Eye gaze tracking for endoscopic camera positioning: an application of a hardware/software interface developed to automate Aesop.

A redesigned motion control system for the medical robot Aesop allows automating and programming its movements. An IR eye tracking system has been integrated with this control interface to implement an intelligent, autonomous eye gaze-based laparoscopic positioning system. A laparoscopic camera held by Aesop can be moved based on the data from the eye tracking interface to keep the user's gaze point region at the center of a video feedback monitor. This system setup provides autonomous camera control that works around the surgeon, providing an optimal robotic camera platform.

Hand position effects on precision and speed in telerobotic surgery.

BACKGROUND: Many surgical robotic interfaces allow users to interact with robots over a wide potential range of motion, yet variation in operator performance across a range of motion remains unexamined. This research identifies and explores a new construct, the surgeon's 'comfortable working envelope' within the available range of motion, as a factor in surgical robotic interface design. METHODS: Task accuracy and completion time for a simple aimed movement task were analysed as a function of participant hand positions obtained via infrared motion tracking. RESULTS: Hand positions outside the 'comfortable working envelope' led to a 20% increase in error magnitude. With respect to the overall input device range of motion, there were large variations in performance, up to 31% difference in error magnitude and 11% difference in movement time. CONCLUSIONS: These results suggest that advanced surgical robots should have intelligent re-indexing strategies. Alternatively, the robot's control gain should adaptively change with respect to hand position to normalize a surgeon's performance throughout his/her working volume.

A prototype biosensor-integrated image-guided surgery system.

BACKGROUND: In this study we investigated the integration of a Raman spectroscopy-based biosensor with an image-guided surgery system. Such a system would provide a surgeon with both a diagnosis of the tissue being analysed (e.g. cancer) and localization information displayed within an imaging modality of choice. This type of mutual and registered information could lead to faster diagnoses and enable more accurate tissue resections. METHODS: A test bed consisting of a portable Raman probe attached to a passively articulated mechanical arm was used to scan and classify objects within a phantom skull. RESULTS: The prototype system was successfully able to track the Raman probe, classify objects within the phantom skull, and display the classifications on medical imaging data within a virtual reality environment. CONCLUSION: We discuss the implementation of the integrated system, its accuracy and improvements to the system that will enhance its usefulness and further the field of sensor-based computer-assisted surgery.

Work and fatigue characteristics of unsuited and suited humans during isolated isokinetic joint motions.

The effects of a pressurized suit on human performance were investigated. The suit is known as an Extra-Vehicular Mobility Unit (EMU) and is worn by astronauts while working outside their spacecraft in a low earth orbit. Isolated isokinetic joint torques of three female and three male subjects (all experienced users of the suit in 1G gravity) were measured while working at 100% and 80% of their maximum voluntary torque (MVT, which is synonymous with maximum voluntary contraction (MVC)). It was found that the average decrease in the total amount of work (the sum of the work in each repetition until fatigue) done when the subjects were wearing the EMU were 48% and 41% while working at 100% and 80% MVT, respectively. There is a clear relationship between the MVT and the time and amount of work done until fatigue. Here, the time to fatigue is defined as the ending time of the repetition for which the computed work done during that repetition dropped below 50% of the work done during the first repetition. In general the stronger joints took longer to fatigue and did more work than the weaker joints. It was found that the EMU decreases the work output at the wrist and shoulder joints the most, due to the EMU joint geometry. The EMU also decreased the joint range of motion. The average total amount of work done by the test subjects increased by 5.2% (20.4%) for the unsuited (suited) case, when the test subjects decreased the level of effort from 100% to 80% MVT. Also, the average time to fatigue increased by 9.2% (25.6%) for the unsuited (suited) case, when the test subjects decreased the level of effort from 100% to 80% MVT. It was also found that the experimentally measured torque decay could be predicted by a logarithmic equation. The absolute average errors in the predictions were found to be 18.3% and 18.9% for the unsuited and suited subjects, respectively, when working at 100% MVT, and 22.5% and 18.8% for the unsuited and suited subjects, respectively, when working at 80% MVT. These results could be very useful in the design of future EMU suits and the planning of Extra-Vehicular Activity (EVA) for the future International Space Station assembly operations.

Serum calcium, magnesium and inorganic phosphorous levels during various phases of menstrual cycle.

Serum Calcium (Ca), Magnesium (Mg) and Inorganic phosphorous (Pi) were investigated serially during menstrual, follicular, ovulatory and luteal phases of menstrual cycle in 25 healthy medical student volunteers. The result shows significant cyclic variations within physiological limits in all parameters. Ca level was highest during ovulation (P < 0.001) and lowest during luteal phase (P < 0.001) compared to other phases. Exactly opposite result was observed for Ca level. It is lowest during ovulation (P < 0.001) and highest during the luteal phase (P < 0.001). However, the highest level of Pi was seen during menstrual phase (P < 0.001) and lowest during the luteal phase (P < 0.001). These changes are probably brought about under the influence of cyclic variations of the ovarian hormones.

Menarche: prior knowledge and experience.

The purpose of this study was to determine the details of first menstruation and the differences between those who had knowledge of menstruation prior to menarche and those who did not. Information from 305 young women in India was collected regarding menarcheal bleeding pattern, disturbances in normal menstruation, and menarcheal age. Those who had knowledge prior to menarche considered it to be a normal physiological function, while those who did not were "appalled" and "horrified." Those having prior knowledge had a high rate of regularity, lower rate of dysmenorrhea, and earlier onset of menarche. The subjects were unanimous in their desire for more information to be provided prior to menarche.