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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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Durmaz FA, Brusan A, Ozturk C. Unified Open Hardware Platform for Digital X-Ray Devices; its Conceptual Model and First Implementation. IEEE JOURNAL OF TRANSLATIONAL ENGINEERING IN HEALTH AND MEDICINE 2020; 8:1800311. [PMID: 32617198 PMCID: PMC7326152 DOI: 10.1109/jtehm.2020.3000011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Revised: 04/05/2020] [Accepted: 05/06/2020] [Indexed: 11/27/2022]
Abstract
Background: Digital radiography devices are still the gold standard for diagnosis or therapy guidance in medicine. Despite the similarities between all direct digital x-ray systems, researchers and new companies face significant challenges during the development phase of innovative x-ray devices; each component is manufactured independently, guidance towards device integration from manufacturers is limited, global standards for device integration is lacking. Method: In scope of this study a plug-integrate-play (PIP) conceptual model for x-ray imaging system is introduced and implemented as an open hardware platform, SyncBox. The researchers are free to select each individual device component from different vendors based on their intended application and target performance are utilized in criteria. Result: As its first implementation, SyncBox and its platform a full body high resolution radiographic scanner that employs a novel TDI digital detector. Conclusion: We believe that SyncBox has a potential for introducing an open source hardware platform to x-ray equipment design.
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Affiliation(s)
- F Aytac Durmaz
- Institute of Biomedical Engineering, Boğaziçi University34684IstanbulTurkey
- Durmaz Technology AS34684IstanbulTurkey
- Pievision AS34684IstanbulTurkey
| | - Altay Brusan
- Institute of Biomedical Engineering, Boğaziçi University34684IstanbulTurkey
- Durmaz Technology AS34684IstanbulTurkey
| | - Cengizhan Ozturk
- Institute of Biomedical Engineering, Boğaziçi University34684IstanbulTurkey
- Center of Life Sciences and TechnologiesBoğaziçi University34684IstanbulTurkey
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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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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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Samei E, Ikejimba LC, Harrawood BP, Rong J, Cunningham IA, Flynn MJ. Report of AAPM Task Group 162: Software for planar image quality metrology. Med Phys 2018; 45:e32-e39. [DOI: 10.1002/mp.12718] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Revised: 10/31/2017] [Accepted: 11/30/2017] [Indexed: 12/17/2022] Open
Affiliation(s)
- Ehsan Samei
- Carl E. Ravin Advanced Imaging Laboratories; Medical Physics Graduate Program; Departments of Radiology, Biomedical Engineering, Physics, and Electrical and Computer Engineering; Clinical Imaging Physics Group; Duke University; 2424 Erwin Road Durham NC 27710 USA
| | - Lynda C. Ikejimba
- Carl E. Ravin Advanced Imaging Laboratories; Medical Physics Graduate Program; Department of Radiology; Duke University; 2424 Erwin Road Durham NC 27710 USA
| | - Brian P. Harrawood
- Carl E. Ravin Advanced Imaging Laboratories; Department of Radiology; Duke University; 2424 Erwin Road Durham NC 27710 USA
| | - John Rong
- Department of Imaging Physics; UT MD Anderson Cancer Center; 1400 Pressler St, Unit 1472 Houston TX 77030 USA
| | - Ian A. Cunningham
- Robarts Research Institute; Western University; 1151 Richmind St N London ON N6A 5B7 Canada
| | - Michael J. Flynn
- Department of Diagnostic Radiology; Henry Ford Health System; One Ford Pl, 3F Detroit MI 48202 USA
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Månsson LG, Kheddache S, Schlossman D, Börjesson J, Håkansson E, Mattsson S, Tylén U. Digital Chest Radiography with a Large Image Intensifier. Acta Radiol 2016. [DOI: 10.1177/028418518903000401] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
A digital system for chest radiography based on a large image intensifier was compared with a conventional film-screen system. The diagnostic performance was evaluated with special reference to the digital monitor images with a modified version of receiver operating characteristic (ROC) analysis—free response ROC (FROC) analysis—on a chest equivalent phantom. Measurements of spatial resolution and energy imparted were also performed. The detectability of low-contrast objects as well as spatial resolution was better for the full-size film-screen radiographs than for both the digital monitor images and the 100 mm photofluorograms. The image-intensifier system has a potential for considerable dose savings in relation to the conventional technique provided that fluoroscopy is excluded in the positioning of the patients.
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Affiliation(s)
- L. G. Månsson
- From the Departments of Radiation Physics and Radiology, Sahlgrenska Sjukhuset, University of Gothenburg, S-41345 Gothenburg, Sweden
| | - S. Kheddache
- From the Departments of Radiation Physics and Radiology, Sahlgrenska Sjukhuset, University of Gothenburg, S-41345 Gothenburg, Sweden
| | - D. Schlossman
- From the Departments of Radiation Physics and Radiology, Sahlgrenska Sjukhuset, University of Gothenburg, S-41345 Gothenburg, Sweden
| | - J. Börjesson
- From the Departments of Radiation Physics and Radiology, Sahlgrenska Sjukhuset, University of Gothenburg, S-41345 Gothenburg, Sweden
| | - E. Håkansson
- From the Departments of Radiation Physics and Radiology, Sahlgrenska Sjukhuset, University of Gothenburg, S-41345 Gothenburg, Sweden
| | - S. Mattsson
- From the Departments of Radiation Physics and Radiology, Sahlgrenska Sjukhuset, University of Gothenburg, S-41345 Gothenburg, Sweden
| | - U. Tylén
- From the Departments of Radiation Physics and Radiology, Sahlgrenska Sjukhuset, University of Gothenburg, S-41345 Gothenburg, Sweden
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Richter PH, Steinbrener J, Schicho A, Gebhard F. Does the choice of mobile C-arms lead to a reduction of the intraoperative radiation dose? Injury 2016; 47:1608-12. [PMID: 27297706 DOI: 10.1016/j.injury.2016.04.031] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Revised: 04/19/2016] [Accepted: 04/21/2016] [Indexed: 02/02/2023]
Abstract
INTRODUCTION Mobile C-arm imaging is commonly used in operating rooms worldwide. Especially in orthopaedic surgery, intraoperative C-arms are used on a daily basis. Because of new minimally-invasive surgical procedures a development in intraoperative imaging is required. The purpose of this article is investigate if the choice of mobile C-arms with flat panel detector technology (Siemens Cios Alpha and Ziehm Vision RFD) influences image quality and dose using standard, commercially available test devices. MATERIALS AND METHODS For a total of four clinical application settings, two zoom formats, and all dose levels provided, the transmission dose was measured and representative images were recorded for each test device. The data was scored by four observers to assess low contrast and spatial resolution performance. The results were converted to a relative image quality figure allowing for a direct image quality and dose comparison of the two systems. RESULTS For one test device, the Cios Alpha system achieved equivalent (within the inter-observer standard error) or better low contrast resolution scores at significantly lower dose levels, while the results of the other test device suggested that both systems achieved similar image quality at the same dose. The Cios Alpha system achieved equivalent or better spatial resolution at significantly lower dose for all application settings except for Cardiac, where a comparable spatial resolution was achieved at the same dose. CONCLUSION The correct choice of a mobile C-arm is very important, because it can lead to a reduction of the intraoperative radiation dose without negative effects on image quality. This can be a big advantage to reduce intraoperative radiation not only for the patient but also for the entire OR-team.
