1
|
Nocetti D, Villalobos K, Wunderle K. Physical Image Quality Metrics for the Characterization of X-ray Systems Used in Fluoroscopy-Guided Pediatric Cardiac Interventional Procedures: A Systematic Review. CHILDREN (BASEL, SWITZERLAND) 2023; 10:1784. [PMID: 38002875 PMCID: PMC10670102 DOI: 10.3390/children10111784] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2023] [Revised: 08/27/2023] [Accepted: 10/30/2023] [Indexed: 11/26/2023]
Abstract
Pediatric interventional cardiology procedures are essential in diagnosing and treating congenital heart disease in children; however, they raise concerns about potential radiation exposure. Managing radiation doses and assessing image quality in angiographs becomes imperative for safe and effective interventions. This systematic review aims to comprehensively analyze the current understanding of physical image quality metrics relevant for characterizing X-ray systems used in fluoroscopy-guided pediatric cardiac interventional procedures, considering the main factors reported in the literature that influence this outcome. A search in Scopus and Web of Science, using relevant keywords and inclusion/exclusion criteria, yielded 14 relevant articles published between 2000 and 2022. The physical image quality metrics reported were noise, signal-to-noise ratio, contrast, contrast-to-noise ratio, and high-contrast spatial resolution. Various factors influencing image quality were investigated, such as polymethyl methacrylate thickness (often used to simulate water equivalent tissue thickness), operation mode, anti-scatter grid presence, and tube voltage. Objective evaluations using these metrics ensured impartial assessments for main factors affecting image quality, improving the characterization of fluoroscopic X-ray systems, and aiding informed decision making to safeguard pediatric patients during procedures.
Collapse
Affiliation(s)
- Diego Nocetti
- Departamento de Tecnología Médica, Facultad de Ciencias de la Salud, Universidad de Tarapacá, Arica 1010069, Chile
| | - Kathia Villalobos
- Departamento de Tecnología Médica, Facultad de Ciencias de la Salud, Universidad de Tarapacá, Arica 1010069, Chile
| | - Kevin Wunderle
- Department of Radiology, Cleveland Clinic, Cleveland, OH 44195, USA
| |
Collapse
|
2
|
Mendes HR, Silva JC, Marcondes M, Tomal A. Optimization of image quality and dose in adult and pediatric chest radiography via Monte Carlo simulation and experimental methods. Radiat Phys Chem Oxf Engl 1993 2022. [DOI: 10.1016/j.radphyschem.2022.110396] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
|
3
|
Dose Reduction and Image Quality Optimization of Pediatric Chest Radiography Using a Tungsten Filter. Bioengineering (Basel) 2022; 9:bioengineering9100583. [PMID: 36290551 PMCID: PMC9598093 DOI: 10.3390/bioengineering9100583] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 10/19/2022] [Accepted: 10/19/2022] [Indexed: 11/23/2022] Open
Abstract
The use of diagnostic radiology in pediatric patients has increased, and various positive effects have been reported, including methods to reduce radiation doses in children. Research has been conducted to preserve image quality while reducing exposure and doses in pediatric patients. This study aimed to measure four different filters to identify an optimized filter for pediatric patients. The experiment was conducted using four types of filters, including aluminum, copper, molybdenum, and tungsten. The optimal filter thickness was verified using a histogram to visually evaluate the spectrum by filter thickness, effective dose on a pediatric phantom, entrance skin dose, organ absorbed dose using the PC-based Monte Carlo (PCXMC) program version 2.0 simulation, figure of merit (FOM), and image quality. As a result of measuring the spectrum according to the tube voltage and the four types of filters, dose reduction and contrast improvement effects were obtained with a 0.05 mm tungsten filter. Additionally, effective entrance skin and organ absorbed dose decreased with the said filter. The aluminum, copper, and molybdenum filters demonstrated that the effective dose scarcely decreased even when the thickness was increased; meanwhile, the effective dose decreased when the tungsten filter was 0.05 mm. The FOM with a 0.05 mm tungsten increased by 91% in the lung field and 39% in the mediastinal field. The entrance skin and organ absorbed dose in pediatric patients can be reduced by removing low-energy photons that fail in image formation using a tungsten filter.
