Concept demonstrator: 3D laryngoscope & VR headset for examination of the throat.
Background: Laryngoscopy is endoscopy of the larynx, a part of the throat. It is a medical procedure that is used to obtain a view, for example, of the vocal folds and the glottis (Wikipedia definition). A laryngoscope is a medical instrument for examining the larynx. An anaesthetist (anesthesiologist in the US) might do this in order to pass a tube into the main airway to the lungs in order to maintain adequate ventilation of the lungs during a surgical procedure.
The traditional laryngoscope has a light near the far end of the part that enters the mouth to give a good view. More recently video-laryngoscopes have appeared on the market which also include a camera providing a 2 dimensional image of the airways on a small screen nearby or attached to the instrument. These may have advantages in those patients where the correct view is difficult to obtain.
Question to be considered: Would it not be better in these more difficult patients to be able to see the view in 3D? This might be especially true if there is time pressure to insert a breathing tube into the correct place.
About this project: This is a working concept demonstrator of a 3D laryngoscope which can be tried out in training manikins which have an anatomically correct upper airway. These are commonly available in hospitals for emergency medical and anaesthesia training. It CANNOT be used in patients as (i) it is a prototype with no formal approvals for medical use and (ii) it is not possible at present to sterilise it.
Why make this and put build instructions freely on the web?
- I could write a research paper examining possible benefits, accompanied by 2D illustrations, that totally fails to convey the key information you want i.e. what does the view look like when you use it?
- I could describe how, in my perhaps biased opinion and that of those I have allowed to try it, the view is just amazing, like flying through the larynx, reminding me of the old Sci-Fi film "Fantastic Voyage" where they shrink a medical team and inject them into a patient.
Therefore the only way for you to form an opinion is to try one for yourself. This currently means building one or having one made, hence this instructable.
Here we go then,
Parts you will need:
a) A cheap VR headset of the type designed to take a mobile phone running example VR software that splits the screen into a right and a left half, one for each eye. The type I use has lenses which can be moved to suit your face size and I recommend this one. Approx $10
b) TWO identical "borescopes" - small cameras supplied with TFT screens. Typically 5 to 6mm in diameter and have their own LED lights built into the cameras. These are readily available from China on well known web sites. Buy them with their screens. Approx $35 each.
c) A Macintosh laryngscope or similar. A single-use one will be fine and the light does not have to be working. I used a blade from the company "Flexicare" but there are many others available.
d) 3D printed parts: Not essential but useful to keep things neat and to for example keep the pairs of screens and lenses correctly oriented relative to each other.
e) Dremel or similar with cutting disc to modify plastic parts.
f) Glue gun or epoxy adhesive.
g) Small cable ties.
h) A small hobby vice is very useful when setting up.
i) Project box (optional).
Step 1: A Little More Background
These are photographs of my laptop screen and we see a normal laryngoscope with a curved blade (top left view). The blade is the curved part with a light near its tip which enters the mouth to move the tongue out of the away among other things. Although called a blade it is not sharp by the way.
Lower left we see an example of a video-laryngoscope which is of similar design but incorporates a camera and a screen displaying a 2 dimensional image.
On the right we see how a laryngoscope might be used to insert a soft tube into the trachea (wind-pipe) of a patient to ensure that they breathe clearly during an operation.
Step 2: An Airway Training Manikin
In this photo of my computer screen we see the same procedure taking place in an airway training manikin. These are anatomically correct internally and are used to train users in these techniques.
Step 3: The 3D Laryngoscope and Modified VR Headset We Will Use to View the 3D Image in Real Time.
This is what we will be building. The device is in two main parts. One is a laryngoscope blade modified to take two video cameras side-by-side and the other part is a wearable headset which displays the image from the left hand camera to your left eye and the image from the right hand camera to your right eye.
They are currently linked by cables but clearly the technology exists to make both these pieces of apparatus connect wirelessly.