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Affiliation(s)
- P H Richter
- Department for Orthopaedic Trauma, Hand and Reconstructive Surgery, Ulm University, Albert-Einstein-Allee 23, D-89081 Ulm, Germany.
| | - J Steinbrener
- Siemens Healthcare GmbH, Henkestr. 172, 91052 Erlangen, Germany
| | - A Schicho
- Department for Orthopaedic Trauma, Hand and Reconstructive Surgery, Ulm University, Albert-Einstein-Allee 23, D-89081 Ulm, Germany
| | - F Gebhard
- Department for Orthopaedic Trauma, Hand and Reconstructive Surgery, Ulm University, Albert-Einstein-Allee 23, D-89081 Ulm, Germany
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Mourik JEM, van der Tol P, Veldkamp WJH, Geleijns J. COMPARISON OF WIRELESS DETECTORS FOR DIGITAL RADIOGRAPHY SYSTEMS: IMAGE QUALITY AND DOSE. RADIATION PROTECTION DOSIMETRY 2016; 169:303-307. [PMID: 26535003 DOI: 10.1093/rpd/ncv450] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The purpose of this study was to compare dose and image quality of wireless detectors for digital chest radiography. Entrance dose at both the detector (EDD) and phantom (EPD) and image quality were measured for wireless detectors of seven different vendors. Both the local clinical protocols and a reference protocol were evaluated. In addition, effective dose was calculated. Main differences in clinical protocols involved tube voltage, tube current, the use of a small or large focus and the use of additional filtration. For the clinical protocols, large differences in EDD (1.4-11.8 µGy), EPD (13.9-80.2 µGy) and image quality (IQFinv: 1.4-4.1) were observed. Effective dose was <0.04 mSv for all protocols. Large differences in performance were observed between the seven different systems. Although effective dose is low, further improvement of imaging technology and acquisition protocols is warranted for optimisation of digital chest radiography.
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Affiliation(s)
- J E M Mourik
- Department of Radiology and Nuclear Medicine, Sint Franciscus Vlietland Group, Kleiweg 500, Rotterdam 3045 PM, The Netherlands Department of Radiology, Leiden University Medical Center (LUMC), Albinusdreef 2, Leiden 2333 ZA, The Netherlands
| | - P van der Tol
- Department of Radiology, Leiden University Medical Center (LUMC), Albinusdreef 2, Leiden 2333 ZA, The Netherlands
| | - W J H Veldkamp
- Department of Radiology, Leiden University Medical Center (LUMC), Albinusdreef 2, Leiden 2333 ZA, The Netherlands
| | - J Geleijns
- Department of Radiology, Leiden University Medical Center (LUMC), Albinusdreef 2, Leiden 2333 ZA, The Netherlands
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Performance Evaluation of a Multichannel All-In-One Phantom Dosimeter for Dose Measurement of Diagnostic X-ray Beam. SENSORS 2015; 15:28490-501. [PMID: 26569252 PMCID: PMC4701291 DOI: 10.3390/s151128490] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Revised: 10/26/2015] [Accepted: 11/05/2015] [Indexed: 12/14/2022]
Abstract
We developed a multichannel all-in-one phantom dosimeter system composed of nine sensing probes, a chest phantom, an image intensifier, and a complementary metal-oxide semiconductor (CMOS) image sensor to measure the dose distribution of an X-ray beam used in radiation diagnosis. Nine sensing probes of the phantom dosimeter were fabricated identically by connecting a plastic scintillating fiber (PSF) to a plastic optical fiber (POF). To measure the planar dose distribution on a chest phantom according to exposure parameters used in clinical practice, we divided the top of the chest phantom into nine equal parts virtually and then installed the nine sensing probes at each center of the nine equal parts on the top of the chest phantom as measuring points. Each scintillation signal generated in the nine sensing probes was transmitted through the POFs and then intensified by the image intensifier because the scintillation signal normally has a very low light intensity. Real-time scintillation images (RSIs) containing the intensified scintillation signals were taken by the CMOS image sensor with a single lens optical system and displayed through a software program. Under variation of the exposure parameters, we measured RSIs containing dose information using the multichannel all-in-one phantom dosimeter and compared the results with the absorbed doses obtained by using a semiconductor dosimeter (SCD). From the experimental results of this study, the light intensities of nine regions of interest (ROI) in the RSI measured by the phantom dosimeter were similar to the dose distribution obtained using the SCD. In conclusion, we demonstrated that the planar dose distribution including the entrance surface dose (ESD) can be easily measured by using the proposed phantom dosimeter system.
