Comparison of radiographic image quality from four digitization devices as viewed on computer monitors

The objective of this study was to compare the quality of radiographic images digitized from commercial-grade and consumer-grade digital cameras and scanners as viewed on computer monitor. Radiographic images were digitized from hardcopy film using a commercial-grade laser scanner, a consumer-grade desktop flatbed scanner, a commercial-grade digital camera, and a consumer-grade digital camera. The quality of images without and with grayscale histogram adjustment was evaluated subjectively by 10 board-certified radiologists. Optical density response was evaluated objectively using a grayscale test pattern. There was no significant difference in subjective quality among images digitized with the commercial scanner, consumer scanner, and commercial camera. The quality of images digitized with the consumer camera was lower than the other 3. Objective tests showed the commercial scanner to have the most linear optical density response. For the purpose of viewing images on a computer monitor, a consumer-grade desktop scanner can produce images of similar quality to those produced by more expensive laser commercial-grade scanners and digital cameras and provides cost-efficient means to digitize radiographic plain films. A consumer-grade camera may not be optimal for use in this setting.     

Digital processing of radiographic images from PACS to publishing

Several studies have addressed the implications of filmless radiologic imaging on telemedicine, diagnostic ability, and electronic teaching files. However, many publishers still require authors to submit hard-copy images for publication of articles and textbooks. This study compares the quality digital images directly exported from picture archive and communications systems (PACS) to images digitized from radiographic film. The authors evaluated the quality of publication-grade glossy photographs produced from digital radiographic images using 3 different methods: (1) film images digitized using a desktop scanner and then printed, (2) digital images obtained directly from PACS then printed, and (3) digital images obtained from PACS and processed to improve sharpness prior to printing. Twenty images were printed using each of the 3 different methods and rated for quality by 7 radiologists. The results were analyzed for statistically significant differences among the image sets. Subjective evaluations of the filmless images found them to be of equal or better quality than the digitized images. Direct electronic transfer of PACS images reduces the number of steps involved in creating publication-quality images as well as providing the means to produce high-quality radiographic images in a digital environment.     

Digital processing of radiographic images from PACS to publishing

Several studies have addressed the implications of filmless radiologic imaging on telemedicine, diagnostic ability, and electronic teaching files. However, many publishers still require authors to submit hard-copy images for publication of articles and textbooks. This study compares the quality digital images directly exported from picture archive and communications systems (PACS) to images digitized from radiographic film. The authors evaluated the quality of publication-grade glossy photographs produced from digital radiographic images using 3 different methods: (1) film images digitized using a desktop scanner and then printed, (2) digital images obtained directly from PACS then printed, and (3) digital images obtained from PACS and processed to improve sharpness prior to printing. Twenty images were printed using each of the 3 different methods and rated for quality by 7 radiologists. The results were analyzed for statistically significant differences among the image sets. Subjective evaluations of the filmless images found them to be of equal or better quality than the digitized images. Direct electronic transfer of PACS images reduces the number of steps involved in creating publication-quality images as well as providing the means to produce high-quality radiographic images in a digital environment.     

Internet Consultations from a Remote Pacific Island: Impact of Digitized Radiologic Images on Referral Decisions

A study was carried out to determine whether digitized radiologic images added valuable information to Internet consultations from a remote Pacific Island. Chuuk State Hospital (Federated States of Micronesia) has limited film screen radiology, minimal ultrasound capability, and no radiologist. Providers initiate Web-based referrals for consultation or patient transfer. Digitized images (via low-cost digital camera or flatbed scanner) were uploaded to a Web site. Images were assessed for impact on referral decisions. A radiologist scored image quality and confidence (scale: 1–7). Of 97 referrals with images that were reviewed, 74 (76%) image sets were abnormal, 20 (20%) were normal, and 3 (4%) were indeterminate. Median scores were 4 for image quality and 5 for diagnostic confidence. In most cases with abnormal radiology (52/74, 70%), images were considered valuable. Radiologic images digitized with a low-cost camera or flatbed scanner provided valuable information for decision making in an Internet-based consultation and referral process from a remote, impoverished Pacific Island jurisdiction, despite relatively low image quality.The views expressed herein are those of the authors and do not reflect the official policy of the Department of the Army, Department of Defense, or the US Government.     

