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Purpose: This technical note presents an inexpensive tool and method for determining lead equivalency using digital radiography x-ray equipment., Methods: A test tool was developed using commercially available lead tape (3M™ Lead Foil Tape 421). The test tool consisted of nine varying lead thick squares arranged in a larger square (0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, and 1.0 mm). It was imaged on a DR plate with a digital portable x-ray unit across a range of energies (60-120 kVp) and two beam filtrations. Lead equivalency was determined by using the linear relationship between dose to the detector and pixel values in the raw images. The lead equivalency of the tape was validated using known lead thicknesses (physically measured with caliper). Additional lead equivalency measurements were made for protective eyewear, a thyroid shield, and a lead apron., Results: The test tool and method measured the two known lead thicknesses to be -9.7% to 7.1% different from the actual values across the range of energies under normal x-ray beam conditions and under a 1-mm copper filtered x-ray beam. The additional lead equivalency measurements of radiation protection apparel across energies ranged from -6% to 20% for both beam conditions when compared with the values provided by the manufacturer., Conclusion: This work validates the test tool and methodology as an inexpensive alternative to checking the lead equivalency of radiation protection apparel in a clinical setting. The methodology is equipment independent with a few prerequisites., (© 2020 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.)

Purpose: Insufficient image contrast associated with radiation therapy daily setup x-ray images could negatively affect accurate patient treatment setup. We developed a method to perform automatic and user-independent contrast enhancement on 2D kilo voltage (kV) and megavoltage (MV) x-ray images. The goal was to provide tissue contrast optimized for each treatment site in order to support accurate patient daily treatment setup and the subsequent offline review., Methods: The proposed method processes the 2D x-ray images with an optimized image processing filter chain, which consists of a noise reduction filter and a high-pass filter followed by a contrast limited adaptive histogram equalization (CLAHE) filter. The most important innovation is to optimize the image processing parameters automatically to determine the required image contrast settings per disease site and imaging modality. Three major parameters controlling the image processing chain, i.e., the Gaussian smoothing weighting factor for the high-pass filter, the block size, and the clip limiting parameter for the CLAHE filter, were determined automatically using an interior-point constrained optimization algorithm., Results: Fifty-two kV and MV x-ray images were included in this study. The results were manually evaluated and ranked with scores from 1 (worst, unacceptable) to 5 (significantly better than adequate and visually praise worthy) by physicians and physicists. The average scores for the images processed by the proposed method, the CLAHE, and the best window-level adjustment were 3.92, 2.83, and 2.27, respectively. The percentage of the processed images received a score of 5 were 48, 29, and 18%, respectively., Conclusion: The proposed method is able to outperform the standard image contrast adjustment procedures that are currently used in the commercial clinical systems. When the proposed method is implemented in the clinical systems as an automatic image processing filter, it could be useful for allowing quicker and potentially more accurate treatment setup and facilitating the subsequent offline review and verification., (© 2017 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.)

Objective: To compare the performance of three generations of CT reconstruction techniques using structural similarity (SSIM) as a measure of image quality for CT scans of a chest phantom with 3D printed lung vessels., Methods: CT images of the chest phantom were acquired at seven dose levels by changing the tube current while other acquisition parameters were kept constant. Three CT reconstruction techniques were applied on each acquisition. The first technique was filtered backprojection (FBP), the second technique was FBP with iterative filtering (adaptive iteration dose reduction in 3 dimensions (AIDR 3D)) and the third technique was model-based iterative reconstruction (Forward projected model-based Iterative Reconstruction SoluTion (FIRST)). Image quality of the CT data was quantified in terms of SSIM. The SSIM index was used for image quality comparison between the dose levels and different reconstruction techniques. The SSIM index gives a value between 0 and 1, with 0 as the lowest image quality and 1 as an excellent image quality., Results: The lowest SSIM index was observed for FBP at all dose levels. The reconstruction technique with the highest SSIM depends on the dose level. For tube currents higher than 80 mA, AIDR 3D showed the highest SSIM index, and for tube currents lower or equal to 80 mA FIRST showed the highest SSIM index., Conclusion: SSIM index is a robust quantity and is correlated to the image quality as perceived by the humans. Advanced CT reconstruction techniques provide better image quality in all conditions compared to FBP. Advances in knowledge: SSIM is a robust measure to compare CT image quality for advanced reconstruction techniques relative to a reference. The 3D print technology is an useful method for the development of dedicated phantoms for CT image quality evaluation.