Collapse
|
4
|
Lawson M, Qian L, Lau KK, Lau T, Massey D, Badawy M. Efficacy of the scatter correction algorithm in portable chest radiography. Emerg Radiol 2022; 29:809-817. [PMID: 35612644 PMCID: PMC9130995 DOI: 10.1007/s10140-022-02063-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Accepted: 05/17/2022] [Indexed: 11/26/2022]
Abstract
PURPOSE Portable chest radiographs (CXRs) continue to be a vital diagnostic tool for emergency and critical care medicine. The scatter correction algorithm (SCA) is a post-processing algorithm aiming to reduce scatter within portable images. This study aimed to assess whether the SCA improved image quality (IQ) in portable CXRs. METHODS Objective and subjective IQ assessments were undertaken on both phantom and clinical images, respectively. For objective analysis, attenuators were placed on the anterior surface of the patient's thorax to simulate pathologies present within uniform regions of the phantom's lung and heart. Phantom CXRs were acquired with three different tube-current-times (mAs). Phantom images were processed with different SCA strengths. Contrast to noise ratios (CNR) within the attenuator were determined for each algorithm strength and compared to non-SCA images. For subjective analysis, two independent radiologists graded 30 clinical images with and without the SCA activated. The images were graded for IQ in different anatomical structures and overall diagnostic confidence. RESULTS Objectively, most strengths of the SCA improved the CNR in both regions. However, a detrimental effect was recorded for some algorithm strengths in regions of high contrast. Subjectively, both observers recorded the SCA significantly improved IQ in clinical CXRs in all anatomical regions. Observers indicated the greatest improvement in the lung and hilar regions, and least improvement in the chest wall and bone. All images with and without the SCA were deemed diagnostic. CONCLUSION This study shows the potential radiation dose neutral IQ improvement when using an SCA in clinical patient CXRs.
Collapse
Affiliation(s)
- Michael Lawson
- Monash Imaging, Monash Health, Clayton, VIC 3168 Australia
- Centre for Medical and Radiation Physics, School of Physics, Faculty of Engineering and Information Sciences, University of Wollongong, Wollongong, NSW 2500 Australia
| | - Lijun Qian
- Monash Imaging, Monash Health, Clayton, VIC 3168 Australia
| | - Kenneth K. Lau
- Monash Imaging, Monash Health, Clayton, VIC 3168 Australia
- Department of Medicine, Monash University, Clayton, VIC 3168 Australia
| | - Theo Lau
- QScan Radiology Clinics, Aspley, QLD Australia
| | - David Massey
- Monash Imaging, Monash Health, Clayton, VIC 3168 Australia
| | - Mohamed Badawy
- Monash Imaging, Monash Health, Clayton, VIC 3168 Australia
- Department of Medical Imaging and Radiation Sciences, School of Primary and Allied Health Care, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, VIC 3800 Australia
| |
Collapse
|
5
|
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.
Collapse
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
| | | |
Collapse
|
6
|
Comparative analysis of radiation dose and low contrast detail detectability using routine paediatric chest radiography protocols. Eur J Radiol 2019; 113:198-203. [DOI: 10.1016/j.ejrad.2019.02.017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Revised: 12/11/2018] [Accepted: 02/13/2019] [Indexed: 11/24/2022]
|
7
|
Jang JS, Yang HJ, Koo HJ, Kim SH, Park CR, Yoon SH, Shin SY, Do KH. Image quality assessment with dose reduction using high kVp and additional filtration for abdominal digital radiography. Phys Med 2018; 50:46-51. [PMID: 29891093 DOI: 10.1016/j.ejmp.2018.05.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Revised: 05/04/2018] [Accepted: 05/06/2018] [Indexed: 11/25/2022] Open
Abstract
PURPOSE Dose reduction using additional filters with high kilovoltage peak (kVp) for abdominal digital radiography has received much attention recently. We evaluated image quality with dose reduction in abdominal digital radiography by using high kVp and additional copper filters at a tertiary hospital. METHODS Between June 2016 and July 2016, 82 patients underwent abdominal digital radiography using 80 kVp in X-ray room 1 and 82 were imaged using 92 kVp with 0.1-mm copper filtration in X-ray room 2. The effective dose was calculated using a PC-based Monte Carlo program. Image quality of the abdominal radiography acquired in the two rooms was evaluated using a five-point ordinal scale, as well as the signal-to-noise and contrast-to-noise ratios. RESULTS The mean effective dose decreased by 25.8% and 25.7% for the supine and standing positions, respectively, when abdominal digital radiography using 92 kVp with 0.1-mm copper filtration was performed. In the 20 patients who performed abdominal digital radiography twice in each room, visual grading scores for visualisation of psoas outlines and kidney outlines are higher in room 1. However, there was no statistical significant difference of visual grading scores among the 124 patients who underwent only one abdominal radiography in the room 1 or 2 (P > 0.05). CONCLUSIONS Dose reduction for abdominal digital radiography can be achieved with comparable image quality by performing abdominal digital radiography using 92 kVp with 0.1-mm copper filtration, despite the higher AEC dose.
