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Kattau M, Willer K, Noichl W, Urban T, Frank M, De Marco F, Schick R, Koehler T, Maack HI, Renger B, Renz M, Sauter A, Leonhardt Y, Fingerle A, Makowski M, Pfeiffer D, Pfeiffer F. X-ray dark-field chest radiography: a reader study to evaluate the diagnostic quality of attenuation chest X-rays from a dual-contrast scanning prototype. Eur Radiol 2023; 33:5549-5556. [PMID: 36806571 PMCID: PMC10326144 DOI: 10.1007/s00330-023-09477-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 12/09/2022] [Accepted: 01/23/2023] [Indexed: 02/21/2023]
Abstract
OBJECTIVES To compare the visibility of anatomical structures and overall quality of the attenuation images obtained with a dark-field X-ray radiography prototype with those from a commercial radiography system. METHODS Each of the 65 patients recruited for this study obtained a thorax radiograph at the prototype and a reference radiograph at the commercial system. Five radiologists independently assessed the visibility of anatomical structures, the level of motion artifacts, and the overall image quality of all attenuation images on a five-point scale, with 5 points being the highest rating. The average scores were compared between the two image types. The differences were evaluated using an area under the curve (AUC) based z-test with a significance level of p ≤ 0.05. To assess the variability among the images, the distributions of the average scores per image were compared between the systems. RESULTS The overall image quality was rated high for both devices, 4.2 for the prototype and 4.6 for the commercial system. The rating scores varied only slightly between both image types, especially for structures relevant to lung assessment, where the images from the commercial system were graded slightly higher. The differences were statistically significant for all criteria except for the bronchial structures, the cardiophrenic recess, and the carina. CONCLUSIONS The attenuation images acquired with the prototype were assigned a high diagnostic quality despite a lower resolution and the presence of motion artifacts. Thus, the attenuation-based radiographs from the prototype can be used for diagnosis, eliminating the need for an additional conventional radiograph. KEY POINTS • Despite a low tube voltage (70 kVp) and comparably long acquisition time, the attenuation images from the dark-field chest radiography system achieved diagnostic quality for lung assessment. • Commercial chest radiographs obtained a mean rating score regarding their diagnostic quality of 4.6 out of 5, and the grating-based images had a slightly lower mean rating score of 4.2 out of 5. • The difference in rating scores for anatomical structures relevant to lung assessment is below 5%.
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Affiliation(s)
- Margarete Kattau
- Chair of Biomedical Physics, Munich Institute of Biomedical Engineering & School of Natural Sciences, Technical University of Munich, 85748, Garching, Germany.
| | - Konstantin Willer
- Chair of Biomedical Physics, Munich Institute of Biomedical Engineering & School of Natural Sciences, Technical University of Munich, 85748, Garching, Germany
- Department of Diagnostic and Interventional Radiology, School of Medicine, Klinikum Rechts Der Isar, Technical University of Munich, 81675, Munich, Germany
| | - Wolfgang Noichl
- Chair of Biomedical Physics, Munich Institute of Biomedical Engineering & School of Natural Sciences, Technical University of Munich, 85748, Garching, Germany
| | - Theresa Urban
- Chair of Biomedical Physics, Munich Institute of Biomedical Engineering & School of Natural Sciences, Technical University of Munich, 85748, Garching, Germany
- Department of Diagnostic and Interventional Radiology, School of Medicine, Klinikum Rechts Der Isar, Technical University of Munich, 81675, Munich, Germany
| | - Manuela Frank
- Chair of Biomedical Physics, Munich Institute of Biomedical Engineering & School of Natural Sciences, Technical University of Munich, 85748, Garching, Germany
- Department of Diagnostic and Interventional Radiology, School of Medicine, Klinikum Rechts Der Isar, Technical University of Munich, 81675, Munich, Germany
| | - Fabio De Marco
- Chair of Biomedical Physics, Munich Institute of Biomedical Engineering & School of Natural Sciences, Technical University of Munich, 85748, Garching, Germany
| | - Rafael Schick
- Chair of Biomedical Physics, Munich Institute of Biomedical Engineering & School of Natural Sciences, Technical University of Munich, 85748, Garching, Germany
- Department of Diagnostic and Interventional Radiology, School of Medicine, Klinikum Rechts Der Isar, Technical University of Munich, 81675, Munich, Germany
| | - Thomas Koehler
- Philips Research, 22335, Hamburg, Germany
- Institute for Advanced Study, Technical University of Munich, 85748, Garching, Germany
| | | | - Bernhard Renger
- Department of Diagnostic and Interventional Radiology, School of Medicine, Klinikum Rechts Der Isar, Technical University of Munich, 81675, Munich, Germany
| | - Martin Renz
- Department of Diagnostic and Interventional Radiology, School of Medicine, Klinikum Rechts Der Isar, Technical University of Munich, 81675, Munich, Germany
| | - Andreas Sauter
- Department of Diagnostic and Interventional Radiology, School of Medicine, Klinikum Rechts Der Isar, Technical University of Munich, 81675, Munich, Germany
| | - Yannik Leonhardt
- Department of Diagnostic and Interventional Radiology, School of Medicine, Klinikum Rechts Der Isar, Technical University of Munich, 81675, Munich, Germany
| | - Alexander Fingerle
- Department of Diagnostic and Interventional Radiology, School of Medicine, Klinikum Rechts Der Isar, Technical University of Munich, 81675, Munich, Germany
| | - Marcus Makowski
- Department of Diagnostic and Interventional Radiology, School of Medicine, Klinikum Rechts Der Isar, Technical University of Munich, 81675, Munich, Germany
| | - Daniela Pfeiffer
- Department of Diagnostic and Interventional Radiology, School of Medicine, Klinikum Rechts Der Isar, Technical University of Munich, 81675, Munich, Germany
- Institute for Advanced Study, Technical University of Munich, 85748, Garching, Germany
| | - Franz Pfeiffer
- Chair of Biomedical Physics, Munich Institute of Biomedical Engineering & School of Natural Sciences, Technical University of Munich, 85748, Garching, Germany
- Department of Diagnostic and Interventional Radiology, School of Medicine, Klinikum Rechts Der Isar, Technical University of Munich, 81675, Munich, Germany
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Evaluation of the image quality and dose reduction in digital radiography with an advanced spatial noise reduction algorithm in pediatric patients. Eur Radiol 2021; 31:8937-8946. [PMID: 34041570 DOI: 10.1007/s00330-021-07942-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2020] [Revised: 03/06/2021] [Accepted: 03/25/2021] [Indexed: 10/21/2022]
Abstract
OBJECTIVES To evaluate whether the advanced spatial noise reduction (ASNR) algorithm installed in a digital radiography system generates acceptable images at a lower dose than a conventional denoising algorithm in pediatric patients. METHODS Nine sets of 30 images of pediatric patients, classified under three protocols and three age groups, were retrospectively selected. Different levels of low-dose image sets of these 270 images were generated by a noise simulation tool after validation testing using phantoms. Each image set was obtained with both the ASNR and conventional algorithm, and grouped randomly and blinded. Three experienced pediatric radiologists were asked to pick the "image with optimum dose" among images of different dose levels with an ALARA (as low as reasonably achievable) perspective. Dose reduction rates for each protocol and age group were calculated, and entrance skin exposure (ESE) was calculated using the values of kVp and mAs, assuming a standard body depth for each age group. RESULTS With the ASNR algorithm, estimated dose reduction rates were highest for abdominal radiographs (45.0%, 27.3%, and 24.3% in infants, children, and adolescents, respectively, p < 0.001). The mean dose reductions for all age groups in the abdominal, chest, and skull radiographs were 32.8%, 12.9%, and 23.2%, respectively (p < 0.001). Average of the calculated ESE was lower with the ASNR algorithm than with the conventional algorithm group (p < 0.001). CONCLUSIONS The ASNR algorithm facilitated optimization of image quality with a higher reduction in radiation dose than the conventional algorithm, making it more acceptable for use in pediatric patients. KEY POINTS •ASNR algorithm in DR system improves image quality via enhanced contrast and noise removal by estimating actual noise distribution based on a multi-scale noise covariance and frequency processing. •Noise simulation tool (NST) generating images of different dose levels can be used for evaluation of the optimum dose without unnecessary additional radiation exposure to pediatric patients. •Retrospective clinical study using NST showed that the ASNR algorithm enabled a higher reduction in radiation dose than the conventional algorithm in pediatric patients.