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Moore CS, Wood TJ, Saunderson JR, Beavis AW. Correlation between the signal-to-noise ratio improvement factor (KSNR) and clinical image quality for chest imaging with a computed radiography system. Phys Med Biol 2015; 60:9047-58. [DOI: 10.1088/0031-9155/60/23/9047] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Jones AK, Heintz P, Geiser W, Goldman L, Jerjian K, Martin M, Peck D, Pfeiffer D, Ranger N, Yorkston J. Ongoing quality control in digital radiography: Report of AAPM Imaging Physics Committee Task Group 151. Med Phys 2015; 42:6658-70. [DOI: 10.1118/1.4932623] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Affiliation(s)
- A. Kyle Jones
- Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030
| | - Philip Heintz
- Department of Radiology, University of New Mexico, Albuquerque, New Mexico 87104
| | - William Geiser
- Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030
| | - Lee Goldman
- Hartford Hospital, Hartford, Connecticut 06102
| | | | | | - Donald Peck
- Henry Ford Health System, Detroit, Michigan 48202
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Alves AFF, Miranda JRDA, Bacchim Neto FA, Duarte SB, Pina DRD. Construction of pediatric homogeneous phantoms for optimization of chest and skull radiographs. Eur J Radiol 2015; 84:1579-1585. [PMID: 26044295 DOI: 10.1016/j.ejrad.2015.05.015] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Revised: 04/06/2015] [Accepted: 05/08/2015] [Indexed: 10/23/2022]
Abstract
OBJECTIVES To develop two pediatric patient-equivalent phantoms, the Pediatric Chest Equivalent Patient (PCEP) and the Pediatric Skull Equivalent Patient (PSEP) for children aged 1 to 5 years. We also used both phantoms for image quality evaluations in computed radiography systems to determine Gold Standard (GS) techniques for pediatric patients. METHODS To determine the simulator materials thickness (Lucite and aluminum), we quantified biological tissues (lung, soft, and bone) using an automatic computational algorithm. To objectively establish image quality levels, two physical quantities were used: effective detective quantum efficiency and contrast-to-noise ratio. These quantities were associated to values obtained for standard patients from previous studies. RESULTS For chest radiographies, the GS technique applied was 81kVp, associated to 2.0mAs and 83.6μGy of entrance skin dose (ESD), while for skull radiographies, the GS technique was 70kVp, associated to 5mAs and 339μGy of ESD. CONCLUSION This procedure allowed us to choose optimized techniques for pediatric protocols, thus improving quality of diagnosis for pediatric population and reducing diagnostic costs to our institution. These results could also be easily applied to other services with different equipment technologies.
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Affiliation(s)
- Allan Felipe Fattori Alves
- Instituto de Biociências de Botucatu, P.O. BOX 510, Departamento de Física e Biofísica, UNESP-Universidade Estadual Paulista, Distrito de Rubião Junior S/N, Botucatu, 18618-000 São Paulo, Brazil.
| | - José Ricardo de Arruda Miranda
- Instituto de Biociências de Botucatu, Departamento de Física e Biofísica, UNESP-Universidade Estadual Paulista, Distrito de Rubião Junior S/N, Botucatu, 18618-000 São Paulo, Brazil.
| | - Fernando Antonio Bacchim Neto
- Instituto de Biociências de Botucatu, Departamento de Física e Biofísica, UNESP-Universidade Estadual Paulista, Distrito de Rubião Junior S/N, Botucatu, 18618-000 São Paulo, Brazil.
| | - Sérgio Barbosa Duarte
- Centro Brasileiro de Pesquisas Físicas, Laboratório de Altas Energias, Dr. Xavier Sigaud, 150, Rio de Janeiro, 22290-180 Rio de Janeiro, Brazil.
| | - Diana Rodrigues de Pina
- Departamento de Doenças Tropicais e Diagnóstico por Imagem, Faculdade de Medicina de Botucatu, UNESP-Universidade Estadual Paulista, Distrito de Rubião Junior S/N, Botucatu, 18618-000 São Paulo, Brazil.
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Moore CS, Wood TJ, Avery G, Balcam S, Needler L, Beavis AW, Saunderson JR. An investigation of automatic exposure control calibration for chest imaging with a computed radiography system. Phys Med Biol 2014; 59:2307-24. [DOI: 10.1088/0031-9155/59/9/2307] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Hsieh CY, Gladish G, Willis CE. Evaluation of a commercial cardiac motion phantom for dual-energy chest radiography. J Appl Clin Med Phys 2014; 15:4508. [PMID: 24710435 PMCID: PMC5875465 DOI: 10.1120/jacmp.v15i2.4508] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2013] [Revised: 10/10/2013] [Accepted: 10/03/2013] [Indexed: 11/23/2022] Open
Abstract
Misregistration due to cardiac motion causes artifacts in two-exposure dual-energy subtraction images, in both the soft-tissue-only image and the bone-only image. Two previous investigations have attempted to avoid misregistration artifacts by using cardiac gating of the first and second exposures. The severity of misregistration was affected by the heart rate, the time interval between the low- and high-energy exposures, the total duration of the two exposures, and the phase of the cardiac cycle at the start of the exposure sequence. We sought to determine whether a commercial phantom with a simulated beating heart can be used to investigate the factors affecting misregistration in dual-energy chest radiography. We made dual-energy images of the phantom in postero-anterior orientation using the indirect digital radiography system (GE XQ/i). We acquired digital images at heart rates between 40 beats per minute and 120 beats per minute and transferred them to a computer, where the area of the artifact on the silhouette of the heart was measured from both soft-tissue-only and bone-only images. For comparison, we measured misregistration in clinical dual-energy subtraction images by the same method. Generally speaking, without synchronization of the exposure sequence with the cardiac cycle, the area of the misregistration artifact increased with heart rate for both the phantom and clinical images. However, the phantom exaggerated the magnitude of misregistration relative to clinical images. Although this phantom was designed for horizontal operation and computed tomography imaging, it can be used in an upright configuration to simulate heart motion for investigation of dual-energy misregistration artifacts and control.
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Park HS, Kim YS, Park OS, Kim ST, Jeon CW, Kim HJ. Effective DQE (eDQE) and dose to optimize radiographic technical parameters: a survey of pediatric chest X-ray examinations in Korea. Radiol Med 2013; 119:231-9. [DOI: 10.1007/s11547-013-0337-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2012] [Accepted: 03/13/2012] [Indexed: 01/17/2023]
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Moore CS, Wood TJ, Beavis AW, Saunderson JR. Correlation of the clinical and physical image quality in chest radiography for average adults with a computed radiography imaging system. Br J Radiol 2013; 86:20130077. [PMID: 23568362 DOI: 10.1259/bjr.20130077] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
OBJECTIVE The purpose of this study was to examine the correlation between the quality of visually graded patient (clinical) chest images and a quantitative assessment of chest phantom (physical) images acquired with a computed radiography (CR) imaging system. METHODS The results of a previously published study, in which four experienced image evaluators graded computer-simulated postero-anterior chest images using a visual grading analysis scoring (VGAS) scheme, were used for the clinical image quality measurement. Contrast-to-noise ratio (CNR) and effective dose efficiency (eDE) were used as physical image quality metrics measured in a uniform chest phantom. Although optimal values of these physical metrics for chest radiography were not derived in this work, their correlation with VGAS in images acquired without an antiscatter grid across the diagnostic range of X-ray tube voltages was determined using Pearson's correlation coefficient. RESULTS Clinical and physical image quality metrics increased with decreasing tube voltage. Statistically significant correlations between VGAS and CNR (R=0.87, p<0.033) and eDE (R=0.77, p<0.008) were observed. CONCLUSION Medical physics experts may use the physical image quality metrics described here in quality assurance programmes and optimisation studies with a degree of confidence that they reflect the clinical image quality in chest CR images acquired without an antiscatter grid. ADVANCES IN KNOWLEDGE A statistically significant correlation has been found between the clinical and physical image quality in CR chest imaging. The results support the value of using CNR and eDE in the evaluation of quality in clinical thorax radiography.