Collapse
Affiliation(s)
- Ji Sung Jang
- Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan, College of Medicine, Seoul, South Korea; Department of Medical Physics, Korea University, South Korea
| | - Hyung Jin Yang
- Department of Medical Physics, Korea University, South Korea
| | - Hyun Jung Koo
- Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan, College of Medicine, Seoul, South Korea
| | - Sung Ho Kim
- Department of Medical Physics, Korea University, South Korea
| | - Chan Rok Park
- Department of Medical Physics, Korea University, South Korea
| | - Suk Hwan Yoon
- Department of Medical Physics, Korea University, South Korea
| | - So Youn Shin
- Department of Radiology, Kyung Hee University Hospital, College of Medicine, Kyung Hee University, Seoul, South Korea
| | - Kyung-Hyun Do
- Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan, College of Medicine, Seoul, South Korea.
| |
Collapse
|
8
|
Guillou M, Maurel B, Necib H, Vent PA, Costargent A, Chaillou P, Gouëffic Y, Kaladji A. Comparison of Radiation Exposure during Endovascular Treatment of Peripheral Arterial Disease with Flat-Panel Detectors on Mobile C-arm versus Fixed Systems. Ann Vasc Surg 2018; 47:104-113. [DOI: 10.1016/j.avsg.2017.08.036] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Revised: 08/11/2017] [Accepted: 08/31/2017] [Indexed: 11/15/2022]
|
9
|
Lee Y, Lee S, Kang S, Eom J. Dose optimization for dual-energy contrast-enhanced digital mammography based on an energy-resolved photon-counting detector: A Monte Carlo simulation study. Radiat Phys Chem Oxf Engl 1993 2017. [DOI: 10.1016/j.radphyschem.2016.11.016] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
|
10
|
Salvagnini E, Bosmans H, Struelens L, Marshall NW. Tailoring automatic exposure control toward constant detectability in digital mammography. Med Phys 2016; 42:3834-47. [PMID: 26133585 DOI: 10.1118/1.4921417] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
PURPOSE The automatic exposure control (AEC) modes of most full field digital mammography (FFDM) systems are set up to hold pixel value (PV) constant as breast thickness changes. This paper proposes an alternative AEC mode, set up to maintain some minimum detectability level, with the ultimate goal of improving object detectability at larger breast thicknesses. METHODS The default "opdose" AEC mode of a Siemens MAMMOMAT Inspiration FFDM system was assessed using poly(methyl methacrylate) (PMMA) of thickness 20, 30, 40, 50, 60, and 70 mm to find the tube voltage and anode/filter combination programmed for each thickness; these beam quality settings were used for the modified AEC mode. Detectability index (d'), in terms of a non-prewhitened model observer with eye filter, was then calculated as a function of tube current-time product (mAs) for each thickness. A modified AEC could then be designed in which detectability never fell below some minimum setting for any thickness in the operating range. In this study, the value was chosen such that the system met the achievable threshold gold thickness (Tt) in the European guidelines for the 0.1 mm diameter disc (i.e., Tt ≤ 1.10 μm gold). The default and modified AEC modes were compared in terms of contrast-detail performance (Tt), calculated detectability (d'), signal-difference-to-noise ratio (SDNR), and mean glandular dose (MGD). The influence of a structured background on object detectability for both AEC modes was examined using a CIRS BR3D phantom. Computer-based CDMAM reading was used for the homogeneous case, while the images with the BR3D background were scored by human observers. RESULTS The default opdose AEC mode maintained PV constant as PMMA thickness increased, leading to a reduction in SDNR for the homogeneous background 39% and d' 37% in going from 20 to 70 mm; introduction of the structured BR3D plate changed these figures to 22% (SDNR) and 6% (d'), respectively. Threshold gold thickness (0.1 mm diameter disc) for the default AEC mode in the homogeneous background increased by 62% in going from 20 to 70 mm PMMA thickness; in the structured background, the increase was 39%. Implementation of the modified mode entailed an increase in mAs at PMMA thicknesses >40 mm; the modified AEC held threshold gold thickness constant above 40 mm PMMA with a maximum deviation of 5% in the homogeneous background and 3% in structured background. SDNR was also held constant with a maximum deviation of 4% and 2% for the homogeneous and the structured background, respectively. These results were obtained with an increase of MGD between 15% and 73% going from 40 to 70 mm PMMA thickness. CONCLUSIONS This work has proposed and implemented a modified AEC mode, tailored toward constant detectability at larger breast thickness, i.e., above 40 mm PMMA equivalent. The desired improvement in object detectability could be obtained while maintaining MGD within the European guidelines achievable dose limit. (A study designed to verify the performance of the modified mode using more clinically realistic data is currently underway.).
