Design and Calibration of Plane Mirror Setups for Mobile Robots with a 2D-Lidar.

Lidar sensors are widely used for environmental perception on autonomous robot vehicles (ARV). The field of view (FOV) of Lidar sensors can be reshaped by positioning plane mirrors in their vicinity. Mirror setups can especially improve the FOV for ground detection of ARVs with 2D-Lidar sensors. This paper presents an overview of several geometric designs and their strengths for certain vehicle types. Additionally, a new and easy-to-implement calibration procedure for setups of 2D-Lidar sensors with mirrors is presented to determine precise mirror orientations and positions, using a single flat calibration object with a pre-aligned simple fiducial marker. Measurement data from a prototype vehicle with a 2D-Lidar with a 2 m range using this new calibration procedure are presented. We show that the calibrated mirror orientations are accurate to less than 0.6° in this short range, which is a significant improvement over the orientation angles taken directly from the CAD. The accuracy of the point cloud data improved, and no significant decrease in distance noise was introduced. We deduced general guidelines for successful calibration setups using our method. In conclusion, a 2D-Lidar sensor and two plane mirrors calibrated with this method are a cost-effective and accurate way for robot engineers to improve the environmental perception of ARVs.

Cochrane Reviews and Dermatological Trials Outcome Concordance: Why Core Outcome Sets Could Make Trial Results More Usable.

Evidence-based health care requires that relevant outcomes for patients are included in clinical trials investigating treatment effects, allowing subsequent systematic reviews to summarize all relevant evidence to guide clinical practice. Currently, no gold standard of outcome choice for dermatology trials and reviews exists. We systematically assessed concordance between efficacy outcomes in a random sample of 10 Cochrane Skin systematic reviews and the 220 dermatology trials included. Reviews did not include 742 (68%) of the 1,086 trial outcomes. Of the 60 outcomes the reviews sought, 17 (28%) were not reported in any trial, while 12 were assessed in <50% of trials. For 11 of 23 (48%) primary review outcomes, meta-analysis was impossible, because trial outcomes were absent or unclear. This small overlap of review/trial outcomes could suggest that trials are not measuring the outcomes perceived to be the most important by patients, clinicians, systematic reviewers, and trialists. The lack of standardized outcome measures, poor reporting of outcomes in trials, and low concordance of outcomes between reviews and primary studies could be improved by the development and implementation of Core Outcome Sets. These are an agreed-upon minimum set of key outcomes, for specified conditions, to be reported in all trials.

The diagnostic test accuracy of rectal examination for prostate cancer diagnosis in symptomatic patients: a systematic review.

BACKGROUND: Prostate cancer is the most common cancer in men in the UK. NICE guidelines on recognition and referral of suspected cancer, recommend performing digital rectal examination (DRE) on patients with urinary symptoms and urgently referring if the prostate feels malignant. However, this is based on the results of one case control study, so it is not known if DRE performed in primary care is an accurate method of detecting prostate cancer. METHODS: The aim of this review is to ascertain the sensitivity, specificity, positive and negative predictive value of DRE for the detection of prostate cancer in symptomatic patients in primary care. CENTRAL, MEDLINE, EMBASE and CINAHL databases were searched in august 2015 for studies in which a DRE was performed in primary care on symptomatic patients and compared against a reference diagnostic procedure. RESULTS: Four studies were included with a total of 3225 patients. The sensitivity and specificity for DRE as a predictor of prostate cancer in symptomatic patients was 28.6 and 90.7%, respectively. The positive and negative predictive values were 42.3 and 84.2%, respectively. CONCLUSION: This review found that DRE performed in general practice is accurate, and supports the UK NICE guidelines that patients with a malignant prostate on examination are referred urgently for suspected prostate cancer. Abnormal DRE carried a 42.3% chance of malignancy, above the 3% risk threshold which NICE guidance suggests warrants an urgent referral. However this review questions the benefit of performing a DRE in primary care in the first instance, suggesting that a patient's risk of prostate cancer based on symptoms alone would warrant urgent referral even if the DRE feels normal.

[Obligation of guideline recommendations: Perception survey among guideline developers]. / Verbindlichkeit von Empfehlungsformulierungen in Leitlinien: Survey zur Wahrnehmung unter Leitlinienentwicklern.

