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Image Quality Criteria for Chest Images Proposed by the European Guidelines 4 and Mean Scoring Obtained for the Different Age Bands
Source publication
The objective of this study was to analyze image quality of chest examinations in pediatric patients using computed radiography (CR) obtained with a wide range of doses to suggest the appropriate parameters for optimal image quality. A sample of 240 chest images in four age ranges was randomly selected from the examinations performed during 2004. I...
Contexts in source publication
Context 1
... and level of the images were changed by each radiologist depending on the structure examined, as done in routine visualization. Each image was scored using the criteria proposed by the European Guidelines on Quality Criteria for Diagnostic Radiographic Images in Pediatrics 4,12,13 ( Table 1). Each of the seven criteria was scored with 1 or 0 (1 point if the criterion is fulfilled, 0 point if it is not fulfilled). ...
Context 2
... arithmetic mean of the three radiologists was used as final scoring for each image. Some of the image criteria are more related to the level of noise in the image (criteria from 4 to 7 in Table 1 In addition, other qualitative analysis of the images with the most extreme DL values existing in the database (702 chest images) was made to identify the boundaries of DL range giving enough diagnostic quality. A total of 22 images with DL G1.2 and 23 images with DL 92.85 were individually analyzed. ...
Context 3
... this qualitative analysis, all images were considered, including those not valid for diagnosis. Table 1 presents, together with the European qual- ity criteria, the mean scoring and standard deviation of each criteria and the mean values and standard deviation of DL for the four age ranges. A second scoring for the individual criteria (4 to 7) more sensi- tive to the noise (and theoretically to the DL) is also (Fig. 6) and another with saturation in left lung base (Fig. 7). ...
Context 4
... our center, the mean DL for the four age ranges is approximately 2.0 (Table 1), and from the cor- relation study between image quality scoring and DL, it can be concluded that no strong correlation exists for either the global score or for the individual noise-related criteria. Thus, it seems appropriate to recommend radiographers to reduce radiographic techniques (and ESD) in a factor of 2 (corresponding to a decrease in DL of 0.3) for pediatric patients bringing the mean value of DL to 1.6-1.7 instead of the actual value of 1.9-2.0. ...
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Citations
... Many studies have demonstrated that CR can routinely produce images that are perceived as equal or superior to conventional S/F images, in terms of image quality and/or clinical performance, in chest X-ray digital thoracic imaging, even with less radiation dose. (217,231,(239)(240)(241)(242) Computed radiography with phosphor plates allowed the development of PACS, as radiography accounted for more than 50% of the imaging activity performed in any large radiology department. Therefore, CR allowed the separation between image acquisition and image display with soft-copy reporting. ...
ISBN 9788449061615
EOS is a new 2D/3D radio-imaging technology that uses a gaseous radiation detector and micro-grid ionization chamber derived from Micromegas, the micro-grid developed by the Nobel Prize winner Georges Charpak and extensively used in high-energy research (eg, CERN, Geneva, Switzerland). The detectors are very efficient and enable low-dose medical imaging by stringent collimation, which avoids the undesired scattered radiation that increases dose and degrades image quality. The EOS prototype uses very thin (500 µm) fan-like x-ray beams and was planned for low-dose standing radiography of the human skeleton. It has two x-ray tubes and two detectors that allow synchronous biplanar linear acquisition of two 90-degree images of the body. The biplanar method was designed for automatic extraction of anatomic reference points that can be mathematically projected as a 3D model of a patient's skeleton. EOS software can build 3D models using lower radiation doses (1/10 to 1/100) than existing systems (computed radiography [CR], digital radiography [DR], or low-dose CT). The main application of the prototype, spine imaging, has been validated, and the subsequent, re-designed industrial EOS (EOS Imaging, Paris, France) has attained certification for skeletal studies. While preparing the experimental phase of EOS for spine imaging, a second objective was considered: to assess applicability of the EOS prototype to another field of imaging, the chest x-ray, the most common radiologic exam. Chest x-rays could pose several difficulties for a large, linear-scanning, biplanar, low-dose and low-spatial-resolution technique, in this case micro-grid detectors, which would have to be investigated. Material and methods: A prospective study was designed to assess the clinical feasibility, technical problems, dose and image quality of EOS as compared to a state-of-the-art DR system, the aSi-CsI flat panel detector. Forty adult patients undergoing scheduled chest x-ray examinations at the Erasme University Hospital (Brussels, BE) were recruited for paired examinations using EOS (at 50% dose) and DR. Paired data and images were compiled. Image data sets were independently scored by 4 radiologists according to the European Quality Criteria in Diagnostic Imaging, with additional challenges, such as scoring of thin anatomical structures. The dosimetry data obtained were also compared to those of CR, and experimental laboratory data were compiled on collimation and detector performance. Results: 37 of 40 cases were available for complete analysis. EOS chest examinations were acquired with a 13,5% repeat rate. Radiation dose (PA) was higher for EOS (0.22 mGy) than with DX (0.05), but less than CR or reference doses (0.3 mGy). Noise and ripple artifacts lowered the MTF (Modulation Transfer Function) to 1-1.5 pl/mm. Image quality scores between EOS and DX were comparable, but with better scores for EOS in several items as air-ways, mediastinum or anatomic coverage. Conclusion: EOS is feasible for chest imaging and is compliant with the chest reference doses. Radiation dose was higher than with DR, but lower than with CR, achieved by suppressing scatter. EOS image quality scores were not significantly inferior from those of DR, even for thin structures, as the extended density resolution and absence of scatter of EOS compensated for the inferior spatial resolution. Further development is needed to reach better dose containment and improve resolution, with validation in patients having various clinical conditions.