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Kawashima H, Ichikawa K, Kunitomo H. [Relationship between Radiation Quality and Image Quality in Digital Chest Radiography: Validation Study Using Human Soft Tissue-equivalent Phantom]. Nihon Hoshasen Gijutsu Gakkai Zasshi 2021; 77:255-262. [PMID: 33746173 DOI: 10.6009/jjrt.2021_jsrt_77.3.255] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
PURPOSE To evaluate image quality for chest radiography at different radiation qualities, using phantoms with scatter fractions similar to those of lungs. METHODS Two base phantoms with 10 and 4 cm thicknesses, respectively, made of a soft tissue-equivalent material, were used to mimic the X-ray attenuation of the human lung. Two plates with soft tissue- and bone-equivalent materials, respectively, were placed on the base phantom as contrast objects. The image data were obtained with the same entrance surface dose in each radiation quality. Six radiation qualities generated using 120 and 90 kV, and additional copper filters with thicknesses 0, 0.1, and 0.2 mm were selected. The signal-difference-to-noise ratio (SdNR) and a contrast ratio of the soft tissue to the bone were measured for the six radiation qualities. RESULTS The thicker the additional filter, the better the SdNR at both tube voltages. The SdNR values were not significantly different between 120 and 90 kV for the same filter thickness. The contrast ratio was higher at 120 than at 90 kV by approximately 8%. CONCLUSIONS Because of the advantage of the contrast ratio and the highest SdNR, the radiation quality with 120 kV and 0.2-mm copper filtration was the best. It was indicated that the conventional tube voltage of 120 kV remains to be better than the lower tube voltage of 90 kV.
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Affiliation(s)
- Hiroki Kawashima
- Faculty of Health Sciences, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University
| | - Katsuhiro Ichikawa
- Faculty of Health Sciences, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University
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Gunn C, O'Brien K, Fosså K, Tonkopi E, Lanca L, Martins CT, Muller H, Friedrich-Nel H, Abdolell M, Johansen S. A multi institutional comparison of imaging dose and technique protocols for neonatal chest radiography. Radiography (Lond) 2020; 26:e66-e72. [PMID: 32052771 DOI: 10.1016/j.radi.2019.10.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Revised: 10/28/2019] [Accepted: 10/30/2019] [Indexed: 10/25/2022]
Abstract
INTRODUCTION The focus on paediatric radiation dose reduction supports reevaluation of paediatric imaging protocols. This is particularly important in the neonates where chest radiographs are frequently requested to assess respiratory illness and line placement. This study aims to assess the impact of neonatal chest radiographic protocols on patient dose in four hospitals in different countries. METHODS Exposure parameters, collimation, focus to skin distance (FSD) and radiation dose from 200 neonatal chest radiographs were registered prospectively. Inclusion criteria consisted of both premature and full-term neonates weighing between 1000 and 5000 g. Only data from the examinations meeting diagnostic criteria and approved for the clinical use were included. Radiation dose was assessed using dose area product (DAP). RESULTS The lowest DAP value (4.58 mGy cm2) was recorded in the Norwegian hospital, employing a high kVp, low mAs protocol using a DR system. The Canadian hospital recorded the highest DAP (9.48), using lower kVp and higher mAs with a CR system, including the addition of a lateral projection. The difference in the mean DAP, weight, field of view (FOV) and kVp between the hospitals is statistically significant (p < 0.001). CONCLUSION Use of non-standardised imaging protocols in neonatal chest radiography results in differences in patient dose across hospitals included in the study. Using higher kVp, lower mAs and reducing the number of lateral projections to clinically relevant indications result in a lower DAP measured in the infant sample studied. Further studies to examine image quality based on exposure factors and added filtration are recommended. IMPLICATIONS FOR PRACTICE Reevaluation of paediatric imaging protocols presents an opportunity to reduce patient dose in a population with increased sensitivity to ionising radiation.
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Affiliation(s)
- C Gunn
- School of Health Sciences, Dalhousie University, Halifax, Canada
| | - K O'Brien
- Faculty of Medicine, Dalhousie University, Halifax, Canada; IWK Health Centre, Diagnostic Imaging, Halifax, Canada
| | - K Fosså
- Division of Diagnostics and Intervention, Oslo University Hospital, Rikshospitalet, Norway
| | - E Tonkopi
- Faculty of Medicine, Dalhousie University, Halifax, Canada
| | - L Lanca
- ESTeSL - Escola Superior de Tecnologia da Saude de Lisboa, Instituto Poliecnico de Lisboa, Portugal; Karolinska Institutet, Stockholm, Sweden; Singapore Institute of Technology, Health and Social Sciences Cluster, Singapore
| | - C T Martins
- ESTeSL - Escola Superior de Tecnologia da Saude de Lisboa, Instituto Poliecnico de Lisboa, Portugal; Centro Hospitalar Lisboa Norte, EPE, Hospital de Santa Maria (HSM) Radiology Department, Lisboa, Portugal
| | - H Muller
- Central University of Technology, Free State (CUT), Faculty of Health and Environmental Sciences, South Africa; Department of Clinical Imaging Sciences, Universitas Academic Hospital, Bloemfontein, South Africa
| | - H Friedrich-Nel
- Department of Clinical Imaging Sciences, Universitas Academic Hospital, Bloemfontein, South Africa
| | - M Abdolell
- Faculty of Medicine, Dalhousie University, Halifax, Canada
| | - S Johansen
- Oslo Metropolitan University (OsloMet), Faculty of Health Sciences, Oslo, Norway; Department of Oncology, Division of Cancer Medicine, Oslo University Hospital, Norway.
