations. The advantage of this method is that the stressful conditions can be controlled. Something that in real reality cannot be created.
Other types of applications in rehabilitation include:
Help therapist in physical-motor-mental disabilities (such as autism)
Nutrition syndromes
Syndromes after stroke and ....
Treatment of mental disorders in cyberspace
To date, few virtual reality systems have been designed and implemented to rehabilitate visual, auditory, physical, and mental disabilities. Because audio-visual monitors are a key component of integrating with the virtual world, visual-auditory rehabilitation systems are not uncommon, but virtual reality seems to be very useful in treating mental disorders. These systems are able to overcome the limitations of the real world and open new horizons for this group of patients. This section introduces some examples of these systems.
Treat all kinds of fears using virtual reality
More than ten percent of people experience some form of anxiety disorder during their lifetime. To treat these fears, the method of exposure is usually used. To achieve this goal, two methods of imaging and physical exposure are used. The physical method, apart from being real, can be very costly, embarrassing, dangerous, or impossible. On the other hand, imaging is not real enough and there is little control by the therapist.
Virtual reality offers a third method of treatment that, while preserving most of the advantages of both methods, does not have their disadvantages. Especially in the case of fear of flying, medical expenses are greatly reduced. But at the same time, virtual reality has its own limitations. Knowing that the environment is virtual may not cause the user any anxiety at all that he or she wants to be treated. While it is a very new method and its side effects are still unknown.
In this treatment method, usually two setups are used, ie using HMD or CAVE system . With HMD , only the virtual world will be visible and the real world will be eliminated altogether.
In the CAVE system, the walls of a cube are used as projectors, and real and virtual environments are placed side by side inside this cube. Both systems have phase latency. The difference between motion and image movement can cause nausea. Real sound or objects can also be used to enhance the sense of presence. The use of data gloves also allows the application to interact with the environment.
The idea of introducing the therapist into the virtual environment can also be beneficial, but in this case, due to the need for twice the number of devices, the cost of implementing the system will increase a lot. In the systems that have been developed so far, the therapist controls the environment but does not enter it.
View virtual meeting environment (Virtual Visual Environment Display-VIVED)
Designed by NASA Johnson Space Center (JSC) / Lincom Corporation in collaboration with the University of Texas Medical School, VIVED provides unique learning experiences. For example, through it, the inside of the human skull and heart can be accessed through interactive Multi-media facilities ( audio-video, etc.).
Discussion and conclusion
Virtual reality is one of the most extensive fields of research in the field of medical engineering. In the not-too-distant future, medicine will be impossible without the use of virtual reality and its applications.
The virtual reality system is the product of a cybernetic approach that puts the real environment in interaction with the human-centered human-centered environment and thus opens the horizons of invisibility to the man of the present century. It seems necessary for engineers to interact more with physicians (especially surgeons) and to study and model their demands in the field of virtual reality.
Areas where there is more work and it is suggested that more research be done on them:
Human interfaces - computers like force-feedback or touch interfaces
Tough modeling techniques to simulate body organs
Image display techniques
It is possible to create a new approach to medical imaging by applying the concepts of virtual reality and making more effective observations.
Source: clinicalmedicine