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At least 757 records · Page 42Linked to original sources
PubMed2002

A clearly visible endoscopic instrument shaft on the monitor facilitates hand-eye coordination.

BACKGROUND: Passing an instrument through a small incision alters the kinematics of the instrument, thus hampering hand-eye coordination. Nevertheless, the incision provides a stable, nearly invariant, point of rotation for instrument movements. Therefore, we set out to evaluate the effects of the altered kinematics on hand-eye coordination. In addition, we assessed the hypothesis that the hand-eye coordination of laparoscopic surgeons incorporates the incision as a point of reference. METHODS: Eight surgeons with experience in laparoscopy repeatedly performed a positioning task on a two-dimensional endoscopic manipulation simulator. Task time was measured. In the first experiment, normal endoscopic manipulation was compared to a condition in which the kinematic effects of the incision were compensated for. In the second experiment, the instrument shaft on the monitor was not visible during half of the trials, so that all visual information about the location of the incision was obscured. RESULTS: Task performance improved significantly when the kinematic effects of the incision were compensated for (p = 0.001). Task performance improved when the instrument shaft was clearly visible on the monitor (p <0.05). CONCLUSIONS: Compensating for the kinematic effects introduced by the incision improves hand-eye coordination. The results of this study indicate that the incision provides a point of reference for hand-eye coordination during endoscopic manipulation.

Computer Simulation↗
PubMed2003

Comparison of conventional and gaze-down imaging in laparoscopic task performance.

BACKGROUND: In video-assisted laparoscopy, the image is usually displayed on a monitor placed at approximately eye level. Video projection systems project the image onto a screen placed close to the hands. This is said to be ergonomically superior. To evaluate this approach, a proprietary projection system (PS) was compared to a monitor display (MD). METHOD: The resolution, ghosting, flickering, glare, contrast, color smear, and color matching of the two modalities were compared. A bowel-suturing task was employed to evaluate performance differences. RESULTS: The image displayed by the first-generation PS is inferior to that of the MD in contrast and resolution measures, but it is comparable in the other image qualities. No significant differences in task performance were identified. CONCLUSIONS: The first-generation PS does not confer performance or comfort advantages over an MD. The theoretical advantages of the gaze-down stance are likely to be realized only if a high-quality projector is used.

Clinical Competence↗
PubMed2004

Simulated laparoscopy using a head-mounted display vs traditional video monitor: an assessment of performance and muscle fatigue.

BACKGROUND: The direction of visual gaze may be an important ergonomic factor that affects operative performance. We designed a study to determine whether a head-mounted display (HMD) worn by the surgeon would improve task performance and/or reduce muscle fatigue during a laparoscopic task when compared to the use of a traditional video monitor display (VMD). METHODS: Surgical residents (n = 30) were enrolled in the study. A junior group, consisting of 15 postgraduate year (PGY) = 1 subjects with no previous laparoscopic experience, and a senior group, consisting of 15 PGY 4 and PGY 5 subjects with experience, completed a laparoscopic task that was repeated four times using the Computer Enhanced Laparoscopic Training System (CELTS). Groups alternated between using the HMD with the task placed in a downward frontal position and the VMD with the task at a 30 degrees lateral angle. The CELTS module assessed task completion time, depth perception, path length of instruments, response orientation, motion smoothness; the system then generated an overall score. Electromyography (EMG) was used to record sternocleidomastoid muscle activity. Display preference was surveyed. RESULTS: The senior residents performed better than the junior residents overall on all parameters (p < 0.05) except for motion smoothness, where there was no difference. In both groups, the HMD significantly improved motion smoothness when compared to the VMD (p < 0.05). All other parameters were equal. There was less muscle fatigue when using the VMD (p < 0.05). We found that 66% of the junior residents but only 20% of the senior residents preferred the HMD. CONCLUSIONS: The CELTS module demonstrated evidence of construct validity by differentiating the performances of junior and senior residents. By aligning the surgeon's visual gaze with the instruments, HMD improved smoothness of motion. Experienced residents preferred the traditional monitor display. Although the VMD produced less muscle fatigue, inexperienced residents preferred the HMD, possibly because of improved smoothness of motion.

Computer Simulation↗
PubMed2005

Monitor position in laparoscopic surgery.

