Alex Cao

NASA TLX: Software for assessing subjective mental workload

The NASA Task Load Index (TLX) is a popular technique for measuring subjective mental workload. It relies on a multidimensional construct to derive an overall workload score based on a weighted average of ratings on six subscales: mental demand, physical demand, temporal demand, performance, effort, and frustration level. A program for implementing a computerized version of the NASA TLX is described. The software version assists in simplifying collection, postprocessing, and storage of raw data. The program collects raw data from the subject and calculates the weighted (or unweighted) workload score, which is output to a text file. The program can also be tailored to a specific experiment using a simple input text file, if desired. The program was designed in Visual Studio 2005 and is capable of running on a Pocket PC with Windows CE or on a PC with Windows 2000 or higher. The NASA TLX program is available for free download.

Improved Telemanipulator Navigation During Display-Control Misalignments Using Augmented Reality Cues

An augmented reality (AR) cueing method designed to improve teleoperator performance under conditions of display-control misalignment is investigated. The teleoperation task was designed to mimic the operation of space robot arms, which are manipulated using hand controllers (HCs) to orient and translate the body-fixed coordinates at the end effector (EE). Cameras provide visual feedback. However, the pose of the EE seen through the camera hinders operator performance due to misalignments between the displayed EE axes and the HC axes. In this paper, the coordinate system of the EE is graphically overlaid in three dimensions on the video views with uniquely colored axes using AR. The same color scheme is used to label the corresponding axes on the HCs. Operators use these color cues to map each axis on the HCs to the corresponding colored axis of the augmented coordinates at the EE to obtain EE movement in the desired direction. Between-groups and within-participant experiments comparing EE trajectory distance, deviation from path, navigation errors, and HC axis usage were used to determine the effectiveness of the augmented coordinates over conventional teleoperation without augmented coordinates. Significant reductions in EE trajectory distance, deviation from path, navigation errors, and single-axis HC usage were observed when participants manipulated the remote robot with augmented coordinates. The results demonstrate that the use of simple AR cues in remote robot arm teleoperation is beneficial to the operator.

Diagnosis of neuroblastoma and ganglioneuroma using Raman spectroscopy.

BACKGROUND Raman spectroscopy has proven to be useful in studying premalignant and malignant lesions in adults. This is the first report to evaluate Raman spectroscopy in the diagnosis and classification of neuroblastoma in children. METHODS A biopsy or resection of fresh tissue samples from normal adrenal glands, neuroblastomas, ganglioneuromas, nerve sheath tumors, and pheochromocytoma at our hospital were equally divided between routine histology and spectroscopic studies. At least 12 spectra were collected from different regions of each sample using a Renishaw Raman microscope. Raw spectra were processed to remove noise, fluorescence, and shot noise, and then analyzed using principle component analysis and discriminant function analysis. RESULTS We collected 698 spectra from 16 neuroblastomas, 5 ganglioneuromas, 3 normal adrenal glands, 6 nerve sheath tumors, and 1 pheochromocytoma. Raman spectroscopy differentiated between normal adrenal gland, and neuroblastoma and ganglioneuroma with 100% sensitivity and 100% specificity. It correlated well with the Shimada histologic classification system with 100% sensitivity and 100% specificity. It was also able to differentiate neuroblastoma from nerve sheath tumors and pheochromocytoma with high sensitivity and specificity. CONCLUSION This technique can differentiate neuroblastoma from ganglioneuroma and other tumors. It has a potential as a noninvasive real-time diagnostic tool in classifying pediatric tumors.

Evaluation of pancreatic cancer with Raman spectroscopy in a mouse model.

Objectives: Detection of neoplastic changes using optical spectroscopy has been an active area of research in recent times. Raman spectroscopy is a vibrational spectroscopic technique that can be used to diagnose various tumors with high sensitivity and specificity. We evaluated the ability of Raman spectroscopy to differentiate normal pancreatic tissue from malignant tumors in a mouse model. Methods: We collected 920 spectra, 475 from 31 normal pancreatic tissue and 445 from 29 tumor nodules using a 785-nm near-infrared laser excitation. Discriminant function analysis was used for classification of normal and tumor samples. Results: Using principal component analysis, we were able to highlight subtle chemical differences in normal and malignant tissue. Using histopathology as the gold standard, Raman analysis gave sensitivities between 91% and 96% and specificities between 88% and 96%. Conclusions: Raman spectroscopy along with discriminant function analysis is a useful method to detect cancerous changes in the pancreas. Pancreatic tumors were characterized by increased collagen content and decreased DNA, RNA, and lipids components compared with normal pancreatic tissue.

