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Velonis M, Papanastasiou E, Hatziioannou K, Siountas A, Kamperis E, Papavasileiou P, Koukourakis MI, Seimenis I. Dose optimization of 2D X-ray image acquisition protocols in image-guided radiotherapy. Phys Med 2023; 115:103161. [PMID: 37847953 DOI: 10.1016/j.ejmp.2023.103161] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/06/2022] [Revised: 09/06/2023] [Accepted: 10/06/2023] [Indexed: 10/19/2023] Open
Abstract
PURPOSE In contemporary radiotherapy, patient positioning accuracy relies on kV imaging. This study aims at optimizing planar kV image acquisition protocols regarding patient dose without degrading image quality. MATERIALS AND METHODS An image quality test-object was placed in-between PMMA plates, suitably arranged to model head or pelvis. Constructed phantoms were imaged using default protocols, the resultant image quality was assessed and the corresponding radiation dose was measured. The process was repeated using numerous kV/mAs combinations to identify those acquisition settings providing images at lower dose than the default protocols but without deterioration in image quality. Default and dose-optimized protocols were then tested on an anthropomorphic phantom and on 51 patients during two successive treatment sessions. Image quality was independently assessed by two readers. Organ and effective doses were estimated using a Monte Carlo simulation software. RESULTS Low-contrast detectability exhibited a stronger dependence on kV/mAs settings, compared to high-contrast resolution. Dose-optimized protocols resulted in significant dose reductions (anteroposterior-head 48.0 %, lateral-head 30.0 %, anteroposterior-pelvis 28.4 %, lateral-pelvis 27.0 %) compared to the default ones, without compromising image quality. Optimized protocols decreased effective doses by 54 % and 29.6 % in head and pelvic acquisitions, respectively. Regarding image quality, anthropomorphic and patient images acquired using the dose-optimized protocols were subjectively evaluated equivalent to those obtained with the corresponding default settings, indicating that the proposed protocols may be routinely used. CONCLUSIONS Given the potentially large number of radiotherapy fractions and the pertinent image acquisitions, dose-optimized protocols could significantly reduce patient dose associated with planar imaging without compromising positioning accuracy.
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Affiliation(s)
- Marios Velonis
- Department of Medicine, Faculty of Health Sciences, Democritus University of Thrace, Greece; Department of Medical Physics, Papageorgiou General Hospital, Thessaloniki, Greece.
| | - Emmanouil Papanastasiou
- Medical Physics & Digital Innovation Laboratory, Medical School, Aristotle University of Thessaloniki, Greece
| | | | - Anastasios Siountas
- Medical Physics & Digital Innovation Laboratory, Medical School, Aristotle University of Thessaloniki, Greece
| | - Efstathios Kamperis
- Department of Radiotherapy, Papageorgiou General Hospital, Thessaloniki, Greece
| | - Periklis Papavasileiou
- Department of Biomedical Sciences, School of Health Sciences, University of West Attica, Greece
| | - Michael I Koukourakis
- Department of Medicine, Faculty of Health Sciences, Democritus University of Thrace, Greece
| | - Ioannis Seimenis
- Medical Physics Laboratory, School of Medicine, National and Kapodistrian University of Athens, Greece
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Park S, Cha YK, Park S, Chung MJ, Kim K. Automated precision localization of peripherally inserted central catheter tip through model-agnostic multi-stage networks. Artif Intell Med 2023; 144:102643. [PMID: 37783538 DOI: 10.1016/j.artmed.2023.102643] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Revised: 05/30/2023] [Accepted: 08/28/2023] [Indexed: 10/04/2023]
Abstract
BACKGROUND Peripherally inserted central catheters (PICCs) have been widely used as one of the representative central venous lines (CVCs) due to their long-term intravascular access with low infectivity. However, PICCs have a fatal drawback of a high frequency of tip mispositions, increasing the risk of puncture, embolism, and complications such as cardiac arrhythmias. To automatically and precisely detect it, various attempts have been made by using the latest deep learning (DL) technologies. However, even with these approaches, it is still practically difficult to determine the tip location because the multiple fragments phenomenon (MFP) occurs in the process of predicting and extracting the PICC line required before predicting the tip. OBJECTIVE This study aimed to develop a system generally applied to existing models and to restore the PICC line more exactly by removing the MFs of the model output, thereby precisely localizing the actual tip position for detecting its misposition. METHODS To achieve this, we proposed a multi-stage DL-based framework post-processing the PICC line extraction result of the existing technology. Our method consists of the following three stages: 1. Existing PICC line segmentation network for a baseline, 2. Patch-based PICC line refinement network, 3. PICC line reconnection network. The proposed second and third-stage models address MFs caused by the sparseness of the PICC line and the line disconnection due to confusion with anatomical structures respectively, thereby enhancing tip detection. RESULTS To verify the objective performance of the proposed MFCN, internal validation and external validation were conducted. For internal validation, learning (130 samples) and verification (150 samples) were performed with 280 data, including PICC among Chest X-ray (CXR) images taken at our institution. External validation was conducted using a public dataset called the Royal Australian and New Zealand College of Radiologists (RANZCR), and training (130 samples) and validation (150 samples) were performed with 280 data of CXR images, including PICC, which has the same number as that for internal validation. The performance was compared by root mean squared error (RMSE) and the ratio of single fragment images (RatioSFI) (i.e., the rate at which model predicts PICC as multiple sub-lines) according to whether or not MFCN is applied to seven conventional models (i.e., FCDN, UNET, AUNET, TUNET, FCDN-HT, UNET-ELL, and UNET-RPN). In internal validation, when MFCN was applied to the existing single model, MFP was improved by an average of 45 %. The RMSE improved over 63% from an average of 27.54 mm (17.16 to 35.80 mm) to 9.77 mm (9.11 to 10.98 mm). In external validation, when MFCN was applied, the MFP incidence rate decreased by an average of 32% and the RMSE decreased by an average of 65%. Therefore, by applying the proposed MFCN, we observed the consistent detection performance improvement of PICC tip location compared to the existing model. CONCLUSION In this study, we applied the proposed technique to the existing technique and demonstrated that it provides high tip detection performance, proving its high versatility and superiority. Therefore, we believe, in countries and regions where radiologists are scarce, that the proposed DL approach will be able to effectively detect PICC misposition on behalf of radiologists.
