Ana Luisa Trejos

Robot-assisted Tactile Sensing for Minimally Invasive Tumor Localization

The 10 mm incisions used in minimally invasive cancer surgery prevent the direct palpation of internal organs, making intraoperative tumor localization difficult. A tactile sensing instrument (TSI), which uses a commercially available sensor to measure distributed pressure profiles along the contacting surface, has been developed to facilitate remote tissue palpation. The objective of this research is to assess the feasibility of using the TSI under robotic control to reliably locate underlying tumors while reducing collateral tissue trauma. The performance of humans and a robot using the TSI to locate tumor phantoms embedded into ex vivo bovine livers is compared. An augmented hybrid impedance control scheme has been implemented on a Mitsubishi PA10-7C to perform the force/position control used in the trials. The results show that using the TSI under robotic control realizes an average 35% decrease in the maximum forces applied and a 50% increase in tumor detection accuracy when compared to manual manipulation of the same instrument. This demonstrates that the detection of tumors using tactile sensing is highly dependent on how consistently the forces on the tactile sensing area are applied, and that robotic assistance can be of great benefit when trying to localize tumors in minimally invasive surgery.

A Sensorized Instrument for Skills Assessment and Training in Minimally Invasive Surgery

Minimally invasive surgery (MIS) is carried out using long, narrow instruments and significantly reduces trauma to the body, postoperative pain, and recovery time. Unfortunately, the restricted access conditions, limited instrument motion, and degraded sense of touch inherent in MIS result in new perceptual-motor relationships, which are unfamiliar to the surgeon and require training to overcome. Current training methods do not adequately address the needs of surgeons interested in acquiring these skills. Although a significant amount of research has been focused on the development of sensorized systems for surgery, there is still a need for a system that can be used in any training scenario (laparoscopic trainer, animal laboratories, or real surgery) for the purpose of skills assessment and training. A sensorized laparoscopic instrument has been designed that is capable of noninvasively measuring its interaction with tissue in the form of forces or torques acting in all five degrees-of-freedom (DOFs) available during MIS. Strain gauges attached to concentric shafts within the instrument allow the forces acting in different directions to be isolated. An electromagnetic tracking system is used for position tracking. Two prototypes of the sensorized instrument were constructed. Position calibration shows a maximum root mean square (RMS) error of 1.3 mm. The results of the force calibration show a maximum RMS error of 0.35 N for the actuation force, 0.07 N in the x and y directions, and 1.5 N mm for the torque calibration with good repeatability and low hysteresis. Axial measurements were significantly affected by drift, noise, and coupling leading to high errors in the readings. Novel sensorized instruments for skills assessment and training have been developed and a patent has been filed for the design and operation. The instruments measure forces and torques acting at the tip of the instrument corresponding to all five DOFs available during MIS and provide position feedback in six DOFs. The instruments are similar in shape, size, and weight to traditional laparoscopic instruments allowing them to be used in any training environment. Furthermore, replaceable tips and handles allow the instruments to be used for a variety of different tasks.

Feasibility of locating tumours in lung via kinaesthetic feedback

Localizing lung tumours during minimally invasive surgery is difficult, since restricted access precludes manual palpation and pre‐operative imaging cannot map directly to the intra‐operative lung. This study analyses the force‐sensing performance that would allow an instrumented kinaesthetic probe to localize tumours based on stiffness variations of the lung parenchyma.

Development of force-based metrics for skills assessment in minimally invasive surgery

BackgroundThe loss of haptic information that results from the reduced-access conditions present in minimally invasive surgery (MIS) may compromise the safety of the procedures. This limitation must be overcome through training. However, current methods for determining the skill level of trainees do not measure critical elements of skill attainment. This study aimed to evaluate the usefulness of force information for the assessment of skill during MIS.MethodsTo achieve the study goal, experiments were performed using a set of sensorized instruments capable of measuring instrument position and tissue interaction forces. Several force-based metrics were developed as well as metrics that combine force and position information.ResultsThe results show that experience level has a strong correlation with the new force-based metrics presented in this article. In particular, the integral and the derivative of the forces or the metrics that combine force and position provide the strongest correlations.ConclusionsThis study showed that force-based metrics are better indications of performance than metrics based on task completion time or position information alone. The proposed metrics can be automatically computed, are completely objective, and measure important aspects of performance.

