Telepresence in Medicine

an application of Virtual Reality

by Vincent WONG


Contents



1. Introduction

Telepresence[4] is the use of virtual reality to enter a shared cyberspace graphic environment for the purposes of human communication and interaction, or to become electronically present in a distant real-world environment for the purposes of remote-controlled action and / or observation.

Using this idea, telepresence is applied to the medical field in order to help the doctors / surgeons perform surgeries effectively.


2. Teleoperation[1][5]

In order to perform surgery using telepresence, some devices, known as the teleoperated devices , are placed into the patients' internal organs to be operated such as heart, liver, eye etc. and the surgeons manipulate these thin medical instruments and see what is happening by way of small cameras located at the work site, i.e. the inside of the heart, liver, eye etc. This technique is known as teleoperation.

2.1 Why Teleoperation?

2.1.1 Minimally surgical techniques

Using teleoperation, most of the surgeries can be performed by using minimally invasive surgical techniques[2], in which there is only small incision site for instrument entry. As a result, this causes less pain to the patients and there will be less tissue trauma, thus reducing hospitalization time and enhancing recovery. Besides, cosmetic considerations are improved due to the small incision site required for instrument entry. The diagram on the right shows a method of minimally invasive stereotactic resection of deep seated tumors in a patient's brain.

2.1.2 Precise Movement

Many operations require the surgeons operate very precisely in hand movement over the delicate body structures such as heart, eye, brain etc. With the sophisticated teleoperated devices, extremely small forces can be applied, thus making the operation safer and more efficient.

2.1.3 Multiple Viewers

As the patient's internal organ under operation is displayed on the video monitor, all members of the surgical team can observe the procedure from the surgeon's perspective, facilitating instantaneous interventions, and consultations. For example, the ability for several individuals to view the patient's structure prior to dissection may enhance patient care. It would also certainly facilitate close support from surgical assistants.

2.1.4 Teaching Purposes

In both the operating theatre and the laboratory, the possibility for recording a complete procedure, and playing it back to any number of students would improve the training of individual on the subject.


3. Techniques

3.1 Movement[1]

In many operations such as eye surgery, small precise movements are needed. As a result, the operators ( i.e. the surgeons ) hand movements on the controls are scaled down so that very fine instrument movements can be performed. Besides, the surgeon also feels artificial resistance on the controls, giving him / her the full immersion effect of telepresence.

3.2 Visual Aspect[2]

3.2.1 Problem

As mentioned above, in teleoperation, images are displayed on video monitor. However, this kind of 2D display causes several problems :

  1. The remote location of the monitor and its orientation in the surgical setting have an effect on both the surgeon's perception of the surgical field and the difficulties encountered when interacting with it. For example, with the displacement and axial rotation of the monitor, the surgeon must relearn the image to tissue relationship at each procedure, and with each manipulation of the camera.
  2. The single screen video monitor that the surgeon uses as the image source has no stereo information, i.e. no spatial information and no concept of the depth of field. As a result, it is very difficult for the surgeon to locate their instruments into a correct position. The diagram on the right shows an instrument being placed into the ostium of a patient. It clearly shows that spatial information is very important in order to place the instrument into a correct location.
  3. The surgeon may suffer from the hand-eye coordination problem. For example, with a 90° rotation of the camera, an intended movement South to North direction will result into a display movement in an East to West direction, presenting the surgeon with a working field that is difficult to comprehend.

3.2.2 Solution

The above problems can be tackled by using a Head Mounted Display ( HMD ), worn on by the surgeon. A HMD is a helmet fitted with paired wide-angle television screens placed in front of the eyes, giving a 3D display, thus solving the first two problems listed above. Besides, by correct alignment of the video image relative to the surgeon's hand and instrument position, they could also contribute significantly to reducing problems of hand-eye coordination.

However, the HMD must be capable of displaying information in a format that is understandable by the viewer ( i.e. the surgeon ), is easily assimilated, relates to the real tissue, and is contained in an unobtrusive head mount. This is because for many surgeons, operating schedules and complex procedures require them to be in the operation room for many hours. Therefore, a surgical HMD, should be unobtrusive, light in weight, balanced, allowing easy head movement without problem of inertial or neck strain. The HMD should also offer a clear visual path to the external world. Besides, optical surfaces capable of fogging due to perspiration could be a hindrance during a critical procedure. The HMD is worn by a surgeon as shown in the right diagram. The 3D image is adjusted to be coincident with the preferred work place of the surgeon by moving the focus ring.


4. Remote Operation

Extending the above idea, surgery can actually be operated by a surgeon from large distances. For example, a surgeon in the USA can perform a heart surgery on a patient in India.

For this remote operation to be effective, the surgeon or other medical practitioner must have the sense of actually being at the site performing the procedure[3]. This requires very fast transmission of information between the connecting places ( i.e. very small delay between them ) and 3D display of high resolution to allow immersion of the surgeons.

There are several advantages of effective remote operation :

4.1 Immediate Operation

Sometimes, some critical surgeries, such as brain operation, require experts ( usually very few in the world ) in the corresponding field to perform. As a result, using remote operation, patients under critical condition can undergo surgery immediately even if the corresponding expert is in the other part of the world, thus increasing the patient's survival chance.

4.2 Surgical Cooperation

Sometimes, some critical surgeries require many experts in different fields to participate. Remote operation allows this kind of surgery to be performed even if these experts are distributed all around the world. However, for this kind of cooperative surgery to be effective, efficient transmission of information must be ensured and so as a sophisticated computer network system.

