Safeguarding Minimally Invasive Drilling Processes in Medicine

27/05/2021

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Sensor Technology and Artificial Intelligence Support Operational Procedures

  Surgical instrument and skull Copyright: © WZL Linear drill channels make the surgical area accessible

In head and neck surgery, as in many other medical specialties, there is a desire to make surgical procedures minimally invasive in order to minimize trauma to patients. New surgical approaches and surgical methods are often required to perform these procedures when conven-tional instruments cannot be used. In order to implement the surgical wishes and ideas in everyday clinical practice and in the real surgical environment, physicians from the Ear, Nose and Throat Clinic of the University Hospital Düsseldorf are cooperating with engineers from the Laboratory for Machine Tools and Production Engineering (WZL) of RWTH Aachen University.

As part of the research project “Mambo Measurement-based Valida-tion of a Drilling Process in Image-guided Minimally Invasive Proce-dures Using the Example of the Otobasis”, whose second project phase started in April 2021, the realization of linear drilling channels is to be advanced in cooperation between the two facilities.

The insertion of one or more linear drill channels into the patient's skull, which meet at a so-called rendezvous point, grants access to the surgical area. This allows, for example, tumors at the base of the skull to be removed or biopsied, implants to be inserted or drugs to be ad-ministered in a targeted manner.

The advantage of this surgical procedure is that it uses multiple drill channels and does not require extensive bone removal, which is cur-rently still state-of-the-art. “The skull base is a major surgical chal-lenge, especially due to the close spatial relationships between highly sensitive structures and individual anatomy. Precise instruments are needed here,” says Dr. Tom Prinzen, a research associate at the Ear, Nose and Throat Clinic of the University Hospital Düsseldorf.

The greatest risk of drilling is injury to nerves, vessels or the inner ear. These can be damaged by the drill not only mechanically, by the direct hit, but also thermally, by the heat generated during the drilling process in the vicinity of the drilling site. Therefore, the development of a sen-sor-based concept to avoid thermal damage to tissue during medical drilling processes is the aim of the Mambo project, which is funded by the German Research Foundation.

  Drill on skull Copyright: © WZL A sensor-based concept is designed to avoid thermal damage to the tissue during the drilling process

In the first phase of the project, a drill with an integrated temperature sensor was developed to determine the heat at the bottom of the drill in real time. This drill now serves as the basis for an intraoperative as-sistance system, which processes the temperature data supplied by the drill during the operation using machine learning algorithms and communicates it to the surgeons in the form of recommendations for action. In this way, the temperature development during drilling can be pre-dicted and adaptively controlled by the surgeons performing the opera-tion. The surgeons' many years of expertise are thus supplemented by modern methods of data analysis and used to ensure the success of the operation for the patients.

“We face particular challenges in implementing the requirements from medicine for such devices, especially with regard to the small diameter of the instruments as well as the sterilizability of the electronics,”

says Anna-Lena Knott, a research associate at the Chair of Production Me-trology and Quality Management at the Laboratory for Machine Tools and Production Engineering (WZL) of RWTH Aachen University.

In the next two years of the project, the team expects to achieve progress in the clinical usability of the drill in order to further improve minimally in-vasive surgical procedures.