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Affiliation(s)
- Subin Park
- Department of Health Sciences and Technology, SAIHST, Sungkyunkwan University, Seoul 06351, Republic of Korea
| | - Yoon Ki Cha
- Department of Radiology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul 06351, Republic of Korea
| | - Soyoung Park
- Department of Health Sciences and Technology, SAIHST, Sungkyunkwan University, Seoul 06351, Republic of Korea
| | - Myung Jin Chung
- Department of Radiology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul 06351, Republic of Korea; Medical AI Research Center, Research Institute for Future Medicine, Samsung Medical Center, Seoul 06351, Republic of Korea.
| | - Kyungsu Kim
- Medical AI Research Center, Research Institute for Future Medicine, Samsung Medical Center, Seoul 06351, Republic of Korea; Department of Data Convergence and Future Medicine, Sungkyunkwan University School of Medicine, Seoul 06351, Republic of Korea.
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Abbeyquaye D, Inkoom S, Hammond NB, Fletcher JJ, Botwe BO. PATIENT DOSE ASSESSMENT AND OPTIMISATION OF PELVIC RADIOGRAPHY WITH COMPUTED RADIOGRAPHY SYSTEMS. RADIATION PROTECTION DOSIMETRY 2021; 195:41-49. [PMID: 34320643 DOI: 10.1093/rpd/ncab111] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2019] [Revised: 06/23/2021] [Accepted: 07/07/2021] [Indexed: 06/13/2023]
Abstract
Digital radiography systems can reduce radiation dose, this capability was harnessed to explore dose and image quality (IQ) optimisation strategies. Entrance surface dose (ESD), effective dose (ED) and organ doses were determined by the indirect method for patients undergoing pelvic anteroposterior X-ray examinations with computed radiography systems. The IQ of patients' radiographs was assessed in terms of signal-to-noise ratio (SNR). An anthropomorphic phantom was exposed with varying tube potential (kVp), tube current-time product (mAs), and focus-to-detector distance (FDD) to determine phantom-entrance dose for the optimisation studies. SNR of each phantom radiograph was determined. Patients' mean ESD of 2.38 ± 0.60 mGy, ED of 0.25 ± 0.07 mSv and SNR of 8.5 ± 2.2 were obtained. After optimisation, entrance dose was reduced by 29.2% with 5 cm increment in FDD, and 5 kVp reduction in tube potential. kVp and/or mAs reduction with an increment in FDD reduced entrance dose without adversely compromising radiographic-IQ.
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Affiliation(s)
- D Abbeyquaye
- Department of Medical Physics, School of Nuclear and Allied Sciences, University of Ghana, Atomic Energy Campus, P.O. Box AE 1, Atomic Energy-Accra, Ghana
- Department of Biomedical Engineering Technology, Faculty of Health and Allied Sciences, Koforidua Technical University, P.O. Box KF-981, Koforidua, Ghana
| | - S Inkoom
- Department of Medical Physics, School of Nuclear and Allied Sciences, University of Ghana, Atomic Energy Campus, P.O. Box AE 1, Atomic Energy-Accra, Ghana
- Radiation Protection and Consultancy Centre, Radiation Protection Institute, Ghana Atomic Energy Commission, P.O. Box LG 80, Legon-Accra, Ghana
| | - N B Hammond
- Department of Medical Physics, School of Nuclear and Allied Sciences, University of Ghana, Atomic Energy Campus, P.O. Box AE 1, Atomic Energy-Accra, Ghana
- Department of Nuclear Medicine, National Centre for Radiotherapy and Nuclear Medicine, Korle-Bu Teaching Hospital, P.O. Box 77, Accra, Ghana
| | - J J Fletcher
- Department of Medical Physics, School of Nuclear and Allied Sciences, University of Ghana, Atomic Energy Campus, P.O. Box AE 1, Atomic Energy-Accra, Ghana
- Department of Applied Physics, Faculty of Applied Sciences, University for Development Studies, Navrongo Campus, Upper East Region, P.O. Box TL 1350, Tamale, Ghana
| | - B O Botwe
- Department of Radiography, School of Biomedical and Allied Health Science, College of Health Sciences, University of Ghana, P.O. Box KB143, Korle-Bu Campus, Accra, Ghana
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Rai A, MacGregor K, Hunt B, Gontar A, Ditkofsky N, Deva D, Mathur S. Proof of Concept: Phantom Study to Ensure Quality and Safety of Portable Chest Radiography Through Glass During the COVID-19 Pandemic. Invest Radiol 2021; 56:135-140. [PMID: 32773486 DOI: 10.1097/rli.0000000000000716] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
BACKGROUND Chest radiography is often used to detect lung involvement in patients with suspected pneumonia. Chest radiography through glass walls of an isolation room is a technique that could be immensely useful in the current COVID-19 pandemic. PURPOSE The purpose of this study was to ensure quality and radiation safety while acquiring portable chest radiographs through the glass doors of isolation rooms using an adult anthropomorphic thorax phantom. MATERIALS AND METHODS Sixteen chest radiographs were acquired utilizing different exposure factors without glass, through the smart glass, and through regular glass. Images were scored independently by 2 radiologists for quantum mottle and sharpness of anatomical structures using a 5-point Likert scale. Statistically significant differences in Likert scale scores and entrance surface dose (ESD) between images acquired without glass and through the smart and regular glass were tested. Interreader reliability was also evaluated. RESULTS Compared with conventional radiography, equal or higher mean image quality scores (mottle and anatomical structures) were observed with the smart glass using 100 kVp at 12 mAs and 20 mAs and 125 kVp at 6.3 mAs (100 kVp at 2 mAs and 125 kVp at 3.2 mAs were used for conventional radiography observations). There was no statistically significant difference in the Likert scale scores for image quality and the entrance surface dose for radiographs acquired without glass, through the smart glass, and through regular glass. Backscatter from the smart glass was minimal at a distance of 3 m and was recorded as zero at a distance of 4 m from the x-ray tube outside an isolation room. CONCLUSIONS Good-quality portable chest radiographs can be obtained safely through the smart glass doors of the isolation room. However, this technique does result in minor backscatter radiation. Modifications in the exposure factors (such as increasing milliampere seconds) may be required to optimize image quality while using this technique.