Step 4: What You Need to Buy
There are three major things you need to buy.
a) A video "borescope". This is the key search term online. You must buy it WITH an attached screen as some are sold for use for example with a mobile phone as the screen. Usually they seem to be sold with 4 inch screens and these are the ones I bought. The cameras are typically 5-6mm in diameter and contain white LED lights for illumination.
BUY TWO OF THESE
b) A VR headset for use with a mobile phone. I prefer the one shown which is available worldwide as far as I can see as each lens can be moved in both the sideways and in the forwards/back directions to suit your personal preference.
You only need ONE of these.
Step 5: Modifying Things
You will now have two cameras, two 12V adapters to plug into your mains supply and two screens plus lots of wires and instructions on how to connect them all together. Before you attack them with power tools do just check that each camera-screen assembly works OK.
The flat screen assemblies need to be removed form their nice plastic surrounds. First undo the screw that holds the two halves of each screen-surround together in each corner
Step 6: Screen Modification (2)
Then, remove the little stand from each screen assembly, this is a long bolt with a nut on the other side.
Step 7: Screen Modification (3)
Remove the back of the screen assembly.
To remove it without damaging the wires, make a channel for the wire to come out of the rear panel by snapping off small "bites" of plastic with narrow ended pliers.
With care you should now have two screens with their plastic enclosures completely removed.
Step 8: 3D Printed Parts
This is a picture of the 3D printed parts. The 3D files are attached to this step. These are NOT essential but useful for keeping all the wires etc neat and tidy. The mount that holds the 2 cameras in place is especially useful.
The files are in .skp format (Google Sketchup) and also as .stl files for printing.
Step 9: Double Camera Mount
Here is mine being 3D printed.
This went through 14 revisions before it was correct.
The first unknown was how far apart as a minimum the cameras needed to be to give the correct 3D image in the face mounted viewer. If the minimum distance turned out to be too wide then the laryngoscope would not fit into the mouth and the whole project would have been a non-starter. However, I can save you hours of time by assuring you that even side by side like this, they work really well.
This mount is designed to fit the slot in the metal "Flexicare" brand blade I used. If you use a different make of blade, as is likely, then a small amount of modification might be required.
Step 10: Filing Camera Holes
The holes for each of the cameras are deliberately slightly undersized.
When you mount each camera in its hole you will then need to view its output in the face mounted viewer while the blade is clamped into a vice or similar with a small test object mounted in front of the camera. The camera will need to be rotated until the image is perfectly upright. When you let go of it you want the camera to stay put until you can then put a small mount of glue onto it. Until then the camera needs to be a moderately tight fit in its hole.
Therefore, file out each hole a small amount, test to see if the camera will fit, if not file a little more and so on. Take your time and hopefully each camera will then stay at whatever orientation within its mounting hole you rotate it to.
Step 11: Prepare the Laryngoscope Blade.
Here I am using a Dremel rotary tool with an abrasive cutting disc to remove the fibre bundle used in this particular type of laryngoscope blade as we do not need it.
Step 12: Remove Anything Not Required
Here the fibre light guide is being removed to leave a slot within the metal of the laryngoscope blade.
Step 13: Insert the Twin Camera Mounts and Drill Holes
The camera mount has a hook at one end that locates it into one end of the elongated slot in the laryngoscope blade.
Also, at the points marked, we need to drill 3mm holes to take small cable ties. These will be used to tidy up the cables emerging from the rear of each camera.
Step 14: Fix the Double Camera Mount in Place
I used a very short screw with a tab to locate the other end of the 3D printed double camera mount at the other end of the slot within the laryngoscope blade. For other makes of blade you will need to modify this slightly.
You can also see how the cable ties are used to tidy up the wires emerging from the rear of each camera (cameras not visible here as they are on reverse side of the laryngoscope blade).
Step 15: Insert Cameras and Tidy the Wires
Here is the reverse side view.