Validation of whole slide imaging for frozen section diagnosis of lymph node metastasis: A retrospective study from a tertiary care hospital in Thailand

BackgroundThe use of whole slide imaging (WSI) for frozen section (FS) diagnosis is helpful, particularly in the context of pathologist shortages. However, there is minimal data on such usage in resource-limited settings. This study aims to validate the use of WSI for FS diagnosis of lymph node metastasis using a low-cost virtual microscope scanner with consumer-grade laptops at a tertiary care hospital in Thailand.MethodsFS slides were retrieved for which the clinical query was to evaluate lymph node metastasis. They were digitized by a virtual microscope scanner (MoticEasyScan, Hong Kong) using up to 40× optical magnification. Three observers with different pathology experience levels diagnosed each slide, reviewing glass slides (GS) followed by digital slides (DS) after two weeks of a wash out period. WSI and GS diagnoses were compared. The time used for scanning and diagnosis of each slide was recorded.Results295 FS slides were retrieved and digitized. The first-time successful scanning rate was 93.6 %. The mean scanning time was 2 min per slide. Both intraobserver agreement and interobserver agreement of WSI and GS diagnoses were high (Cohen's K; kappa value >0.84). The time used for DS diagnosis decreased as the observer's experience with WSI increased.ConclusionsDespite varying pathological experiences, observers using WSI provided accurate FS diagnoses of lymph node metastasis. The time required for DS diagnoses decreased with additional observer's experience with WSI. Therefore, a WSI system containing low-cost scanners and consumer-grade laptops could be used for FS services in hospital laboratories lacking pathologists.     

Image quality of an analog radiation therapy simulator-based tomographic scanner

The spatial resolution and noise level of images produced by a commercial analog tomographic scanner have been measured and compared to those of images reconstructed digitally from projections from the same detector. The full width at half maximum of the line spread function was 3.6 mm for images from the analog scanner and 1.1 mm for the digitally reconstructed images. The standard deviation of the CT numbers over a 10-cm2 circular area at the center of a large water phantom, calculated as a percentage of the linear attenuation coefficient of water, was 3.5% for the analog images, 15.4% for high-resolution digital images, and 3.2% for digital images reconstructed using a convolution filter which reduced the resolution to that of the analog images. The data contributing to each digital image were fewer than those contributing to each analog image by a factor of 10. The noise level did not depend on tube current in either the analog or the digital images. The utility of this analog device in radiation therapy planning will depend upon whether errors in contour localization resulting from transferring data from diagnostic CT scanners exceed the errors due to its poorer image quality.     

Diagnostic accuracy of film-based, TIFF, and wavelet compressed digital temporomandibular joint images

The purpose of this research was to determine if digitization and the application of various compression routines to digital images of temporomandibular joint (TMJ) radiographs would diminish observer accuracy in the detection of specific osseous characteristics associated with TMJ degenerative joint disease (DJD). Nine observers viewed 6 cropped hard-copy radiographic films each of 34 TMJs (17 radiographic series). Regions of interest measuring 2 in x 2 in were digitized using an 8-bit scanner with transparency adapter at 300 dpi. The images were placed into a montage of 6 images and stored as tagged image file format (TIFF), compressed at 4 levels (25:1, 50:1, 75:1, and 100:1) using a wavelet algorithm, and displayed to the observers on a computer monitor. Their observations regarding condylar faceting, sclerosis, osteophyte formation, erosion, and abnormal shape were analyzed using ROC. Kappa values were determined for relative condylar size and condylar position within the glenoid fossa. Indices were compared using ANOVA at a significance level of P < .05. Although significant and substantial observer variability was demonstrated, there were no statistically significant differences between image modalities, except for condylar position, in which TIFF and wavelet (at all compression ratios) performed better than the original image. For faceting, wavelet 100:1 performed better than radiographic film images. Little actual image file reduction was achieved at compression ratios above 25:1.     

Cost-effective handling of digital medical images in the telemedicine environment

BACKGROUND: This paper concentrates on strategies for less costly handling of medical images. Aspects of digitization using conventional digital cameras, lossy compression with good diagnostic quality, and visualization through less costly monitors are discussed. METHOD: For digitization of film-based media, subjective evaluation of the suitability of digital cameras as an alternative to the digitizer was undertaken. To save on storage, bandwidth and transmission time, the acceptable degree of compression with diagnostically no loss of important data was studied through randomized double-blind tests of the subjective image quality when compression noise was kept lower than the inherent noise. A diagnostic experiment was undertaken to evaluate normal low cost computer monitors as viable viewing displays for clinicians. RESULTS: The results show that conventional digital camera images of X-ray images were diagnostically similar to the expensive digitizer. Lossy compression, when used moderately with the imaging noise to compression noise ratio (ICR) greater than four, can bring about image improvement with better diagnostic quality than the original image. Statistical analysis shows that there is no diagnostic difference between expensive high quality monitors and conventional computer monitors. CONCLUSION: The results presented show good potential in implementing the proposed strategies to promote widespread cost-effective telemedicine and digital medical environments.     