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Affiliation(s)
- C S Moore
- Radiation Physics Department, Queen's Centre for Oncology and Haematology, Castle Hill Hospital, Hull and East Yorkshire Hospitals, Hull, UK.
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Structural noise from automatic exposure control device and its relationship to X-ray tube voltage used for calibration of a flat-panel detector system. Radiol Phys Technol 2012; 5:20-6. [DOI: 10.1007/s12194-011-0129-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2010] [Revised: 07/21/2011] [Accepted: 07/25/2011] [Indexed: 10/17/2022]
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Poletti J. The HVL in soft tissue and the AAPM and IEC exposure indices. AUSTRALASIAN PHYSICAL & ENGINEERING SCIENCES IN MEDICINE 2011; 34:535-43. [PMID: 21968613 DOI: 10.1007/s13246-011-0100-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2011] [Accepted: 09/11/2011] [Indexed: 10/17/2022]
Abstract
Manual exposure settings for radiographic projections were once based on a points system which assumed that the HVL in soft tissue is 3.0 cm and that each change of 1.0 cm of soft tissue corresponded to a change of 25% in image receptor dose. A set of mAs steps and equivalent kVp steps was estimated that would give appropriate technique factors for changes in patient thickness. With the advent of rare-earth screen-film systems and AEC systems the points system fell into disuse. Screen-film imaging systems have almost entirely been replaced by CR or DR systems and recently, standardised exposure indices have been recommended by the AAPM and IEC to provide exposure guidance for these systems. If the fundamental assumptions on which the points system was based are still valid for modern high-frequency generators and digital imaging systems, then there would be an elegant correspondence between the predictions of the points system and the requirements for correction of exposure errors indicated by the AAPM and IEC indices. This study estimated the HVL and attenuation per cm in soft tissue using computer simulation, finding that practically, the HVL is between 2.0 and 5.0 cm and attenuation per cm ranges from 15 to 25%. The study concluded that agreement between the points system predictions and the true effects of technique factors changes on dose to the image receptor was moderately good, that use of the points system and technique charts based on this system should be encouraged and that use of the IEC or AAPM digital exposure indices should be standardised.
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Affiliation(s)
- John Poletti
- Department of Medical Imaging, Unitec New Zealand, Private Bag, 92025 Auckland, New Zealand.
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Willis CE, Vinogradskiy YY, Lofton BK, White RA. Gain and offset calibration reduces variation in exposure-dependent SNR among systems with identical digital flat-panel detectors. Med Phys 2011; 38:4422-9. [PMID: 21859043 DOI: 10.1118/1.3602458] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE The conditions under which vendor performance criteria for digital radiography systems are obtained do not adequately simulate the conditions of actual clinical imaging with respect to radiographic technique factors, scatter production, and scatter control. Therefore, the relationship between performance under ideal conditions and performance in clinical practice remains unclear. Using data from a large complement of systems in clinical use, the authors sought to develop a method to establish expected performance criteria for digital flat-panel radiography systems with respect to signal-to-noise ratio (SNR) versus detector exposure under clinical conditions for thoracic imaging. METHODS The authors made radiographic exposures of a patient-equivalent chest phantom at 125 kVp and 180 cm source-to-image distance. The mAs value was modified to produce exposures above and below the mAs delivered by automatic exposure control. Exposures measured free-in-air were corrected to the imaging plane by the inverse square law, by the attenuation factor of the phantom, and by the Bucky factor of the grid for the phantom, geometry, and kilovolt peak. SNR was evaluated as the ratio of the mean to the standard deviation (SD) of a region of interest automatically selected in the center of each unprocessed image. Data were acquired from 18 systems, 14 of which were tested both before and after gain and offset calibration. SNR as a function of detector exposure was interpolated using a double logarithmic function to stratify the data into groups of 0.2, 0.5, 1.0, 2.0, and 5.0 mR exposure (1.8, 4.5, 9.0, 18, and 45 microGy air KERMA) to the detector. RESULTS The mean SNR at each exposure interval after calibration exhibited linear dependence on the mean SNR before calibration (r2=0.9999). The dependence was greater than unity (m = 1.101 +/- 0.006), and the difference from unity was statistically significant (p <0.005). The SD of mean SNR after calibration also exhibited linear dependence on the SD of the mean SNR before calibration (r2 = 0.9997). This dependence was less than unity (m = 0.822 +/- 0.008), and the difference from unity was also statistically significant (p < 0.005). Systems were separated into two groups: systems with a precalibration SNR higher than the median SNR (N = 7), and those with a precalibration SNR lower than the median SNR (N= 7). Posthoc analysis was performed to correct for expanded false positive results. After calibration, the authors noted differences in mean SNR within both high and low groups, but these differences were not statistically significant at the 0.05 level. SNR data from four additional systems and one system from those previously tested after replacement of its detector were compared to the 95% confidence intervals (CI) calculated from the postcalibration SNR data. The comparison indicated that four of these five systems were consistent with the CI derived from the previously tested 14 systems after calibration. Two systems from the paired group that remained outside the CI were studied further. One system was remedied with a grid replacement. The nonconformant behavior of the other system was corrected by replacing the image receptor. CONCLUSIONS Exposure-dependent SNR measurements under conditions simulating thoracic imaging allowed us to develop criteria for digital flat-panel imaging systems from a single manufacturer. These measurements were useful in identifying systems with discrepant performance, including one with a defective grid, one with a defective detector, and one that had not been calibrated for gain and offset. The authors also found that the gain and offset calibration reduces variation in exposure-dependent SNR performance among the systems.
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Affiliation(s)
- Charles E Willis
- Department of Imaging Physics, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030-3721, USA.