The use of computer simulated digital x-radiographs for optimisation purposes has become widespread in recent years. To make these optimisation investigations effective, it is vital simulated radiographs contain accurate anatomical and system noise. Computer algorithms that simulate radiographs based solely on the incident detector x-ray intensity ('dose') have been reported extensively in the literature. However, while it has been established for digital mammography that x-ray beam quality is an important factor when modelling noise in simulated images there are no such studies for diagnostic imaging of the chest, abdomen and pelvis. This study investigates the influence of beam quality on image noise in a digital radiography (DR) imaging system, and incorporates these effects into a digitally reconstructed radiograph (DRR) computer simulator. Image noise was measured on a real DR imaging system as a function of dose (absorbed energy) over a range of clinically relevant beam qualities. Simulated 'absorbed energy' and 'beam quality' DRRs were then created for each patient and tube voltage under investigation. Simulated noise images, corrected for dose and beam quality, were subsequently produced from the absorbed energy and beam quality DRRs, using the measured noise, absorbed energy and beam quality relationships. The noise images were superimposed onto the noiseless absorbed energy DRRs to create the final images. Signal-to-noise measurements in simulated chest, abdomen and spine images were within 10% of the corresponding measurements in real images. This compares favourably to our previous algorithm where images corrected for dose only were all within 20%.

Rationale and Objectives: Benefits of iterative reconstruction (IR) algorithms combined with dose-reduction techniques have been shown at computed tomography pulmonary angiography (CTPA) in several medium to small patient collectives. In this study, we performed a systematic comparison of image quality to combinations of reduced tube current (RC) and IR for both standard-pitch (SP) single-source and high-pitch (HP) dual-source CTPA in a large, single-center population., Materials and Methods: Three hundred eighty-two consecutive patients (October 2010 through December 2012) received clinically indicated CTPA with one of four consecutively changed protocols: (1) HPSC: 180 mAs, weighted filtered back projection, pitch = 3; (2) HPRC: 90 mAs, IR, pitch = 3; (3) SPSC: 180 mAs, weighted filtered back projection, pitch = 1.2; and (4) HPRC: 90 mAs, IR, pitch = 1.2. Tube potential was 100 kV. Vascular attenuation and standardized signal-to-noise ratio (sSNR) were measured in the pulmonary trunk (sSNRPT) and on segmental artery level (sSNRS1, sSNRS10). Dose-length-product was recorded per series. Two independent investigators rated image quality. Kolmogorov-Smirnov test, Kruskal-Wallis test, and kappa statistics were used for statistical analysis. Median values are presented per group., Results: Image quality was consistent between all groups (observer 1: P = 0.118; observer 2: P = 0.122). Inter-reader consistency was very good (κ = 0.866, P < 0.001). Dose-length-product was significantly reduced in HP and RC groups (P < 0.001 for each; SPSC: 139.5 mGycm; HPRC: 92 mGycm; SPSC: 211 mGycm; HPRC: 137 mGycm). sSNR was comparable (sSNRPT overall: P = 0.052; sSNRS1 overall: P = 0.161; and sSNRS10 overall: P = 0.259)., Conclusions: Substantial dose reduction can be within a routine clinical setting without quantifiable loss of image quality either by HP pulmonary angiography or by a combination of IR and RC in either HP or SP acquisition., (Crown Copyright © 2016. Published by Elsevier Inc. All rights reserved.)

The modulation transfer function (MTF) of a radiographic system is often evaluated by measuring the system's edge spread function (ESF) using edge device. However, the numerical differentiation procedure of the traditional slanted edge method amplifies noises in the line spread function (LSF) and limits the accuracy of the MTF measurement at low frequencies. The purpose of this study is to improve the accuracy of low-frequency MTF measurement for digital x-ray imaging systems. An edge spread function (ESF) deconvolution technique was developed for MTF measurement based on the degradation model of slanted edge images. Specifically, symmetric oversampled ESFs were constructed by subtracting a shifted version of the ESF from the original one. For validation, the proposed MTF technique was compared with conventional slanted edge method through computer simulations as well as experiments on two digital radiography systems. The simulation results show that the average errors of the proposed ESF deconvolution technique were 0.11% ± 0.09% and 0.23% ± 0.14%, and they outperformed the conventional edge method (0.64% ± 0.57% and 1.04% ± 0.82% respectively) at low-frequencies. On the experimental edge images, the proposed technique achieved better uncertainty performance than the conventional method. As a result, both computer simulation and experiments have demonstrated that the accuracy of MTF measurement at low frequencies can be improved by using the proposed ESF deconvolution technique.

Objective: To establish the optimal image post-processing parameters for digital chest radiography as preliminary research for introducing digital radiography (DR) to pneumoconiosis diagnosis in China., Methods: A total of 204 pneumoconiosis patients and 31 dust-exposed workers were enrolled as the subjects in this research. Film-screen radiography (FSR) and DR images were taken for all subjects. DR films were printed after raw images were processed and parameters were altered using DR workstation (GE Healthcare, U.S.A.). Image gradations, lung textures, and the imaging of thoracic vertebra were evaluated by pneumoconiosis experts, and the optimal post-processing parameters were selected. Optical density was measured for both DR films and FSR films., Results: For the DR machine used in this research, the contrast adjustment (CA) and brightness adjustment (BA) were the main parameters that determine the brightness and gray levels of images. The optimal ranges for CA and BA were 115%∼120% and 160%∼165%, respectively. The quality of DR chest films would be optimized when tissue contrast was adjusted to a maximum of 0.15, edge to a minimum of 1, and both noise reduction and tissue equalization to0.The failure rate of chest DR (0.4%) was significantly lower than that of chest FSR (17%) (P < 0.05)., Conclusion: After appropriate image post-processing on DR machine purchased from GE Healthcare, the DR chest films can meet all requirements for the quality of chest X-ray films in the Chinese diagnostic criteria for pneumoconiosis.