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Weir A, Salo EN, Janeczko AJ, Douglas J, Weir NW. Evaluation of CDRAD and TO20 test objects and associated software in digital radiography. Biomed Phys Eng Express 2019. [DOI: 10.1088/2057-1976/ab285b] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Metaxas VI, Messaris GA, Lekatou AN, Petsas TG, Panayiotakis GS. PATIENT DOSES IN COMMON DIAGNOSTIC X-RAY EXAMINATIONS. RADIATION PROTECTION DOSIMETRY 2019; 184:12-27. [PMID: 30289498 DOI: 10.1093/rpd/ncy169] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2018] [Revised: 08/18/2018] [Accepted: 09/05/2018] [Indexed: 05/28/2023]
Abstract
A local survey was conducted, to evaluate the radiation dose to adult patients who underwent diagnostic X-ray examinations. Patient-related and technical data were recorded, in 1504 patients, for each of the 11 individual projections, of the 7 most common examinations performed in an X-ray room, with 1 digital radiography system. The patient entrance surface air kerma (ESAK) and the effective dose (ED) were calculated based on the X-ray tube output and the exposure parameters, as well as utilisation of suitable conversion coefficients, respectively. The 75th percentiles of the distribution of the ESAK and kerma area product (KAP) values were also established. The mean, median and 75th percentiles were compared with the national reference levels and the most common values reported at the European level through the DOSE DATAMED II project. The corresponding ED values were also compared with the average values reported for all European countries. The mean ESAK, KAP and ED values along with the uncertainty U values for chest PA, chest LAT, cranium AP, cranium LAT, cervical spine AP, cervical spine LAT, lumbar spine AP, lumbar spine LAT, pelvis AP, abdomen AP, kidneys and urinary bladder (KUB) AP were 0.12 (0.001) mGy, 0.66 (0.023) mGy, 1.01 (0.034) mGy, 0.69 (0.098) mGy, 0.72 (0.014) mGy, 0.63 (0.011) mGy, 4.12 (0.050) mGy, 5.74 (0.082) mGy, 2.57 (0.024) mGy, 1.94 (0.017) mGy, 2.47 (0.073) mGy, and 0.09 (0.001) Gy cm2, 0.38 (0.012) Gy cm2, 0.32 (0.009) Gy cm2, 0.27 (0.052) Gy cm2, 0.17 (0.004) Gy cm2, 0.21 (0.006) Gy cm2, 1.18 (0.018) Gy cm2, 1.86 (0.023) Gy cm2, 1.41 (0.012) Gy cm2, 1.27 (0.010) Gy cm2, 1.28 (0.038) Gy cm2, as well as 0.01 (0.0001) mSv, 0.05 (0.0016) mSv, 0.02 (0.0006) mSv, 0.01 (0.0012) mSv, 0.03 (0.0008) mSv, 0.03 (0.0006) mSv, 0.26 (0.0038) mSv, 0.17 (0.0022) mSv, 0.20 (0.0016) mSv, 0.23 (0.0018) mSv, 0.23 (0.0068) mSv, respectively. The 75th percentiles along with the uncertainty U values for chest PA, chest LAT, cranium AP, cranium LAT, cervical spine AP, cervical spine LAT, lumbar spine AP, lumbar spine LAT, pelvis AP, abdomen AP, kidneys and urinary bladder (KUB) AP were 0.14 (0.006) mGy, 0.88 (0.031) mGy, 1.22 (0.049) mGy, 0.94 (0.098) mGy, 0.93 (0.027) mGy, 0.78 (0.013) mGy, 5.16 (0.073) mGy, 7.24 (0.134) mGy, 2.96 (0.047) mGy, 2.59 (0.036) mGy, 3.07 (0.116) mGy, as well as 0.10 (0.0006) Gy cm2, 0.51 (0.017) Gy cm2, 0.37 (0.020) Gy cm2, 0.33 (0.040) Gy cm2, 0.23 (0.007) Gy cm2, 0.26 (0.011) Gy cm2, 1.50 (0.036) Gy cm2, 2.26 (0.035) Gy cm2, 1.61 (0.023) Gy cm2, 1.67 (0.017) Gy cm2, 1.56 (0.069) Gy cm2, in terms of ESAK and KAP values, respectively. The results were significantly lower compared with the national reference levels, the most common DRL values reported at the European level and other previously reported dose values. Patient dose surveys could contribute towards optimising radiation protection for patients, therefore, highlighting the necessity to increase the awareness and knowledge of the radiation dose in conjunction with the required image quality.
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Affiliation(s)
- Vasileios I Metaxas
- Department of Medical Physics, School of Medicine, University of Patras, Patras, Greece
| | - Gerasimos A Messaris
- Department of Medical Physics, School of Medicine, University of Patras, Patras, Greece
| | - Aristea N Lekatou
- Department of Medical Physics, School of Medicine, University of Patras, Patras, Greece
| | - Theodore G Petsas
- Department of Radiology, School of Medicine, University of Patras, Patras, Greece
| | - George S Panayiotakis
- Department of Medical Physics, School of Medicine, University of Patras, Patras, Greece
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Konst B, Weedon-Fekjaer H, Båth M. Image quality and radiation dose in planar imaging - Image quality figure of merits from the CDRAD phantom. J Appl Clin Med Phys 2019; 20:151-159. [PMID: 31152576 PMCID: PMC6612684 DOI: 10.1002/acm2.12649] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Revised: 03/25/2019] [Accepted: 05/04/2019] [Indexed: 12/24/2022] Open
Abstract
Purpose A contrast‐detail phantom such as CDRAD is frequently used for quality assurance, optimization of image quality, and several other purposes. However, it is often used without considering the uncertainty of the results. The aim of this study was to assess two figure of merits (FOM) originating from CDRAD regarding the variations of the FOMs by dose utilized to create the x‐ray image. The probability of overlapping (assessing an image acquired at a lower dose as better than an image acquired at a higher dose) was determined. Methods The CDRAD phantom located underneath 12, 20, and 26 cm PMMA was imaged 16 times at five dose levels using an x‐ray system with a flat‐panel detector. All images were analyzed by CDRAD Analyser, version 1.1, which calculated the FOM inverse image quality figure (IQFinv) and gave contrast detail curves for each image. Inherent properties of the CDRAD phantom were used to derive a new FOM h, which describes the size of the hole with the same diameter and depth that is just visible. Data were analyzed using heteroscedastic regression of mean and variance by dose. To ease interpretation, probabilities for overlaps were calculated assuming normal distribution, with associated bootstrap confidence intervals. Results The proportion of total variability in IQFinv, explained by the dose (R2), was 91%, 85%, and 93% for 12, 20, and 26 cm PMMA. Corresponding results for h were 91%, 89%, and 95%. The overlap probability for different mAs levels was 1% for 0.8 vs 1.2 mAs, 5% for 1.2 vs 1.6 mAs, 10% for 1.6 vs 2.0 mAs, and 10% for 2.0 mAs vs 2.5 mAs for 12 cm PMMA. For 20 cm PMMA, it was 0.5% for 10 vs 16 mAs, 13% for 16 vs 20 mAs, 14% for 20 vs 25 mAs, and 14% for 25 vs 32 mAs. For 26 cm PMMA, the probability varied from 0% to 6% for various mAs levels. Even though the estimated probability for overlap was small, the 95% confidence interval (CI) showed relatively large uncertainties. For 12 cm PMMA, the associated CI for 0.8 vs 1.2 mAs was 0.1–3.2%, and the CI for 1.2 vs 1.6 mAs was 2.1–7.8%. Conclusions Inverse image quality figure and h are about equally related to dose level. The FOM h, which describes the size of a hole that should be seen in the image, may be a more intuitive FOM than IQFinv. However, considering the probabilities for overlap and their confidence intervals, the FOMs deduced from the CDRAD phantom are not sensitive to dose. Hence, CDRAD may not be an optimal phantom to differentiate between images acquired at different dose levels.