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Samei E, Ranger NT, Dobbins JT, Ravin CE. Effective dose efficiency: an application-specific metric of quality and dose for digital radiography. Phys Med Biol 2011; 56:5099-118. [DOI: 10.1088/0031-9155/56/16/002] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Egbe N, Heaton B, Sharp P. Application of a simple phantom in assessing the effects of dose reduction on image quality in chest radiography. Radiography (Lond) 2010. [DOI: 10.1016/j.radi.2009.09.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Abstract
PURPOSE Methods for simulating dose reduction are valuable tools in the work of optimizing radiographic examinations. Using such methods, clinical images can be simulated to have been collected at other, lower, dose levels without the need of additional patient exposure. A recent technology introduced to healthcare that needs optimization is tomosynthesis, where a number of low-dose projection images collected at different angles is used to reconstruct section images of an imaged object. The aim of the present work was to develop a method of simulating dose reduction for digital radiographic systems, suitable for tomosynthesis. METHODS The developed method uses information about the noise power spectrum (NPS) at the original dose level and the simulated dose level to create a noise image that is added to the original image to produce an image that has the same noise properties as an image actually collected at the simulated dose level. As the detective quantum efficiency (DQE) of digital detectors operating at the low dose levels used for tomosynthesis may show a strong dependency on the dose level, it is important that a method for simulating dose reduction for tomosynthesis takes this dependency into account. By applying an experimentally determined relationship between pixel mean and pixel variance, variations in both dose and DQE in relevant dose ranges are taken into account. RESULTS The developed method was tested on a chest tomosynthesis system and was shown to produce NPS of simulated dose-reduced projection images that agreed well with the NPS of images actually collected at the simulated dose level. The simulated dose reduction method was also applied to tomosynthesis examinations of an anthropomorphic chest phantom, and the obtained noise in the reconstructed section images was very similar to that of an examination actually performed at the simulated dose level. CONCLUSIONS In conclusion, the present article describes a method for simulating dose reduction suitable for tomosynthesis. However, the method applies equally well to any digital radiographic system, although the benefits of correcting for DQE variations may be smaller.
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Affiliation(s)
- Angelica Svalkvist
- Department of Radiation Physics, University of Gothenburg, SE-413 45 Gothenburg, Sweden.
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Spelic DC, Kaczmarek RV, Hilohi MC, Moyal AE. Nationwide surveys of chest, abdomen, lumbosacral spine radiography, and upper gastrointestinal fluoroscopy: a summary of findings. HEALTH PHYSICS 2010; 98:498-514. [PMID: 20147791 DOI: 10.1097/hp.0b013e3181c182cd] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
This paper reports findings from Nationwide Evaluation of X-ray Trends surveys conducted in 2001, 2002, and 2003 of clinical facilities that perform routine radiographic examinations of the adult chest, abdomen, lumbosacral spine, and upper gastrointestinal fluoroscopic examinations. Randomly identified clinical facilities were surveyed in approximately 40 participating states. For the surveyed radiographic exams, additional facilities that use computed radiography or digital radiography were surveyed to ensure adequate sample sizes for determining comparative statistics. State radiation control personnel performed site visits and collected data on patient exposure, radiographic/fluoroscopic technique factors, image quality, and quality-control and quality-assurance practices. Results of the NEXT surveys are compared with those of previous surveys conducted in 1964 and 1970 by the U.S. Public Health Service and the Food and Drug Administration. An estimated 155 million routine adult chest exams were performed in 2001. Average patient entrance skin air kerma from chest radiography at facilities using digital-based imaging modalities was found to be significantly higher (p < 0.001), but not so for routine abdomen or lumbosacral spine radiography. Digital-based imaging showed a substantial reduction in patient exposure for the radiographic portion of the routine upper gastrointestinal fluoroscopy exam. Long-term trends in surveyed diagnostic examinations show that average patient exposures are at their lowest levels. Of concern is the observation that a substantial fraction of surveyed non-hospital sites indicated they do not regularly have a medical physics survey conducted on their radiographic equipment. These facilities are likely unaware of the radiation doses they administer to their patients.
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Affiliation(s)
- David C Spelic
- Food and Drug Administration, Silver Spring, MD 20993-0002, USA.
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Samei E, Ranger NT, MacKenzie A, Honey ID, Dobbins JT, Ravin CE. Effective DQE (eDQE) and speed of digital radiographic systems: an experimental methodology. Med Phys 2009; 36:3806-17. [PMID: 19746814 DOI: 10.1118/1.3171690] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Prior studies on performance evaluation of digital radiographic systems have primarily focused on the assessment of the detector performance alone. However, the clinical performance of such systems is also substantially impacted by magnification, focal spot blur, the presence of scattered radiation, and the presence of an antiscatter grid. The purpose of this study is to evaluate an experimental methodology to assess the performance of a digital radiographic system, including those attributes, and to propose a new metric, effective detective quantum efficiency (eDQE), a candidate for defining the efficiency or speed of digital radiographic imaging systems. The study employed a geometric phantom simulating the attenuation and scatter properties of the adult human thorax and a representative indirect flat-panel-based clinical digital radiographic imaging system. The noise power spectrum (NPS) was derived from images of the phantom acquired at three exposure levels spanning the operating range of the clinical system. The modulation transfer function (MTF) was measured using an edge device positioned at the surface of the phantom, facing the x-ray source. Scatter measurements were made using a beam stop technique. The eDQE was then computed from these measurements, along with measures of phantom attenuation and x-ray flux. The MTF results showed notable impact from the focal spot blur, while the NPS depicted a large component of structured noise resulting from use of an antiscatter grid. The eDQE was found to be an order of magnitude lower than the conventional DQE. At 120 kVp, eDQE(0) was in the 8%-9% range, fivefold lower than DQE(0) at the same technique. The eDQE method yielded reproducible estimates of the system performance in a clinically relevant context by quantifying the inherent speed of the system, that is, the actual signal to noise ratio that would be measured under clinical operating conditions.
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Affiliation(s)
- Ehsan Samei
- Department of Radiology, Carl E. Ravin Advanced Imaging Laboratories, Medical Physics Graduate Program, Duke University and Medical Center, 2424 Erwin Road, Suite 302, Durham, North Carolina 27705, USA.
