Dr Kwok Ka Wai (on the right), Associate Professor of Department of Mechanical Engineering, HKU
A joint research team involving the Department of Mechanical Engineering, The University of Hong Kong (HKU) has found a way to improve the procedures for treating head and neck cancer patients.
The research outcome - a novel MR-safe system in miniature size, with compliant architecture and five degrees of freedom - enables safe and dexterous laser ablation within the confined spaces of the oral and pharyngeal cavities. Leading the engineering research team is Dr Kwok Ka Wai, an associate professor from the Department of Mechanical Engineering, who collaborated with HKU’s Faculty of Dentistry, and the Department of Otorhinolaryngology, Head and Neck Surgery, Faculty of Medicine, CUHK.
Recently published in the journal Science Robotics, the outcome marks the beginning of more applications for the treatment of a wide range of patients afflicted with head and neck cancer, i.e. cancers in areas including the oral cavity, laryngopharynx, nasopharynx and nasal cavity, which is the seventh most common cancer in the world causing 450,000 deaths every year.
Unlike the traditional treatment approach involving the use of bulky and rigid laser manipulator, the soft robotic manipulator for transoral laser microsurgery is guided by intra-operative magnetic resonance imaging (MRI). The MRI environment allows for evaluating 3D ablation margins alongside thermal distributions in real time, protecting critical neurovascular structures while ensuring adequate ablation margins. But the confines of the MRI bore and its strong magnetic field (1.5/3T) means conventional metallic robot components cannot be implemented. Instead, the novel soft robotic manipulator driven by hydraulics is fit for the job.
Dr Kwok said the complexity and rigidity of the traditional method drove the latest innovation. “With the current conventional approach, it is challenging for surgeons to assess the laser ablation progress during surgery, which is essential to ensure that surrounding healthy tissue is preserved, particularly the muscles for speech and swallowing. Moreover, the current lasers are also delivered through rigid and straight instruments which can put patients in extreme neck extension.”
On the contrary, the new MRI-compatible robot integrated with a laser fibre can direct energy delivery to the target lesion through a patient-specific dental anchorage in the oral cavity, enabling surgical guidance under the MRI.
Creating even smaller robots
Dr Kwok is working on scaling down the robot size further to facilitate endoscopic applications so that mechanical transmission can happen in minimally invasive surgery for different body organs, for example, those attacked by cancer cells. “We can treat the earliest stage of cancer in the digestive system, for example, in the colon, rectum, stomach, esophagus or even bladder.”
Dr Kwok has been working for seven years on robotic systems that can operate in an environment with extremely strong magnetic fields. Aiding that effort was the discovery of positional markers, described by Dr Kwok as the GPS within the MRI system, through collaborations with the university’s Department of Diagnostic Radiology.
Dr Kwok also enjoys close collaborations with counterparts at Johns Hopkins University. “They have an experienced team in developing various kinds of robotic systems for surgical applications. We shared a lot of insight regarding the surgical workflow.”
The vibrant research community at HKU comprising clinicians, radiologists, engineers and other scientists is another important source of support, as is the university’s Technology Transfer Office which helps with seeking backing from potential investors. “Through commercialization or spin-offs, we can sustain the research and carry out further clinical trials towards real clinical applications,” said Dr Kwok.
Demonstration of novel robot system for MRI-guided Transoral Laser Microsurgery
Soft robotic manipulator for Intra-operative MRI-guided transoral laser microsurgery
MR thermometry to precisely monitor the tissue ablation