Collapse
Affiliation(s)
- Elena Salvagnini
- Department of Imaging and Pathology, Medical Physics and Quality Assessment, KUL, Herestraat 49, Leuven B-3000, Belgium and SCK•CEN, Boeretang 200, Mol 2400, Belgium
| | - Hilde Bosmans
- Department of Imaging and Pathology, Medical Physics and Quality Assessment, KUL, Herestraat 49, Leuven B-3000, Belgium and Department of Radiology, UZ Gasthuisberg, Herestraat 49, Leuven B-3000, Belgium
| | | | - Nicholas W Marshall
- Department of Radiology, UZ Gasthuisberg, Herestraat 49, Leuven B-3000, Belgium
| |
Collapse
|
11
|
Choi YN, Lee S, Kim HJ. Reducing radiation dose by application of optimized low-energy x-ray filters to K-edge imaging with a photon counting detector. Phys Med Biol 2016; 61:N35-49. [DOI: 10.1088/0031-9155/61/2/n35] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|
12
|
Kulkarni M, Dendere R, Nicolls F, Steiner S, Douglas TS. Monte-Carlo simulation of a slot-scanning X-ray imaging system. Phys Med 2016; 32:284-9. [DOI: 10.1016/j.ejmp.2015.12.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Revised: 11/02/2015] [Accepted: 12/01/2015] [Indexed: 11/28/2022] Open
|
13
|
Wu D, Yan A, Li Y, Wong MD, Zheng B, Wu X, Liu H. Characterization of a high-energy in-line phase contrast tomosynthesis prototype. Med Phys 2015; 42:2404-20. [PMID: 25979035 PMCID: PMC4401810 DOI: 10.1118/1.4917227] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Revised: 03/09/2015] [Accepted: 03/13/2015] [Indexed: 12/25/2022] Open
Abstract
PURPOSE In this research, a high-energy in-line phase contrast tomosynthesis prototype was developed and characterized through quantitative investigations and phantom studies. METHODS The prototype system consists of an x-ray source, a motorized rotation stage, and a CMOS detector with a pixel pitch of 0.05 mm. The x-ray source was operated at 120 kVp for this study, and the objects were mounted on the rotation stage 76.2 cm (R1) from the source and 114.3 cm (R2) from the detector. The large air gap between the object and detector guarantees sufficient phase-shift effects. The quantitative evaluation of this prototype included modulation transfer function and noise power spectrum measurements conducted under both projection mode and tomosynthesis mode. Phantom studies were performed including three custom designed phantoms with complex structures: a five-layer bubble wrap phantom, a fishbone phantom, and a chicken breast phantom with embedded fibrils and mass structures extracted from an ACR phantom. In-plane images of the phantoms were acquired to investigate their image qualities through observation, intensity profile plots, edge enhancement evaluations, and/or contrast-to-noise ratio calculations. In addition, the robust phase-attenuation duality (PAD)-based phase retrieval method was applied to tomosynthesis for the first time in this research. It was utilized as a preprocessing method to fully exhibit phase contrast on the angular projection before reconstruction. RESULTS The resolution and noise characteristics of this high-energy in-line phase contrast tomosynthesis prototype were successfully investigated and demonstrated. The phantom studies demonstrated that this imaging prototype can successfully remove the structure overlapping in phantom projections, obtain delineate interfaces, and achieve better contrast-to-noise ratio after applying phase retrieval to the angular projections. CONCLUSIONS This research successfully demonstrated a high-energy in-line phase contrast tomosynthesis prototype. In addition, the PAD-based method of phase retrieval was combined with tomosynthesis imaging for the first time, which demonstrated its capability in significantly improving the contrast-to-noise ratios in the images.
