Identifying if participants with differing diagnostic accuracy and visual search behavior during radiologic tasks also differ in nonradiologic tasks is investigated. Four clinician groups with different radiologic experience were used: a reference expert group of five consultant radiologists, four radiology registrars, five senior house officers, and six interns. Each of the four clinician groups is known to have significantly different performance in the identification of pneumothoraces in chest x-ray. Each of the 20 participants was shown 6 nonradiologic images (3 maps and 3 sets of geometric shapes) and was asked to perform search tasks. Eye movements were recorded with a Tobii TX300 (Tobii Technology, Stockholm, Sweden) eye tracker. Four eye-tracking metrics were analyzed. Variables were compared to identify any differences among the groups. All data were compared by using nonparametric methods of analysis. The average number of targets identified in the maps did not change among groups [mean=5.8 of 6 targets (range 5.6 to 6 p=0.861)]. None of the four eye-tracking metrics investigated varied with experience in either search task (p>0.5). Despite clear differences in radiologic experience, these clinician groups showed no difference in nonradiologic search pattern behavior or skill across complex images. This is another viewpoint adding to the evidence that radiologic image interpretation is a learned skill and is task specific.
Several studies have demonstrated the importance of environmental conditions in the radiology reporting environment, with many indicating that incorrect parameters could lead to error and misinterpretation. Literature is available with recommendations as to the levels that should be achieved in clinical practice, but evidence of adherence to these guidelines in radiology reporting environments is absent. This study audited the reporting environments of four teleradiologist and eight hospital based radiology reporting areas. This audit aimed to quantify adherence to guidelines and identify differences in the locations with respect to layout and design, monitor distance and angle as well as the ambient factors of the reporting environments. In line with international recommendations, an audit tool was designed to enquire in relation to the layout and design of reporting environments, monitor angle and distances used by radiologists when reporting, as well as the ambient factors such as noise, light and temperature. The review of conditions were carried out by the same independent auditor for consistency. The results obtained were compared against international standards and current research. Each radiology environment was given an overall compliance score to establish whether or not their environments were in line with recommended guidelines. Poor compliance to international recommendations and standards among radiology reporting environments was identified. Teleradiology reporting environments demonstrated greater compliance than hospital environments. The findings of this study identified a need for greater awareness of environmental and perceptual issues in the clinical setting. Further work involving a larger number of clinical centres is recommended.
Eye tracking has been used by many researchers to try to shed light on the perceptual processes involved in medical image perception. Despite a large volume of data having been published regarding radiologist viewing patterns for static images, and more recently for stacked imaging modalities, little has been produced concerning angiographic images, which commonly have substantially different characteristics. A study was performed in which 7 expert radiologists viewed a range of digital subtraction angiograms of the peripheral vascular system. Initial results are presented. The observers were free to control the rate at which they viewed the images. Eye position data was recorded for each participant using Tobii TX300 eyetrackers. Analysis was performed in Tobii Studio software and included qualitative analysis of gaze pattern and analysis of metrics including first and total fixation duration etc. for areas of clinical interest. Early results indicate that experts briefly fixate on lesions but do not dwell in the area, rather continuing to inspect the more distal vascular segments before returning. Some individual variation was noted. Further research is required and ongoing.
A number of different viewing distances are recommended by international agencies, however none with specific reference to radiologist performance. The purpose of this study was to ascertain the extent to which radiologists performance is affected by viewing distance on softcopy skeletal reporting. Eighty dorsi-palmar (DP) wrist radiographs, of which half feature 1 or more fractures, were viewed by seven observers at 2 viewing distances, 30cm and 70cm. Observers rated the images as normal or not on a scale of 1 to 5 and could mark multiple locations on the images when they visualised a fracture. Viewing distance was measured from the centre of the face plate to the outer canthus of the eye. The DBM MRM analysis showed no statistically significant differences between the area under the curve for the two distances (p = 0.482). The JAFROC analysis, however, demonstrated a statistically significantly higher area under the curve with the 30cm viewing distance than with the 70 cm distance (p = 0.035). This suggests that while observers were able to make decisions about whether an image contained a fracture or not equally well at both viewing distances, they may have been less reliable in terms of fracture localisation or detection of multiple fractures. The impact of viewing distance warrants further attention from both clinical and scientific perspectives.