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Affiliation(s)
- Bente Konst
- Department of Radiology, Vestfold Hospital Trust, Tønsberg, Norway
| | - Harald Weedon-Fekjaer
- Oslo Center for Biostatistics and Epidemiology, Research Support Services, Oslo University Hospital, Oslo, Norway
| | - Magnus Båth
- Department of Medical Physics and Biomedical Engineering, Sahlgrenska University Hospital, Gothenburg, Sweden.,Department of Radiation Physics, Institute of Clinical Sciences, Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden
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Comparison of incident air kerma (k i) of common digital and analog radiology procedures in Kohgiluyeh and Boyer-Ahmad province. POLISH JOURNAL OF MEDICAL PHYSICS AND ENGINEERING 2018. [DOI: 10.2478/pjmpe-2018-0006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Abstract
Introduction: Although in many developed countries, Analog radiography (AR) is replaced with digital radiography (DR) but AR is still widely used in many countries included Iran. Therefore, dosimetrically assessment of delivered dose is very important to avoid unnecessary patient dose.
Materials and Methods: In this study, all imaging centers in Kohgiluyeh and Boyer-Ahmad were selected. The initial information included the mean kVp and mAs used by the personnel to perform each radiological procedure were gathered through a questionnaire. Barracuda dosimeter was then used to measure Incident air kerma (ki). Data obtained from digital radiography (DR) and analogue radiography (AR) were then analyzed and compared to each other.
Results: The mean incident air kerma (ki) for five radiological procedures (chest AP&Lat, Skull AP&Lat, Lumbar spine AP&Lat, Thoracic spine AP&Lat and Pelvis) in digital devices were 0.38&1.34, 2.1&1.94, 4.99&7.83, 4.18& 6.41 and 4.33 mGy and those for analogue devices were 0.7&1.28, 3.05&3.02, 7.25&9.9, 7.125&8.36 and 5.36 mGy, respectively.
Discussion and Conclusion: The use of low kVp or high mAs is one of the reasons to increase the incident air kerma (ki) in analogue methods comparing to digital methods in all procedures except the chest (in Lateral view). Also the results, surprisingly, showed that in some of the analogue methods incident air kerma (ki) was less than digital methods which is most probably because of the auto-exposure conditions.
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Zheng X. PATIENT SIZE BASED GUIDING EQUATIONS FOR AUTOMATIC mAs AND kVp SELECTIONS IN GENERAL MEDICAL X-RAY PROJECTION RADIOGRAPHY. RADIATION PROTECTION DOSIMETRY 2017; 174:545-550. [PMID: 27574322 DOI: 10.1093/rpd/ncw246] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Accepted: 07/27/2016] [Indexed: 06/06/2023]
Abstract
A patient size based guiding equation for the automatic selections of mAs and peak voltage kVp in general medical X-ray projection radiography was derived from the first principles of dose and image quality optimization. Under various specific conditions of constant patient size d, kVp or mAs, this equation leads to various longstanding 'rules of thumbs' currently being employed in clinical practice. For automatic mAs control, this work suggests that the current level of dose to patient in X-ray radiography should be halved without compromise image quality. Further studies on the dependence of the absorbed dose on the patient's thickness are required in general X-ray projection radiography.
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Affiliation(s)
- Xiaoming Zheng
- Medical Radiation Science, School of Dentistry and Health Sciences, Faculty of Science, Charles Sturt University, Wagga Wagga, New South Wales2678, Australia
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Elshiekh E, Suliman II, Habbani F. A comparative study of adult patient doses in film screen and computed radiography in some Sudanese hospitals. RADIATION PROTECTION DOSIMETRY 2015; 165:402-405. [PMID: 25889604 DOI: 10.1093/rpd/ncv186] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
A study was performed to compare adult patient doses in film screen (FS) and computed radiography (CR) diagnostic X-ray examinations in some hospitals in Sudan over a period of 1 y; during this period of time, the CR systems were introduced to replace FS systems. Radiation doses were estimated for 354 patients in five hospitals (two FS units and three CR units). Entrance surface air kerma (ESAK) was estimated from incident air kerma using patient exposure parameters and tube output. Dose calculations were performed using CALDOSE X 3.5 Monte Carlo-based software. In FS, third quartile of ESAK values for skull PA, skull LAT, chest PA, pelvis AP, lumbar spine AP and lumbar spine LAT were 1.5, 1.3, 0.3, 1.9, 2.8 and 5.9 mGy, respectively, while in CR, third quartile of ESAK values for the same examinations were 2.7, 1.7, 0.18, 1.7, 3.2 and 10.8 mGy, respectively. Comparable ESAK values were presented in FS and CR units. The results are important for future dose optimisation and setting national diagnostic reference levels.