Collapse
Affiliation(s)
- Di Wu
- Center of Bioengineering and School of Electrical and Computer Engineering, University of Oklahoma, Norman, Oklahoma 73019
| | - Aimin Yan
- Department of Radiology, University of Alabama at Birmingham, Birmingham, Alabama 35249
| | - Yuhua Li
- Center of Bioengineering and School of Electrical and Computer Engineering, University of Oklahoma, Norman, Oklahoma 73019
| | - Molly D Wong
- Center of Bioengineering and School of Electrical and Computer Engineering, University of Oklahoma, Norman, Oklahoma 73019
| | - Bin Zheng
- Center of Bioengineering and School of Electrical and Computer Engineering, University of Oklahoma, Norman, Oklahoma 73019
| | - Xizeng Wu
- Department of Radiology, University of Alabama at Birmingham, Birmingham, Alabama 35249
| | - Hong Liu
- Center of Bioengineering and School of Electrical and Computer Engineering, University of Oklahoma, Norman, Oklahoma 73019
| |
Collapse
|
14
|
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]
|
15
|
Figl M, Semturs F, Kaar M, Hoffmann R, Kaldarar H, Homolka P, Mostbeck G, Scholz B, Hummel J. Dose sensitivity of three phantoms used for quality assurance in digital mammography. Phys Med Biol 2013; 58:N13-23. [PMID: 23257608 DOI: 10.1088/0031-9155/58/2/n13] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Technical quality assurance (QA) is one of the key issues in breast cancer screening protocols. For this QA task, three different methods are commonly used to assess image quality. The European protocol suggests a contrast-detail phantom (e.g. the CDMAM phantom), while in North America the American College of Radiology (ACR) accreditation phantom is proposed. Alternatively, phantoms based on image quality parameters from applied system theory such as the noise-equivalent number of quanta (NEQ) are applied (e.g. the PAS 1054 phantom). The aim of this paper was to correlate the changes in the output of the three evaluation methods (CDMAM, ACR and NEQ) with changes in dose. We varied the time-current product within a range of clinically used values (40-140 mAs, corresponding to 3.5-12.4 mGy entrance dose and detector dose of 32-110 μGy). For the ACR phantom, the examined parameter was the number of detected objects. With the CDMAM phantom we chose the diameters 0.10, 0.13, 0.20, 0.31 and 0.5 mm and recorded the threshold thicknesses. With respect to the third method, we evaluated the NEQ at typical spatial frequencies to calculate the relative changes in NEQ. Plotting NEQ versus dose increment shows a linear relationship and can be described by a linear function (with R > 0.99). Every manually selectable current- time product increment can be detected. With the ACR phantom, the number of detected objects increases only in the lower dose range and reaches saturation at about 9 mGy entrance dose (80 μGy detector dose). The CDMAM can detect a 50% increase in dose over the examined dose range with all five diameters, although the increases of threshold thickness are not monotonous. We conclude that an NEQ-based method has the potential to replace the established detail phantom methods to detect dose changes in the course of QA.
Collapse
Affiliation(s)
- M Figl
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
| | | | | | | | | | | | | | | | | |
Collapse
|
16
|
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.
Collapse
Affiliation(s)
- G Compagnone
- UO Fisica Sanitaria, Policlinico S Orsola Malpighi, Azienda Ospedaliero Universitaria di Bologna, Via Massarenti 9, 40138 Bologna, Italy.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
17
|
Singh G, Martin CJ, McCurrach A, Phanco G. Optimisation of performance for computed radiography in the West of Scotland. RADIATION PROTECTION DOSIMETRY 2012; 154:293-300. [PMID: 22929555 DOI: 10.1093/rpd/ncs238] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
This paper describes experiences in the introduction of computed radiography systems to hospitals within the West of Scotland. Setting of automatic exposure control levels has enabled dose-area product values to be maintained at 160 cGy cm² for lumbar spine antero-posterior (AP), 250 cGy cm² for lumbar spine lateral, 210 cGy cm² for pelvis AP and 260 cGy cm² for abdomen AP. The study looks at dose levels achieved after 8 y in use and compares the dose levels found from surveys undertaken in 2007 and in 2010. The effects of raising tube potentials on image quality in terms of details and on contrast-to-noise ratio (CNR) were assessed. The results showed that CNR details seen in test images at tube potentials of 85-90 kV did not differ significantly from those with lower potentials and gave lower entrance surface doses.