Purpose: This study examines the relationship between ambient lighting level and image manipulation. Method: Academic radiographers (n=10), with experience in observer performance studies, each assessed 70 postero-anterior projection radiographs of the wrist / scaphoid in both low (12.5 lux) and high (150 lux) ambient lighting. Half of the images featured one or more acute fractures and the remainder did not. Observers were encouraged to window the images to a level they felt was appropriate and, requested to rate their confidence that an acute fracture was present, marking the locations of any suspected acute fractures on the image. The images were displayed on a secondary-class monitor using Ziltron software, which recorded the adjustments to brightness and contrast made for each image. The images were presented in different orders for each lighting level to reduce potential memory effects. Results: Student’s t-tests were applied to compare the mean brightness and contrast adjustments made to the images in each ambient lighting level. Tests were carried out to include all images, only positive cases, and only cases where observers elected to change the brightness and/or contrast. No statistically significant differences were noted except when images where no brightness/contrast adjustments were made were discounted. In that case, mean brightness levels were slightly higher in the high ambient light level (p=0.049). Conclusion: No convincing difference in adjustments of brightness and contrast between high and low ambient lighting levels, although further research is warranted.
In February 2011 the University of Chicago Medical School distributed iPads to its trainee doctors for use when
reviewing clinical information and images on the ward or clinics. The use of tablet computing devices is becoming
widespread in medicine with Apple™ heralding them as "revolutionary" in medicine. The question arises, just because
it is technical achievable to use iPads for clinical evaluation of images, should we do so? The current work assesses the
diagnostic efficacy of iPads when compared with LCD secondary display monitors for identifying lung nodules on chest
x-rays.
Eight examining radiologists of the American Board of Radiology were involved in the assessment, reading chest images
on both the iPad and the an off-the-shelf LCD monitor. Thirty chest images were shown to each observer, of which 15
had one or more lung nodules. Radiologists were asked to locate the nodules and score how confident they were with
their decision on a scale of 1-5. An ROC and JAFROC analysis was performed and modalities were compared using
DBM MRMC.
The results demonstrate no significant differences in performance between the iPad and the LCD for the ROC AUC
(p<0.075) or JAFROC FOM (p<0.059) for random readers and random cases. Sample size estimation showed that this
result is significant at a power of 0.8 and an effect size of 0.05 for ROC and 0.07 for JAFROC.
This work demonstrates that for the task of identifying pulmonary nodules, the use of the iPad does not significantly
change performance compared to an off-the-shelf LCD.
The hazards associated with ionizing radiation have been documented in the literature and therefore justifying the need
for X-ray examinations has come to the forefront of the radiation safety debate in recent years1. International legislation
states that the referrer is responsible for the provision of sufficient clinical information to enable the justification of the
medical exposure. Clinical indications are a set of systematically developed statements to assist in accurate diagnosis and
appropriate patient management2. In this study, the impact of clinical indications upon fracture detection for
musculoskeletal radiographs is analyzed. A group of radiographers (n=6) interpreted musculoskeletal radiology cases
(n=33) with and without clinical indications. Radiographic images were selected to represent common trauma
presentations of extremities and pelvis. Detection of the fracture was measured using ROC methodology. An eyetracking
device was employed to record radiographers search behavior by analysing distinct fixation points and search
patterns, resulting in a greater level of insight and understanding into the influence of clinical indications on observers'
interpretation of radiographs. The influence of clinical information on fracture detection and search patterns was
assessed. Findings of this study demonstrate that the inclusion of clinical indications result in impressionable search
behavior. Differences in eye tracking parameters were also noted. This study also attempts to uncover fundamental
observer search strategies and behavior with and without clinical indications, thus providing a greater understanding and
insight into the image interpretation process. Results of this study suggest that availability of adequate clinical data
should be emphasized for interpreting trauma radiographs.
Digital radiography poses the risk of unnoticed increases in patient dose. Manufacturers responded to this by offering
an exposure index (EI) value to clinicians. Use of the EI value in clinical practice is encouraged by the American
College of Radiology and American Association of Physicists in Medicine. This study assesses the impact of
processing delay on the EI value. An anthropormorphic phantom was used to simulate three radiographic examinations;
skull, pelvis and chest. For each examination, the phantom was placed in the optimal position and exposures were
chosen in accordance with international guidelines. A Carestream (previously Kodak) computed radiography system
was used. The imaging plate was exposed, and processing was delayed in various increments from 30 seconds to 24
hours, representing common delays in clinical practice. The EI value was recorded for each exposure. The EI value
decreased considerably with increasing processing delay. The EI value decreased by 100 within 25 minutes delay for
the chest, and 20 minutes for the skull and pelvis. Within 1 hour, the EI value had fallen by 180, 160 and 100 for the
chest, skull and pelvis respectively. After 24 hours, the value had decreased by 370, 350 and 340 for the chest, skull
and pelvis respectively, representing to the clinician more then a halving of exposure to the detector in Carestream systems. The assessment of images using EI values should be approached with caution in clinical practice when delays in processing occur. The use of EI values as a feedback mechanism is questioned.