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Affiliation(s)
| | | | | | - Alex Gontar
- Michener Institute of Education at UHN, Toronto, Ontario, Canada
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England A, Littler E, Romani S, Cosson P. Modifications to mobile chest radiography technique during the COVID-19 pandemic - implications of X-raying through side room windows. Radiography (Lond) 2021; 27:193-199. [PMID: 32855021 PMCID: PMC7396953 DOI: 10.1016/j.radi.2020.07.015] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 07/21/2020] [Accepted: 07/23/2020] [Indexed: 12/15/2022]
Abstract
INTRODUCTION Modifications to common radiographic techniques have resulted from the challenges presented by the COVID-19 pandemic. Reports exist regarding the potential benefits of undertaking mobile radiography through side room windows. The aim of this study was to evaluate the impact on image quality and exposure factors when undertaking such examinations. METHODS A phantom based study was undertaken using a digital X-ray room. Control acquisitions, using a commercially available image quality test tool, were performed using standard mobile chest radiography acquisition factors. Image quality (physical and visual), incidence surface air kerma (ISAK), Exposure Index (EI) and Deviation Index (DI) were recorded. Image quality and radiation dose were further assessed for two additional (experimental) scenarios, where a side room window was located immediately adjacent to the exit port of the light beam diaphragm. The goal of experimental scenario one was to modify exposure factors to maintain the control ISAK. The goal of experimental scenario two was to modify exposure factors to maintain the control EI and DI. Dose and image quality data were compared between the three scenarios. RESULTS To maintain the pre-window (control) ISAK (76 μGy), tube output needed a three-fold increase (90 kV/4 mAs versus 90 kV/11.25 mAs). To maintain EI/DI a more modest increase in tube output was required (90 kV/8 mAs/ISAK 54 μGy). Physical and visual assessments of spatial resolution and signal-to-noise ratio were indifferent between the three scenarios. There was a slight statistically significant reduction in contrast-to-noise ratio when imaging through the glass window (2.3 versus 1.4 and 1.2; P = 0.005). CONCLUSION Undertaking mobile X-ray examinations through side room windows is potentially feasible but does require an increase in tube output and is likely to be limited by minor reductions in image quality. IMPLICATIONS FOR PRACTICE Mobile examinations performed through side room windows should only be used in limited circumstances and future clinical evaluation of this technique is warranted.
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Affiliation(s)
- A England
- School of Allied Health Professions, Keele University, Staffordshire, UK.
| | - E Littler
- Department of Radiology, Warrington and Halton Teaching Hospitals NHS Foundation Trust, Warrington, UK
| | | | - P Cosson
- Medical Imaging Department, Teesside University, Middlesbrough, UK
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Automated determination of chest characteristics of Indonesians as the basis of chest dosimetrical phantom design. POLISH JOURNAL OF MEDICAL PHYSICS AND ENGINEERING 2020. [DOI: 10.2478/pjmpe-2020-0031] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Abstract
Purpose: The purpose of this study was to develop software to automatically measure the main areas of the chest, i.e. soft tissue, bone, and air and to implement it in Kraton Regional General Hospital for designing a specific dosimetrical phantom for chest digital radiography (DR) examination.
Methods: This study was a retrospective study on all DR images from 2015 to 2019, and computed tomography (CT) images of 102 patients in Digital Imaging and Communications in Medicine (DICOM) format files scanned from January-December 2019 at the Kraton Regional General Hospital. We evaluated the number of basic DR chest examinations compared to all DR radiological examinations. We developed a MatLab graphical user interface (GUI) for automated measurement of the areas of the main chest components (soft tissue, bone, and air). We computed the areas of the main components of the chest in order to develop a specific chest phantom for DR in the hospital. In order to compute the areas of the main components, we used chest CT images of patients with clinical indications of chest tumors.
Results: The basic DR chest examination comprised 59.5% of all DR examinations in the hospital during 2015-2019. The average areas of soft tissue, bone, and air within the chest in all patients were 331, 20, and 125 cm2, respectively, with values of 345, 23, and 139 cm2 for males, and 309, 15, and 103 cm2 for females. The areas were also dependent on age with values of 121, 10, 55 cm2 for patients aged 5-11 years, 371, 27, and 88 cm2 for patients aged 12-25 years, 322, 22, and 131 cm2 for patients aged 26-45 years, and 334, 19, and 126 cm2 for patients > 45 years old.
Conclusion: A GUI for computing the main composition of the chest was successfully developed. The areas of chest male patients were greater than female patients. The areas of soft tissue, bone, and air were dependent on the patient’s age. Therefore, the design of dosimetrical DR phantom must consider the gender and age of the patient.
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Moore CS, Wood T, Balcam S, Needler L, Guest T, Ngu WP, Chong LW, Saunderson J, Beavis A. Optimisation of tube voltage range (kVp) for AP abdomen, pelvis and spine imaging of average patients with a digital radiography (DR) imaging system using a computer simulator. Br J Radiol 2020; 93:20200565. [DOI: 10.1259/bjr.20200565] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
Objectives: To investigate via computer simulation, an optimised tube voltage (kVp) range for caesium iodide (CsI)-based digital radiography (DR) of the abdomen, pelvis and lumbar spine. Methods: Software capable of simulating abdomen, pelvis and spine radiographs was used. Five evaluators graded clinical image criteria in images of 20 patients at tube voltages ranging from 60 to 120 kVp in 10 kVp increments. These criteria were scored blindly against the same patient reconstructed at a specific reference kVp. Linear mixed effects analysis was used to evaluate image scores for each criterion and test for statistical significance. Results: Score was dependent on tube voltage and image criteria; both were statistically significant. All criteria for all anatomies scored very poorly at 60 kVp. Scores for abdomen, pelvis and spine imaging peaked at 70, 70 and 100 kVp, respectively, but other kVp values were not significantly poorer. Conclusions: Results indicate optimum tube voltages of 70 kVp for abdomen and pelvis (with an optimum range 70–120 kVp), and 100 kVp (optimum range 80–120 kVp) for lumbar spine. Advances in knowledge: There are no recommendations for optimised tube voltage parameters for DR abdomen, pelvis or lumbar spine imaging. This study has investigated and recommended an optimal tube voltage range.
