A ‘robotic surgeon’ that can delicately remove tumours from the tongue has been hailed a game-changer.
Resection in the head and neck is challenging for even the most experienced surgeon.
The ASTR (Autonomous System for Tumour Resection) performs the surgery by translating human guidance into robotic precision.
When removing cancerous tissue, preserving as much healthy tissue as possible to prevent unnecessary losses to the patient can be challenging.
Remove too little tissue; the risks are missing cancer cells that may return or even spread.
The success of the ASTR system, designed by a team of Johns Hopkins researchers to overcome human factors that may influence outcomes, has now been assessed in research published by the team behind the innovation.
Team leader Axel Krieger is an assistant professor of mechanical engineering at the Whiting School of Engineering.
He explained, ‘So much of these surgeries involve hope and even some guessing. Many surgeons struggle with this. Our goal was to make these procedures more precise.’
In such surgical cases, precision can require the removal of a 5mm margin of healthy tissue, a benchmark that surgeons strive to achieve in excising cancerous tissue.
The measure encompasses the affected cells while mitigating collateral damage. Adding complexity, cancerous tumours frequently exhibit discernible horizontal boundaries but less apparent vertical ones.
Professor Axel added: ‘The problem we heard from many of the surgeons we collaborate with is that it’s so hard to resection a tumour precisely. Surgeons bring a little ruler in to see the 5mm distance and mark off the edges on the sides. But how deep to go – that’s so difficult.’
Doctoral student and team member Jiawei Ge said that even though pre-surgery preparation is painstakingly thorough, that crucial 5mm border acts as a blind zone.
‘The challenge is that surgeons do not have direct access to the tumour due to surrounding tissue. They can see the surface of the tumour but can only see the healthy tissue otherwise. The map is in the surgeon’s mind.’
Using porcine tongue tissue, the team drew outlines of tumours based on empirical research and programmed ASTR to remove the tumour and precisely 5mm of healthy tissue using its combination of vacuum grasping and cutting. ASTR succeeded each time and did not require stoppage by the supervisors.
Professor Krieger added, ‘The physician can supervise the robot and give pre-surgery inputs, and then the robot does it step by step. What we showed is that surgeons can get very good horizontal margins with the ruler, but on the depth margins, our robot shows improvement.’
Krieger and his team based their new robotic system on the technology they developed for their Smart Tissue Autonomous Robot (STAR), which made international news two years ago for performing the first fully autonomous laparoscopic surgery.
The researchers adapted STAR’s technical workings to create ASTR’s new, autonomous, dual-arm, vision-guided robotic system.
But while STAR focuses on connecting tissue, ASTR is specifically tailored to remove it. Professor Krieger added: ‘We’ve sent the robot to make an incision before, but this is the first time we’ve done a bulk resection and taken a tumour out fully. That’s the big novelty here.’
The next step is to apply the technology to internal organs like the kidney, which require internal surgery and dissection to access the tumour.
Photo - Images of the (b) monopolar electrosurgical instrument, (c) vacuum grasping instrument, d) dual-camera vision system, sample holder, grounding pad, smoke evacuation tube, linear motion stage, and (e) simulated clinical setting featuring a porcine tongue specimen stretched using retraction sutures. The close views during the (f) surface incision and (g) deep margin dissection for a pseudotumor on a porcine tongue tissue.
