PACS Displays: How to Select the Right Display Technology

Endodontic radiography - what's displaying the radiograph? The yield of commercial computer screens vs. DICOM calibrated medical screens in endodontic radiography

OBJECTIVE

A comparison between commercial computer screens and DICOM-calibrated medical screens for characterizing anatomy and diagnosing dental pathologies was performed. The aim of this study was to evaluate and compare the ability of each of those screens to identify root apices and widening of the periodontal ligament (PDL) in the posterior maxillary area.

MATERIALS AND METHODS

Digital X-ray images of 53 maxillary molar teeth were examined by means of a commercial computer screen and again two months later with a DICOM screen to compare their ability to help identify and diagnose PDL widening and to locate the root apices of those teeth.

RESULTS

The DICOM screen had a significantly better ability to identify widened PDLs (from 31.4% to 34.8% of the cases compared to 19% to 26.1% for the commercial screens, P < .001), depending upon the observer. The DICOM screen was also significantly superior in depicting the root apices compared to the commercial screens (from 77.4% to 83.6% of the cases compared to 56% to 66.7% for the commercial screens, P < 0.001), depending upon the observer.

CONCLUSION

DICOM-calibrated medical screens were significantly superior to commercial computer screens for identifying widened PDLs and locating the root apex in the posterior maxillary area.

Medical Malpractice and Diagnostic Radiology: Challenges and Opportunities

Medicolegal challenges in radiology are broad and impact both radiologists and patients. Radiologists may be affected directly by malpractice litigation or indirectly due to defensive imaging ordering practices. Patients also could be harmed physically, emotionally, or financially by unnecessary tests or procedures. As technology advances, the incorporation of artificial intelligence into medicine will bring with it new medicolegal challenges and opportunities. This article reviews the current and emerging direct and indirect effects of medical malpractice on radiologists and summarizes evidence-based solutions.

Recent technical advances in whole slide imaging instrumentation

Microscopic observation of biological specimen smears is the mainstay of diagnostic pathology, as defined by the Digital Pathology Association. Though automated systems for this are commercially available, their bulky size and high cost renders them unusable for remote areas. The research community is investing much effort towards building equivalent but portable, low-cost systems. An overview of such research is presented here, including a comparative analysis of recent reports. This paper also reviews recently reported systems for automated staining and smear formation, including microfluidic devices; and optical and computational automated microscopy systems including smartphone-based devices. Image pre-processing and analysis methods for automated diagnosis are also briefly discussed. It concludes with a set of foreseeable research directions that could lead to affordable, integrated and accurate whole slide imaging systems.

PUMA - An open-source 3D-printed direct vision microscope with augmented reality and spatial light modulator functions

3D-printed microscopes are a topical emerging field in the literature. However most microscopes presented to date are quite novel re-imaginings of the microscope's mechanical design and they are either solely dependent on, or primarily geared towards, camera-based observations rather than ergonomic direct vision screening through an ocular lens. The reliance on camera, computer and monitor for observation introduces a compromise between portability, cost and the quality of an instant wide field of view. In this report, I introduce the Portable Upgradeable Modular and Affordable (PUMA) microscope which is an open-source 3D-printed multimodality microscope that employs a traditional upright design for ease of human direct visual observations and slide screening. PUMA uses standard RMS or C-mount objectives, with a tube length 160 mm, 170 mm or infinity and wide field high eye point ocular lenses. PUMA can use simple mirror-based illumination or can be configured to a full Köhler system with Abbe condenser for high numerical aperture observations including oil immersion. PUMA also has advanced digital/optical imaging features such as a digital spatial light modulator and - unique to any 3D printed microscope to date - an augmented reality heads-up display for interactive calibrated measurements. Digital camera imaging can also be used with PUMA - in fact PUMA can take up to three separate digital cameras simultaneously. PUMA can also function as a direct vision multi-header microscope for teaching or discussion. The illumination system is also modular and includes transillumination, epi-illumination, fluorescence, polarisation, dark ground and also Schlieren-based phase contrast and other Fourier optics filtering modalities. All these advanced features are available through an on-board, battery operated, microprocessor so no mains supply, smartphone, network connection, PC or external monitor are required making PUMA a truly portable system suitable for remote field work.

Intra- and Interobserver Agreement during the Assessment of the Different Stages of Root Development Using 4 Radiographic Classifications

INTRODUCTION

This study analyzed intra- and interobserver agreements during radiographic assessment of the different stages of root development using the dichotomous, Moorrees, Demirjian, and Cvek classifications, as well as the effect of the observer's level of experience on the result.