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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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Pina D, Duarte S, Ghilardi Netto T, Morceli J. Phantom development for radiographic image optimization of chest, skull and pelvis examination for nonstandard patient. Appl Radiat Isot 2009; 67:61-9. [DOI: 10.1016/j.apradiso.2008.07.018] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2007] [Revised: 07/28/2008] [Accepted: 07/30/2008] [Indexed: 11/15/2022]
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Samei E, Ranger NT, MacKenzie A, Honey ID, Dobbins JT, Ravin CE. Detector or system? Extending the concept of detective quantum efficiency to characterize the performance of digital radiographic imaging systems. Radiology 2008; 249:926-37. [PMID: 19011189 PMCID: PMC2691810 DOI: 10.1148/radiol.2492071734] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
PURPOSE To develop an experimental method for measuring the effective detective quantum efficiency (eDQE) of digital radiographic imaging systems and evaluate its use in select imaging systems. MATERIALS AND METHODS A geometric phantom emulating the attenuation and scatter properties of the adult human thorax was employed to assess eight imaging systems in a total of nine configurations. The noise power spectrum (NPS) was derived from images of the phantom acquired at three exposure levels spanning the operating range of the system. The modulation transfer function (MTF) was measured by using an edge device positioned at the anterior surface of the phantom. Scatter measurements were made by using a beam-stop technique. All measurements, including those of phantom attenuation and estimates of x-ray flux, were used to compute the eDQE. RESULTS The MTF results showed notable degradation owing to focal spot blur. Scatter fractions ranged between 11% and 56%, depending on the system. The eDQE(0) results ranged from 1%-17%, indicating a reduction of up to one order of magnitude and different rank ordering and performance among systems, compared with that implied in reported conventional detective quantum efficiency results from the same systems. CONCLUSION The eDQE method was easy to implement, yielded reproducible results, and provided a meaningful reflection of system performance by quantifying image quality in a clinically relevant context. The difference in the magnitude of the measured eDQE and the ideal eDQE of 100% provides a great opportunity for improving the image quality of radiographic and mammographic systems while reducing patient dose.
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Affiliation(s)
- Ehsan Samei
- Duke Advanced Imaging Laboratories, Department of Radiology, Duke University and Medical Center, 2424 Erwin Rd, Suite 302, Durham, NC 27705, USA
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Shah C, Jones AK, Willis CE. Consequences of modern anthropometric dimensions for radiographic techniques and patient radiation exposures. Med Phys 2008; 35:3616-25. [PMID: 18777922 DOI: 10.1118/1.2952361] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Radiographic techniques are devised on the basis of anatomic dimensions. Inaccurate dimensions can cause radiographs to be exposed inappropriately and patient radiation exposures to be calculated incorrectly. The source of anatomic dimensions in common usage dates back to 1948. The objective of this study was to compare traditional and modern anthropometric data, use modern dimensions to estimate potential errors in patient exposure, and suggest modified technique guidelines. Anthropometry software was used to derive modern anatomic dimensions. Data from routine annual testing were analyzed to develop an x-ray generator output curve. Published tabulated data were used to determine the relationship between tissue half-value layer and kilovoltage. These relationships were used to estimate entrance skin exposure and create a provisional technique guide. While most anatomic regions were actually larger than previously indicated, some were similar, and a few were smaller. Accordingly, exposure estimates were higher, similar, or lower, depending on the anatomic region. Exposure estimates using modern dimensions for clinically significant regions of the trunk were higher than those calculated with traditional dimensions. Exposures of the postero-anterior chest, lateral chest, antero-posterior (AP) abdomen, male AP pelvis, and female AP pelvis were larger by 48%, 31%, 54%, 52%, and 112%, respectively. The dimensions of bony regions of the anatomy, such as the joints and skull, were unchanged. These findings are consistent with the idea that anatomic areas where fat is deposited are larger in the modern U.S. population than they were in previous years. Exposure techniques for manual radiography and calculations of patient dose for automatic exposure control radiography should be adjusted according to the modern dimensions. Population radiation exposure estimates calculated in national surveys should also be modified appropriately.
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Affiliation(s)
- Chintan Shah
- Department of Bioengineering, University of Toledo, Toledo, Ohio 43606, USA
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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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Veldkamp WJH, Kroft LJM, van Delft JPA, Geleijns J. A technique for simulating the effect of dose reduction on image quality in digital chest radiography. J Digit Imaging 2008; 22:114-25. [PMID: 18259814 DOI: 10.1007/s10278-008-9104-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2007] [Revised: 12/08/2007] [Accepted: 01/15/2008] [Indexed: 10/22/2022] Open
Abstract
PURPOSE The purpose of this study is to provide a pragmatic tool for studying the relationship between dose and image quality in clinical chest images. To achieve this, we developed a technique for simulating the effect of dose reduction on image quality of digital chest images. MATERIALS AND METHODS The technique was developed for a digital charge-coupled-device (CCD) chest unit with slot-scan acquisition. Raw pixel values were scaled to a lower dose level, and a random number representing noise to each specific pixel value was added. After adding noise, raw images were post processed in the standard way. Validation was performed by comparing pixel standard deviation, as a measure of noise, in simulated images with images acquired at actual lower doses. To achieve this, a uniform test object and an anthropomorphic phantom were used. Additionally, noise power spectra of simulated and actual images were compared. Also, detectability of simulated lesions was investigated using a model observer. RESULTS The mean difference in noise values between simulated and real lower-dose phantom images was smaller than 5% for relevant clinical settings. Noise power spectra appeared to be comparable on average but simulated images showed slightly higher noise levels for higher spatial frequencies and slightly lower noise levels for lower spatial frequencies. Comparable detection performance was shown in simulated and actual images with slightly worse detectability for simulated lower dose images. CONCLUSION We have developed and validated a method for simulating dose reduction. Our method seems an acceptable pragmatic tool for studying the relationship between dose and image quality.
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Affiliation(s)
- Wouter J H Veldkamp
- Department of Radiology, C2S, Leiden University Medical Center, Albinusreef 2, 2333, ZA, Leiden, The Netherlands.
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Affiliation(s)
- David C Spelic
- US Food and Drug Administration, Division of Mammography Quality and Radiation Programs, 1350 Piccard Drive, HFZ-240, Rockville, MD 20850, USA.
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Moore CS, Liney GP, Beavis AW, Saunderson JR. A method to optimize the processing algorithm of a computed radiography system for chest radiography. Br J Radiol 2007; 80:724-30. [PMID: 17709364 DOI: 10.1259/bjr/33261679] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
A test methodology using an anthropomorphic-equivalent chest phantom is described for the optimization of the Agfa computed radiography "MUSICA" processing algorithm for chest radiography. The contrast-to-noise ratio (CNR) in the lung, heart and diaphragm regions of the phantom, and the "system modulation transfer function" (sMTF) in the lung region, were measured using test tools embedded in the phantom. Using these parameters the MUSICA processing algorithm was optimized with respect to low-contrast detectability and spatial resolution. Two optimum "MUSICA parameter sets" were derived respectively for maximizing the CNR and sMTF in each region of the phantom. Further work is required to find the relative importance of low-contrast detectability and spatial resolution in chest images, from which the definitive optimum MUSICA parameter set can then be derived. Prior to this further work, a compromised optimum MUSICA parameter set was applied to a range of clinical images. A group of experienced image evaluators scored these images alongside images produced from the same radiographs using the MUSICA parameter set in clinical use at the time. The compromised optimum MUSICA parameter set was shown to produce measurably better images.