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Affiliation(s)
- E Elshiekh
- Radiation Safety Institute, Sudan Atomic Energy Commission, PO Box 3001, Khartoum, Sudan
| | - I I Suliman
- Radiation Safety Institute, Sudan Atomic Energy Commission, PO Box 3001, Khartoum, Sudan Department of Radiology and Molecular Imaging, Medical Physics Section; College of Medicine and Health Sciences, Sultan Qaboos University, Postcode 123, PO Box 35, Al-Khod, Oman
| | - F Habbani
- Department Department of Physics, Faculty of Science, University of Khartoum, PO Box 321, Khartoum, Sudan
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Elshiekh E, Suliman II, Habbani F. Performance evaluation of two computed radiography systems and patient dose in pelvic examination. RADIATION PROTECTION DOSIMETRY 2015; 165:392-396. [PMID: 25836691 DOI: 10.1093/rpd/ncv125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
This study was carried out to evaluate the performance of two computed radiography (CR) units. These evaluations became necessary following the introduction of CR systems in Sudan. Evaluation of the CR systems was performed using physical image quality parameters: signal transfer property, modulation transfer function, normalised noise power spectrum, detective quantum efficiency and the subjective contrast detail detectability. Patient dose was measured in terms of entrance surface air kerma estimated from tube output and exposure factors for 100 patients who had undergone pelvic X-ray examinations. Fuji computed radiography velocity system with columnar screen dose results was much lower than those using CR975 system with granular screen. Patient doses delivered by both systems were within the international diagnostic reference levels.
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Affiliation(s)
- E Elshiekh
- Radiation Safety Institute, Sudan Atomic Energy Commission, P.O. Box. 3001, Khartoum, Sudan
| | - I I Suliman
- Radiation Safety Institute, Sudan Atomic Energy Commission, P.O. Box. 3001, Khartoum, Sudan Department of Radiology & Molecular Imaging, Medical Physics Section; College of Medicine and Health Sciences, Sultan Qaboos University, Postcode 123, P.O. Box 35, Al-Khod, Oman
| | - F Habbani
- Department of Physics, Faculty of Science, University of Khartoum, P.O. Box 321, Khartoum, Sudan
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Matthews K, Brennan PC, McEntee MF. An evaluation of paediatric projection radiography in Ireland. Radiography (Lond) 2014. [DOI: 10.1016/j.radi.2013.10.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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13
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Moore CS, Wood TJ, Avery G, Balcam S, Needler L, Beavis AW, Saunderson JR. An investigation of automatic exposure control calibration for chest imaging with a computed radiography system. Phys Med Biol 2014; 59:2307-24. [DOI: 10.1088/0031-9155/59/9/2307] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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14
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Radiation dose optimization research: Exposure technique approaches in CR imaging – A literature review. Radiography (Lond) 2013. [DOI: 10.1016/j.radi.2013.07.005] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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15
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Effects of tube potential and scatter rejection on image quality and effective dose in digital chest X-ray examination: An anthropomorphic phantom study. Radiography (Lond) 2013. [DOI: 10.1016/j.radi.2013.07.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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16
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Moore CS, Wood TJ, Beavis AW, Saunderson JR. Correlation of the clinical and physical image quality in chest radiography for average adults with a computed radiography imaging system. Br J Radiol 2013; 86:20130077. [PMID: 23568362 DOI: 10.1259/bjr.20130077] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
OBJECTIVE The purpose of this study was to examine the correlation between the quality of visually graded patient (clinical) chest images and a quantitative assessment of chest phantom (physical) images acquired with a computed radiography (CR) imaging system. METHODS The results of a previously published study, in which four experienced image evaluators graded computer-simulated postero-anterior chest images using a visual grading analysis scoring (VGAS) scheme, were used for the clinical image quality measurement. Contrast-to-noise ratio (CNR) and effective dose efficiency (eDE) were used as physical image quality metrics measured in a uniform chest phantom. Although optimal values of these physical metrics for chest radiography were not derived in this work, their correlation with VGAS in images acquired without an antiscatter grid across the diagnostic range of X-ray tube voltages was determined using Pearson's correlation coefficient. RESULTS Clinical and physical image quality metrics increased with decreasing tube voltage. Statistically significant correlations between VGAS and CNR (R=0.87, p<0.033) and eDE (R=0.77, p<0.008) were observed. CONCLUSION Medical physics experts may use the physical image quality metrics described here in quality assurance programmes and optimisation studies with a degree of confidence that they reflect the clinical image quality in chest CR images acquired without an antiscatter grid. ADVANCES IN KNOWLEDGE A statistically significant correlation has been found between the clinical and physical image quality in CR chest imaging. The results support the value of using CNR and eDE in the evaluation of quality in clinical thorax radiography.
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Affiliation(s)
- C S Moore
- Radiation Physics Department, Queen's Centre for Oncology and Haematology, Castle Hill Hospital, Hull and East Yorkshire Hospitals, Hull, UK.
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Guo H, Liu WY, He XY, Zhou XS, Zeng QL, Li BY. Optimizing imaging quality and radiation dose by the age-dependent setting of tube voltage in pediatric chest digital radiography. Korean J Radiol 2012; 14:126-31. [PMID: 23323043 PMCID: PMC3542296 DOI: 10.3348/kjr.2013.14.1.126] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2012] [Accepted: 06/27/2012] [Indexed: 11/21/2022] Open
Abstract
Objective The quality and radiation dose of different tube voltage sets for chest digital radiography (DR) were compared in a series of pediatric age groups. Materials and Methods Forty-five hundred children aged 0-14 years (yr) were randomly divided into four groups according to the tube voltage protocols for chest DR: lower kilovoltage potential (kVp) (A), intermediate kVp (B), and higher kVp (C) groups, and the fixed high kVp group (controls). The results were analyzed among five different age groups (0-1 yr, 1-3 yr, 3-7 yr, 7-11 yr and 11-14 yr). The dose area product (DAP) and visual grading analysis score (VGAS) were determined and compared by using one-way analysis of variance. Results The mean DAP of protocol C was significantly lower as compared with protocols A, B and controls (p < 0.05). DAP was higher in protocol A than the controls (p <0.001), but it was not statistically significantly different between B and the controls (p = 0.976). Mean VGAS was lower in the controls than all three protocols (p < 0.001 for all). Mean VGAS did not differ between protocols A and B (p = 0.334), but was lower in protocol C than A (p = 0.008) and B (p = 0.049). Conclusion Protocol C (higher kVp) may help optimize the trade-off between radiation dose and image quality, and it may be acceptable for use in a pediatric age group from these results.
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Affiliation(s)
- Hui Guo
- Xinjiang Medical University, Affiliated Hospital 1, Medical Imaging Research Center, Urumqi 830054, China
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Compagnone G, Casadio Baleni M, Di Nicola E, Valentino M, Benati M, Calzolaio LF, Oberhofer N, Fabbri E, Domenichelli S, Barozzi L. Optimisation of radiological protocols for chest imaging using computed radiography and flat-panel X-ray detectors. Radiol Med 2012; 118:540-54. [PMID: 23090253 DOI: 10.1007/s11547-012-0892-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2011] [Accepted: 02/14/2012] [Indexed: 11/30/2022]
Abstract
PURPOSE Digital radiography technology has replaced conventional screen-film systems in many hospitals. Despite the different characteristics of new detector materials, frequently, the same radiological protocols previously optimised for screen film are still used with digital equipment without any critical review. This study addressed optimisation of exposure settings for chest examinations with digital systems, considering both image quality and patient dose. MATERIALS AND METHODS Images acquired with direct digital radiography equipment and a computed radiography system were analysed with specially developed commercial software with a four-alternative forced-choice method: the most promising protocols were then scored by two senior radiologists. RESULTS Digital technology offers a wide dynamic range and the ability to postprocess images, allowing use of lower tube potentials in chest examinations. The computed radiography system showed both better image quality and lower dose at lower energies (85 kVp and 95 kVp) than those currently used (125 kVp). Direct digital radiography equipment confirmed both its superior image quality and lower dose requirements compared with the storage phosphor plate system. CONCLUSIONS Generally, lowering tube potentials in chest examinations seems to allow better image quality/effective dose ratio when using digital equipment.