METHODS

Two hundred eighty-five digital periapical radiographs were examined via visual inspection by 3 experienced and 3 nonexperienced observers (n = 6) under strict technological and viewing conditions. After observer calibration, determination of the presence or absence of an open apex and the assignment of a root development stage according to the different subdivisions of the 4 indexes were performed. This evaluation was carried out by each observer in duplicate in the first round (n = 8) and repeated in the second round (n = 8). The 16 examinations performed by each observer (N = 96) were analyzed to determine the percentage of concordance followed by intraobserver, interobserver, and global observer agreement using the kappa coefficient and a weighted kappa. Additionally, to determine the level of concordance between the visual determination of an open or closed apex and the apical foramen width measured in millimeters, a dichotomized kappa coefficient was applied.

RESULTS

A good level of global observer agreement was found for the dichotomous, Demirjian, and Cvek classifications. However, a significantly low percentage of total concordance and global observer agreement (6.66% and 0.498, respectively) was obtained using the Moorrees classification, which was more pronounced among nonexperienced observers (0.247). Apical foramen width measurements indicated the presence of 143 roots with an open apex (50.2%) and 142 with a closed apex (49.8%), and the dichotomized kappa coefficient test revealed a good level of agreement during the visual determination of an open or closed apex (range, 0.611-0.636).

CONCLUSIONS

The classifications of Cvek and Demirjian provided reliable results when determining the different stages of root development. In contrast, the Moorrees classification provided the lowest agreement values, with a significant negative effect among nonexperienced observers. Finally, the visual estimation of the presence (or absence) of an open apex provided a good level of concordance with the radiographic apical foramen width.

Display Characteristics and Their Impact on Digital Pathology: A Current Review of Pathologists' Future "Microscope"

Digital displays (monitors) are an indispensable component of a pathologists’ daily workflow, from writing reports, viewing whole-slide images, or browsing the Internet. Due to a paucity of literature and experience surrounding display use and standardization in pathology, the Food and Drug Administration's (FDA) has currently restricted FDA-cleared whole-slide imaging systems to a specific model of display for each system, which at this time consists of only medical-grade (MG) displays. Further, given that a pathologists’ display will essentially become their new surrogate “microscope,” it becomes exceedingly important that all pathologists have a basic understanding of fundamental display properties and their functional consequences. This review seeks to: (a) define and summarize the current and emerging display technology, terminology, features, and regulation as they pertain to pathologists and review the current literature on the impact of different display types (e.g. MG vs. consumer off the shelf vs. professional grade) on pathologists’ diagnostic performance and (b) discuss the impact of the recent digital pathology device componentization and the coronavirus disease 2019 public emergency on the pixel pathway and display use for remote digital pathology. Display technology has changed dramatically over the past 20 years and continues to change at a rapid rate. There is a paucity of published studies to date that investigate how display type affects pathologist performance, with more research necessary in order to develop standards and minimum specifications for displays in digital pathology. Given the complexity of modern displays, pathologists must become better informed regarding display technology if they wish to have more choice over their future “microscopes.”

The potential influence of LED lighting on mental illness

OBJECTIVES

Two recent scientific breakthroughs may alter the treatment of mental illness, as discussed in this narrative review. The first was the invention of white light-emitting diodes (LEDs), which enabled an ongoing, rapid transition to energy-efficient LEDs for lighting, and the use of LEDs to backlight digital devices. The second was the discovery of melanopsin-expressing photosensitive retinal ganglion cells, which detect environmental irradiance and mediate non-image forming (NIF) functions including circadian entrainment, melatonin secretion, alertness, sleep regulation and the pupillary light reflex. These two breakthroughs are interrelated because unlike conventional lighting, white LEDs have a dominant spectral wavelength in the blue light range, near the peak sensitivity for the melanopsin system.

METHODS

Pertinent articles were identified.

RESULTS

Blue light exposure may suppress melatonin, increase alertness, and interfere with sleep in young, healthy volunteers and in animals. Areas of concern in mental illness include the influence of blue light on sleep, other circadian-mediated symptoms, prescribed treatments that target the circadian system, measurement using digital apps and devices, and adolescent sensitivity to blue light.

CONCLUSIONS

While knowledge in both fields is expanding rapidly, future developments must address the potential impact of blue light on NIF functions for healthy individuals and those with mental illness.

