APIL Normal Spine Epidural Phantom

3D Printed lumbar epidural spine based on CT data. Our epidural spine phantom is encased in an synthetic, shelf-stable gel which has a realistic tactile feel to human muscle and is echogenic. We can augment the echogenic properties to be transparent (clear gel) to mimicing that of biological tissue (opaque) based on the learning objective. Additionally, the Normal Spine Epidural Phantom contains an echogenic faux-thecal sac to replicate loss-of resistance on puncture. The faux-thecal sca can be inflated with water to simulate spinal fluid.

This phantom is designed with the ability to adjust the depth of 'tissue' over the spine to simulate different anatomies/difficulties. By default, the most surface spinous process is embedded underneath approximately +5 mm of echogenic gel. However, we have also produced this phantom with deeper embeds -- the two most common being +10 mm and +17 mm. These different depths require different case lids which are provided in this repo. Please refer to the table provided in the 3D Printing Components section of this guide to reference which lid will fit the depth.

This model was developed at the Lynn & Arnold Irwin Advanced Perioperative Imaging Lab, Toronto General Hospital, University Health Network.

Purchasing Information

To purchase this phantom, please email apil@uhn.ca and a represtative will be in touch with you with more details.

A purchased phantom contains the following:

1. Fully assembled Normal Spine Phantom
   1. Spine embed depth can be customized to order.
2. Custom table clamp to hold phantom to tabe surface

Ultrasound Images

Coming soon

Care and Maintenance

1. Apply generous amount of ultrasound gel to surface of phantom.
2. Inflate thecal sac with water and ensure quickturn locks are closed

Materials & Equipment

Hardware

• 2 x M5*14 pins
• 6 x M4*25 Bolts
• 4 x M4*8 Bolts (for use with default lid)
• 4 x M4*14 Bolts (for use with 5mm lid)
• 4 x M4*16 Bolts
• 4 x M4*20 Bolts (for use with 12mm lid)
• 4 x M4*20 Bolts (for use with case bottom)
• 2 * Quick-turn Lock
• 8 mm ID Silicone Tubing (as low durometer as possible)
• 2 * Tube Fittings

Printing Equipment

• Polylactic Acid (PLA)
• Bridge Nylon
• Fused Deposition Modelling 3D printer

Casting Equipment

• Ballistics Gel
  • Gelatin #3 from Humimic Medical
• Graphite Powder (optional)
  • used to replicate echogenic scatter of muscle
• Slowcooker
• Two-part Platinum Cure Silicone Rubber (or equivalent)
  • Available from Smooth-On
• Degas Chamber (Optional)

Assembly Instructions

Printing

This repo includes stl files for each printed part.

In general, we use the following settings for all parts of this phantom:

Material	Colour	Nozzle Temp (C)	Bed Temp (C)	Infill (%)	Perimiters (#)
PLA	White	210.0	60.0	10.0	2
Bridge Nylon	Natural	250.0	80.0	15.0	3

Silicone Casting

Silicone Mold Casting

1. Print all components in the directory /molds/ using the PLA printing settings outlined above.
2. Assemble mold parts 1 and 2 and together using:
   1. 2 x M5*14 pins
   2. 6 x M4*25 bolts
3. Mix 2700 g of silicone according to manufacturers instructions.
   • Degassing the silicone is encoraged, but optional.
   • Adding colourant to silicone is optional.
4. Pour all silicone into the assembled mold.
5. Allow silicone to cure according to manufacturer's instructions.
6. Carefully disassmble the mold and release the silicone.
   • NOTE: This step can be very difficult. Procede with caution and patience to avoid damaging the silicone shell.

3D Printing Components

1. Print all components in the directory /insert/ using the Bridge printing settings outlined above.
   1. Refer to the following table for the appropriate lid to print depending on depth of spine embed:

Spine Embed Depth	Corresponding Lid Type
5 mm	spine_epidural_phantom_case_default_lid
10 mm	spine_epidural_phantom_case_5mm_lid
17 mm	spine_epidural_phantom_case_12mm_lid

2. Print all components in the directory /case/ using the PLA printing settings outlined above.
3. Carefully remove all supports from the part when complete.

Ballistics Gel Casting

1. CAUTION: Use appropriate heat-proof gloves when working with liquefied ballistic gel and/or heat gun.
2. CAUTION: work only in a very well ventilated area. A fumehood is highly recommended.

Ballistics Gel Casting

1. Melt at least 1500 g gel in crockpot @ 105C - 115C (approx. 225F - 240F).
2. If the gel does not contain graphite powder, slowly add graphite powder into fully liquefied mixture until saturated.
   1. For this phantom, this step is optional. You can leave it clear if the learning objective is to insert an epidural without the use of ultrasound.
3. Thread a length of silicone tubing through the scoliotic sipne to replicate the thecal sac. The length should be just enough to reach end-to-end of the scoliotic spine.
4. Anchor spine insert and thecal sac silicone tube into the silicone mold with 4 x M4*16 bolts.
5. Pour gel into mold until you reach the required depth of submersion.
6. Allow gel to fully cool before removal from silicone molds.
7. Remove previously installed silicone tube.
8. Install a new silicone tube measuring 125 mm.
   1. we use a longer silicone tube in this step so the ends of the tubing extend well past the case for ease of access.

Phantom Assembly

1. Insert spine with gel block into printed case.
2. Thread both ends of silicone tubing through printed case.
3. Attach case bottom with 4 x M4*20 bolts.
4. Attach case lid with appropriate M4 bolts.
5. Attach a tube fitting to each end of the silicone tube.
6. Attach a quick-turn lock to each end of the tube fittings.