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Affiliation(s)
- C S Moore
- Radiation Physics Department, Hull & East Yorkshire Hospitals, Princess Royal Hospital, Saltshouse Road, Kingston Upon Hull HU8 9HE.
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Willis CE. Letter to the Editor. J Digit Imaging 2007; 20:1-3; author reply 4-5. [PMID: 17410404 PMCID: PMC3043885 DOI: 10.1007/s10278-007-1067-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Affiliation(s)
- Charles E. Willis
- Department of Imaging Physics, The University of Texas M. D. Anderson Cancer Center, Houston, TX 77030 USA
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Aldrich JE, Duran E, Dunlop P, Mayo JR. Optimization of dose and image quality for computed radiography and digital radiography. J Digit Imaging 2006; 19:126-31. [PMID: 16511674 PMCID: PMC3045190 DOI: 10.1007/s10278-006-9944-9] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
The surface doses to patients during chest, abdomen and pelvis radiography were measured over a period of 3 years, during which time computed radiography (CR) and digital radiography (DR) systems were introduced to replace film-screen systems. For film-screen and CR the surface doses were measured with thermoluminescent dosimeters. For DR the surface doses were calculated from the dose-area product (DAP) meter readings. Measurements were made for each type of examination and detector type on 10 average-size patients. Measurements were made immediately after the new systems were introduced, and subsequently as adjustments were made to optimize dose and image quality. Published diagnostic reference levels were used as target values in this optimization. Initially, CR doses were the same as or higher than for film-screen, and the doses were lower for DR compared to film-screen. Subsequent clinical experience with the systems led to changes in the technique used for chest examinations both for CR and for DR. For CR, it was possible to change the algorithm and decrease the dose to one quarter of the initial value with acceptable image quality. For DR, it was decided to reduce noise by increasing the dose by a factor of two. No changes were made to abdomen or pelvic imaging techniques for either CR or DR. The final patient surface doses using CR were similar to published diagnostic reference doses; for DR, all patient doses were less than published reference levels.
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Affiliation(s)
- John E Aldrich
- Department of Radiology, Vancouver General Hospital and University of British Columbia, 899 West 12th Avenue, Vancouver, BC, Canada V5Z 1M9.
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Veldkamp WJH, Kroft LJM, Boot MV, Mertens BJA, Geleijns J. Contrast-detail evaluation and dose assessment of eight digital chest radiography systems in clinical practice. Eur Radiol 2006; 16:333-41. [PMID: 16132918 DOI: 10.1007/s00330-005-2887-6] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2005] [Revised: 06/27/2005] [Accepted: 07/29/2005] [Indexed: 11/27/2022]
Abstract
The purpose of this study was to assess contrast-detail performance and effective dose of eight different digital chest radiography systems. Digital chest radiography systems from different manufacturers were included: one storage phosphor system, one selenium-coated drum system, and six direct readout systems including four thin-film transistor (TFT) systems and two charge-coupled device (CCD) systems. For measuring image quality, a contrast-detail test object was used in combination with a phantom that simulates the primary and scatter transmission through lung fields (LucAl). Six observers judged phantom images of each modality by soft-copy reading in a four-alternative-forced-choice experiment. The entrance dose was also measured, and the effective dose was calculated for an average patient. Contrast-detail curves were constructed from the observer data. The blocked two-way ANOVA test was used for statistical analysis. Significant difference in contrast-detail performance was found between the systems. Best contrast-detail performance was shown by a CCD system with slot-scan technology, and the selenium-coated drum system was compared to the other six systems (p values <or=0.003). Calculated effective dose varied between 0.010 mSv and 0.032 mSv. Significant differences in contrast-detail performance and effective dose levels were found between different digital chest radiography systems in clinical practice.
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Affiliation(s)
- Wouter J H Veldkamp
- Department of Radiology, C2S, Leiden University Medical Center, Albinusdreef 2, 2333 ZA, Leiden, The Netherlands.
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Veldkamp WJH, Kroft LJM, Mertens BJA, Geleijns J. Digital Slot-Scan Charge-coupled Device Radiography versus AMBER and Bucky Screen-Film Radiography: Comparison of Image Quality in a Phantom Study. Radiology 2005; 235:857-66. [PMID: 15845787 DOI: 10.1148/radiol.2353031919] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
PURPOSE To evaluate the image quality and performance of a chest digital radiography system and to compare this with the image quality and performance of advanced multiple-beam equalization radiography (AMBER) and Bucky screen-film radiography systems. MATERIALS AND METHODS The chest digital radiography system is a digital charge-coupled device (CCD) chest imaging unit that uses slot-scan technology. A contrast-detail test object was used in combination with a phantom that simulates the primary and scatter transmission for the lungs and mediastinum. Twelve phantom images were obtained with each modality (ie, CCD digital radiography and AMBER and Bucky screen-film radiography) and were judged by six observers. CCD digital radiography soft-copy reading was compared with AMBER hard-copy reading. To measure image quality, contrast-detail curves were constructed from the observer data. The Wilcoxon signed rank test was used for statistical analysis. RESULTS For the lung configuration, contrast-detail curves showed lower threshold depth for hard-copy images obtained with CCD digital radiography than for those obtained with Bucky screen-film radiography. For hard-copy images, the difference between contrast-detail curves for CCD digital radiography and those for Bucky screen-film radiography was statistically significant (P < .006). No significant difference was found between CCD digital radiography and AMBER for hard-copy images obtained in either the lung or mediastinum configuration. For the lung configuration, a lower threshold depth was observed for CCD digital radiography soft-copy reading than for AMBER hard-copy reading, with significantly different contrast-detail curves for CCD digital radiography soft copy and AMBER hard copy (P < .006). No significant difference was found between either system for the mediastinum configuration. CONCLUSION Contrast-detail curves indicate that image quality for the CCD chest system provides a digital alternative to AMBER and Bucky screen-film radiography.
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Affiliation(s)
- Wouter J H Veldkamp
- Department of Radiology, C2S, Leiden University Medical Center, Albinusdreef 2, 2333 ZA Leiden, The Netherlands.