Cameras are in place and cable ties used to tidy the wiring up.
Step 16: Closer View
Here is another closer view. You can see how a small amount of glue has been used to fix the orientation of each camera once by trial and error these have been optimised.
They are optimised by clamping the blade in a vice and arranging a small test object in front of it. Ideally this object will have a vertical straight edge on it. Power each camera up with the head mounted viewer working and rotate each camera until each individual image is perfectly vertical. Check using the headset whether the overall image, i.e. both screen operating and viewed with both eyes, now appears to be in 3D. Instructions for completion of the viewer follow in later steps of this build description. It is probably better however to make the viewer before you finally position the cameras within the camera holder.
Step 17: Blade Finished
Here is the finished blade showing the business ends of the two cameras with their white LEDs.
Step 18: Making the Face Mounted 3D Viewer
You are now about to modify the VR headset.
You may feel silly wearing this but after this Christmas (2016) when your teenage children will be wanting/having Sony / HTC ViVe / Oculus Rift or other 3D VR gaming systems, you will probably find that it will not be that odd after all in the near-future to have something strapped to your face.
On the top of this headset you can see the tabs that are used to slide the lenses left/right and forward/back.
Step 19: Where to Cut
You need to cut the whole front of the headset off where the phone is designed to go, ideally leaving as flat a surface as you can manage. Be careful not to cut off the centre top elastic head strap mounting.
Step 20: Cut Surface of the Headset
View of the cut surface of the headset ready for the orange part with the two screens to be glued on.
Step 21: Mount the Screens
Glue the orange 3D printed "window frame" (stl. file attached) to the flattened cut surface of your headset, I use a glue gun for this.
Before you actually do this, gently place each of the TFT screens you carefully removed earlier on into each side of this "window frame" structure. It will hold them side by side in the perfect orientation. Notice how the screens are mounted lengthways. Once the screen are in use a small amount of glue at each corner to hold them in.
Step 22: View of the Two Screens in Their Mounting
Here is a view of the two screens in their 3D printed mounting.
Step 23: Screens (2)
There is a little board with 3 buttons on it attached to each screen. Relocate these with some glue to the lower edge of each screen as shown.
Step 24: Cut Out Lower Part of the Headset
I did this after I mounted the screens. I suggest doing it before you mount the screens. Cover the lenses first temporarily as well to stop little black flecks of plastic falling on them.
You do not have to cut this material away but it does allow you to look down at the training manikin when inserting the laryngoscope into the mouth after which you then look dead ahead to see the 3D view from the cameras. This aspect could do with further improvement, such as flip down screens for example.
Step 25: Protective Cover
The big blue object is a protective cover for the rear circuit boards etc that come fixed to the TFT screens.
Make sure you tape/tidy the cables so they all emerge centrally from the top edge of the screen through the slot provided in the middle of the blue 3D printed structure.
Step 26: Headset Almost Complete
Protective cover held on with a small self-tapping screw each side.
Step 27: Cable Tidy on Top Head Strap
There are two 3D printed clips on the top head strap that are used to tidy the cables and run them over the top of your head to keep things neat.
Step 28: Cable Tidies on Head Strap
Here is a better view of the two cable tidy clips on the top head strap.
Step 29: Keeping the Cables Tidy
This is quite a challenge. It is fairly self-evident from the instructions with the two borescopes how they are to be plugged together. However, the wiring soon builds up. One problem is that the cameras each have 5m of wire emerging from them. I coiled about 3m of each one up and kept them coiled using small cable ties. The plan was to hide this coil of cables and connectors in a plastic project box.
Step 30: Tidy Cables Up in a Small Box.
Here is how I tidied up the mass of cables and connectors.
Step 31: Finished Scope and Wiring
Here is the scope and wiring tidied up ready to connect to the headset.
Step 32: Whole Assembly Completed
Here is the whole set of apparatus ready for testing.