Objective: Foreign body ingestion is common and potentially lethal. This study evaluates the use of low-dose Statscans (LODOX) in emergency departments., Design: This comparative cross-sectional study retrospectively assessed 28289 digital chest x-rays and 2301 LODOX scans performed between 2006 and 2010 at a tertiary emergency centre. The radiographic appearance, image quality and location of ingested foreign bodies were evaluated in standard digital chest and LODOX radiography. The mean irradiation (μSv) and cumulative mean radiation dose per patient with the ingested foreign body were calculated according to literature-based data, together with the sensitivity and specificity for each modality., Results: A total of 62 foreign bodies were detected in 39 patients, of whom 19 were investigated with LODOX and 20 with conventional digital chest radiography. Thirty-three foreign bodies were located in the two upper abdominal quadrants, 21 in the lower quadrants-which are not visible on conventional digital chest radiography-seven in the oesophagus and one in the bronchial system. The sensitivity and specificity of digital chest radiography were 44.4% and 94.1%, respectively, and for the LODOX Statscan 90% and 100%, respectively. The calculated mean radiation dose for LODOX investigations was 184 μS, compared with 524 μS for digital chest radiography., Conclusions: LODOX Statscan is superior to digital chest radiography in the diagnostic work-up of ingested foreign bodies because it makes it possible to enlarge the field of view to the entire body, has higher sensitivity and specificity, and reduces the radiation dose by 65%.

Purpose: Cone-beam computed tomography (CBCT) is increasingly used in craniofacial imaging and may be an interesting option for navigated surgery. The purpose of this study was to evaluate the accuracy of various registration techniques in CBCT compared with intraoperative and diagnostic multislice spiral computed tomography (MSCT)., Materials and Methods: High-resolution images of an anthropomorphic skull phantom with target markers were obtained using 2 CBCT machines (KaVo 3D eXam, ILUMA), an intraoperative MSCT (Sensation Open), and the standard diagnostic MSCT (LightSpeed VCT). Bone markers, a registration template, and an external registration frame were used for registration with an optical-based navigation system. Target registration errors (TREs) were evaluated and statistically analyzed in SPSS (P < .05)., Results: The mean ± standard deviation for overall TREs of the KaVo 3D eXam, ILUMA, Sensation Open, and LightSpeed VCT devices were 1.37 ± 0.54, 1.67 ± 0.65, 1.27 ± 0.52, and 1.31 ± 0.30 mm, respectively. The KaVo 3D eXam showed no significant differences compared with the MSCTs. The ILUMA imaged the external registration frame only marginally and showed significant higher TREs compared with the other registration methods (P < .001). In the 2 MSCTs, no significant differences between the registration methods were found., Conclusions: CBCT and intraoperative MSCT may show comparable TREs as standard diagnostic MSCT. Bone markers are the gold standard. Registration templates and external registration frames are valuable alternatives. When using only external registration frames, CBCTs with a large scan field are recommended., (Copyright © 2012 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.)

This study was carried out to assess whether the spatial resolution has an impact on the detection accuracy of proximal caries in flat panel CBCT (cone beam computerized tomography) images and if the detection accuracy can be improved by flat panel CBCT images scanned with high spatial resolution when compared to digital intraoral images. The CBCT test images of 45 non-restored human permanent teeth were respectively scanned with the ProMax 3D and the DCT Pro scanners at different resolutions. Digital images were obtained with a phosphor plate imaging system Digora Optime. Eight observers evaluated all the test images for carious lesion within the 90 proximal surfaces. With the histological examination serving as the reference standard, observer performances were evaluated by receiver operating characteristic (ROC) curves. The areas under the ROC curves were analyzed with two-way analysis of variance. No significant differences were found among the CBCT images and between CBCT and digital images when only proximal enamel caries was detected (p = 0.989). With respect to the detection of proximal dentinal caries, significant difference was found between CBCT and digital images (p < 0.001) but not among CBCT images. The spatial resolution did not have an impact on the detection accuracy of proximal caries in flat panel CBCT images. The flat panel CBCT images scanned with high spatial resolution did not improve the detection accuracy of proximal enamel caries compared to digital intraoral images. CBCT images scanned with high spatial resolutions could not be used for proximal caries detection.