... For instance, in the computer radiology (CR) modality, the exposure factors associated with each captured image are not stored in the DICOM object metadata. In CR, the attribute that can give us an indication of the radiation level is the exposure index (EI) [21,22]. Nevertheless, this index does not represent the radiation dose absorbed by the patient, only the information about the suitability of the exposure that the detector has been submitted to, compared with a reference value [23]. ...
The production of medical imaging is a continuing trend in healthcare institutions. Quality assurance for planned radiation exposure situations (e.g. X-ray, computer tomography) requires examination-specific set-ups according to several parameters, such as patient's age and weight, body region and clinical indication. These data are normally stored in several formats and with different nomenclatures, which hinder the continuous and automatic monitoring of these indicators and the comparison between several institutions and equipment. This article proposes a framework that aggregates, normalizes and provides different views over collected indicators. The developed tool can be used to improve the quality of radiologic procedures and also for benchmarking and auditing purposes. Finally, a case study and several experimental results related to radiation exposure and productivity are presented and discussed.
... Manufacturer-recommended EIs may be set too high as images produced at lower EIs have been found to be clinically acceptable.32 Similarly, clinically acceptable images at lower EI levels were obtained in a study to optimise the use of CR in paediatric chest imaging using Agfa CR (here the Agfa EI is the logarithm of median exposure level “lgM”13), where the researchers found that a possible reduction by a factor of 2.5 in mean patient entrance surface dose (ESD) could be achieved in their centre.33 It has been suggested that CR manufacturers reassess their EI value recommendations.34 ...
Digital radiography (DR) technologies have the advantage of a wide dynamic range compared to their film-screen predecessors, however, this poses a potential for increased patient exposure if left unchecked. Manufacturers have developed the exposure index (EI) to counter this, which provides radiographers with feedback on the exposure reaching the detector. As these EIs were manufacturer-specific, a wide variety of EIs existed. To offset this, the international standardised EI has been developed by the International Electrotechnical Commission (IEC) and the American Association of Physicists in Medicine (AAPM). The purpose of this article is to explore the current literature relating to EIs, beginning with the historical development of the EI, the development of the standardised EI and an exploration of common themes and studies as evidenced in the research literature. It is anticipated that this review will provide radiographers with a useful guide to understanding EIs, their application in clinical practice, limitations and suggestions for further research.
... (83) Appropriate image processing is crucial in producing the optimal paediatric CR or DR image. Most CR and DR manufacturers now recognise that paediatric patients are unique, and have developed, or are developing, special provisions for paediatric examinations, including image processing (Sanchez Jacob et al., 2009). ...