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Affiliation(s)
- Craig Steven Moore
- Medical Physics Department, Castle Hill Hospital, Hull University Teaching Hospitals NHS Trust, Castle Road, Hull, HU16 5JQ, UK
| | - Tim Wood
- Medical Physics Department, Castle Hill Hospital, Hull University Teaching Hospitals NHS Trust, Castle Road, Hull, HU16 5JQ, UK
- Department of Biomedical Sciences, Faculty of Health Science, University of Hull, Cottingham Road, Hull, HU6 7RX, UK
| | - Stephen Balcam
- Radiology Department, Castle Hill Hospital, Hull University Teaching Hospitals NHS Trust, Castle Road, Hull, HU16 5JQ, UK
| | - Liam Needler
- Radiology Department, Castle Hill Hospital, Hull University Teaching Hospitals NHS Trust, Castle Road, Hull, HU16 5JQ, UK
| | - Tim Guest
- Radiology Department, Castle Hill Hospital, Hull University Teaching Hospitals NHS Trust, Castle Road, Hull, HU16 5JQ, UK
| | - Wee Ping Ngu
- Radiology Department, Castle Hill Hospital, Hull University Teaching Hospitals NHS Trust, Castle Road, Hull, HU16 5JQ, UK
| | - Lee Wun Chong
- Radiology Department, Castle Hill Hospital, Hull University Teaching Hospitals NHS Trust, Castle Road, Hull, HU16 5JQ, UK
| | - John Saunderson
- Medical Physics Department, Castle Hill Hospital, Hull University Teaching Hospitals NHS Trust, Castle Road, Hull, HU16 5JQ, UK
| | - Andrew Beavis
- Medical Physics Department, Castle Hill Hospital, Hull University Teaching Hospitals NHS Trust, Castle Road, Hull, HU16 5JQ, UK
- Department of Biomedical Sciences, Faculty of Health Science, University of Hull, Cottingham Road, Hull, HU6 7RX, UK
- Faculty of Health and Wellbeing, Sheffield Hallam University, City Campus, Howard Street, Sheffield, S1 1WB, UK
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Yalcin A, Olgar T, Sancak T, Atac GK, Akyar S. Correlation between physical measurements and observer evaluations of image quality in digital chest radiography. Med Phys 2020; 47:3935-3944. [DOI: 10.1002/mp.14244] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Revised: 04/27/2020] [Accepted: 05/01/2020] [Indexed: 11/06/2022] Open
Affiliation(s)
- Asena Yalcin
- Institute of Nuclear Sciences Ankara University Ankara 06100 Turkey
| | - Turan Olgar
- Institute of Nuclear Sciences Ankara University Ankara 06100 Turkey
- Faculty of Engineering Department of Engineering Physics Ankara University Ankara 06100 Turkey
| | - Tanzer Sancak
- Department of Radiology TOBB University of Economics and Technology Hospital Ankara Turkey
| | - Gokce Kaan Atac
- Faculty of Medicine Department of Radiology Ufuk University Ankara Turkey
| | - Serdar Akyar
- Department of Radiology Ankara University School of Medicine Ankara Turkey
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Rowan C, Puggioni A, Hoey SE, O'Leary JM, Kearney C, Connolly SE, Skelly C. Assessing the Effect of Packing the Sulcus on Image Quality in Equine Digital Radiography. Vet Rec 2019; 184:221. [PMID: 30711918 DOI: 10.1136/vr.104737] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2017] [Revised: 10/07/2018] [Accepted: 12/22/2018] [Indexed: 11/04/2022]
Abstract
The requirement to pack the sulcus of the equine foot as an aid to diagnostic interpretation before acquisition of dorsoproximal-palmarodistal oblique projections is debatable. The purpose of this study was to investigate the benefit of packing the sulcus in the assessment of normal anatomy. 23 cadaver limbs were radiographed in a podoblock (https://www.podoblock.com/products-page/podoblock/podoblock/) A non-packed image (NP) and a packed image (P) of the same foot were acquired. The image quality of P was graded against the reference NP by five observers, where -1=P was superior, 0=no difference between P and NP, and +1=NP was superior. Four anatomical criteria were used: the distal solar margin of the distal phalanx (DP), the vascular channels of DP, the palmar aspect of the distal interphalangeal joint and the articulation of the navicular bone with DP. A total Visual Grading Analysis Score of 0.28 indicates a preference for NP images. Packing was of benefit in only 10.8 per cent of cases. While judicious high-quality packing may be of benefit in a minority of cases, the routine packing of the sulcus in equine radiography was not found to be of benefit in the assessment of anatomical features in this study.
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Affiliation(s)
- Conor Rowan
- Equine Clinical Studies, Diagnostic Imaging and Anaesthesia, School of Veterinary Medicine, University College Dublin, Dublin, Ireland
| | - Antonella Puggioni
- Equine Clinical Studies, Diagnostic Imaging and Anaesthesia, School of Veterinary Medicine, University College Dublin, Dublin, Ireland
| | - Séamus E Hoey
- Equine Clinical Studies, Diagnostic Imaging and Anaesthesia, School of Veterinary Medicine, University College Dublin, Dublin, Ireland
| | - John Mark O'Leary
- Equine Clinical Studies, Diagnostic Imaging and Anaesthesia, School of Veterinary Medicine, University College Dublin, Dublin, Ireland
| | - Clodagh Kearney
- Equine Clinical Studies, Diagnostic Imaging and Anaesthesia, School of Veterinary Medicine, University College Dublin, Dublin, Ireland
| | | | - Cliona Skelly
- Equine Clinical Studies, Diagnostic Imaging and Anaesthesia, School of Veterinary Medicine, University College Dublin, Dublin, Ireland
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Mohammed Ali A, Hogg P, Johansen S, England A. Construction and validation of a low cost paediatric pelvis phantom. Eur J Radiol 2018; 108:84-91. [PMID: 30396676 DOI: 10.1016/j.ejrad.2018.09.015] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Revised: 09/10/2018] [Accepted: 09/12/2018] [Indexed: 11/17/2022]
Abstract
PURPOSE Imaging phantoms can be cost prohibitive, therefore a need exists to produce low cost alternatives which are fit for purpose. This paper describes the development and validation of a low cost paediatric pelvis phantom based on the anatomy of a 5-year-old child. METHODS Tissue equivalent materials representing paediatric bone (Plaster of Paris; PoP) and soft tissue (Poly methyl methacrylate; PMMA) were used. PMMA was machined to match the bony anatomy identified from a CT scan of a 5-year-old child and cavities were created for infusing the PoP. Phantom validation comprised physical and visual measures. Physical included CT density comparison between a CT scan of a 5-year old child and the phantom and Signal to Noise Ratio (SNR) comparative analysis of anteroposterior phantom X-ray images against a commercial anthropomorphic phantom. Visual analysis using a psychometric image quality scale (face validity). RESULTS CT density, the percentage difference between cortical bone, soft tissue and their equivalent tissue substitutes were -4.7 to -4.1% and -23.4%, respectively. For SNR, (mAs response) there was a strong positive correlation between the two phantoms (r > 0.95 for all kVps). For kVp response, there was a strong positive correlation between 1 and 8 mAs (r = 0.85), this then decreased as mAs increased (r = -0.21 at 20 mAs). Psychometric scale results produced a Cronbach's Alpha of almost 0.8. CONCLUSIONS Physical and visual measures suggest our low-cost phantom has suitable anatomical characteristics for X-ray imaging. Our phantom could have utility in dose and image quality optimisation studies.