BACKGROUND: One of the key problems in laparoscopy is the ergonomic positioning of the monitor. In this study we tested task performance and muscle strain of subjects in relation to monitor position during laparoscopic surgery. METHODS: Eighteen subjects simulated laparoscopic suturing by threading tiny pearls with a curved needle. This was repeated in three monitor positions (15 min each): frontal at eye level (A), frontal in height of the operating field (B), and 45 degrees to the right side at eye level (C). Subjects were not allowed to turn their heads during these sessions. After the test they were asked for their preferred monitor position. During all tests the electromyographic (EMG) activity of the main neck muscles was recorded and the number of pearls was counted. RESULTS: The EMG activity was significantly lower for position A compared to positions C and B (p < 0.05). No significant difference was found between positions B and C. The number of threaded pearls as an indicator for task performance was highest for position B. The difference was statistically significant compared to position C (p = 0.0008) but not between positions A and C (p = 0.0508) or A and B (p = 0.0575). When asked for the preferred monitor position, nine subjects chose two monitors in the frontal positions A and B. No subject preferred the monitor at the side position (C). CONCLUSION: Regarding EMG data, the monitor positioned frontal at eye level is preferable. Reflecting personal preferences of subjects and task performance, it should be of advantage to place two monitors in front of the surgeon: one in position A for lowest neck strain and the other in position B for difficult tasks with optimal task performance. The monitor position at the side is not advisable.

Computer Terminals↗
PubMed2003

Simultaneous live video presentation during knee arthroscopy.

To improve patient understanding, we evaluated prospectively the effect of patient-observed simultaneous surgeon-explained live video during knee arthroscopy. Patient satisfaction, understanding, and tolerance of the tenderness and pain were measured by a questionnaire completed immediately after the procedure. There were 72 patients (41 men, 31 women) with a mean age of 47 years; 76 joints were treated among them. All but one were comfortably able to watch the live video of the procedure, and 89% of the patients reported a good understanding of and satisfaction with the procedure. Moreover, if the patients ever had to have another arthroscopy, 66% answered that they "certainly" wanted a live video presentation, and 25% "somewhat" desired it. Live video-presented outpatient arthroscopic knee surgery could be considered a method for improving patient understanding of knee pathology.

Adolescent↗
PubMed2002

An interactive method of assessing the characteristics of softcopy display using observer performance tests.

An interactive computer program has been developed to assess the quality of softcopy display by measuring the contrast sensitivity, spatial resolution, and spatial uniformity at various backgrounds and objects. This program runs on Microsoft Window or NT platform and is easy to use. It has been shown to be a sensitive and accurate tool to measure the characteristics of monitors of any kind. It can be used for routine QA as well as for the acceptance testing of picture archiving and communication systems. Data obtained using this program on monitors can be plotted chronologically so as to monitor any trend of deterioration. By introducing a randomization of the location of the test objects, this program eliminates the guessing error often associated with psychophysical measurements.

Computer Terminals↗
PubMed2002

SoftCopy Display Quality Assurance Program at Texas Children's Hospital.

With growing dependence on picture archiving and communication systems for viewing images, a quality assurance program to monitor the condition of workstation displays has become increasingly important. At present there is no universally accepted program for PACS, but there are groups such as DICOM Working Group 11 of the ACR-NEMA and AAPM Task Group 18 that are working on image quality guidelines for interpretation from soft-copy displays. Texas Children's Hospital (TCH) is developing our own quality assurance program. Data is being collected to determine the appropriate frequency of calibration, the useful life of the displays, appropriate manufacturers, and model-dependent limits on maximum and minimum luminance (black level), symptoms of degradation, and monitor cleanliness. Our system includes a variety of monitors manufactured by Sun, AFP, Siemens, Image Systems, Barco, and Orwin. We are presently collecting data on individual monitor luminance functions but have not yet initiated service calls based on deviation from the DICOM Part 14 Grayscale Display Function (GSDF). The GSDF was intended to produce a grayscale in which driving levels produce changes in luminance that are perceptually equivalent throughout the entire luminance range for a specific test target. Our data is based on measurements of luminance from a digital Society of Motion Picture and Television Engineers (SMPTE) test pattern, which is a standard used by many other institutions. TCH's biomedical engineer measures luminance data each month from the display of the SMPTE pattern and record the results in a spreadsheet. The engineer also makes subjective evaluations of sharpness, geometric distortion, and artifacts. When a monitor's luminance falls outside of arbitrary 10% limits of maximum or minimum luminance, then a service call is placed to the vendor. The luminance check by the biomedical engineer is used to verify both routine and unscheduled calibrations. In addition to the monthly monitor checks, the vendor calibrates the monitor every three months. The vendor checks the following: width and height of display, focus and position of image, SMPTE test pattern, and a graph of the GSDF Index produced by an automatic calibration software by the video driver card. Monitors are also cleaned occasionally for dust, fingerprints, ink, and pencil marks, which accumulate with routine use. This paper reports data collected to date on luminance drift, as well as conclusions on appropriate frequency of test and calibration, and our experience with monitor useful life.

Computer Terminals↗
PubMed2002

PACS monitors: an evolution of radiologist's viewing techniques.