Collapse
Affiliation(s)
- Gurpreet Singh
- Health Physics, West House Gartnavel Royal Hospital, 1055 Great Western Road, Glasgow G12 0XH, UK.
| | | | | | | |
Collapse
|
18
|
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.
Collapse
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
| |
Collapse
|
19
|
Shibata K. [Chest tomosynthesis]. Nihon Hoshasen Gijutsu Gakkai Zasshi 2011; 67:1486-1491. [PMID: 22104244 DOI: 10.6009/jjrt.67.1486] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
|
20
|
Gislason AJ, Davies AG, Cowen AR. Dose optimization in pediatric cardiac x-ray imaging. Med Phys 2010; 37:5258-69. [PMID: 21089760 DOI: 10.1118/1.3488911] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Affiliation(s)
- Amber J Gislason
- LXi Research, Division of Medical Physics, University of Leeds, Worsley Building, Clarendon Way, Leeds LS2 9JT, United Kingdom.
| | | | | |
Collapse
|
21
|
Guan H. An attenuation integral digital imaging technique for the treatment portal verification of conventional and intensity-modulated radiotherapy. Med Phys 2010; 37:3738-43. [DOI: 10.1118/1.3447729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
|
22
|
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]
|
23
|
Hussein K, Vaughan CL, Douglas TS. Modeling, validation and application of a mathematical tissue-equivalent breast phantom for linear slot-scanning digital mammography. Phys Med Biol 2009; 54:1533-53. [PMID: 19229099 DOI: 10.1088/0031-9155/54/6/009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
This paper presents a mathematical tissue-equivalent breast phantom for linear slot-scanning digital mammography. A recently developed prototype linear slot-scanning digital mammography system was used for model validation; image quality metrics such as image contrast and contrast-to-noise ratio were calculated. The results were in good agreement with values measured using a physical breast-equivalent phantom designed for mammography. The estimated pixel intensity of the mathematical phantom, the analogue-to-digital conversion gain and the detector additive noise showed good agreement with measured values with correlation of nearly 1. An application of the model, to examine the feasibility of using a monochromatic filter for dose reduction and improvement of image quality in slot-scanning digital mammography, is presented.
Collapse
Affiliation(s)
- K Hussein
- MRC/UCT Medical Imaging Research Unit, Department of Human Biology, University of Cape Town, Observatory 7935 South Africa
| | | | | |
Collapse
|
24
|
Influence of Tagged Fecal Material on Detectability of Colorectal Polyps at CT: Phantom Study. AJR Am J Roentgenol 2008; 191:1101. [DOI: 10.2214/ajr.07.3740] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
|
25
|
Vano E, Ubeda C, Leyton F, Miranda P. Radiation dose and image quality for paediatric interventional cardiology. Phys Med Biol 2008; 53:4049-62. [PMID: 18612174 DOI: 10.1088/0031-9155/53/15/003] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
|
26
|
Tsalafoutas IA, Blastaris GA, Moutsatsos AS, Chios PS, Efstathopoulos EP. Correlation of image quality with exposure index and processing protocol in a computed radiography system. RADIATION PROTECTION DOSIMETRY 2008; 130:162-171. [PMID: 18245792 DOI: 10.1093/rpd/ncm493] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
The correlation of image quality with the exposure index (EI) and the processing protocol was investigated in a Kodak computed radiography (CR) system using clinical radiographs and a water phantom containing an aluminium and a copper step-wedge. The phantom was exposed to different dose levels and the acquired images were processed using four clinical protocols. The quality of these images was evaluated in terms of image brightness, contrast and noise. In clinical radiographs, there was no straightforward correlation of image quality with EI. In phantom images, higher EI values improved contrast and reduced noise but after a point this improvement does not justify the implied increase in patient dose. Image brightness, contrast and noise were also strongly dependent on the processing protocol. To obtain the images of satisfactory quality with the Kodak CR system, a dose slightly higher than those used in 400 relative speed screen-film systems and a processing protocol designated for the specific radiographic examination are required.
