Gentle robot improves cancer surgery

London, Canada – A new surgical robot with a delicate touch is claimed to detect tumors far more accurately than a human.

Researchers from the University of Western Ontario and Canadian Surgical Technologies and Advanced Robotics (CSTAR) say the robot can detect tumor tissue in half the time, and with 40 percent more accuracy.

Using robots during MIS – minimally invasive surgery, or keyhole surgery –  to detect tumours is “not only feasible, but results in reduced tissue trauma and increased tumor detection,” said lead author Analuisa Trejos.

Malignant tissue is usually stiffer than the surrounding tissue. After using scanning techniques such as MRI and CT, surgeons use gentle pressure (palpation) to confirm where the tumor is, or to locate further tumors. In MIS, this can be tricky.

An alternative is to relay touch cues via an instrument. A variety of handheld sensors and grasping instruments have been developed since the mid 1990s, but these do not control the amount of pressure used, nor do they position themselves correctly. Many are also too large for use in MIS.

With cows’ livers standing in for human tissue and 10mm and 5mm blobs of glue wrapped in wire representing tumors, the researchers compared palpation by surgeons, non-surgeons and the robot in blinded trials. They used a torque sensor to measure the force of the palpations.

Robotic control reduced the maximum force applied to the tissue by over 35 percent compared to a human controlling the same instrument. Accuracy in detecting tumours was also far greater – between 59 and 90 percent depending on the robot control method used for palpation. Unlike humans, the robot applies consistent force in each step and moves over the tissue systematically, producing a complete map.

In fact, both surgeons and non-surgeons were more likely to cause tissue damage than the robot. When a subject observed increased pressure on the visual display, they tended to focus on the area and apply even more force to see if what they had observed was a tumour.

The authors suggest that this type of instrument would particularly benefit surgeons performing lung tumor resection, where tissue often shifts significantly.

To develop the prototype for use in real MIS, the researchers plan to incorporate a flexible rotating head and a remote centre of motion. They would also add an improved interface to allow them to increase the number of palpations around a suspicious area.

The report appears in the International Journal of Robotics Research.