When initially evaluating picture archiving communication systems (PACS) many radiologists try to duplicate the film environment and believe that multiple monitors are required to maintain the productivity of the radiologist. The authors were under the same impression initially but found that they underwent a paradigm shift over a period of time. This report documents the evolution that the radiologists underwent. The author's department consists of 28 diagnostic radiologists and 21 residents who actively read cases on a PACS. The department has been filmless for 6 months, although they have been reading soft copy films for 2 years. All modalities except mammography are included. The authors conducted interviews with both attending radiologists and residents to evaluate the change in methodology from the preconceptions to initial use to current use. The number and kind of monitors preferred for plain films, ultrasound scan, computed tomography (CT), and magnetic resonance imaging (MRI) were recorded. Additionally, viewing methods of different modalities were discussed. The authors found that there was a decrease in the number of monitors from preconceptions to actual use. Furthermore, to a lesser degree, there is a reduction of monitors used initially to that which is currently being used. The style of viewing cross-sectional images has changed. There has been a decrease in the number of images displayed on each monitor. The use of the roller ball on the mouse has affected this viewing style. Changing from a film-based reading environment to PACS environment not only brings about change in the overall technology in image delivery but also in the viewing techniques by radiologists. At our institution we have evolved from initially expecting to use 4 monitors all the time to actually preferring 2 monitors and occasionally 1 monitor to view images. Presentation software and viewing aids such as the roller ball on a mouse for viewing CTs in stack mode are key contributions to this paradigm shift. The decrease in monitors makes PACS more affordable and will allow further penetration of filmless radiology. The authors have found that after using PACS, radiologists prefer using 2 monitors. The style of reading films has changed with experience. Hospitals that plan to purchase PACS should consider this and ensure that the vendor has presentation software that optimizes the 2 monitor system.

Computer Terminals↗
PubMed2005

Image quality assurance of soft copy display systems.

Image quality assurance has traditionally been a high priority in medical imaging departments. Recently, it has often been neglected with the transition from hard copy (film) to soft copy (computer) display systems, which could potentially result in difficulty in reading images or even misdiagnosis. This transition therefore requires careful management such that comparable image quality is achieved at a minimum. It is particularly difficult to maintain appropriate image quality in the clinical settings outside of medical imaging departments because of the volume of display systems and the financial restraints that prohibit the widespread use of dedicated computers and high-quality monitors. In this study, a protocol to test and calibrate display systems was developed and validated by using an inexpensive calibration tool. Using this protocol, monitors were identified in a hospital in which image quality was found to be inadequate for medical image viewing. It was also found that most monitors could achieve a substantial increase in image quality after calibration. For example, the 0 and 5% luminance difference was discernable on 30% of the piloted display systems before calibration, but it was discernable on 100% post calibration. In addition, about 50% of the piloted display systems did not have the maximum luminance (white level) suitably set, and 35% of them did not have the minimum luminance (dark level) suitably set. The results indicate that medical display systems must be carefully selected and strictly monitored, maintained, and calibrated to ensure adequate image quality.

Calibration↗
PubMed2005

Assessment of PACS display systems.

This work describes our experience in reviewing the performance criteria for display systems and how we have implemented a practical approach to the assessment of the workstation environment in a large tertiary care hospital. The acceptance criteria contained in the draft report of Topic Group 18 of the American Association of Physicists in Medicine (AAPM) were used as a basis for assessment of primary and secondary displays. A telescopic photometer was used to measure the maximum luminance and the contrast ratio of the image for the displays used in our radiology department and in the operating and emergency rooms using the standard Society of Motion Picture and Television Engineers (SMPTE) pattern, in ambient light and with light decreased as much as possible. About half of the displays met the AAPM criteria for minimum luminance and contrast ratio in low light. None of the systems met the contrast ratio criteria in ambient light. The challenges in improving the performance and calibrating displays are discussed.

Computer Terminals↗
PubMed2005

Determining the MTF of medical imaging displays using edge techniques.

The modulation transfer function (MTF) of a medical imaging display is typically determined by measuring its response to square waves (bar patterns), white noise, and/or line stimuli. However, square waves and white noise methods involve capture and analysis of multiple images and are thus quite tedious. Measurement of the line-spread function (LSF) offers a good alternative. However, as previously reported, low-frequency response obtained from the LSF method is not as good as that obtained from measurement of edge-spread function (ESF). In this paper, we present two methods for evaluating the MTF of a medical imaging display from its ESF. High degree of accuracy in the higher frequency region (near the Nyquist frequency of the system) was achieved by reducing the noise. In the first method, which is a variant of the Gans' original method, the periodic raster noise is reduced by subtracting a shifted ESF from the ESF. The second method employs a low-pass differentiator (LPD). A novel near maximally flat LPD with the desired cut-off frequency was designed for this purpose. Noise reduction in both the methods was also achieved by averaging over large portions of the image data to form the ESF. Experimental results show that the MTF obtained by these methods is comparable to that obtained from the square wave response. Furthermore, the MTFs of rising and falling edges of a cathode ray tube (CRT) were measured. The results show that the rising and falling vertical MTFs are practically the same, whereas the rising horizontal MTF is poorer than the falling horizontal MTF in the midfrequency region.