Initial Evaluation of a Tactile/Kinesthetic Force Feedback System for Minimally Invasive Tumor Localization

Minimally invasive surgery (MIS), while beneficial to patients, leads to new challenges for surgeons and prevents tumors from being localized using finger palpation. A tactile-sensing system (TSS), consisting of a hand-held tactile-sensing instrument (TSI) with a visualization interface, was developed to assist in intraoperative tumor localization. This paper presents the calibration of the TSI and its integration with a visualization interface that allows palpation forces to be displayed. Experiments were conducted to determine whether providing visual force feedback (VFF) to the user would significantly benefit TSS performance when attempting to locate 10 mm hemispherical tumors in ex vivo bovine liver. The TSS with VFF realized a 33% and 21% relative reduction in average and maximum applied forces, respectively, and a 53% relative increase in detection accuracy when compared to the use of the TSS without VFF. Thus, VFF improves the performance of the TSS and has the potential to help surgeons identify tumors intraoperatively during MIS.

Experimental evaluation of robot-assisted tactile sensing for minimally invasive surgery

The 10 mm incisions used in minimally invasive cancer surgery prevent direct manual palpation of internal organs, making intraoperative tumor localization difficult. A tactile sensing instrument (TSI), that uses a commercially available sensor to measure distributed pressure profiles along the contacting surface, has been developed to facilitate remote tissue palpation. The objective of this research was to assess the feasibility of using the TSI under robotic control to reliably locate underlying tumors. The performance of human and robot manipulation of the TSI to locate tumor phantoms embedded into ex vivo bovine livers was compared. An Augmented Hybrid Impedance Control scheme was implemented on a Mitsubishi PA10-7C robot to perform force/position control during the trials. The results showed that using the TSI under robotic control realized an average 35% decrease in the maximum forces applied, and more than a 50% increase in tumor detection accuracy when compared to manual manipulation of the same instrument. This demonstrates that tumor detection using tactile sensing is highly dependent on the consistent application of forces on the tactile sensing area and that robotic assistance can be of great benefit when trying to localize tumors during minimally invasive surgery.

New tactile sensing system for minimally invasive surgical tumour localization

Minimally invasive surgery (MIS) suffers from the inability to directly palpate organs for tumour localization. A tactile sensing system (TSS), consisting of a probe and a visualization interface, was developed to present an active pressure map of the contact surface to locate tumours during MIS.

Design of a sensorized instrument for skills assessment and training in minimally invasive surgery

The restricted access conditions during minimally invasive surgery (MIS) result in perceptual-motor relationships that are unfamiliar to the novice surgeon and require training to overcome. To aid in MIS skills assessment and training, a novel sensorized instrument has been designed. Strain gauges attached to the instrument measure forces and torques acting at its tip, corresponding to all 5 degrees of freedom (DOFs) available during MIS. A position tracker provides tip motion feedback in 6 DOFs. The instrument is similar in shape, size and weight to traditional laparoscopic instruments, allowing it to be used in any MIS training environment. Furthermore, replaceable tips and handles make the instruments highly versatile. The results of the experimental evaluation show that there are clear differences in both the force and position profiles of trainees and surgeons with different levels of experience.

A device for robot-assisted minimally-invasive lung brachytherapy

A device for robot-assisted brachytherapy has been designed for use with a minimally-invasive surgical robot such as the ZEUStrade It may be loaded with a standard brachytherapy needle allowing the robot to position its tip at a specified location within cancerous tissue. The device accurately retracts a hollow needle loaded with radioactive seeds while a stationary plunger pushes the seeds out into the tissue. The position error when retracting the needle is less than 0.05 mm. The use of this device, together with image-guidance for needle placement, can improve radiation dose delivery when treating certain types of lung cancer. The incorporation of this device into robotic systems that are already approved for clinical use can potentially allow it to be commercialized much sooner than competitive technology

Port Placement for Endoscopic Cardiac Surgery Based on Robot Dexterity Optimization

Accurate and proper placement of ports during robotically-assisted endoscopic surgery is critical to the success of the procedure. Improper placement of ports can lead to robot collisions, the inability to reach the surgical site, the inability to manipulate the tools properly, or collisions between the tools inside the patient’s body. In current practice, port placement methods do not consider the ability of the robot to manoeuvre the tools. Furthermore, there is a lack of guidance on what the position of the robot or the configuration of its arms should be. This paper proposes to choose the best port location and determine the position of the base and arms of the robot such that its performance is maximized. Performance measures developed in the past to optimize robot design and manipulation are used to optimize the placement of ports when using a surgical manipulator for artery dissection during coronary bypass surgery.