Collapse
Affiliation(s)
- I A Tsalafoutas
- Medical Physics Department, Agios Savvas Hospital, 171 Alexandras Avenue, 115 22 Athens, Greece.
| | | | | | | | | |
Collapse
|
27
|
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.
Collapse
Affiliation(s)
- Yoshiyuki Asai
- Department of Central Radiology, Kinki University Hospital, Osaka-Sayama, Osaka, Japan.
| | | | | | | |
Collapse
|
28
|
Martin C. The importance of radiation quality for optimisation in radiology. Biomed Imaging Interv J 2007; 3:e38. [PMID: 21614278 PMCID: PMC3097659 DOI: 10.2349/biij.3.2.e38] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2006] [Accepted: 12/12/2006] [Indexed: 11/20/2022] Open
Abstract
Selection of the appropriate radiation quality is an important aspect of optimisation for every clinical imaging task in radiology, since it affects both image quality and patient dose. Spreadsheet calculations of attenuation and absorption have been applied to basic imaging tasks to provide an assessment of imaging performance for a selection of phosphors used in radiology systems. Contrast, which is an important component of image quality affected by radiation quality, has been assessed in terms of the contrast to noise ratio (CNR) for a variety of X-ray beams. Both CNR and patient dose fall with tube potential, and selection of the best option is a compromise that will provide an adequate level of image quality with as low a radiation dose as practicable. It is important that systems are set up to match the response of the imaging phosphor, as there are significant differences between phosphors. For example, the sensitivity of barium fluorohalides used in computed radiography declines at higher tube potentials, whereas that of gadolinium oxysulphide used in rare earth screens increases. Addition of 0.2 mm copper filters, which can reduce patient entrance surface dose by 50%, may be advantageous for many applications in radiography and fluoroscopy. The disadvantage of adding copper is that tube output levels have to be increased. Application of simple calculations of the type employed here could prove useful for investigating and assessing the implications of potential changes in X-ray beam quality prior to implementation of new techniques.
Collapse
Affiliation(s)
- Cj Martin
- Health Physics, Gartnavel Royal Hospital, Glasgow, Scotland
| |
Collapse
|
29
|
Toroi P, Zanca F, Young KC, van Ongeval C, Marchal G, Bosmans H. Experimental investigation on the choice of the tungsten/rhodium anode/filter combination for an amorphous selenium-based digital mammography system. Eur Radiol 2007; 17:2368-75. [PMID: 17268798 DOI: 10.1007/s00330-006-0574-x] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2006] [Revised: 11/30/2006] [Accepted: 12/28/2006] [Indexed: 11/29/2022]
Abstract
The signal difference-to-noise ratio (SDNR) between aluminium sheets and a homogeneous background was measured for various radiation qualities and breast thicknesses to determine the optimal radiation quality when using a Novation DR mammography system. Breast simulating phantoms, with a thickness from 2 cm to 7 cm, and aluminium sheet, with a thickness of 0.2 mm, were used. Three different combinations of anode/filter material and a wide range of tube voltages were employed for each phantom thickness. Each radiation quality was studied using three different dose levels. The tungsten (W) anode and rhodium (Rh) filter combination achieved the specified SDNR at the lowest mean glandular dose for all the phantom thicknesses and X-ray tube voltages. The difference between the doses for different anode/filter combinations increased with the phantom thickness. For a 5-cm phantom, with a peak tube voltage of 27 kV and a SDNR of 5, the mean glandular dose associated with the use of W/Rh was reduced by 49% when compared to the molybdenum/molybdenum (Mo/Mo) anode/filter combination and by 33% when compared to Mo/Rh. Based on these measurements, the use of the W/Rh anode/filter can be recommended. It remains important, however, to select the appropriate dose level.
Collapse
Affiliation(s)
- Paula Toroi
- STUK-Radiation and Nuclear Safety Authority, P.O. Box 14, 00881 Helsinki, Finland.
| | | | | | | | | | | |
Collapse
|