Objectives: The purpose of this study was to develop and validate a computer model to produce realistic simulated computed radiography (CR) chest images using CT data sets of real patients., Methods: Anatomical noise, which is the limiting factor in determining pathology in chest radiography, is realistically simulated by the CT data, and frequency-dependent noise has been added post-digitally reconstructed radiograph (DRR) generation to simulate exposure reduction. Realistic scatter and scatter fractions were measured in images of a chest phantom acquired on the CR system simulated by the computer model and added post-DRR calculation., Results: The model has been validated with a phantom and patients and shown to provide predictions of signal-to-noise ratios (SNRs), tissue-to-rib ratios (TRRs: a measure of soft tissue pixel value to that of rib) and pixel value histograms that lie within the range of values measured with patients and the phantom. The maximum difference in measured SNR to that calculated was 10%. TRR values differed by a maximum of 1.3%., Conclusion: Experienced image evaluators have responded positively to the DRR images, are satisfied they contain adequate anatomical features and have deemed them clinically acceptable. Therefore, the computer model can be used by image evaluators to grade chest images presented at different tube potentials and doses in order to optimise image quality and patient dose for clinical CR chest radiographs without the need for repeat patient exposures.

Current guidelines quote tolerances for automatic exposure control (AEC) device performance for X-ray systems as 'Baseline ± X %'. However, in the situation where a baseline figure has not yet been achieved, as in the case of commissioning assessments, this tolerance is not relevant. The purpose of this work is to provide mean doses for direct digital radiography (DDR) X-ray system, operating in AEC, against which comparisons can be made. Dose measurements have been recorded under AEC operation on 29 DDR detectors from three different manufacturers. Two different testing protocols were examined: (1) water equivalent phantoms in front of the DDR detector and (2) aluminium block at the tube head. The average patient exit dose, using the aluminium block was 4.6 μGy with the antiscatter grid in place and 4.0 μGy with the grid removed. Using the water phantoms, the average dose was measured at 17.1 μGy with the antiscatter grid in place and 5.4 μGy with grid removed. Based on these results, it is clear that different testing configurations significantly impact on the measured dose.

Objectives: The aim of this study was to evaluate the variability of intensity values in cone beam computed tomography (CBCT) imaging compared with multislice computed tomography Hounsfield units (MSCT HU) in order to assess the reliability of density assessments using CBCT images., Material and Methods: A quality control phantom was scanned with an MSCT scanner and five CBCT scanners. In one CBCT scanner, the phantom was scanned repeatedly in the same and in different positions. Images were analyzed using registration to a mathematical model. MSCT images were used as a reference., Results: Density profiles of MSCT showed stable HU values, whereas in CBCT imaging the intensity values were variable over the profile. Repositioning of the phantom resulted in large fluctuations in intensity values., Conclusions: The use of intensity values in CBCT images is not reliable, because the values are influenced by device, imaging parameters and positioning., (© 2011 John Wiley & Sons A/S.)

Digital radiography has created a growing opportunity for computer-aided diagnostic (CAD) tools. The Logicon Caries Detector (LCD), with upgraded CAD software based on user feedback, was re-evaluated for its effectiveness via a retrospective clinical study. Using the upgraded LCD software, 12 dentists (evaluators) blindly assessed 17 radiographs taken by another (attending) dentist, who restored 28 proximal surfaces. The attending dentist confirmed the presence of early dentinal caries, as well as identifying 48 surfaces as caries-free or with enamel caries only subject to noninvasive treatment. The radiographs, imported into the software using a digital imaging and communications in medicine (DICOM) reader, were visually assessed under typical operatory lighting conditions, then with the aid of the software's density analysis tool. The effectiveness of the evaluators was gauged by calculating two measures of performance, sensitivity and specificity, for the detection and classification of dentinal caries. Sensitivity among all evaluator dentists was 30% with the initial image; 34% with the brightness and contrast adjusted image; 39% when the image was sharpened; and 69% when the density analysis tool was utilized. Specificity was found to be 97% with the initial image; 95% with the brightness and contrast adjusted image; 93% with the sharpened image; and 94% when the density analysis tool was used. Compared to the unaided eye, the LCD can significantly improve dentists' ability to detect and classify caries. Dentists may be able to find twice as much early dentinal caries requiring restoration (or at least aggressive noninvasive treatment) than previously, while not unnecessarily restoring additional healthy teeth. The LCD enables dentists to obtain more information from dental digital radiography than is possible with the unaided eye, leading to improved patient care.