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Affiliation(s)
- Ali Mohammed Ali
- School of Health Sciences, University of Salford, Salford, M6 6PU, United Kingdom.
| | - Peter Hogg
- School of Health Sciences, University of Salford, Salford, M6 6PU, United Kingdom.
| | - Safora Johansen
- Oslo Metropolitan University, Faculty of Health Sciences, Norway; Department of Oncology, Division of Cancer Medicine, Surgery and Transplantation, Oslo University Hospital, Radiumhospitalet, Oslo, Norway.
| | - Andrew England
- School of Health Sciences, University of Salford, Salford, M6 6PU, United Kingdom.
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Alzyoud K, Hogg P, Snaith B, Flintham K, England A. Impact of body part thickness on AP pelvis radiographic image quality and effective dose. Radiography (Lond) 2018; 25:e11-e17. [PMID: 30599841 DOI: 10.1016/j.radi.2018.09.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Revised: 09/04/2018] [Accepted: 09/06/2018] [Indexed: 10/28/2022]
Abstract
INTRODUCTION Within medical imaging variations in patient size can generate challenges, especially when selecting appropriate acquisition parameters. This experiment sought to evaluate the impact of increasing body part thickness on image quality (IQ) and effective dose (E) and identify optimum exposure parameters. METHODS An anthropomorphic pelvis phantom was imaged with additional layers (1-15 cm) of animal fat as a proxy for increasing body thickness. Acquisitions used the automatic exposure control (AEC), 100 cm source to image distance (SID) and a range of tube potentials (70-110 kVp). IQ was evaluated physically and perceptually. E was estimated using PCXMC software. RESULTS For all tube potentials, signal to noise ratio (SNR) and contrast to noise ratio (CNR) deceased as body part thickness increased. 70 kVp produced the highest SNR (46.6-22.6); CNR (42.8-17.6). Visual grading showed that the highest IQ scores were achieved using 70 and 75 kVp. As thickness increases, E increased exponentially (r = 0.96; p < 0.001). Correlations were found between visual and physical IQ (SNR r = 0.97, p < 0.001; CNR r = 0.98, p < 0.001). CONCLUSION To achieve an optimal IQ across the range of thicknesses, lower kVp settings were most effective. This is at variance with professional practice as there is a tendency for radiographers to increase kVp as thickness increases. Dose reductions were experienced at higher kVp settings and are a valid method for optimisation when imaging larger patients.
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Affiliation(s)
- K Alzyoud
- School of Health Sciences, University of Salford, Salford M6 6PU, United Kingdom; Faculty of Allied Health Sciences, Hashemite University, Zarqa, Jordan.
| | - P Hogg
- School of Health Sciences, University of Salford, Salford M6 6PU, United Kingdom.
| | - B Snaith
- The Mid Yorkshire Hospitals NHS Trust, Wakefield WF1 4DG, United Kingdom; University of Bradford, Bradford BD7 1DP, United Kingdom.
| | - K Flintham
- The Mid Yorkshire Hospitals NHS Trust, Wakefield WF1 4DG, United Kingdom.
| | - A England
- School of Health Sciences, University of Salford, Salford M6 6PU, United Kingdom.
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Smet MH, Breysem L, Mussen E, Bosmans H, Marshall NW, Cockmartin L. Visual grading analysis of digital neonatal chest phantom X-ray images: Impact of detector type, dose and image processing on image quality. Eur Radiol 2018; 28:2951-2959. [PMID: 29460076 DOI: 10.1007/s00330-017-5301-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Revised: 12/13/2017] [Accepted: 12/29/2017] [Indexed: 11/29/2022]
Abstract
OBJECTIVES To evaluate the impact of digital detector, dose level and post-processing on neonatal chest phantom X-ray image quality (IQ). METHODS A neonatal phantom was imaged using four different detectors: a CR powder phosphor (PIP), a CR needle phosphor (NIP) and two wireless CsI DR detectors (DXD and DRX). Five different dose levels were studied for each detector and two post-processing algorithms evaluated for each vendor. Three paediatric radiologists scored the images using European quality criteria plus additional questions on vascular lines, noise and disease simulation. Visual grading characteristics and ordinal regression statistics were used to evaluate the effect of detector type, post-processing and dose on VGA score (VGAS). RESULTS No significant differences were found between the NIP, DXD and CRX detectors (p>0.05) whereas the PIP detector had significantly lower VGAS (p< 0.0001). Processing did not influence VGAS (p=0.819). Increasing dose resulted in significantly higher VGAS (p<0.0001). Visual grading analysis (VGA) identified a detector air kerma/image (DAK/image) of ~2.4 μGy as an ideal working point for NIP, DXD and DRX detectors. CONCLUSIONS VGAS tracked IQ differences between detectors and dose levels but not image post-processing changes. VGA showed a DAK/image value above which perceived IQ did not improve, potentially useful for commissioning. KEY POINTS • A VGA study detects IQ differences between detectors and dose levels. • The NIP detector matched the VGAS of the CsI DR detectors. • VGA data are useful in setting initial detector air kerma level. • Differences in NNPS were consistent with changes in VGAS.
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Affiliation(s)
- M H Smet
- Department of Radiology, University Hospital Leuven, Herestraat, 49, 3000 - Leuven, Louvain, Belgium.
