XCheck:Protecting Integrity of 3D-Printed Critical Patient-Specific Devices via Automated CT Analysis

Medical Printing Saving Lives

Hearing aids
Organ implants
Organs-on-chips
Medicine, etc.

User Interface

The following figures show XCheck in action detecting malicious modifications of a dental surgical guide, which is used to help guide surgical instruments or implants to the proper location during surgeries. The attack takes place where an additional sphere is inserted into the guiding channel to block the drilling hole, which XCheck is able to help the users identify by painting the region in red.

Visualization without Colormap

Visualization with Colormap

Experimental Setup

The evaluation of this work can be summarized into three steps. First we selected and created representative base models that cover broad medical printing applications. Then we designed and implemented geometry attacks and material attacks with small modifications. Lastly we printed and CT scanned both benign and attacked models for XCheck analyses.

Base Models

- Bone screw - Downloaded from NIH resource sharing platforms in the medical community
- Bone scaffold - Created based on real patient CT scan
- Lung-on-a-chip - Recreated from existing researches
- Dental guide - Downloaded from NIH resource sharing platforms in the medical community

Geometry Attacks

- - Bone Scaffold
    - (1) Create internal solid regions, each with radius of 0.025cm, 0.05cm, 0.075cm, 0.1cm
    - (2) Create internal hollow regions, each with radius of 0.025cm, 0.05cm, 0.075cm, 0.1cm
    - (3) Decrease pore size in internal regions, each with radius of 0.025cm, 0.075cm, 0.125cm, 0.175cm
    - (4) Rotate condyle angle by 10deg, 20deg, 30deg
  - Bone Screw
    - (1) Increase minor diameter by 0.06cm, 0.18cm, 0.28cm, 0.54cm
    - (2) Elongate thread distance by 0.15cm, 0.3cm, 0.5cm
    - (3) Elongate non-threaded shank by 0.4cm, 0.8cm, 1.2cm
    - (4) Remove 1 section of thread

Material Attacks

- - Bone Screw
    - (1) LCD-C
    - (2) LCD-E
    - (3) LCD-N
    - (4) SG Guide
    - (5) LCD-MG
    - (6) Standard
  - Lung-on-a-chip
    - (1) LCD-C
    - (2) LCD-N
    - (3) LCD-MG
    - (4) LCD-E
  - Dental Guide
    - (1) LCD-G
    - (2) SG Guide

Printed & CT Scanned Models

Printed & Scanned Models for Geometry Attacks

Printed & Scanned Models for Material Attacks

A sample of source code and CT scan can be downloaded via this Google drive link