The purpose of this study was to evaluate a custom portal image - digitally reconstructed radiograph (DRR) registration software application. The software works by transforming the portal image into the coordinate space of the DRR image using three control points placed on each image by the user, and displaying the fused image. In order to test statistically that the software actually improves setup error estimation, an intra- and interobserver phantom study was performed. Portal images of anthropomorphic thoracic and pelvis phantoms with virtually placed irradiation fields at known setup errors were prepared. A group of five doctors was first asked to estimate the setup errors by examining the portal and DRR image side-by-side, not using the software. A second group of four technicians then estimated the same set of images using the registration software. These two groups of human subjects were then compared with an auto-registration feature of the software, which is based on the mutual information between the portal and DRR images. For the thoracic case, the average distance between the actual setup error and the estimated error was 4.3 ± 3.0 mm for doctors using the side-by-side method, 2.1 ± 2.4 mm for technicians using the registration method, and 0.8 ± 0.4mm for the automatic algorithm. For the pelvis case, the average distance between the actual setup error and estimated error was 2.0 ± 0.5 mm for the doctors using the side-by-side method, 2.5 ± 0.4 mm for technicians using the registration method, and 2.0 ± 1.0 mm for the automatic algorithm. The ability of humans to estimate offset values improved statistically using our software for the chest phantom that we tested. Setup error estimation was further improved using our automatic error estimation algorithm. Estimations were not statistically different for the pelvis case. Consistency improved using the software for both the chest and pelvis phantoms. We also tested the automatic algorithm with a database of over 5,000 clinical cases from our hospital. The algorithm performed well for head and breast but performed poorly for pelvis cases, probably due to lack of contrast in the megavoltage portal image. The software incorporates an original algorithm to fuse portal and DRR images, which we describe in detail. The offset optimization algorithm used in the automatic mode of operation is also unique, and may be useful if the contrast of the portal images can be improved.

Aim: To determine whether radiologists can recognize images retouched to include sham lesions., Materials and Methods: Ten representative key images were selected of aortic dissection, hepatocellular carcinoma, renal cell carcinoma, colon cancer, liver metastasis, hepatic cyst, gallbladder stones, splenic artery aneurysm, adrenal adenoma, and stomach cancer from abdominal computed tomography (CT) imaging performed in 2008. Five of the key images were replaced with retouched images using image-editing software. The time to complete retouching was recorded for each image. Radiologists were requested to make a diagnosis for the 10 images, and were then asked to identify possible retouched images. The time taken to reach a decision in each case was recorded. Thirty radiologists (13 residents and 17 attending radiologists) participated as reviewers., Results: The time to complete retouching was 15.2±3.15 min. None of the reviewers recognized that some images were retouched during diagnosis. The rate of correct diagnosis was 90% (range 71.7-100%). After reviewers were informed of possible image retouching, the detection rate of retouched images was 50% (40-58.3%). This rate was statistically the same as random choice (p=0.876). There was no significant difference between residents and attending radiologists in the detection rate of retouched images (p=0.786). The time to diagnosis and the time to detection of the retouched images were 15 (14-17) and 6 (5-7) min, respectively., Conclusion: Digital images can be easily retouched, and radiologists have difficulty in identifying retouched images. Radiologists should be aware of the potential fraudulent use of retouched images., (Copyright © 2010 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.)

Purpose: Evaluation of subjective image quality in dose-reduced multi-detector CT (MDCT) of paranasal sinuses using a 2D non-linear adaptive post-processing filter (2D-NLAF)., Materials and Methods: MDCT of paranasal sinuses was simulated using a human head phantom at a Somatom Sensation Cardiac 64 (Siemens, Erlangen). At constant collimation (64 × 0.6 mm) und pitch (p = 1), the tube current (50, 100, 200 mAs) and tube potential (80, 100, 120 kVp) were modified. The radiation exposure was represented by CTDIvol. Four independent blinded radiologists evaluated the image quality of axial 2 mm images and coronal reformations concerning the assessment of "fractures" and "soft tissue processes". The subjective image quality of original and post-processed images using a 2D-NLAF (SharpViewCT®, Sweden) was graded on a 5-point scale ("1" excellent - "5" not adequate) and compared., Results: Compared to the protocol with the best image quality (120kVp/ 200 mAs) 2D-NLAF led to a significant improvement in the subjective image quality at 100 kVp/ 100 mAs (score "1.4" with filter versus "2.2" without) and 120 kVp/ 50 mAs ("1.6" versus "2.0") (p < 0.03) particularly for high contrasts ("fractures", p < 0.001). In "soft tissue processes", 2D-NLAF provided improved quality from "2.1" to "1.4" (p < 0.04) at 100 kVp/ 100 mAs. Down to a CTDIvol of 8 mGy, the image quality was rated "good", and down to 5 mGy "diagnostic"., Conclusion: The phantom study indicates a dose reduction potential in MDCT of paranasal sinuses up to 58% compared to a standard dose protocol using a 2D-NLAF without an essential loss of image quality. 2D-NLAF is particularly effective at 100 kVp/ 100 mAs and 120 kVp/ 50 mAs., (© Georg Thieme Verlag KG Stuttgart · New York.)