Paediatric patients have a higher average risk of developing cancer compared with adults receiving the same dose. The longer life expectancy in children allows more time for any harmful effects of radiation to manifest, and developing organs and tissues are more sensitive to the effects of radiation. This publication aims to provide guiding principles of radiological protection for referring clinicians and clinical staff performing diagnostic imaging and interventional procedures for paediatric patients. It begins with a brief description of the basic concepts of radiological protection, followed by the general aspects of radiological protection, including principles of justification and optimisation. Guidelines and suggestions for radiological protection in specific modalities - radiography and fluoroscopy, interventional radiology, and computed tomography - are subsequently covered in depth. The report concludes with a summary and recommendations. The importance of rigorous justification of radiological procedures is emphasised for every procedure involving ionising radiation, and the use of imaging modalities that are non-ionising should always be considered. The basic aim of optimisation of radiological protection is to adjust imaging parameters and institute protective measures such that the required image is obtained with the lowest possible dose of radiation, and that net benefit is maximised to maintain sufficient quality for diagnostic interpretation. Special consideration should be given to the availability of dose reduction measures when purchasing new imaging equipment for paediatric use. One of the unique aspects of paediatric imaging is with regards to the wide range in patient size (and weight), therefore requiring special attention to optimisation and modification of equipment, technique, and imaging parameters. Examples of good radiographic and fluoroscopic technique include attention to patient positioning, field size and adequate collimation, use of protective shielding, optimisation of exposure factors, use of pulsed fluoroscopy, limiting fluoroscopy time, etc. Major paediatric interventional procedures should be performed by experienced paediatric interventional operators, and a second, specific level of training in radiological protection is desirable (in some countries, this is mandatory). For computed tomography, dose reduction should be optimised by the adjustment of scan parameters (such as mA, kVp, and pitch) according to patient weight or age, region scanned, and study indication (e.g. images with greater noise should be accepted if they are of sufficient diagnostic quality). Other strategies include restricting multiphase examination protocols, avoiding overlapping of scan regions, and only scanning the area in question. Up-to-date dose reduction technology such as tube current modulation, organ-based dose modulation, auto kV technology, and iterative reconstruction should be utilised when appropriate. It is anticipated that this publication will assist institutions in encouraging the standardisation of procedures, and that it may help increase awareness and ultimately improve practices for the benefit of patients.
... Nevertheless, when similar patient thickness and X-ray beam quality are used, the dose indicators may be related to the ESD. 7 In work involving CR exposure indicators, the behaviour of the dose indicators of an Agfa CR system as a function of delivered dose has been investigated. The imaging plate response was characterised in terms of exposure and in terms of the digital signal for different beam qualities applicable in mammography using a phantom with standard thickness. ...
Studies indicate that computed radiography (CR) can lead to increased radiation dose to patients. It is therefore important to relate the exposure indicators provided by CR manufacturers to the radiation dose delivered so as to assess the radiation dose delivered to patients directly from the exposure indicators. The aim of this study was to investigate the performance of an Agfa CR system in order to characterize the dose indicators provided by the system. The imaging plate response was characterized in terms of entrance exposure to the plate and the digital signal indicators generated by the system (SAL - Scanning Average Level and lgM - Logarithmic median) for different beam qualities. Several exposures were performed on a mammography unit and the digital signal, expressed as SAL and lgM for each image was correlated with the entrance exposure on a standard ACR phantom. From this, the relationship between the Agfa dose indices (SAL and lgM) and the average glandular dose (AGD) in mammography was established. An equation was derived to calculate the AGD delivered to the patient as a function of the exposure indicator, lgM, and the kV. The results indicated that the measured AGD at 28kV for a standard breast thickness during routine calibration with the ACR phantom was 1.58mGy (lgM = 1.99), which is within 1.5% of the value calculated using the derived equation for a standard Perspex thickness of 4.2cm using the AEC (1.56mGy). The standard error in using this equation was calculated to be 8.3%.
Introduction
Radiographers have a duty to ensure that radiation doses to patients are as low as reasonably achievable. With digital technologies, exposure factors which achieve the optimum balance between image noise and patient dose must be sought. In digital radiography, Deviation Index (DI) values provide the radiographer with feedback on the appropriateness of individual exposures but can also be tracked as part of a departmental quality assurance programme.
Methods
In November 2017, exposure logs were extracted from six digital radiography (DR) x-ray systems, collated and analysed. Five examinations were identified which frequently produced DI values outside the manufacturer's recommended Optimal Range (-3 to +2). Incremental improvements were made to the default exposure settings for these examinations via a cyclical process of modification and re-evaluation. A full data collection exercise was then repeated in April 2019.
Results
At baseline, 10,658 out of 29,637 (36.0%) exposures had DI values outside the manufacturer's recommended Optimal Range, but for some individual examinations the proportion was as high as 547 out of 725 (74.5%). Following multiple optimisation cycles, the overall proportion of examinations outside the Optimal Range had fallen to 7611 out of 26,759 (28.4%). Default milliampere-seconds (mAs) values for these examinations were reduced by between 22% and 50%.
