Publications by authors named "Swensson R"

The supervision of field experiences is an indispensable component of Board-Certified Behavior Analyst (BCBA®) training. During the supervised field experience, supervisors regularly provide performance feedback to trainees for the purpose of improving fidelity of implementation of various assessments and interventions. Emerging evidence supports the efficacy of using telehealth to train teachers and parents to implement interventions, but no study has evaluated the effectiveness of the remote delayed performance feedback among individuals completing BCBA® training.

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The trial-based functional analysis (TBFA) offers several advantages in natural settings, such as time efficiency and ecological validity. Previous studies have successfully trained or coached a variety of professionals and parents to conduct a TBFA utilizing in-person training procedures; however, no study has evaluated the effectiveness of telehealth coach or train others to implement a TBFA. Utilizing telehealth coaching, we coached three mothers of children with autism to conduct a TBFA in their home.

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Children with autism spectrum disorder often display deficits in daily living skills. Behavior analysts can use telehealth, such as videoconferencing technology, to deliver interventions to families of these children. Given the COVID-19 pandemic and the common barriers to accessing behavioral interventions, it is imperative to evaluate the effectiveness and practicality of delivering behavioral interventions via telehealth.

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Vestibular Shwannomas are responsible for 80-90% of the cerebelar-pontine angle tumors and their incidence is of 0.8 to 20.5% of all tumors.

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Rationale And Objectives: The authors evaluated the impact of different computer-aided detection (CAD) cueing conditions on radiologists' performance levels in detecting and classifying masses depicted on mammograms.

Materials And Methods: In an observer performance study, eight radiologists interpreted 110 subtle cases six times under different display conditions to detect depicted masses and classify them as benign or malignant. Forty-five cases depicted biopsy-proven masses and 65 were negative.

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Unlabelled: We compare 3 image reconstruction algorithms for use in 3-dimensional (3D) whole-body PET oncology imaging. We have previously shown that combining Fourier rebinning (FORE) with 2-dimensional (2D) statistical image reconstruction via the ordered-subsets expectation-maximization (OSEM) and attenuation-weighted OSEM (AWOSEM) algorithms demonstrates improvements in image signal-to-noise ratios compared with the commonly used analytic 3D reprojection (3DRP) or FORE+FBP (2D filtered backprojection) reconstruction methods. To assess the impact of these reconstruction methods on detecting and localizing small lesions, we performed a human observer study comparing the different reconstruction methods.

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We propose a principled formulation of the ROC curve that is constrained in a realistic way by the mechanism of probability summation. The constrained and conventional ROC formulations were fitted to 150 separate sets of rating data taken from previous observer studies of 250 or 529 chest radiographs. A total of 20 different readers had used either discrete or continuous rating scales to evaluate those chest cases for likelihood of separate specified abnormalities: interstitial disease, pulmonary nodule, pneumothorax, alveolar infiltrate, or rib fracture.

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Six radiologists used continuous scales to rate 529 chest-film cases for likelihood of five different types of abnormalities (interstitial disease, nodule, pneumothorax, alveolar infiltrate, and rib fracture) in each of six replicated readings, yielding 36 separate ratings of each case for the five abnormalities. Separate data analyses of all cases and subsets of the difficult/subtle cases for each abnormality estimated the relative gains in accuracy (linear-scaled area below the ROC curve) obtained by averaging the case-ratings across (a) six independent replications by each reader (25% gain), (b) six different readers within each replication (34% gain), or (c) all 36 readings (48% gain). Although accuracy differed among both readers and abnormalities, ROC curves for the median ratings showed similar relative gains in accuracy, somewhat greater than those predicted from the measured rating correlations.

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A recently developed model uses the localization of abnormalities on images to improve statistical precision in measuring detection accuracy Az, the area below an observer's receiver operating characteristic (ROC) curve for ratings of sampled normal and abnormal cases. This study evaluated that improvement by investigating how much the standard error of estimated Az decreased when the statistical analysis included localization data. Comparisons of analyses with vs without localizations were made for: 1) the estimates of Az from observers' rating ROC curves for nodular lesions on clinical chest films and liver CT scans; 2) the probability of correct choices between paired samples of normal and abnormal cases (equivalent to Az); and 3) the sampling distributions of Az measured in Monte Carlo simulations of 2,000 independent rating experiments.

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Rationale And Objectives: The authors evaluated the ability of observers to identify simulated nodules placed electronically on normal contrast material-enhanced computed tomography (CT) scans of the liver to assess the effect of nodule size and polarity on detection and localization.

Methods: Seven readers evaluated two sets of CT scans that contained 80 stimuli each. The simulated nodules were either darker or brighter than the contrast-enhanced liver and were 5.