Computer Terminals↗
PubMed2006

Automated post hoc removal of power-line and CRT frame pulse contamination from retinal and cortical evoked potentials (EPs).

Recordings of the ERG, PERG, VEP and their multi-focal variants are occasionally contaminated with harmonic noise arising from the mains supply and CRT monitors. These noise contributions can be modelled as distorted sinusoids and identified by means of non-linear multiple regression and removed: no a priori estimates of number or frequency of noise sources are required. This approach is termed noise cancellation and does not constitute any form of notch filter: the fidelity of the underlying waveform is preserved. Here the simple theory is illustrated in artificial datasets and then applied to clinical examples of PERG and VEP. The programming language used throughout is MatLab R13SP3 (Mathworks UK Ltd.).

Artifacts↗
PubMed2005

Basis for an FCE methodology for patients with work-related upper limb disorders.

A reported reduction in work-related functional capacity in Work-related Upper Limb Disorders (WRULD) patients is among the most common problems in WRULD. The extent to which this reduction in functional capacity can be objectified remains unknown. A validated instrument to test functional capacity in this patient group is unavailable. The objective of this study was to design a Functional Capacity Evaluation (FCE) for WRULD patients working with Visual Display Units (VDU) and provide evidence for content validity. A review to epidemiological literature was conducted to identify physical risk factors for VDU-related WRULD. The results indicate that physical risk factors were related to repetition, duration, working in awkward and static positions and forceful movements of the upper extremity and neck. An FCE was designed based on the risk factors identified. Eight tests were selected to cover all risk factors: the overhead lift, overhead work, repetitive reaching, handgrip strength, finger strength, wrist extension strength, fingertip dexterity, and a hand and forearm dexterity test. Content validity of this FCE was established by providing the rationale, specific objectives and operational definitions of the FCE. Further research is needed to establish reliability and other aspects of validity of the WRULD FCE.

Biomechanical Phenomena↗
PubMed2006

Psychophysical evaluation of calibration curve for diagnostic LCD monitor.

PURPOSE: In 1998, Digital Imaging Communications in Medicine (DICOM) proposed a calibration tool, the grayscale standard display function (GSDF), to obtain output consistency of radiographs. To our knowledge, there have been no previous reports of investigating the relation between perceptual linearity and detectability on a calibration curve. MATERIALS AND METHODS: To determine a suitable calibration curve for diagnostic liquid crystal display (LCD) monitors, the GSDF and Commission Internationale de l'Eclairage (CIE) curves were compared using psychophysical gradient delta and receiver operating characteristic (ROC) analysis for clinical images. RESULTS: We succeeded in expressing visually recognized contrast directly using delta instead of the just noticeable difference (JND) index of the DICOM standard. As a result, we found that the visually recognized contrast at low luminance areas on the LCD monitor calibrated by the CIE curve is higher than that calibrated by the GSDF curve. On the ROC analysis, there was no significant difference in tumor detectability between GSDF and CIE curves for clinical thoracic images. However, the area parameter Az of the CIE curve is superior to that of the GSDF curve. The detectability of tumor shadows in the thoracic region on clinical images using the CIE curve was superior to that using the GSDF curve owing to the high absolute value of delta in the low luminance range. CONCLUSION: We conclude that the CIE curve is the most suitable tool for calibrating diagnostic LCD monitors, rather than the GSDF curve.

Calibration↗
PubMed1992

Imaged thoracic lobectomy: should it be done?

Imaged thoracic surgery is a new modality that is rapidly gaining acceptance from thoracic surgeons. Procedures that traditionally required a thoracotomy can now be done successfully using this technique in some patients. Three patients with primary carcinoma of the lung have undergone lobectomy using imaged thoracic surgery.

Adenocarcinoma, Bronchiolo-Alveolar↗
PubMed1992

Imaged thoracoscopic surgery: a new thoracic technique for resection of mediastinal cysts.

Previously, intrathoracic organs have been approached by either thoracotomy or thoracoscopy. A technique, imaged thoracoscopic surgery, using video optics and projection of images on a screen provides another option for the thoracic surgeon. Two patients with mediastinal cysts, one bronchogenic and one esophageal, underwent surgical removal using imaged thoracoscopic surgery. Postoperative pain was markedly reduced, hospitalization shortened, and recovery accelerated. Numerous complex surgical procedures can be performed using imaged thoracoscopic surgery.

Adult↗