Digital image acquisition using a consumer-type digital camera in the anatomic pathology setting

Imaging is central to anatomic pathology. The captured images are used for documentation, archiving, teaching, and publication. The advent of low-cost, consumer-type, high-end digital cameras has provided a convenient, easy-to-use alternative for routine image acquisition. The various applications for digital image acquisition in anatomic pathology include, among others, digitizing conventional photographs, digital gross photography and digital macrophotography, digitizing radiographic images, and digital photomicrography. This article reviews digital image acquisition in the anatomic pathology setting using a consumer-type digital camera. The camera type chosen as an example for the discussion was selected for its popularity and wide use among pathologists and for its potential to function as a sole image input device in all applications combined. Techniques and accessories to further increase the functionality of the camera and help overcome some of the commonly encountered problems in some applications are described.     

How to improve microscopic images obtained with consumer-type digital cameras

AIM: Digital imaging is useful in conventional photography because it immediately provides images, and the image quality can be improved afterwards by the use of computer programs. The major disadvantages of consumer-type digital cameras mounted on microscopes are (i) unequal illumination through the image, and (ii) a coloured background. A computer program was specifically adapted and refined to improve images obtained with consumer-type digital cameras mounted on microscopes. METHODS AND RESULTS: An approach using a division operation between the specimen image and a background image leads to homogeneous illumination throughout the image, with automatically corrected brightness and white background. The correct colour spectrum is preserved by correction of the histogram. This approach was obtained from the freeware computer program 'Image Arithmetic'. In a test, three different consumer-type digital cameras (Sony, Nikon, Olympus) on different microscopes were used to obtain images of different types of histological specimens (cervical smear, bone marrow biopsy, and colonic biopsy). The computer program dramatically improved the quality of images obtained with all tested cameras. CONCLUSION: Using this approach, even low-cost digital cameras mounted on microscopes produce brilliant images with homogeneous illumination and a white background, the image quality being comparable with expensive cameras especially designed for microscopes.     

Comparison between Different Cost Devices for Digital Capture of X-ray Films: An Image Characteristics Detection Approach

A common teleradiology practice is digitizing films. The costs of specialized digitizers are very high, that is why there is a trend to use conventional scanners and digital cameras. Statistical clinical studies are required to determine the accuracy of these devices, which are very difficult to carry out. The purpose of this study was to compare three capture devices in terms of their capacity to detect several image characteristics. Spatial resolution, contrast, gray levels, and geometric deformation were compared for a specialized digitizer ICR (US$ 15,000), a conventional scanner UMAX (US$ 15,000), a conventional scanner UMAX (US 1,800), and a digital camera LUMIX (US$ 450, but require an additional support system and a light box for about US$ 450, but require an additional support system and a light box for about US 400). Test patterns printed in films were used. The results detected gray levels lower than real values for all three devices; acceptable contrast and low geometric deformation with three devices. All three devices are appropriate solutions, but a digital camera requires more operator training and more settings.     

Telemedicine screening of diabetic retinopathy using a hand-held fundus camera.

The objective was to evaluate digital images of the retina from a handheld fundus camera (Nidek NM-100) for suitability in telemedicine screening of diabetic retinopathy. A handheld fundus camera (Nidek) and a standard fundus camera (Zeiss) were used to photograph 49 eyes from 25 consecutive patients attending our diabetic clinic. One patient had cataracts, making it impossible to get a quality image of one of the eyes (retina). The Nidek images were digitized, compressed, and stored in a Fujix DF-10M digitizer supplied with the camera. The digital images and the photographs were presented separately in a random order to three ophthalmologists. The quality of the images was ranked as good, acceptable or unacceptable for diabetic retinopathy diagnosis. The images were also evaluated for the presence of microaneurysms, blot hemorrhages, exudates, fibrous tissue, previous photocoagulation, and new vessel formation. kappa Values were computed for agreement between the photographs and digital images. Overall agreement between the photographs and digital images was poor (kappa < 0.30). On average, only 24% of the digital images were graded as being good quality and 56% as having an acceptable quality. However, 93% of the photographs were graded as good-quality images for diagnosis. The results indicate that the digital images from the handheld fundus camera may not be suitable for diagnosis of diabetic retinopathy. The images shown on the liquid crystal display (LCD) screen of the camera were of good quality. However, the images produced by the digitizer (Fujix DF-10M) attached to the camera were not as good as the images shown on the LCD screen. A better digitizing system may produce better quality images from the Nidek camera.     