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Affiliation(s)
- G Compagnone
- UO Fisica Sanitaria, Policlinico S Orsola Malpighi, Azienda Ospedaliero Universitaria di Bologna, Via Massarenti 9, 40138 Bologna, Italy.
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Moore CS, Avery G, Balcam S, Needler L, Swift A, Beavis AW, Saunderson JR. Use of a digitally reconstructed radiograph-based computer simulation for the optimisation of chest radiographic techniques for computed radiography imaging systems. Br J Radiol 2012; 85:e630-9. [PMID: 22253349 PMCID: PMC3487078 DOI: 10.1259/bjr/47377285] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2011] [Revised: 05/18/2011] [Accepted: 05/31/2011] [Indexed: 11/05/2022] Open
Abstract
OBJECTIVES The purpose of this study was to derive an optimum radiographic technique for computed radiography (CR) chest imaging using a digitally reconstructed radiograph computer simulator. The simulator is capable of producing CR chest radiographs of adults with various tube potentials, receptor doses and scatter rejection. METHODS Four experienced image evaluators graded images of average and obese adult patients at different potentials (average-sized, n=50; obese, n=20), receptor doses (n=10) and scatter rejection techniques (average-sized, n=20; obese, n=20). The quality of the images was evaluated using visually graded analysis. The influence of rib contrast was also assessed. RESULTS For average-sized patients, image quality improved when tube potential was reduced compared with the reference (102 kVp). No scatter rejection was indicated. For obese patients, it has been shown that an antiscatter grid is indicated, and should be used in conjunction with as low a tube potential as possible (while allowing exposure times <20 ms). It is also possible to reduce receptor air kerma by 50% without adversely influencing image quality. Rib contrast did not interfere at any tube potential. CONCLUSIONS A virtual clinical trial has been performed with simulated chest CR images. Results indicate that low tube potentials (<102 kVp) are optimal for average and obese adults, the former acquired without scatter rejection, the latter with an anti-scatter grid. Lower receptor (and therefore patient doses) than those used clinically are possible while maintaining adequate image quality.
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Affiliation(s)
- C S Moore
- Radiation Physics Department, Queen's Centre for Oncology and Haematology, Hull, UK.
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Grewal RK, Young N, Collins L, Karunaratne N, Sabharwal R. Digital chest radiography image quality assessment with dose reduction. AUSTRALASIAN PHYSICAL & ENGINEERING SCIENCES IN MEDICINE 2012; 35:71-80. [DOI: 10.1007/s13246-012-0125-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2011] [Accepted: 01/17/2012] [Indexed: 10/14/2022]
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Moore CS, Liney GP, Beavis AW, Saunderson JR. A method to produce and validate a digitally reconstructed radiograph-based computer simulation for optimisation of chest radiographs acquired with a computed radiography imaging system. Br J Radiol 2011; 84:890-902. [PMID: 21933979 PMCID: PMC3473768 DOI: 10.1259/bjr/30125639] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2010] [Revised: 06/29/2010] [Accepted: 06/30/2010] [Indexed: 11/05/2022] Open
Abstract
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.
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Affiliation(s)
- C S Moore
- Radiation Physics Department, Queen's Centre for Oncology and Haematology, Castle Hill Hospital, Hull & East Yorkshire Hospitals, Castle Road, Hull, UK.
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Image quality in the anteroposterior cervical spine radiograph: Comparison between moving, stationary and non-grid techniques in a lamb neck. Radiography (Lond) 2011. [DOI: 10.1016/j.radi.2010.12.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Muhogora W, Padovani R, Msaki P. Initial quality performance results using a phantom to simulate chest computed radiography. J Med Phys 2011; 36:22-8. [PMID: 21430855 PMCID: PMC3048950 DOI: 10.4103/0971-6203.75468] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2010] [Revised: 06/03/2010] [Accepted: 07/30/2010] [Indexed: 11/04/2022] Open
Abstract
The aim of this study was to develop a homemade phantom for quantitative quality control in chest computed radiography (CR). The phantom was constructed from copper, aluminium, and polymenthylmethacrylate (PMMA) plates as well as Styrofoam materials. Depending on combinations, the literature suggests that these materials can simulate the attenuation and scattering characteristics of lung, heart, and mediastinum. The lung, heart, and mediastinum regions were simulated by 10 mm x 10 mm x 0.5 mm, 10 mm x 10 mm x 0.5 mm and 10 mm x 10 mm x 1 mm copper plates, respectively. A test object of 100 mm x 100 mm and 0.2 mm thick copper was positioned to each region for CNR measurements. The phantom was exposed to x-rays generated by different tube potentials that covered settings in clinical use: 110-120 kVp (HVL=4.26-4.66 mm Al) at a source image distance (SID) of 180 cm. An approach similar to the recommended method in digital mammography was applied to determine the CNR values of phantom images produced by a Kodak CR 850A system with post-processing turned off. Subjective contrast-detail studies were also carried out by using images of Leeds TOR CDR test object acquired under similar exposure conditions as during CNR measurements. For clinical kVp conditions relevant to chest radiography, the CNR was highest over 90-100 kVp range. The CNR data correlated with the results of contrast detail observations. The values of clinical tube potentials at which CNR is the highest are regarded to be optimal kVp settings. The simplicity in phantom construction can offer easy implementation of related quality control program.