INTRODUCTION: Specific recommendations form the centerpiece of medical guidelines. The intended strength of a recommendation is usually expressed by the use of different wordings. Recent investigations showed that guideline users (recipients) interpret the binding character of wordings in different ways. The perception of different wording and their binding character of the strength of guideline recommendations among guideline developers (sender) have so far not been investigated in the German-speaking area. METHODS: German-speaking guideline developers were invited online and at specialist meetings to participate in a survey investigating 13 different terms used in guideline recommendations. The aim was to measure their perceived binding character on a visual analog scale (VAS: 0-100). Additional demographic and occupational data were collected. The results were compared with data from a previous survey among guideline users. RESULTS: Overall, 136 guideline developers with an average of 4.2 (median 3) guideline (co-) authorships participated in the survey. While guideline developers interpreted the two imperative recommendations "must" and "must not" with a similarly high level of obligation, the level of obligation was not rated homogenously for strong and weak recommendations like "shall" or "should". Two out of five negative formulations were perceived as more binding than their corresponding positive formulations. In comparisons with the ratings of the guideline users the terms "darf nicht" (must not), (-5.8 VAS, p≤0.0001) and "muss" (must), (-2.9 VAS, p≤0.0006) were perceived as less binding by the guideline developers, as was "sollte nicht"(should not) (-6.6 VAS, p≤0.0001) and "kann nicht empfohlen werden" (cannot be recommended) (-9.4 VAS, p≤0.0001). Only "soll" (shall) was perceived as more binding (+8.7 VAS, p≤0.0001). DISCUSSION: The current survey demonstrates that guideline developers perceive the binding character of terms used in guideline recommendations in a similar way as it was found for guideline users in a previous survey. Negative recommendations are more often rated as more binding by guideline developers as the corresponding positive terms. The discordant ratings by the guideline developers can be explained by their methodological knowledge regarding formulations of recommendations. It would be desirable that efforts be made to identify wordings in guidelines which better discriminate the intended level of obligation of guideline recommendations with regard to these results.

Performance of a new binocular wavefront aberrometer based on a self-imaging diffractive sensor.

PURPOSE: To compare the performance of the Ophthonix Z-View diffractive aberrometer with two different Hartmann-Shack aberrometers. METHODS: The Ophthonix Z-View was compared with the Alcon LADARWave and VISX WaveScan using 4 model eyes and 68 human eyes. Comparisons using three fixed, single-surface model eyes each with a different wavefront pattern were used to determine higher order accuracy. Lower order accuracy, linearity, and higher order repeatability were tested with a fourth model eye with a movable retinal surface. Manifest refraction spherical equivalent and the calculated spherical equivalent refraction of the aberrometers were compared in 68 human eyes. RESULTS: The Z-View was more accurate with lower noise compared to the WaveScan and LADARWave systems for higher order measurements of the fixed model eyes. Total root-mean-square difference from surface topography derived average values for all model eye configurations were 0.48, 0.95, and 0.74 microm for the Z-View, WaveScan, and LADARWave aberrometers, respectively. Average inter-measurement standard deviations for the fixed model eyes were 0.024, 0.025, and 0.034 microm for the Z-View, WaveScan, and LADARWave aberrometers, respectively. Results were similar among the systems for measuring the movable retina surface model eye and comparing manifest refraction spherical equivalent of the patients. CONCLUSIONS: Data gathered using one variable and several fixed-parameter model eyes showed good correlation to predicted values for all of the aberrrometers with one exception. A significant difference was found in the measurement of one individual fixed model eye with one of the three aberrometers. The wavefront refraction provided by the Z-View correlated well with the results of manifest refraction.

Imaging a child's fundus without dilation using a handheld confocal scanning laser ophthalmoscope.

Images of the fundus were acquired in children without pupil dilation using a prototype handheld confocal scanning laser ophthalmoscope (SLO). A 780-nm laser beam imaged a 20 degrees x 20 degrees area of the fundus while a 645-nm beam scanned a fixation target. Scorable images of the optic nerve, macula, and vessels were obtained in 67 (72%) of 93 eyes from pediatric patients with nystagmus, amblyopia, media opacities, or optic nerve or macular abnormalities. Images were obtained in all eyes of pediatric and adult controls. Unsuccessful imaging was associated with media opacities, high refractive error, and poor cooperation. Disadvantages of the SLO were the inability to detect optic nerve pallor or consistently image the periphery. Advantages of the SLO were seen in children with nystagmus, photophobia, eccentric fixation, cone dystrophy, and mild papilledema.