Purpose: A total of 79115 mammograms from statutory health insurance (SHI) physicians within German outpatient care were evaluated with respect to the diagnostic image quality., Materials and Methods: Mammograms were randomly selected between 2006 and 2008 by the regional Associations of Statutory Health Insurance Physicians and submitted to regional boards of experts for external evaluation. The mammogram quality was evaluated using a 3-point scale (adequate, borderline, failure) and documented using a nationally standardized protocol., Results: 87.6% of the mammograms were classified as adequate, 11.0% as borderline and 1.4% as failure. Mediolateral oblique mammograms (mlo) had worse ratings than craniocaudal mammograms (cc). Main reasons for classifying the mammograms as borderline or failure were "inframammary fold not adequately visualized" (mlo), "pectoral muscle not in the correct angle or not to the level with the nipple" (mlo), "the nipple not in profile" (mlo, cc) and "breast not completely or not adequately visualized" (cc)., Conclusion: The results show a good overall quality of mammograms in German outpatient medical care. Failures can be associated predominantly with incorrect positioning of the breast. More precisely defined quality criteria using objective measures are recommended, especially for craniocaudal mammograms (cc)., (© Georg Thieme Verlag KG Stuttgart · New York.)

Computed radiography (CR) systems were originally developed for the purpose of clinical imaging, and there has been much work published on its effectiveness as a film replacement for this end. However, there has been little published on its use for routine linear accelerator and simulator quality control, and therefore we have evaluated the use of the Kodak 2000RT system with large Agfa CR plates as a replacement for film for this function. A prerequisite for any such use is a detailed understanding of the system behaviour, hence characteristics such as spatial uniformity of response, reproducibility of spatial accuracy, plate signal decay with time and the dose-response of plates were investigated. Finally, a comparison of results obtained using CR for the measurement of radiation field dimensions was made against those from radiographic film, and found to be in agreement within 0.1 mm (mean difference for high-resolution images, 0.3 mm root mean square difference) for megavoltage images and 0.3 mm (maximum difference) for simulator images. In conclusion, the CR system has been shown to be a good alternative to radiographic film for routine quality control of linear accelerators and simulators.

Not all digital radiography systems allow an unrestricted image postprocessing for the radiologist. Depending on the X-ray system there are restrictions in varying brightness and contrast of the image. We compared grey level information that are given to the radiologist by various digital radiography systems. Histograms of differently postprocessed X-ray images were calculated, which were acquired by three different X-ray systems. We found that every modality has its own way of saving and converting the images into DICOM data. The processed image is either sent into PACS with the initial grey level range (10 or 12 bit) or the image is sent with a reduced grey level range due to windowing. The grey level range is associated with the ability of unrestricted windowing in PACS. So, taking an image with a reduced grey level range, the radiologist will face limited potential to optimise the window setting individually afterwards. The loss of image quality due to image transfer from the modality to PACS can lead to an information loss in the diagnostic relevant range.

Objectives: To evaluate the reliability of cone beam CT (CBCT) values and dimensional measurements of oropharyngeal air spaces as compared with those of multidetector row CT (MDCT)., Methods: A soft tissue equivalent phantom with different sized holes was used. The phantom was scanned using CBCT and MDCT. In addition, a volunteer was examined using both methods for clinical comparison. The CT data were retrieved to a personal computer and treated using image processing software for three-dimensional rendering and dimensional measurements. The CT values of air, water and soft tissues were measured experimentally and the CT values of air, fat and muscle were measured in a clinical case. The diameter of each hole drilled in the phantom was measured on CBCT and MDCT images using the software tool and digimatic callipers., Results: The CBCT values were quite different from the Hounsfield units obtained with a typical MDCT system. The standard deviations were almost ten times larger with CBCT. In vivo assessment showed that the CBCT values for fat had a wide range that partially overlapped the values for muscle. The measurement of distances greater than 4 mm was consistent for all methods. The difference for holes was less than 0.2 mm., Conclusions: The phantom study showed that CBCT provides limited quantitative CT values for each pixel on sliced images for differentiating air, water and soft tissues. However, the measurement of air spaces with CBCT was quite accurate.

The purpose of this article is to review the features of digital mammography systems available in France. This article includes three parts: definition of the different components of a digital mammography system, description of different performance evaluation parameters, and review of systems currently available in France. Data from the literature as well as questionnaires from different manufacturers were used. The following vendors agreed to participate: Agfa, Fujifilm, GE Healthcare, Hologic-Lorad, IMS, Kodak, Konica Minolta, Philips, Planmed, Sectra, Siemens. For each vendor, the type of detector, type of available mammographic units and workstation, optional features (CAD), archival and printing possibilities (when vendors specifically offer dedicated solutions).