Diagnostic Accuracy and Visual Search Efficiency: Single 8 MP vs. Dual 5 MP Displays

This study compared a single 8 MP vs. dual 5 MP displays for diagnostic accuracy, reading time, number of times the readers zoomed/panned images, and visual search. Six radiologists viewed 60 mammographic cases, once on each display. A sub-set of 15 cases was viewed in a secondary study using eye-tracking. For viewing time, there was significant difference (F = 13.901, p = 0.0002), with 8 MP taking less time (62.04 vs. 68.99 s). There was no significant difference (F = 0.254, p = 0.6145) in zoom/pan use (1.94 vs. 1.89). Total number of fixations was significantly (F = 4.073, p = 0.0466) lower with 8 MP (134.47 vs. 154.29). Number of times readers scanned between images was significantly fewer (F = 10.305, p = 0.0018) with 8 MP (6.83 vs. 8.22). Time to first fixate lesion did not differ (F = 0.126, p = 0.7240). It did not take any longer to detect the lesion as a function of the display configuration. Total time spent on lesion did not differ (F = 0.097, p = 0.7567) (8.59 vs. 8.39). Overall, the single 8 MP display yielded the same diagnostic accuracy as the dual 5 MP displays. The lower resolution did not appear to influence the readers' ability to detect and view the lesion details, as the eye-position study showed no differences in time to first fixate or total time on the lesions. Nor did the lower resolution result in significant differences in the amount of zooming and panning that the readers did while viewing the cases.

Determination of volume scattering parameters that reproduce the luminance characteristics of diffusers

The extension of a well-known inverse technique, inverse adding-doubling (IAD), is investigated for determining the volume scattering properties of diffusers for display and lighting applications. The luminance characteristics of volume scattering diffusers are vital for these applications. Through a simulation study, it is shown that fitting solely to the scattered (angular) intensity information with the extended IAD method, results in a volume scattering characterization that also reproduces the correct (spatial and angular) luminance characteristics for a wide range of samples. The gap between the simulation work and the experimental application of the investigated fitting procedure is bridged by considering the effect of experimental error in the scattered intensity distributions. This does not significantly alter the presented conclusions.

The effect of time in use on the display performance of the iPad

OBJECTIVE

The aim of this study was to evaluate changes to the luminance, luminance uniformity and conformance to the digital imaging and communication in medicine greyscale standard display function (GSDF) as a function of time in use for the iPad.

METHODS

Luminance measurements of the American Association of Physicists in Medicine (AAPM) Group 18 task group (TG18) luminance uniformity and luminance test patterns (TG18-UNL and TG18-LN8) were performed using a calibrated near-range luminance meter. Nine sets of measurements were taken, where the time in use of the iPad ranged from 0 to 2500 h.

RESULTS

The maximum luminance (Lmax) of the display decreased (367-338 cdm(-2)) as a function of time. The minimum luminance remained constant. The maximum non-uniformity coefficient was 11%. Luminance uniformity decreased slightly as a function of time in use. The conformance of the iPad deviated from the GSDF curve at commencement of use. Deviation did not increase as a function of time in use.

CONCLUSION

This study has demonstrated that the iPad display exhibits luminance degradation typical of liquid crystal displays. The Lmax of the iPad fell below the American College of Radiology-AAPM-Society of Imaging Informatics in Medicine recommendations for primary displays (>350 cdm(-2)) at approximately 1000 h in use. The Lmax recommendation for secondary displays (>250 cdm(-2)) was exceeded during the entire study. The maximum non-uniformity coefficient did not exceed the recommendations for either primary or secondary displays. The deviation from the GSDF exceeded the recommendations of the TG18 for use as either a primary or secondary display.

ADVANCES IN KNOWLEDGE

The brightness, uniformity and contrast response are reasonably stable over the useful lifetime of the device; however, the device fails to meet the contrast response standard for either a primary or secondary display.

Radiological interpretation of images displayed on tablet computers: a systematic review

OBJECTIVE

To review the published evidence and to determine if radiological diagnostic accuracy is compromised when images are displayed on a tablet computer and thereby inform practice on using tablet computers for radiological interpretation by on-call radiologists.

METHODS

We searched the PubMed and EMBASE databases for studies on the diagnostic accuracy or diagnostic reliability of images interpreted on tablet computers. Studies were screened for inclusion based on pre-determined inclusion and exclusion criteria. Studies were assessed for quality and risk of bias using Quality Appraisal of Diagnostic Reliability Studies or the revised Quality Assessment of Diagnostic Accuracy Studies tool. Treatment of studies was reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA).

RESULTS

11 studies met the inclusion criteria. 10 of these studies tested the Apple iPad(®) (Apple, Cupertino, CA). The included studies reported high sensitivity (84-98%), specificity (74-100%) and accuracy rates (98-100%) for radiological diagnosis. There was no statistically significant difference in accuracy between a tablet computer and a digital imaging and communication in medicine-calibrated control display. There was a near complete consensus from authors on the non-inferiority of diagnostic accuracy of images displayed on a tablet computer. All of the included studies were judged to be at risk of bias.

CONCLUSION

Our findings suggest that the diagnostic accuracy of radiological interpretation is not compromised by using a tablet computer. This result is only relevant to the Apple iPad and to the modalities of CT, MRI and plain radiography.

ADVANCES IN KNOWLEDGE

The iPad may be appropriate for an on-call radiologist to use for radiological interpretation.