4.3 Cost savings[3]

Trauma units in emergency rooms could improve operating efficiency and reduce costs by using specialists who are not physically present. With remote operation, experts could be linked to remote patients. This is effective whether distances are great or not. Because the need for specialists in emergency situations cannot be predicted, making use of remote specialists in time of need limits the staffing needs of the trauma units without limiting their effectiveness. Doing this would conserve resources by limiting the need for part-time specialists to be physically present in trauma units.

4.4 Isolation of the Surgeons from Hazardous Environments[3]

4.4.1 Military Aspect

With remote operation, the surgeon operates on a virtual image, and a robot on the battlefield reproduces the surgeon's movements. As a result of this, surgeons can perform surgery on the injured soldiers without the need of going to the battlefield where their lives may be endangered. One of the examples is the SRI International's Green Telepresence Surgery System. The system consists of the remote operative sites and a surgical workstation, 3D vision, dexterous precision surgical instrument manipulation, and input of force feedback sensory information which allows the surgeons to perform remote operation effectively.

4.4.2 Decrease Exposure to Disease

Very often, the patients undergoing operations carry infectious disease. As a result of remote operation, surgeon's exposure to diseases is greatly reduced. Besides, it can be applied to treating AIDS carriers, e.g. in the injection of medicine to the patients, during which hypodermic syringe must be handled very carefully in order to avoid being infected.


5. Applications

5.1 General Surgery

As inferred from above, medical telepresence can be applied in many fields of surgery, especially those where the internal organs are very delicate such as eye, brain etc. where precise movements are crucial, and hence the use of minimally invasive surgical technique as mentioned above. The left diagram shows a virtual endoscopic instrument pulling a gastro-intestinal organ while the right diagram shows a brain surgery using minimally invasive surgical technique.

5.2 Remote Operation

With remote operation, surgery can be performed at any time, even if the surgeon is in the other part of the world. For example, the physician can simply look at the electronic video image and remove the internal organs without actually touching them. Again, this technique can be applied in the military area in which the surgeons can perform operations on the injured soldiers without endangering their own lives.

5.3 Education Aspect

Medical telepresence technique can ensure that the would-be surgeons to be trained in a more effective way. For example, the recorded operation procedure allows trainees to investigate the details of the operation and have a sense of being in the operation room.


6. The Future

With the ever developing computer technology, it won't be long to see the emergence of effective ( high resolution 3D display ), low-cost teleoperated devices. Together with the improved medical telepresence technique, surgeons will be able to have a sense of being within the interior of the heart, eyes and other internal organs[4]. Furthermore, it may be possible, by using microrobots not larger than a human cell, to perform surgery of incredible delicacy.

Besides, with better and more high tech remote operation technique, surgeons can effectively perform surgery on people all over the world, especially in the backward and remote places, where a telerobot can ensure the patients to undergo operation without flying to, or the surgeons flying from the other part of the world.

With further extension of the idea, medical telepresence can allow experts in a field to actually go inside and walk through the internal structure under consideration so as to have a much better idea of it and thus enhancing effective discussion.


7. Conclusion

Undoubtedly, telepresence in medicine provides surgeons with a much more effective way of performing surgery. In order to achieve this, good 3D display ( to provide the surgeon with a better perception ) and precise movement ( due to the delicate body structures ) must be ensured. However, this will not be too difficult as a result of the ever-developing computer technology. In short, real life medical practice will increasingly rely on virtual reality for new therapeutic techniques.


References

[1] Telerobotics in Medicine (http://www.mcs.anl.gov/home/jebb/telerobot/medical.html)

   Author  : Michael E. Jebb
   Year    : July 29,1995
   Usefulness  : 9 / 10
   Readability : 9 / 10
   Comment  : It gives a very good idea of telerobotics in
                medicine together with the advantages, problem
            encountered as well as other related links.


[2] Viewing Ocular Tissues with A Stereoscopic Endoscope
Coupled to a Head Mounted Display (HMD)
(http://www.hitl.washington.edu/publications/heacock/)

   Author  : Greg Heacock (1)
           John Marshall, Ph.D.(1), 
           Prof. Franz Fankhauser, M.D.(2).
           Toni C. Emerson, MSLIS (3)
                
           (1) University of London, UMDS, St. Thomas's, U.K.
           (2) University of Bern, Switzerland
           (3) HIT Lab, University of Washington
                
   Year    : 1994
   Usefulness  : 7 / 10
   Readability : 8 / 10
   Comment  : It gives a comprehensive idea of the Head
                 Mounted Display ( HMD ).
[3] Virtual Environments for Heath Care (http://www.nist.gov/itl/div878/ovrt/projects/health/vr-envir.htm)
   Author  : Advanced Technology Program, NIST
   Year    : October, 1995
   Usefulness  : 7 / 10  
   Readability : 7 / 10  
   Comment  : It surveys in great detail the applications of 
            virtual environments and related technologies 
            for health care.
[4] Virtual Reality and the Exploration of Cyberspace pg 254 - 256
   Author  : Francis Hamit
   Publisher : SAMS Publishing
   Year    : 1993
   Usefulness  : 4 / 10
   Readability : 7 / 10
   Comment  : In the pages stated, it talks about general
                telepresence but not concentrate on any medical 
            aspect. So it only gives some idea of 
            general telepresence.
[5] Virtual Reality Systems pg 181 - 202
   Author  : Robert J. Stone          
   Publisher : Academic Press Limited    
   Year    : 1994
   Usefulness  : 4 / 10
   Readability : 6 / 10
   Comment  : Only general telepresence is discussed, with some 
            projects of telerobots such as the UK VERDEX 
            project.