To avoid the purchase of a digital mammography system by radiologists with intrinsic characteristics not able to fulfil the physical-technical quality requirements of the acceptance tests of the European guidance document, typetesting of digital equipment was introduced in the organisation and legislation of the Flemish breast cancer screening programme. Typetesting is performed for two types of instrumentation: systems for image capture and -processing and systems for image presentation. Typetesting is finalised or ongoing for eight DR systems and four CR systems. Eight workstations were or are submitted to the typetesting for image presentation. Experiences gained in typetesting of systems for image capture and -processing up to now show that the contrast-detail analysis of CDMAM phantom imaging and the homogeneity tests are most stringent. In general DR performs better than CR in imaging performance. Typetesting for image presentation has shown no difference in quality between CRT and LCD monitors. Furthermore, 3 MP monitors also pass the tests. However, to get the full resolution capabilities of the image capture system zooming in and scrolling over the image is necessary, which is time-consuming in clinical practice. Finally, we emphasize that typetesting involves also an evaluation of a set of clinical images by the working party of radiologists and that succeeding in typetesting does not mean that a particular system passes automatically the acceptance testing. A perfect tuning of the system and the coupling to a high quality X-ray system is necessary as well.

In this paper the author showed possibilities for adaptation of the most present-day medical achievements in the field of noninvasive diagnosis of individual characteristics of human skeleton pathology--at crime detection and during criminalistic identification particularly. The identification value of image diagnosis for individual characteristics of the pathologically changed skeleton has been exemplified with: X-ray radiography, both conventional and computer-assisted tomography, scintigraphy, ultrasonography and nuclear magnetic resonance tomography. The paper's conclusion is formulating of new definitions for identification method of individuals, based on image diagnosis--named osteopathoscopy--which can be an alternative method to controversial radiology.

Rasterstereography has been shown to be a reliable method for three-dimensional surface measurement of idiopathic scoliosis with Cobb angles up to 50 degrees. In this study, 25 patients with severe idiopathic scolioses (Cobb angles 47 degrees-92 degrees) were examined before and after operation (VDS instrumentation). The a.p. radiographs were digitized according to the Drerup method. The similarity of rasterstereographic and radiometric data was quantified by the rms. differences between the rasterstereographic and radiographic curves of lateral deviation and vertebral or surface rotation. The average rms. differences were 5.8 mm for lateral deviation and 4.4 degrees for vertebral and surface rotation, which is about 40% higher than for mild to medium scolioses.

Objective: Reliable evaluation of joint space width and subchondral sclerosis of osteoarthritic joints is difficult. The present study describes a new digital method to analyse standard radiographs of the ankle., Design: Standardized radiographs were taken of the ankle of 12 patients with severe osteoarthritis (OA) under full weight-bearing conditions, before treatment and 1 year after initiation of treatment. Treatment consisted of 3 months distraction of the tibio-talar joint, for which clinical benefit has been shown previously. The width of the joint space was measured on digitized images of the radiographs by means of the newly developed semi-automatic digital technique called AIDA (Ankle Images Digital Analysis) and by means of the most widely used conventional analogue measurements. In addition, AIDA was used to assess subchondral sclerosis by measuring the intensity of the radiograph at fixed positions at the bone-cartilage interface., Results: AIDA appeared to be a reliable method for measuring small changes in joint space width and subchondral sclerosis because the intra- and interobserver variation was small. Mean JSW for two observers was 1.96 and 2.00 mm, with mean differences between two observations of 0.05 and -0.01, respectively. Mean subchondral sclerosis in the tibia was 1.52 and 1.61 with mean differences between two observations of, respectively, 0.00 and 0.03. In addition to conventional measurements, AIDA could demonstrate a decrease in subchondral sclerosis as a result of joint distraction of 71% and 69% after 1 year for talus and tibia, respectively., Conclusion: The use of AIDA is preferable to the conventional analogue method for evaluating the severity of ankle OA, because the method provides quantitative data not only for the joint space width but also for subchondral sclerosis.

At a first glance the future of digital mammography seems very bright considering the wealth of offerings for new detectors, made by companies on the market or in journals. However technically spoken, digital mammography is one of the most demanding applications in the spectrum of radiology along with a high degree of cost consciousness in the mammography screening programs. The functional requirements are so high for digital mammography that only the best and most expensive components are good enough to compete with the current screen-film systems. Next difficulties are the lack of quality standards for digital detectors, not at all existing in the past and still under discussion, and the non-existence or changing of approval procedures. This is discouraging the industries to enter the field and is slowing down the phase-in time. After these obstacles are removed, there will come the discussions on acceptance of digital mammography within the professional community, due to the 'look' of the images and also the need to gain confidence with these images.