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Affiliation(s)
- Wilbroad Muhogora
- Department of Physics, University of Dar es Salaam, P.O Box 35063, Dar es Salaam, Tanzania, Italy
| | - Renato Padovani
- Fisica Sanitaria, Ospedale Universitario, P.le Santa Maria della Misericordia 15, 33100, Udine, Italy
| | - Peter Msaki
- Department of Physics, University of Dar es Salaam, P.O Box 35063, Dar es Salaam, Tanzania, Italy
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Smans K, Vandenbroucke D, Pauwels H, Struelens L, Vanhavere F, Bosmans H. Validation of an image simulation technique for two computed radiography systems: An application to neonatal imaging. Med Phys 2010; 37:2092-100. [DOI: 10.1118/1.3377772] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
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Uffmann M, Schaefer-Prokop C. Digital radiography: the balance between image quality and required radiation dose. Eur J Radiol 2009; 72:202-8. [PMID: 19628349 DOI: 10.1016/j.ejrad.2009.05.060] [Citation(s) in RCA: 128] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2009] [Accepted: 05/07/2009] [Indexed: 11/29/2022]
Abstract
Although the transition from conventional screen-film imaging to digital image acquisition has been almost completed during the last couple of years, examination parameters, such as tube voltage, tube current, and filtration have been adopted from screen-film technology without further adjustments. Digital systems, however, are characterised by their flexibility: the acquisition dose can be reduced at the expense of image quality and vice versa. The imaging parameters must be optimised according to the best performance of a particular system. The traditional means of dose containment, such as positioning and collimation, are as valid for digital techniques as they were for conventional techniques. Digital techniques increasingly offer options for dose reduction. At the same time, there is a risk of substantially increasing the patient dose, possibly unawares, due to the lack of visual control. Therefore, implementation of dose indicators and dose monitoring is mandatory for digital radiography. The use of image quality classes according to the dose requirements of given clinical indications are a further step toward modern radiation protection.
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Affiliation(s)
- Martin Uffmann
- Dept. of Radiology, Medical University Vienna, Waehringer Guertel 18-20, Vienna, Austria.
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Marshall NW. An examination of automatic exposure control regimes for two digital radiography systems. Phys Med Biol 2009; 54:4645-70. [DOI: 10.1088/0031-9155/54/15/002] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Moore CS, Saunderson JR, Beavis AW. Investigating the exposure class of a computed radiography system for optimisation of physical image quality for chest radiography. Br J Radiol 2009; 82:705-10. [PMID: 19221185 DOI: 10.1259/bjr/27942950] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
The purpose of this study was to investigate whether the exposure (speed) class (EC) of an Agfa computed radiography (CR) system could be used to optimise chest radiography. The frequency-dependent normalised noise-power spectra (NNPS(f)) were determined for a range of EC settings (25-1200) for a receptor dose of 4 microGy. Signal-to-noise ratios (SNRs) were measured in the lung, heart and diaphragm areas of a chest phantom with ECs of 400 and 600 at four tube voltages (60, 75, 90 and 125 kVp). As anatomical background can be a factor in detection of lung nodules, a tissue to rib ratio (TRR), which measures the ratio of pixel values in the nodule to that of rib, was measured in the lung region of the phantom to assess the suppression of the rib at ECs of 400 and 600. The NNPS(f) at ECs lower than 400 was relatively high. The NNPS(f) at EC 600 was found to be 7% lower when averaged over all frequencies than that at EC 400. The statistical significance of this difference was verified. The EC 800 and EC 1200 settings offered no extra advantages in terms of lowering frequency-dependent noise. The EC 600 setting offered improvements in SNR of between 10% and 18% in the lung, 11% and 16% in the heart, and 15% and 20% in the diaphragm compared with EC 400. Statistical analysis verified the significant difference. The EC 600 setting increased the TRR, thereby helping to suppress rib. This work indicates that an exposure class setting of 600 is the most appropriate for standard chest radiography, but clinical verification is required.
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Affiliation(s)
- C S Moore
- Radiation Physics Department, Hull and East Yorkshire Hospitals, Oncology Centre, Castle Hill Hospital, Cottingham, East Yorkshire.
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Geijer H, Norrman E, Persliden J. Optimizing the tube potential for lumbar spine radiography with a flat-panel digital detector. Br J Radiol 2009; 82:62-8. [PMID: 19095816 DOI: 10.1259/bjr/56572915] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
The purpose of this study was to find the optimal settings for lumbar spine radiography with a flat-panel detector. A CDRAD contrast-detail phantom was imaged at various tube potentials, system speeds and filtration settings. Factorial experiments yielded a range of optimized exposure settings, which were submitted to visual grading analysis with images of an Alderson phantom. The first optimized settings involved a system speed increase from 400 to 800. For anteroposterior projection, the optimal tube potential was reduced from the default of 77 kV to 60 kV to give the best image quality without increasing the effective dose, or to 66 kV to give the lowest dose without reducing image quality. For lateral projection, the tube potential was similarly reduced from the default of 90 kV to 70 kV or 77 kV. Visual grading analysis confirmed the results, with significantly better image quality when optimizing for image quality. The study thus shows that the tube potential can be reduced as long as the system speed is increased simultaneously. This leads to a lower effective dose and/or increased image quality depending on the settings chosen. The factorial experiments provided a powerful way to evaluate several parameters concomitantly.
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Affiliation(s)
- H Geijer
- Department of Radiology, Orebro University Hospital, Orebro, Sweden.
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Moore CS, Beavis AW, Saunderson JR. Investigation of optimum X-ray beam tube voltage and filtration for chest radiography with a computed radiography system. Br J Radiol 2008; 81:771-7. [PMID: 18662964 DOI: 10.1259/bjr/21963665] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
The purpose of this study was to determine the optimum tube voltage and amount of added copper (Cu) filtration for processed chest radiographs obtained with an Agfa 75.0 Computed Radiography (CR) system. The contrast-to-noise ratio (CNR) was measured in the lung, heart/spine and diaphragm compartments of a validated chest phantom using various tube voltages and amounts of Cu filtration. The CNR was derived as a function of air kerma at the CR plate and with the effective dose. As rib contrast can interfere with detection of nodules in chest radiography, a tissue-to-rib ratio (TRR) was derived to investigate which tube voltages suppress the contrast of rib. Although processing algorithms affect the signal and noise in a way that is hard to predict, we found that, for a given set of processing parameters, the CNR was related to the plate air kerma and effective dose in a logarithmic manner (all R(2) >or=0.97). For imaging of the lung region, a low voltage (60 kVp) produced the highest CNR, whereas a high voltage (125 kVp) produced the highest TRR. In the heart/spine region, 80-125 kVp produced the highest CNR, while in the diaphragm region 60-90 kVp produced the highest CNR. For chest radiography with this CR system, the optimal tube voltage depends upon the region of interest. Of the filters tested, a 0.1 mm Cu thickness was found to provide a statistically significant increase in the CNR in the diaphragm region with tube potentials of 60 kVp and 80 kVp, without affecting the CNR in the other anatomical compartments.
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Affiliation(s)
- C S Moore
- Radiation Physics Department, Hull & East Yorkshire Hospitals, Princess Royal Hospital, Saltshouse Road, Kingston Upon Hull, UK.
