2.1. Imaging Overview
2.1.1. Introduction
In this course, we are focusing on CAS/CAI. So, while it is true that we are using images, this is not a course on the physics of image acquisition.
We assume you have read:
[Elson2010] - Review of imaging in surgery, pre-op, intra-op, post-op.
[PetersCleary2010] - Includes more examples of what type of imaging devices are used, and where.
In this section, we have a free-form discussion, based on the following material.
2.1.2. Common Modalities
MR/CT/PET/SPECT - 3D, taken pre-operatively. They typically need registering together. Used to plan surgery.
Ultrasound, X-ray (low-dose flouroscopy), video - 2D, taken intra-operatively. Provides real-time updates. How to register together, or register to pre-operative images is an ongoing research question.
Cone-beam CT, Robotic (Siemens Zeego) C-arm, 3D, taken intra-operatively. Not-so-real-time, but represents current state of patient anatomy intra-operatively.
Hybrid OR - typically MR or CT. Mostly only at large research institutions.
Advantages/Disadvantages of Hybrid OR?
2.1.3. Examples - Intra-operative Ultrasound to improve Liver Ablation
CASCination’s system enables enhanced tumour location, using intra-operative ultrasound. In this video, the ultrasound probe is tracked, a volume of data is compounded, and used to improve the registration to pre-op CT, and enhance overlays.
Also note: usability. The monitors close at hand, and resumably draped with sterile film, to allow quick touchscreen.
2.1.5. Examples - Vascular Surgery, Dr Tara Mastracci using Cydar Medical
Dr Tara Mastracci at UCL talks about Cydar Medical for vascular surgery.
2.1.6. Examples - Siemens Hybrid OR
This example gave a good overview of some of the surgeon’s perspectives on having more imaging, in the OR.
2.1.7. Examples - Leica ARVeo
There is increased uses of newer imaging devices like flourescence imaging, and eventually photo-accoustic imaging. Here we see how such imaging is added directly into the operating microscope.
2.1.8. Some Thoughts
You have to understand how a surgeon uses their imaging, BEFORE building a guidance system that is unnecessary.
Consider the frequency of use, and why. Its normally a few key points during a long operating that are critical for imaging and guidance.
A CAS system has to integrate with the workflow, so there are often a lot of imaging parameters that are then hard to tweak on a guidance system.
Remember: A lot of the things we like to work on in Computer Science departments may not be necessary if imaging is improved!