Objective: The purpose of this study was to evaluate the subjective quality of Joint Photographic Experts Group (JPEG) compressed images of intraoral radiographs with file sizes of 30 kilobytes or less, which can be transmitted quickly on the World Wide Web., Study Design: Conventional intraoral radiographs were digitized at sampling rates of 100, 200, 300, 400, and 600 dots per inch through use of a flatbed scanner and saved in JPEG format in 11 compression degrees. Fifty-five combinations of sampling rate and compression degree were evaluated by means of a visual analog scale. Sampling rate and compression degree combinations whose quality was inferior to that of an average image were excluded. The quality of the remaining combinations was subsequently evaluated through assessment of 8 anatomical features in each image., Results: Forty of the 55 combinations provided a file size less than 30 kilobytes. Thirty combinations obtained VAS scores of 0 or higher on the standardized VAS. As a result, 16 combinations of sampling and compression conditions were selected for the second part of the study. Only one combination of sampling rate and compression degree was found to provide sufficient image quality for all 8 anatomical features., Conclusions: Under the file size limit of the study design, the full-sized compressed image of an intraoral radiograph did not always provide sufficient quality. This problem will be reduced by improvements in telecommunications infrastructure, which will permit faster transfer of files of larger size.

Digital acquisition systems are widely used nowadays. The digitization of the cath lab environment is now directed towards the change in the exchange media from an analog (i.e. cinefilm) to a digital (i.e. CD-R) medium. An important consequence of this development is the need for another type of review system. This article focuses on the replacement of the cineprojector by a digital equivalent: the DICOM review station. Since the technologies differ fundamentally, the DICOM review station has very little in common with its analog predecessor. This article explains the basics of DICOM review stations. Different approaches, both in hardware and in software, are possible, each showing their advantages and drawbacks. The impact of choices made by the industry will be illustrated by a number of commercially available DICOM review stations. Further, the article discusses the topics of diagnostic image quality and performance. In our opinion, these are the major topics when it comes to an objective comparison of the capabilities of DICOM review stations. The relation of these subjects with design choices in terms of hardware and software are discussed.

Cine film had been a global standard in the cardiac catheterization lab for the acquisition, archive, review and exchange for decades. The advent of digital imaging in the cath lab heightened the desire to store cath procedure images in a digital format. The issues related to the development of a digital exchange standard, the data capacities and data rates, lossless and lossy compression, and techniques to obtain digital image data from the lab are discussed. In addition, Kodak's approach to cine film replacement with digital systems is described.

This study evaluated dentists' perception of the quality of digitally captured radiographs. Thirty radiographs were taken with the Visualix digital video radiographic system, 10 periapicals for tooth and bone anatomy, 10 periapicals for bone disease and 10 bitewings for dental caries. Three numeric copies were made of each image and treated with three different filters: 'optimize', 'enhance' and 'enhance + smooth', respectively. Four images of the same case were displayed simultaneously in a random sequence on the monitor. Twenty dentists ranked each set of four images on a scale from 1 to 4. In general, most dentists preferred a treated image to the original. The optimized and enhanced images were selected most frequently as first or second choice from the tooth and bone anatomy and bone disease groups. The original image was ranked lowest in more than half (55%) of the series. For the bitewings, the smoothed images were ranked significantly higher. In conclusion, image treatment possibilities should be offered in digital radiography as the majority of dentists preferred a treated image to the original version. The image treatment chosen seemed to be task dependent; less treatment was required to delineate the more subtle tissue differences.

Thoracic imaging constitutes more than one-third of all medical imaging performed in the United States. Despite the substantial impact of computer technology in other areas of imaging, conventional film-screen acquisition systems still provide the bulk of projectional chest radiography. The successful implementation of digital technology in thoracic imaging requires that the standards of current film-screen methods for both diagnostic accuracy and efficient data management be preserved. This article addresses the technical and clinical aspects of film digitization and storage phosphor technology, which are the two digital acquisition systems in widest application. Scanned projection radiography, which may now be applied to computed radiography systems, is also discussed. Finally, some of the issues surrounding the implementation of picture archiving and communication systems for thoracic imaging are addressed.

The application of digital technologies to chest radiography holds the promise of routine application of image processing techniques to effect image enhancement. Because of their inherent spatial resolution, however, digital chest images impose severe constraints on data storage devices. Compression of these images will relax such constraints and facilitate image transmission on a digital network. We evaluated an algorithm for enhancing digital chest images that has allowed significant data compression while improving the diagnostic quality of the image. This algorithm is based on the photographic technique of unsharp masking. Image quality was measured with respect to the task of tumor detection and compression ratios as high as 2:1 were achieved. This compression can be supplemented by irreversible methods.

The Philips Computed Radiography system performs well with pediatric portable chest radiographs, handling the throughout of a busy intensive care service 24 hours a day. Images are excellent and routinely provide a conventional (unenhanced) image and an edge-enhanced image. Radiation dose is decreased by the lowered frequency of repeat examinations and the ability of the plates to respond to a much lower dose and still provide an adequate image. The high quality and uniform density of serial PCR portable radiographs greatly enhances diagnostic content of the films. Decreased resolution has not been a problem clinically. Image manipulation and electronic transfer to remote viewing stations appear to be helpful and are currently being evaluated further. The PCR system provides a marked improvement in pediatric portable chest radiology.