| | - L Breysem
- Department of Radiology, University Hospital Leuven, Herestraat, 49, 3000 - Leuven, Louvain, Belgium
| | - E Mussen
- Department of Radiology, University Hospital Leuven, Herestraat, 49, 3000 - Leuven, Louvain, Belgium
| | - H Bosmans
- Department of Radiology, University Hospital Leuven, Herestraat, 49, 3000 - Leuven, Louvain, Belgium.,Medical Imaging Research Center, Medical Physics and Quality Assessment, Katholieke Universiteit Leuven, 3000 - Leuven, Louvain, Belgium
| | - N W Marshall
- Department of Radiology, University Hospital Leuven, Herestraat, 49, 3000 - Leuven, Louvain, Belgium.,Medical Imaging Research Center, Medical Physics and Quality Assessment, Katholieke Universiteit Leuven, 3000 - Leuven, Louvain, Belgium
| | - L Cockmartin
- Department of Radiology, University Hospital Leuven, Herestraat, 49, 3000 - Leuven, Louvain, Belgium
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13
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Rodríguez Pérez S, Marshall NW, Struelens L, Bosmans H. Characterization and validation of the thorax phantom Lungman for dose assessment in chest radiography optimization studies. J Med Imaging (Bellingham) 2018; 5:013504. [PMID: 29430474 DOI: 10.1117/1.jmi.5.1.013504] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Accepted: 01/11/2018] [Indexed: 11/14/2022] Open
Abstract
This work concerns the validation of the Kyoto-Kagaku thorax anthropomorphic phantom Lungman for use in chest radiography optimization. The equivalence in terms of polymethyl methacrylate (PMMA) was established for the lung and mediastinum regions of the phantom. Patient chest examination data acquired under automatic exposure control were collated over a 2-year period for a standard x-ray room. Parameters surveyed included exposure index, air kerma area product, and exposure time, which were compared with Lungman values. Finally, a voxel model was developed by segmenting computed tomography images of the phantom and implemented in PENELOPE/penEasy Monte Carlo code to compare phantom tissue-equivalent materials with materials from ICRP Publication 89 in terms of organ dose. PMMA equivalence varied depending on tube voltage, from 9.5 to 10.0 cm and from 13.5 to 13.7 cm, for the lungs and mediastinum regions, respectively. For the survey, close agreement was found between the phantom and the patients' median values (deviations lay between 8% and 14%). Differences in lung doses, an important organ for optimization in chest radiography, were below 13% when comparing the use of phantom tissue-equivalent materials versus ICRP materials. The study confirms the value of the Lungman for chest optimization studies.
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Affiliation(s)
- Sunay Rodríguez Pérez
- SCK CEN, Radiation Protection Dosimetry and Calibration, Mol, Belgium.,KU Leuven, Medical Physics and Quality Assessment, Leuven, Belgium
| | | | - Lara Struelens
- SCK CEN, Radiation Protection Dosimetry and Calibration, Mol, Belgium
| | - Hilde Bosmans
- UZ Gasthuisberg, Department of Radiology, Leuven, Belgium
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Moore CS, Wood TJ, Saunderson JR, Beavis AW. A method to incorporate the effect of beam quality on image noise in a digitally reconstructed radiograph (DRR) based computer simulation for optimisation of digital radiography. Phys Med Biol 2017; 62:7379-7393. [PMID: 28742062 DOI: 10.1088/1361-6560/aa81fb] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
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%.
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Affiliation(s)
- Craig S Moore
- Radiation Physics Department, Queen's Centre for Oncology and Haematology, Castle Hill Hospital, Hull & East Yorkshire Hospitals NHS Trust, Castle Road, Hull, HU16 5JQ, United Kingdom. Faculty of Science and Engineering, University of Hull, Cottingham Road, Hull, HU6 7RX, United Kingdom
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15
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Implementation of a patient dose monitoring system in conventional digital X-ray imaging: initial experiences. Eur Radiol 2016; 27:1021-1031. [DOI: 10.1007/s00330-016-4390-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Revised: 03/01/2016] [Accepted: 04/28/2016] [Indexed: 11/29/2022]
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16
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Menser B, Manke D, Mentrup D, Neitzel U. A MONTE-CARLO SIMULATION FRAMEWORK FOR JOINT OPTIMISATION OF IMAGE QUALITY AND PATIENT DOSE IN DIGITAL PAEDIATRIC RADIOGRAPHY. RADIATION PROTECTION DOSIMETRY 2016; 169:371-377. [PMID: 26628612 DOI: 10.1093/rpd/ncv483] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
In paediatric radiography, according to the as low as reasonably achievable (ALARA) principle, the imaging task should be performed with the lowest possible radiation dose. This paper describes a Monte-Carlo simulation framework for dose optimisation of imaging parameters in digital paediatric radiography. Patient models with high spatial resolution and organ segmentation enable the simultaneous evaluation of image quality and patient dose on the same simulated radiographic examination. The accuracy of the image simulation is analysed by comparing simulated and acquired images of technical phantoms. As a first application example, the framework is applied to optimise tube voltage and pre-filtration in newborn chest radiography. At equal patient dose, the highest CNR is obtained with low-kV settings in combination with copper filtration.
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Affiliation(s)
- Bernd Menser
- Philips Research, High Tech Campus 34, 5656 AE Eindhoven, The Netherlands
| | - Dirk Manke
- Diagnostic X-ray, Philips Healthcare DMC GmbH, Röntgenstraße 24, 22335 Hamburg, Germany
| | - Detlef Mentrup
- Diagnostic X-ray, Philips Healthcare DMC GmbH, Röntgenstraße 24, 22335 Hamburg, Germany
| | - Ulrich Neitzel
- Diagnostic X-ray, Philips Healthcare DMC GmbH, Röntgenstraße 24, 22335 Hamburg, Germany
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17
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Tesselaar E, Dahlström N, Sandborg M. CLINICAL AUDIT OF IMAGE QUALITY IN RADIOLOGY USING VISUAL GRADING CHARACTERISTICS ANALYSIS. RADIATION PROTECTION DOSIMETRY 2016; 169:340-346. [PMID: 26410763 DOI: 10.1093/rpd/ncv411] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The aim of this work was to assess whether an audit of clinical image quality could be efficiently implemented within a limited time frame using visual grading characteristics (VGC) analysis. Lumbar spine radiography, bedside chest radiography and abdominal CT were selected. For each examination, images were acquired or reconstructed in two ways. Twenty images per examination were assessed by 40 radiology residents using visual grading of image criteria. The results were analysed using VGC. Inter-observer reliability was assessed. The results of the visual grading analysis were consistent with expected outcomes. The inter-observer reliability was moderate to good and correlated with perceived image quality (r(2) = 0.47). The median observation time per image or image series was within 2 min. These results suggest that the use of visual grading of image criteria to assess the quality of radiographs provides a rapid method for performing an image quality audit in a clinical environment.