Conclusion
A marked reduction in patient doses can be achieved through a departmental programme of DI value monitoring and targeted optimisation of default exposure settings.
Implications for practice
DI values should be routinely monitored as part of routine quality assurance programmes. Radiographers have a responsibility to ensure that they possess a clear understanding of DI values and that appropriate exposure settings are selected for each individual patient.
Methods:
Automatic dose management software (ADMS) was used to analyse 2678 studies of children from birth to 5 years of age, obtaining local diagnostic reference levels (DRLs) in terms of entrance surface air kerma. Given local DRL for infants and chest exams exceeded the European Commission (EC) DRL, an optimisation was performed decreasing the kVp and applying the automatic control exposure. To assess the image quality, an analysis of high-contrast resolution (HCSR), signal-to-noise ratio (SNR) and figure of merit (FOM) was performed, as well as a blind test based on the generalised estimating equations method.
Results:
For newborns and chest exams, the local DRL exceeded the EC DRL by 113%. After the optimisation, a reduction of 54% was obtained. No significant differences were found in the image quality test. A decrease in SNR (-37%) and HCSR (-68%), and an increase in FOM (42%), was observed.
Conclusion:
ADMS allows the fast calculation of local DRLs and the performance of optimisation procedures in babies without delay. However, physical and clinical analyses of image quality remain to be needed to ensure the diagnostic integrity after the optimization process. Advances in knowledge: ADMS are useful to detect radiation protection problems and to perform optimization procedures in paediatric conventional imaging without undue delay, as ED requires.
There are no recommended test conditions for digital photography in Chest PA examinations. However, each company recommends shooting examinations of the high voltage applied to the previous analog examination. The condition that satisfies the value of 200 ~ 800 which is the recommended Exposure Index value recommended by Philips was selected, and the dose was evaluated by Monte Carlo simulation, and the SNR and CNR were compared. As a result, it was possible to reduce the effective dose up to 77% by controlling the tube voltage, tube current, and additional filter, not the conventional high voltage imaging method. Although there were some differences according to the test conditions, the image evaluation results were similar to the images. We will compare the exposure dose according to changes in tube voltage, tube current, and additional filter at the digital chest radiograph and evaluate the image quality of the image to propose optimal conditions.
This study was aimed to demonstrate the feasibility of line profile method in quantitatively evaluating pediatric chest images acquired using computed radiography (CR). A sample of 36 pediatric chest images, which is 26 normal chest images and 10 abnormal chest images, were obtained using a CR system and were evaluated quantitatively using line profile. The method involves the use of ImageJ software for profile setting and Fortran90 for quantifying the results. Each line profiles were subjected using six different quantization methods. These methods are pixel value without any modification (method I), pixel value modification with contrast of bone region of interest (ROI) (method II), pixel value modification with contrast of thorax ROI (method III), filtering pixel value range (method IV), filtering pixel value range with modification using bone ROI contrast (method V), as well as filtering pixel value range with modification using thorax ROI contrast (method VI). Methods were compared by means of their coefficient of variation (CoV). The best method for normal images was
selected and was used to serve as a baseline in distinguishing abnormal images. To quantitatively compare normal and abnormal line profile, a discrepancy with the baseline set was used as a parameter. The result shows that line profile method with pixel value range filtering method (method IV) was able to distinguish abnormal images. From this set of the method, the abnormalities with the smallest and the greatest was bronchitis and effusion. More thorough studies are required to confirm and improve the feasibility of this method.
Quality assurance for planned radiation exposure situations (e.g. x-ray, CT) requires the application of examination-specific scans tailored to patient age or size, body region and clinical indication for ensuring that the dose to each patient is as low as reasonably achievable for the clinical purpose of the image acquisition. Nevertheless, assuring quality implies a heavy manual labor to measure and optimize care services flow. There are already several methodologies and protocols that can be used to achieve this objective. However, the continuous monitoring of quality indicators is still not performed in many healthcare centers. The challenge is to find a way to analyze these metrics in an efficient, effective and convenient manner. Moreover, these results are not often shared, due to confidentiality and privacy of patients and medical staff. In this paper, we propose a methodology and a software tool to aggregate and normalize the monitoring data from distinct points, in order to collect indicators, namely about productivity, efficiency and dose usage, factors that are crucial for benchmarking and for improving the quality of protocol procedures. To evaluate the effectiveness of our solution, several results were collected from two medical institutions.