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These experiments measured the efficiency of disk discrimination performance, relative to an "ideal" observer, and compared 2 visually dissimilar tasks in which noisy image stimuli were identical for a physical calculation yielding optimum decisions. Performance consistency was measured by estimating the assumed underlying correlation in an observer's judgments about the same individual "frozen noise" images across independent replications of each condition. Larger disk sizes on the stimulus images considerably reduced observer performance efficiency (by a factor of 10) in both discrimination tasks, regardless of the image viewing distance.

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In this paper methods used to measure observer performance are reviewed, and a simple general model for finding and reporting target objects in gray-scale image backgrounds is presented. That model provides the basis for a combined measurement of detection and localization performance in various image-interpretation tasks, whether by human observers or by realized computer algorithms. The model assumes that (1) an observer's detection response and first choice of target location both depend on the "maximally suspicious" finding on an image, (2) a correct (first-choice) localization of the actual target occurs if and only if its location is selected as the most suspicious, and (3) a target's presence does not alter the degree of suspicion engendered by any other (normal) image findings.

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Purpose: To determine radiologists' ability to find lung nodules on spiral computed tomographic (CT) scans of the chest with both rapid sequential (cine) and conventional film-based viewing.

Materials And Methods: Eight radiologists searched for lung nodules on spiral CT images (10-mm collimation, 10 mm/sec table speed) presented in two formats. Cine viewing was performed at a computer work-station; sections were viewed in 2-mm increments at frame rates up to 10 frames per second.

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Rationale And Objectives: Many perceptual studies have shown that the detection of large, low-contrast targets is better either in color or in contrast-reversing presentations than in standard gray scale. We determined the value of several new display techniques for viewing liver computed tomography (CT) scans.

Methods: Eight observers (four radiologists and four nonradiologists) viewed sets of 100 liver CT images (50 with lesions and 50 without) under five display conditions on a Macintosh computer: (1) color (equiluminant color contrast); (2) color-luminance (combined luminance and chromatic contrast); (3) flicker (luminance contrast that reversed polarity at 2 Hz); (4) contour (shaded intensity mapping); and (5) control (conventional gray scale).

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This study evaluated the relative roles of physical and perceptual factors in flattening the contrast-detail (CD) curve on liver CT scans. To estimate the role of physical factors, the theoretical CD curve for a calculated theoretical observer (i.e.

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Background: The study objective was to examine the vascular wall changes caused by balloon dilation of coarctation of the aorta (CoA) acutely and at short-term follow-up using intravascular ultrasound imaging. Intravascular ultrasound has been valuable in assessing the vessel wall changes in coronary and peripheral arteries after balloon dilation, often with more detail than angiography.

Methods And Results: Intravascular ultrasound imaging, using 4.

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Contrast-detail curves were constructed for liver computed tomographic (CT) images using an objective method. Stimuli were created by superimposing disks at specified locations on sets of 92 normal liver CT images. Bright and dark disks of 9 sizes and 36 possible image contrasts were used.

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A questionnaire was mailed to 708 practicing radiologists and 348 members of the Society for Computer applications in Radiology (SCAR) in order to evaluate current practices and attitudes regarding the perceived advantages or disadvantages of film- and CRT-based image interpretation. A total of 27% of the 1,056 questionnaires (137 practicing radiologists; 145 SCAR members were returned. Ninety percent of practicing radiologists used film at least 75% of the time.

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A survey of 2,153 radiologists was conducted to assess both their current practices of evaluating hemostatic function and their use of blood tests before performing image-guided nonvascular abdominal interventions. Among the 603 (28%) who responded, more radiologists routinely perform prothrombin time (81%) or partial thromboplastin time (78%) tests than platelet counts (59%), and relatively few (7%) obtain bleeding times. The most common practice (51%) is to order all of the first three tests.

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These studies investigated observers' ability to detect and locate highly visible liver lesions on computed tomographic (CT) images, manipulating both the lesion's location and polarity (brighter or darker than liver background). Visibility of a lesion is not sufficient to guarantee accurate localization. With clinical images, possible confusions between a lesion and coexisting normal structures (like blood vessels) is a serious constraint on observer performance.

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Six radiologists, acting as radiograph reviewers, used two different consultation protocols to differentiate among 292 ambiguous chest radiographic findings: 120 simulated nodules and 172 normal findings (previous readers' false-positive reports of nodules). The nonsearch protocol identified each finding (by film location), and reviewers rated the likelihood of each finding's being a pulmonary nodule. The search protocol asked reviewers to report and rate all locations regarded as possible nodules on each radiograph and assigned a default negative rating to any unreported finding (nodule or normal structure).

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Cardiac catheterization, once the mainstay of diagnosis in children with congenital heart disease, has become a therapeutic modality for many conditions. Balloon dilatation can now open stenotic valves and vessels, coils and umbrellas can now close unwanted communications, and emboli can be withdrawn without surgical intervention.

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