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Affiliation(s)
- Erik Tesselaar
- Radiation Physics, Department of Medical and Health Sciences, Linköping University, Linköping, Sweden
| | - Nils Dahlström
- Radiology, Department of Medical and Health Sciences, Linköping University, Linköping, Sweden Center for Medical Image Science and Visualization (CMIV), Linköping University, Linköping, Sweden
| | - Michael Sandborg
- Radiation Physics, Department of Medical and Health Sciences, Linköping University, Linköping, Sweden Center for Medical Image Science and Visualization (CMIV), Linköping University, Linköping, Sweden
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18
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Pavan A, Alves A, Duarte S, Giacomini G, Sardenberg T, Miranda J, Pina D. Quality and dose optimization in hand computed radiography. Phys Med 2015; 31:1065-1069. [DOI: 10.1016/j.ejmp.2015.06.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Revised: 05/26/2015] [Accepted: 06/15/2015] [Indexed: 10/23/2022] Open
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19
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Alves AFF, Alvarez M, Ribeiro SM, Duarte SB, Miranda JRA, Pina DR. Association between subjective evaluation and physical parameters for radiographic images optimization. Phys Med 2015; 32:123-32. [PMID: 26573131 DOI: 10.1016/j.ejmp.2015.10.095] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Revised: 10/28/2015] [Accepted: 10/30/2015] [Indexed: 11/29/2022] Open
Abstract
PURPOSE The purpose of this study was to develop a methodology to optimize computed radiographic techniques to image the skull, chest, and pelvis of a standard patient. METHODS Optimization was performed by varying exposure levels with different tube voltages to generate images of an anthropomorphic phantom. Image quality was evaluated using visual grading analysis and measuring objective parameters such as the effective detective quantum efficiency and the contrast-to-noise ratio. Objective and subjective evaluations were compared to obtain an optimized technique for each anatomic region. RESULTS Gold standard techniques provided a significant reduction in X-ray doses compared to the techniques used in our radiology service, without compromising diagnostic accuracy. They were chosen as follows 102 kVp/1.6 mAs for skull; 81 kVp/4.5 mAs for pelvis and 90 kVp/3.2 mAs for chest. CONCLUSION There is a range of acceptable techniques that produce adequate images for diagnosis in computed radiography systems. This aspect allows the optimization process to be focused on the patient dose without compromising diagnostic capabilities. This process should be performed through association of quantitative and qualitative parameters, such as effective detective quantum efficiency, contrast-to-noise ratio, and visual grading analysis.
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Affiliation(s)
- A F F Alves
- Department of Physics and Biophysics, Biosciences Institute of Botucatu, São Paulo State University, Distrito de Rubião Junior S/N, Botucatu, São Paulo, 18618-000, Brazil.
| | - M Alvarez
- Department of Physics and Biophysics, Biosciences Institute of Botucatu, São Paulo State University, Distrito de Rubião Junior S/N, Botucatu, São Paulo, 18618-000, Brazil.
| | - S M Ribeiro
- Department of Tropical Diseases and Diagnostic Imaging, Botucatu Medical School São Paulo State University, Distrito de Rubião Junior S/N, Botucatu, São Paulo, 18618-000, Brazil.
| | - S B Duarte
- Brazilian Center of Physics Research - CBPF-MCT, Dr. Xavier Sigaud, 150, Rio de Janeiro, 22290-180, Brazil.
| | - J R A Miranda
- Department of Physics and Biophysics, Biosciences Institute of Botucatu, São Paulo State University, Distrito de Rubião Junior S/N, Botucatu, São Paulo, 18618-000, Brazil.
| | - D R Pina
- Department of Tropical Diseases and Diagnostic Imaging, Botucatu Medical School São Paulo State University, Distrito de Rubião Junior S/N, Botucatu, São Paulo, 18618-000, Brazil.
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Masoud AO, Muhogora WE, Msaki PK. Assessment of patient dose and optimization levels in chest and abdomen CR examinations at referral hospitals in Tanzania. J Appl Clin Med Phys 2015; 16:435–441. [PMID: 26699324 PMCID: PMC5690155 DOI: 10.1120/jacmp.v16i5.5614] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2015] [Revised: 07/04/2015] [Accepted: 05/30/2015] [Indexed: 11/23/2022] Open
Abstract
The aim of this study was to evaluate the radiation doses to patient during chest and abdomen CR examinations, and assess the related level of optimization at five referral hospitals in Tanzania. The international code of practice for dosimetry in diagnostic radiology was applied to determine the entrance surface air kerma (ESAK) to patients. The level of optimization was assessed from low‐contrast objects scores of phantom images at different exposures. The results show that mean ESAK varied from 0.16 to 0.37 mGy for chest PA and from 2 to 6 mGy for abdomen AP. Assuming similar patient and phantom attenuations, the optimization performed at all facilities was consistent with phantom evaluations in terms of tube potential settings in use. However, all facilities seemed to operate at higher tube load values above 5 mAs for chest examination, which can lead to unnecessary patient doses. Inadequate initial training on CR technology explains in large proportion the inappropriate use of exposure parameters. PACS numbers: 87.50.up, 87.59bd
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21
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Jones A, Ansell C, Jerrom C, Honey ID. Optimization of image quality and patient dose in radiographs of paediatric extremities using direct digital radiography. Br J Radiol 2015; 88:20140660. [PMID: 25816115 PMCID: PMC4628445 DOI: 10.1259/bjr.20140660] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2014] [Revised: 02/02/2015] [Accepted: 03/26/2015] [Indexed: 11/05/2022] Open
Abstract
OBJECTIVE The purpose of this study was to evaluate the effect of beam quality on the image quality (IQ) of ankle radiographs of paediatric patients in the age range of 0-1 year whilst maintaining constant effective dose (ED). METHODS Lateral ankle radiographs of an infant foot phantom were taken at a range of tube potentials (40.0-64.5 kVp) with and without 0.1-mm copper (Cu) filtration using a Trixell Pixium 4600 detector (Trixell, Morains, France). ED to the patient was computed for the default exposure parameters using PCXMC v. 2.0 and was fixed for other beam qualities by modulating the tube current-time product. The contrast-to-noise ratio (CNR) was measured between the tibia and adjacent soft tissue. The IQ of the phantom images was assessed by three radiologists and a reporting radiographer. Four IQ criteria were defined each with a scale of 1-3, giving a maximum score of 12. Finally, a service audit of clinical images at the default and optimum beam qualities was undertaken. RESULTS The measured CNR for the 40 kVp/no Cu image was 12.0 compared with 7.6 for the default mode (55 0.1 mm Cu). An improvement in the clinical IQ scores was also apparent at this lower beam quality. CONCLUSION Lowering tube potential and removing filtration improved the clinical IQ of paediatric ankle radiographs in this age range. ADVANCES IN KNOWLEDGE There are currently no UK guidelines on exposure protocols for paediatric imaging using direct digital radiography. A lower beam quality will produce better IQ with no additional dose penalty for infant extremity imaging.