Performance of basic manipulation and intracorporeal suturing tasks in a robotic surgical system: single- versus dual-monitor views

BackgroundTechnical advances in the application of laparoscopic and robotic surgical systems have improved platform usability. The authors hypothesized that using two monitors instead of one would lead to faster performance with fewer errors.MethodsAll tasks were performed using a surgical robot in a training box. One of the monitors was a standard camera with two preset zoom levels (zoomed in and zoomed out, single-monitor condition). The second monitor provided a static panoramic view of the whole surgical field. The standard camera was static at the zoomed-in level for the dual-monitor condition of the study. The study had two groups of participants: 4 surgeons proficient in both robotic and advanced laparoscopic skills and 10 lay persons (nonsurgeons) who were given adequate time to train and familiarize themselves with the equipment. Running a 50-cm rope was the basic task. Advanced tasks included running a suture through predetermined points and intracorporeal knot tying with 3–0 silk. Trial completion times and errors, categorized into three groups (orientation, precision, and task), were recorded.ResultsThe trial completion times for all the tasks, basic and advanced, in the two groups were not significantly different. Fewer orientation errors occurred in the nonsurgeon group during knot tying (p = 0.03) and in both groups during suturing (p = 0.0002) in the dual-monitor arm of the study. Differences in precision and task error were not significant.ConclusionsUsing two camera views helps both surgeons and lay persons perform complex tasks with fewer errors. These results may be due to better awareness of the surgical field with regard to the location of the instruments, leading to better field orientation. This display setup has potential for use in complex minimally invasive surgeries such as esophagectomy and gastric bypass. This technique also would be applicable to open microsurgery.

Optimizing the Surgeon-Robot Interface: The Effect of Control-Display Gain and Zoom Level on Movement Time

While many advances have been made in surgical robotics technology, even for surgeons with relatively high levels of robotic surgery experience, many tasks take less time to perform manually. Although there are other benefits to surgical robotics that may outweigh task completion time, relatively lower efficiency will hinder the adoption of this technology. This study focused on two interface parameters: Control-Display Gain (CDG, i.e., the amount of robot movement resulting from a given robot controller movement) and the optical Zoom level that defines the working field of view. Results from a study with 10 participants suggest that CDG is a promising interface parameter for optimizing movement time in robot-assisted surgical tasks. The results have implications for the development and implementation of intelligent surgeon-robot interface technology and hold the potential to greatly improve the efficiency of robotic-assisted surgery techniques.

Comparing two kinematics methods for telerobotic control applications

Two inverse kinematics algorithms were implemented in a tele-operated robot system and evaluated with a user performance study. The kinematics algorithms were designed such that the point of resolution (POR) of the robot arms wrist and the end-effector was controlled by joysticks, one each for rotation and translation. Operator performance was evaluated with “peg-in-the-hole” type tasks using both the wrist and end-effector POR modes. Wrist kinematics resulted in faster performance times, however, with longer average distances traveled while the opposite effect was observed with end-effector kinematics. Reversal errors were present equally in both modes, while the end-effector mode showed higher 1-axis use of the joysticks. Implications for remote robotic operation design and kinematics are discussed.

Minimizing Movement Time in Surgical Telerobotic Tasks

Surgical robotic devices are rapidly achieving widespread use and acceptance. Despite the many benefits of robotic-assisted surgery, it is typical for robot-assisted procedures to take longer. This study investigates the effect of control:response ratio on simple movement time in surgical telerobotic tasks. Robot control interfaces offer “motion scaling”settings but, in practice, this feature is often not used effectively, and is confounded by factors such as the fulcrum point of the laparoscopic instrument. Results using a simple aimed movement task indicate that control:response ratio indeed has a large effect on movement time, and further that it interacts with task difficulty. These results can guide medical device designers and the developers of surgical training protocols.

Application of a Surgical Robot to Open Microsurgery: The Equipment

Background: Computer-assisted robot-enhanced surgery can enhance minimally invasive surgery by providing a wrist at the end of the instruments and by scaling motion and filtering tremor. Motion scaling and tremor filtration are most enabling at high magnification. Goal: To explore the possibility of using a surgical robot designed for minimally invasive surgery during open microsurgical procedures. Materials and Methods: Using the Zeus MicroWrist™ Robotic Surgical System in conjunction with the triple-alpha port, we performed suture tasks on a glove box with microsurgical suture (8-0 to 10-0) in three different configurations. First, we used a standard 10- mm laparoscope, camera, and the Zeus monitor. Next, we used an operating microscope for visualization with the surgeon at the operative table while controlling the instruments. Third, we allowed the surgeon to sit at the standard Zeus console and transmitted the image from the microscope to the monitor at the Zeus console. Results: In all three configur...

An integrated movement capture and control platform applied towards autonomous movements of surgical robots.

Robotic surgery has gradually gained acceptance due to its numerous advantages such as tremor filtration, increased dexterity and motion scaling. There remains, however, a significant scope for improvement, especially in the areas of surgeon-robot interface and autonomous procedures. Previous studies have attempted to identify factors affecting a surgeons performance in a master-slave robotic system by tracking hand movements. These studies relied on conventional optical or magnetic tracking systems, making their use impracticable in the operating room. This study concentrated on building an intrinsic movement capture platform using microcontroller based hardware wired to a surgical robot. Software was developed to enable tracking and analysis of hand movements while surgical tasks were performed. Movement capture was applied towards automated movements of the robotic instruments. By emulating control signals, recorded surgical movements were replayed by the robots end-effectors. Though this work uses a surgical robot as the platform, the ideas and concepts put forward are applicable to telerobotic systems in general.