A time-delay integration charge-coupled device camera for slot-scanned digital radiography

We have developed a low-noise digital camera based on a 512 x 96 element CCD operating in the time-delay integration mode. This camera has been combined with an x-ray image intensifier to record radiographic images produced by a scanning slot beam of radiation. This results in the rejection of a large fraction of scattered radiation, without a significant increase in x-ray tube heat loading or image acquisition time. Here we describe the design of our CCD camera and the results of our investigations of camera resolution, linearity, noise, and quantum efficiency. We have found that both the resolution limit (50 mm-1) and the dynamic range (2100) of this novel camera are greater than reported values for conventional video cameras. Applications of this system in digital angiography and mammography are discussed.     

Software system for three-dimensional volumetric reconstruction of histological sections: a case study for the snake chondrocranium

Volumetric digital computer-assisted reconstruction of histological sections is an attractive possibility for developmental studies. Commercial solutions are very expensive for many educational institutions. Therefore, we developed a software system for three-dimensional reconstruction of anatomical virtual models. The input data for the system are the digitized images from the histological samples of the chondrocranium of two crotalines, Bothrops jararaca and Crotalus durissus terrificus, and one colubrid, Philodryas olfersii, using a stereomicroscope connected to a digital camera. These images are then manually registered and segmented. We use computer graphics visualization algorithms such as marching cubes and ray casting to generate three-dimensional visualizations of the volumes. The results show that the digital reconstruction is as good as the manual reconstruction with the advantages of speed of reconstruction, accuracy, and flexibility to handle and study the volume. Compared with commercial options, our system has approximately the same features, and it is available free for the scientific community.     

Quality evaluation of ultrasound imaging in the carotid artery based on normalization and speckle reduction filtering

Image quality is important when evaluating ultrasound images of the carotid for the assessment of the degree of atherosclerotic disease, or when transferring images through a telemedicine channel, and/or in other image processing tasks. The objective of this study was to investigate the usefulness of image quality evaluation based on image quality metrics and visual perception, in ultrasound imaging of the carotid artery after normalization and speckle reduction filtering. Image quality was evaluated based on statistical and texture features, image quality evaluation metrics, and visual perception evaluation made by two experts. These were computed on 80 longitudinal ultrasound images of the carotid bifurcation recorded from two different ultrasound scanners, the HDI ATL-3000 and the HDI ATL-5000 scanner, before (NF) and after (DS) speckle reduction filtering, after normalization (N), and after normalization and speckle reduction filtering (NDS). The results of this study showed that: (1) the normalized speckle reduction, NDS, images were rated visually better on both scanners; (2) the NDS images showed better statistical and texture analysis results on both scanners; (3) better image quality evaluation results were obtained between the original (NF) and normalized (N) images, i.e. NF–N, for both scanners, followed by the NF–DS images for the ATL HDI-5000 scanner and the NF–DS on the HDI ATL-3000 scanner; (4) the ATL HDI-5000 scanner images have considerable higher entropy than the ATL HDI-3000 scanner and thus more information content. However, based on the visual evaluation by the two experts, both scanners were rated similarly. The above findings are also in agreement with the visual perception evaluation, carried out by the two vascular experts. The results of this study showed that ultrasound image normalization and speckle reduction filtering are important preprocessing steps favoring image quality, and should be further investigated.     

Comparison of diagnostic accuracy of plain film radiographs between original film and smartphone capture: a pilot study

The use of mobile devices for medical image capture has become increasingly popular given the widespread use of smartphone cameras. Prior studies have generally compared mobile phone capture images to digitized images. However, many underserved and rural areas without picture archiving and communication systems (PACS) still depend greatly on the use of film radiographs. Additionally, there is a scarcity of specialty-trained or formally licensed radiologists in many of these regions. Subsequently, there is great potential for the use of smartphone capture of plain radiograph films which would allow for increased access to economical and efficient consultation from board-certified radiologists abroad. The present study addresses the ability to diagnose a subset of radiographic findings identified on both the original film radiograph and the captured camera phone image.     