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Affiliation(s)
- A Jones
- Medical Physics Department, Guy's and St Thomas' NHS Foundation Trust, London, UK
- Medical Physics Department, Western Sydney Local Health District, Sydney, NSW, Australia
| | - C Ansell
- Radiology Department, Evelina London Children's Hospital, Guy's and St Thomas' NHS Foundation Trust, London, UK
| | - C Jerrom
- Medical Physics Department, Guy's and St Thomas' NHS Foundation Trust, London, UK
| | - I D Honey
- Medical Physics Department, Guy's and St Thomas' NHS Foundation Trust, London, UK
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22
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Image quality and dose analysis for a PA chest X-ray: Comparison between AEC mode acquisition and manual mode using the 10 kVp ‘rule’. Radiography (Lond) 2014. [DOI: 10.1016/j.radi.2014.06.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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23
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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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24
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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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25
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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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Muhogora W, Trianni A, Toso F, Devetti A, Padovani R, Msaki P, Kazema R. Comparison of image quality and patient dose for chest x-ray examinations on conventional and low cost computed radiography systems. Radiography (Lond) 2012. [DOI: 10.1016/j.radi.2012.07.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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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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28
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Zanca F, Van Ongeval C, Claus F, Jacobs J, Oyen R, Bosmans H. Comparison of visual grading and free-response ROC analyses for assessment of image-processing algorithms in digital mammography. Br J Radiol 2012; 85:e1233-41. [PMID: 22844032 DOI: 10.1259/bjr/22608279] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
OBJECTIVE To compare two methods for assessment of image-processing algorithms in digital mammography: free-response receiver operating characteristic (FROC) for the specific task of microcalcification detection and visual grading analysis (VGA). METHODS The FROC study was conducted prior to the VGA study reported here. 200 raw data files of low breast density (Breast Imaging-Reporting and Data System I-II) mammograms (Novation DR, Siemens, Germany)-100 of which abnormal-were processed by four image-processing algorithms: Raffaello (IMS, Bologna, Italy), Sigmoid (Sectra, Linköping, Sweden), and OpView v. 2 and v. 1 (Siemens, Erlangen, Germany). Four radiologists assessed the mammograms for the detection of microcalcifications. 8 months after the FROC study, a subset (200) of the 800 images was reinterpreted by the same radiologists, using the VGA methodology in a side-by-side approach. The VGA grading was based on noise, saturation, contrast, sharpness and confidence with the image in terms of normal structures. Ordinal logistic regression was applied; OpView v. 1 was the reference processing algorithm. RESULTS In the FROC study all algorithms performed better than OpView v. 1. From the current VGA study and for confidence with the image, Sigmoid and Raffaello were significantly worse (p<0.001) than OpView v. 1; OpView v. 2 was significantly better (p=0.01). For the image quality criteria, results were mixed; Raffaello and Sigmoid for example were better than OpView v. 1 for sharpness and contrast (although not always significantly). CONCLUSION VGA and FROC discordant results should be attributed to the different clinical task addressed. ADVANCES IN KNOWLEDGE The method to use for image-processing assessment depends on the clinical task tested.
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Affiliation(s)
- F Zanca
- Leuven University Center of Medical Physics in Radiology, University Hospitals Leuven, Belgium.
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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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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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Egbe N, Heaton B, Sharp P. A simple phantom study of the effects of dose reduction (by kVp increment) below current dose levels on CR chest image quality. Radiography (Lond) 2010. [DOI: 10.1016/j.radi.2010.05.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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Båth M. Evaluating imaging systems: practical applications. RADIATION PROTECTION DOSIMETRY 2010; 139:26-36. [PMID: 20147386 DOI: 10.1093/rpd/ncq007] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
There are many ways in which imaging systems can be evaluated. The aim of the present paper is to provide an overview of a number of selected approaches to evaluating imaging systems, often encountered by the medical physicist, and discuss their validity and reliability. Specifically, it will cover (i) characterisation of an imaging system in terms of its detective quantum efficiency using linear-systems analysis; (ii) attempts to calculate relevant measures directly in images using the Rose model and the pixel signal-to-noise ratio; (iii) task-based methods incorporating human observers such as receiver-operating characteristics and (iv) visual grading-based methods using experienced radiologists as observers.
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Affiliation(s)
- Magnus Båth
- Department of Radiation Physics, University of Gothenburg, Gothenburg SE-413 45, Sweden.
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Smedby O, Fredrikson M. Visual grading regression: analysing data from visual grading experiments with regression models. Br J Radiol 2010; 83:767-75. [PMID: 20223912 DOI: 10.1259/bjr/35254923] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
For visual grading experiments, which are an easy and increasingly popular way of studying image quality, hitherto used data analysis methods are often inadequate. Visual grading analysis makes assumptions that are not statistically appropriate for ordinal data, and visual grading characteristic curves are difficult to apply in more complex experimental designs. The approach proposed in this paper, visual grading regression (VGR), consists of an established statistical technique, ordinal logistic regression, applied to data from single-image and image-pair experiments with visual grading scores selected on an ordinal scale. The approach is applicable for situations in which, for example, the effects of the choice of imaging equipment and post-processing method are to be studied simultaneously, while controlling for potentially confounding variables such as patient and observer identity. The analysis can be performed with standard statistical software packages using straightforward coding of the data. We conclude that the proposed statistical technique is useful in a wide range of visual grading studies.
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Affiliation(s)
- O Smedby
- Radiology (IMH), Faculty of Health Sciences, Linköping University, Linköping, Sweden.
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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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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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Tapiovaara MJ. Review of relationships between physical measurements and user evaluation of image quality. RADIATION PROTECTION DOSIMETRY 2008; 129:244-248. [PMID: 18252851 DOI: 10.1093/rpd/ncn009] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Some of the findings of a review of the relationship between physical measurements and clinical image quality have been summarised. Mixed results were found: some studies had no relationship at presently typical dose levels, whereas others had a clear correlation between them. It is concluded that the various image quality evaluation tasks in an X-ray department are best done by different methods. Presently, exact physical measurements cannot supersede subjective evaluation in judging the acceptability of clinical images, whereas they are indispensable in specification and testing of technical performance.
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Affiliation(s)
- M J Tapiovaara
- STUK - Radiation and Nuclear Safety Authority, PO Box 14, 00881 Helsinki, Finland.
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