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Abstract
Projection radiography is in an advanced stage of progressive transition from conventional screen-film imaging to digital image acquisition modalities. The radiographic technique, including examination parameters such as tube voltage, tube current and filtration has frequently been adopted from screen-film technology. Digital systems, however, are characterized by their flexibility as the dose can be reduced at the expense of image quality and vice versa. The imaging parameters need to be individually optimized according to the best performance of a system. The traditional means of dose adjustment, such as positioning and collimation, are as valid for digital techniques as they were for conventional techniques. Digital techniques increasingly offer options for dose reduction. At the same time there is a risk to accidentally substantially increase patient dose due to the lack of visual control. Therefore, the implementation of dose indicators and dose monitoring is mandatory for digital radiography. The use of image quality classes according to the dose requirements of given clinical indications are a further step towards modern radiation protection.
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Schaefer-Prokop C, Neitzel U, Venema HW, Uffmann M, Prokop M. Digital chest radiography: an update on modern technology, dose containment and control of image quality. Eur Radiol 2008; 18:1818-30. [PMID: 18431577 PMCID: PMC2516181 DOI: 10.1007/s00330-008-0948-3] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2007] [Revised: 02/08/2008] [Accepted: 02/20/2008] [Indexed: 11/25/2022]
Abstract
The introduction of digital radiography not only has revolutionized communication between radiologists and clinicians, but also has improved image quality and allowed for further reduction of patient exposure. However, digital radiography also poses risks, such as unnoticed increases in patient dose and suboptimum image processing that may lead to suppression of diagnostic information. Advanced processing techniques, such as temporal subtraction, dual-energy subtraction and computer-aided detection (CAD) will play an increasing role in the future and are all targeted to decrease the influence of distracting anatomic background structures and to ease the detection of focal and subtle lesions. This review summarizes the most recent technical developments with regard to new detector techniques, options for dose reduction and optimized image processing. It explains the meaning of the exposure indicator or the dose reference level as tools for the radiologist to control the dose. It also provides an overview over the multitude of studies conducted in recent years to evaluate the options of these new developments to realize the principle of ALARA. The focus of the review is hereby on adult applications, the relationship between dose and image quality and the differences between the various detector systems.
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Affiliation(s)
- Cornelia Schaefer-Prokop
- Department of Radiology, Academic Medical Center Amsterdam, Meibergdreef 9, 1105AZ, Amsterdam, The Netherlands.
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Asai Y, Uemura M, Matsumoto M, Kanamori H. Dependence of radiographic sensitivity of CR imaging plate on X-ray tube voltage. Radiol Phys Technol 2008; 1:100-5. [PMID: 20821170 DOI: 10.1007/s12194-007-0015-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2007] [Revised: 11/21/2007] [Accepted: 11/21/2007] [Indexed: 10/22/2022]
Abstract
Our purpose in this study was to compare the energy absorbed in a computed radiography (CR) plate with that absorbed by a film-screen system over the diagnostic X-ray tube voltage range. A Fuji ST-II and Fuji HGM/UR2 were selected as a CR plate and film-screen system, respectively. The X-ray energy absorbed by the phosphor layer (per mA per unit area) was calculated theoretically as an index of the radiographic sensitivity by use of the incident X-ray photon spectrum with the Birch-Marshall formula and the sensitivity spectrum for the range of 40-140 kV. The radiosensitive media were treated as layers involving mass loading. The relative radiographic sensitivity of the ST-II CR plate best approached that of the HGM/UR2 film-screen at 60 kV; it was considerably lower for the ST-II CR plate on both sides of 60 kV. The relative sensitivities at 40 and 140 kV of the ST-II CR plate to the HGM/UR2 film-screen decreased by 16 and 30%, respectively. This result implies that, in the CR system, the mAs values must be increased by 16 and 30% at 40 and 140 kV, respectively. These results were explained by the relative positions of the K-absorption edges of the phosphors. The theoretically calculated result was in good agreement with the experimental result obtained with an acrylic resin phantom. These results would be useful in preventing under- or overexposure in a CR system and thus controlling the dose administered to the patient.
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Affiliation(s)
- Yoshiyuki Asai
- Department of Central Radiology, Kinki University Hospital, Osaka-Sayama, Osaka, Japan.
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Moore CS, Liney GP, Beavis AW, Saunderson JR. A method to optimize the processing algorithm of a computed radiography system for chest radiography. Br J Radiol 2007; 80:724-30. [PMID: 17709364 DOI: 10.1259/bjr/33261679] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
A test methodology using an anthropomorphic-equivalent chest phantom is described for the optimization of the Agfa computed radiography "MUSICA" processing algorithm for chest radiography. The contrast-to-noise ratio (CNR) in the lung, heart and diaphragm regions of the phantom, and the "system modulation transfer function" (sMTF) in the lung region, were measured using test tools embedded in the phantom. Using these parameters the MUSICA processing algorithm was optimized with respect to low-contrast detectability and spatial resolution. Two optimum "MUSICA parameter sets" were derived respectively for maximizing the CNR and sMTF in each region of the phantom. Further work is required to find the relative importance of low-contrast detectability and spatial resolution in chest images, from which the definitive optimum MUSICA parameter set can then be derived. Prior to this further work, a compromised optimum MUSICA parameter set was applied to a range of clinical images. A group of experienced image evaluators scored these images alongside images produced from the same radiographs using the MUSICA parameter set in clinical use at the time. The compromised optimum MUSICA parameter set was shown to produce measurably better images.
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Affiliation(s)
- C S Moore
- Radiation Physics Department, Hull & East Yorkshire Hospitals, Princess Royal Hospital, Saltshouse Road, Kingston Upon Hull HU8 9HE.
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Moores BM. Relative biological effectiveness and exposure of the female breast. Br J Radiol 2007; 80:141-2. [PMID: 17495061 DOI: 10.1259/bjr/55471993] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
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Roberts JA, Evans SC, Rees M. Optimisation of imaging technique used in direct digital radiography. JOURNAL OF RADIOLOGICAL PROTECTION : OFFICIAL JOURNAL OF THE SOCIETY FOR RADIOLOGICAL PROTECTION 2006; 26:287-99. [PMID: 16926471 DOI: 10.1088/0952-4746/26/3/003] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
The purpose of the study was to optimise the technique employed for AP shoulder and lateral cervical spine examinations following an investigation into image quality, based on clinical assessment, and effective dose, calculated from patient entrance surface dose measurements. A study was therefore conducted in an attempt to determine whether the increased radiation dose to the patient following the introduction of an anti-scatter grid was justified by the level of improvement in image quality. The study, involving 100 patients, was able to demonstrate that the increase in radiation dose to the patient when using an anti-scatter grid for AP shoulder examinations is not justified by the improved image quality. A poor level of inter-rater reliability between the consultants scoring the lateral cervical spine images prevented a firm conclusion from being reached. The fact that all images were of diagnostic quality, however, suggested that the use of the anti-scatter grid was unnecessary. Following completion of the project the hospital involved was informed of all findings.
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Affiliation(s)
- J A Roberts
- Medical Physics and Clinical Engineering, Singleton Hospital, Swansea SA2 8QA, UK
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