This paper presents a comparison of different implementations of 3D anisotropic diffusion speckle noise reduction
technique on ultrasound images. In this project we are developing a novel volumetric calcification assessment metric for
the placenta, and providing a software tool for this purpose. The tool can also automatically segment and visualize (in
3D) ultrasound data. One of the first steps when developing such a tool is to find a fast and efficient way to eliminate
speckle noise.
Previous works on this topic by Duan, Q. [1] and Sun, Q. [2] have proven that the 3D noise reducing anisotropic
diffusion (3D SRAD) method shows exceptional performance in enhancing ultrasound images for object segmentation.
Therefore we have implemented this method in our software application and performed a comparative study on the
different variants in terms of performance and computation time. To increase processing speed it was necessary to utilize the full potential of current state of the art Graphics Processing Units (GPUs).
Our 3D datasets are represented in a spherical volume format. With the aim of 2D slice visualization and segmentation, a "scan conversion" or "slice-reconstruction" step is needed, which includes coordinate transformation from spherical to Cartesian, re-sampling of the volume and interpolation.
Combining the noise filtering and slice reconstruction in one process on the GPU, we can achieve close to real-time operation on high quality data sets without the need for down-sampling or reducing image quality. For the GPU programming OpenCL language was used. Therefore the presented solution is fully portable.
Introduction
The American Association of Medical Physicists is currently standardizing the exposure index (EI) value. Recent studies
have questioned whether the EI value offered by manufacturers is optimal. This current work establishes optimum EIs
for the antero-posterior (AP) projections of a pelvis and knee on a Carestream Health (Kodak) CR system and compares
these with manufacturers recommended EI values from a patient dose and image quality perspective.
Methodology
Human cadavers were used to produce images of clinically relevant standards. Several exposures were taken to achieve
various EI values and corresponding entrance surface doses (ESD) were measured using thermoluminescent dosimeters.
Image quality was assessed by 5 experienced clinicians using anatomical criteria judged against a reference image.
Visualization of image specific common abnormalities was also analyzed to establish diagnostic efficacy.
Results
A rise in ESD for both examinations, consistent with increasing EI was shown. Anatomic image quality was deemed to
be acceptable at an EI of 1560 for the AP pelvis and 1590 for the AP knee. From manufacturers recommended values, a
significant reduction in ESD (p=0.02) of 38% and 33% for the pelvis and knee respectively was noted. Initial
pathological analysis suggests that diagnostic efficacy at lower EI values may be projection-specific.
Conclusion
The data in this study emphasize the need for clinical centres to consider establishing their own EI guidelines, and not
necessarily relying on manufacturers recommendations. Normal and abnormal images must be used in this process.
The unavoidable distance between the cervical spine and the image receptor presents measurable levels of geometric
unsharpness, which hinders arthritic scoring. The current work explores the impact on the visualisation of important
arthritic indicators by increasing the distance between the X-ray source and image detector (SID) from the commonly
employed 150cm. Lateral cervical spine images were acquired of an osteoarthritic human cadaver using a DR imaging
system. All exposures were taken at 65kVp using automatic exposure control and various SID distances from 150 to
210cm. Four experienced clinicians assessed the images by means of visual grading analysis, using objective criteria
based on normal anatomic features and arthritic indicators. A statistically significant improvement in image quality was
observed with images acquired at 210cm compared with those acquired at 150cm and 180cm (p<0.05), with values of
56.0 (SE=1.105), 50.85 (SE=1.415) and 65.35 (SE=0.737) respectively. All images with a SID of 210cm scored higher
for visually sharp reproduction of the spinous processes, facet joints, intervertebral disc spaces and trabecular bone
pattern compared with both 180cm and 150cm. Results indicate that total image quality and visualisation of specific
anatomical features is improved in cervical spine radiographs when traditionally employed SID distances are increased.
Radiation doses for 3 common types of cardiac radiological examinations where
investigated: coronary angiography (CA), percutaneous coronary intervention (PCI) and
pacemaker insertions (PPI). 22 cardiac imaging suites participated in the study. Radiation
dose was monitored for 1804 adult patients using dose area product (DAP) meters.
Operational and examination details such as cardiologist grade, patient details and
examination complexity were recorded for each examination. Both intra and inter-hospital variations where demonstrated by the results. Individual patient DAP values ranged from 136-23,101cGycm2, 475-41,038cGycm2 and 45- 17,192cGycm2 for CA, PCI and PPI respectively, with third quartile values of 4,173cGycm2, 8,836cGycm2 and 2,051cGycm2. Screening times varied from 0.22-27.6mins, 1.8-98mins and 0.33-54.5mins for CA, PCI and PPI respectively.
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