A comparison of two methods of analog-to-digital medical video conversion

The purpose of this study was to compare 2 methods of analog-to-digital video conversion in anticipation of improving, refining, and standardizing digital video production for medical education, diagnosis support, and telemedicine. A video workstation was devised containing 2 analog-to-digital video conversion systems: a digital video media converter with fire wire card and a video capture card. A procedure for final digital video production was created that used equivalent compression, pixel resolution, frame rate, and data rate for both systems. A subjective test was performed in which 12 archived analog videotapes, consisting of magnetic resonance angiograms, ultrasounds, neurosurgeries, and telemedicine applications, were converted digitally using the 2 methods. Randomized side by side video comparisons were analyzed and rated by subjective quality. An objective test was performed by videotaping a gray-scale test pattern off a computer monitor, digitally converting it by the 2 methods, and comparing the gray-scale values to the original pattern. There was no significant difference in overall video quality (P = .31) or grayscale reproduction using the 2 methods of analog-to-digital conversion. When performing simple analog-to-digital video conversion, a video capture card is equal in quality and costs less than a digital video (DV) media converter or fire wire card. If a digital video camera is available for use, then a DV media converter or fire wire card is more advantageous because it enables full operation of the digital video camera.     

“Evaluation of a Very Low-Cost and Simple Teleradiology Technique”

This paper describes and analyzes a proposed solution of fundamental limitative factor of teleradiology to overcome the teleradiology usages problems in underdeveloped and developing countries. The goal is to achieve a very simple and cost-efficient way to take advantage of teleradiology in anywhere even in remote and rural areas. To meet the goal of this study, the following methodology which is consists of two main procedures was done: (1) Using a digital camera in order to provide a digital image from radiographs. (2) Using an image compression tool in order to compress digital images. The results showed that there is no significant difference between digital images (non-compress and compress images) and radiographic films. Also, there was a logic relationship between the diagnostic quality and diagnostic accuracy. Since the maximum percent of diagnostic accuracy can be seen among “Good” quality images and the minimum to was related “Poor”. The results of our study indicate that a digital camera could be utilized to capture digital images from radiographic films of chest x-ray. To reduce the size of digital images, a lossy compression technique could be applied at compression percent of 50 or less without any significant differences. The compressed images can be sent easily by email to other places for consultation and also they can be stored with a smaller size.     

A Novel Method for Constructing Histological Section Datasets of the Basal Ganglia in Digitized Human Brain

To investigate the construction of the histological section datasets in the basal ganglia of digitized human brain to provide a reference for the meso‐level histological data acquisition. A fresh adult brain from a cadaver with no neurological disease was selected, and tissue blocks of the basal ganglia in the right hemisphere was extracted using the visualization method, followed by pretreatments including gradient dehydrating, gelatin‐embedding and setting of calibration points. And then the tissue blocks was cryosectioned into 60‐μm‐thick coronal sections and the sectional images were captured simultaneously by a digital camera at a fixed position. Two series of sections (one section out of ten) were Nissl‐stained with Toluidine blue and immunostained with the calbindin D‐28K, respectively. Stained sections were digitized by a high resolution scanner. After alignment and registration, contours of nuclei and different nucleic function divisions in the digital images of stained sections were identified, and then were segmented and labeled using software exploited by ourselves. Datasets of one set of registrated serial sectional images and two sets of registrated histochemically stained images in basal ganglia area were obtained, which provide a histological reference for the neurosurgery and diagnostic imaging. a systematic method of cutting, slicing, staining, data acquisition and image registration of large tissue blocks was established, providing a reference for histological data acquisition on the digital human. Anat Rec, 300:1011–1021, 2017. © 2016 Wiley Periodicals, Inc.     

Construction and testing of a computer-based intraoral laser scanner for determining tooth positions

An optical set-up for intraoral data acquisition based on the principle of laser triangulation was developed. The system consists of a pig-tailed laser with line generating optics, a stepping motor driven positioning stage, a commercial CCD (charge coupled device) camera system with frame grabber interface, a control personal computer and a mirror system compensating for the fact that there is no possibility of watching an object directly in the mouth under a certain angle except from a facial position during intraoral scanning. Due to the size of the prototype measurements were still restricted to plaster casts. In order to evaluate its accuracy, the measurements were compared with those taken with a commercial laser scanner and a coordinate measurement table. The accuracy of the prototype scanner was determined to be DeltaXYZ=0.04 mm using gauge blocks of given dimensions and proved to range between the commercial laser scanner and the coordinate measurement table (i.e., it was slightly better than that of the commercial scanner). Applications in orthodontics were demonstrated by scanning plaster casts and measuring distances on reconstructed surfaces. The measured distances showed a maximum deviation of about +/-0.2 mm compared with the data of the coordinate measurement table, which served as a reference. In addition, reconstruction of three-dimensional tooth movements was performed on the scan data. The translational and rotational parameters gained from the superimposition of scanned point clouds and describing tooth movement were also in good accordance with the reference. The achieved accuracy proved to be sufficient for further development which should include a reduction in size and the use of more precise device components.