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Compagnone G, Pagan L, Bergamini C. Comparison of six phantoms for entrance skin dose evaluation in 11 standard X-ray examinations. J Appl Clin Med Phys 2005; 6:101-13. [PMID: 15770201 PMCID: PMC5723512 DOI: 10.1120/jacmp.v6i1.2020] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2004] [Accepted: 09/14/2004] [Indexed: 11/23/2022] Open
Abstract
Entrance skin dose (ESD) is an important parameter for assessing the dose received by a patient in a single radiographic exposure. The most useful way to evaluate ESD is either by direct measurement on phantoms using an ionization chamber or using calculations based on a mathematical model. We compared six phantoms (three anthropomorphic, two physical, and one mathematical) in 11 standard clinical examinations (anterior-posterior (AP) abdomen, posterior-anterior (PA) chest, AP chest, lateral (LAT) chest, AP lumbar spine, LAT lumbar spine, LAT lumbo-sacral joint, AP pelvis, PA skull, LAT skull, and AP urinary tract) for two reasons: to determine the conversion factors to use for ESDs measured on different phantoms and to validate the mathematical model used. First, a comparison was done between the three anthropomorphic phantoms (Alderson Rando, chest RSD-77SPL, and 3M skull) and the two physical phantoms (Uniform and AAPM 31); for each examination we obtained "relative entrance skin dose factors." Second, we compared these five phantoms with the mathematical phantom: the overall accuracy of the model was better than 14%. Total mathematical model and total ionization chamber uncertainties, calculated by quadratic propagation of errors of the single components, were estimated to be on the order of +/-12% and +/-3%, respectively. To reduce the most significant source of uncertainty, the overall accuracy of the model was recalculated using new backscatter factors. The overall accuracy of the model improved: better than 12%. For each examination an anthropomorphic phantom was considered as the gold standard relative to the physical phantoms. In this way, it was possible to analyze the variations in phantom design and characteristics. Finally, the mathematical model was validated by more than 400 measurements taken on different phantoms and using a variety of radiological equipment. We conclude that the mathematical model can be used satisfactorily in ESD evaluations because it optimizes available resources, it is based on direct measurements, and it is an easy dynamic tool.
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Affiliation(s)
- Gaetano Compagnone
- Medical Physics Department, S. Orsola-Malpighi Hospital, Via Massarenti 9, 40138 Bologna, Italy.
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Håkansson M, Båth M, Börjesson S, Kheddache S, Johnsson AA, Månsson LG. Nodule detection in digital chest radiography: effect of system noise. RADIATION PROTECTION DOSIMETRY 2005; 114:97-101. [PMID: 15933088 DOI: 10.1093/rpd/nch525] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Apart from the image content that is the reproduction of anatomy and possible lesions, an X-ray image also contains system noise due to the limited number of photons and other internal noise sources in the system (image plate artefacts, electronic noise, etc.). The aim of this study was to determine the extent to which the system noise influences the detection of subtle lung nodules in five different regions of the chest. This was done by conducting a receiver operating characteristic (ROC) study with five observers on two different sets of images; clinical chest X-ray images and images of a LucAl phantom at similar dose levels found in the different regions of the chest. In both image types, mathematically simulated nodules (with a full-width-at-fifth-maximum of 10 mm) were added to the images at varying contrast levels. As a measure of the influence of system noise on the detection of subtle lung nodules, the ratio between the contrast needed to obtain an area under the ROC curve of 0.80 in the system noise images to that needed in the clinical images was used. The contrast ratio between system noise images and clinical images ranged from approximately 0.02 (in the hilar region) to 0.18 (in the lower mediastinal region). The maximum difference in contrast needed for the corresponding system noise images, collected at the lowest and the highest dose represented in the anatomical image, was a factor of 2. These results indicate that probably no region in a chest X-ray image is limited by the number of quanta to the detector for the detection of 10 mm lung nodules when a radiation dose corresponding to a system with speed class 200 (leading to a detector dose of approximately 9 muGy behind the parenchyma) is used.
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Affiliation(s)
- Markus Håkansson
- Department of Medical Physics and Biomedical Engineering, Sahlgrenska University Hospital, SE-413 45 Göteborg, Sweden.
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Båth M, Håkansson M, Börjesson S, Kheddache S, Grahn A, Ruschin M, Tingberg A, Mattsson S, Månsson LG. Nodule detection in digital chest radiography: introduction to the RADIUS chest trial. RADIATION PROTECTION DOSIMETRY 2005; 114:85-91. [PMID: 15933086 DOI: 10.1093/rpd/nch575] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Most digital radiographic systems of today have wide latitude and are hence able to provide images with a small constraint on dose level. This opens up for an unprejudiced dose optimisation. However, in order to succeed in the optimisation task, good knowledge of the imaging and detection processes is needed. As a part of the European-wide research project 'unification of physical and clinical requirements for medical X-ray imaging'-governed by the Radiological Imaging Unification Strategies (RADIUS) Group-a major image quality trial was conducted by members of the group. The RADIUS chest trial was focused on the detection of lung nodules in digital chest radiography with the aims of determining to what extent (1) the detection of a nodule is dependent on its location, (2) the system noise disturbs the detection of lung nodules, (3) the anatomical noise disturbs the detection of lung nodules and (4) the image background and anatomical background act as pure noise for the detection of lung nodules. The purpose of the present paper is to give an introduction to the trial and describe the framework and set-up of the investigation.
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Affiliation(s)
- Magnus Båth
- Department of Medical Physics and Biomedical Engineering, Sahlgrenska University Hospital, SE-413 45 Göteborg, Sweden.
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Zoetelief J, Idris HHE, Jansen JTM. Investigation of possible methods for equipment self-tests in digital radiology. RADIATION PROTECTION DOSIMETRY 2005; 117:269-73. [PMID: 16461526 DOI: 10.1093/rpd/nci723] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Quality control in digital radiology can be time-consuming. Equipment self-tests may significantly decrease staff workload. The two most essential parameters for radiology systems are image quality and patient dose. Concerning patient dose, information on the dose-area product (DAP) values generally forms the basis for assessment of patient dose. DAP-values can be measured using a transmission ionisation chamber or calculated from equipment settings. In the present study, various image quality parameters were derived using a contrast-detail (C-D) phantom. The investigation included a computer-aided assessment of C-D images, which produced various parameters, and also parameters based upon scoring by human observers. In addition, another parameter was calculated from modulation transfer function (MTF) measurements. The automatically calculated parameters showed good correlation with human readings, although the number of X-ray systems studied is still limited. We propose a combined evaluation of DAP and automatically calculated C-D or MTF parameters for equipment self-tests.
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Affiliation(s)
- J Zoetelief
- Delft University of Technology, IRI, Mekelweg 15, 2629 JB Delft, The Netherlands.
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Compagnone G, Pagan L, Bergamini C. Local diagnostic reference levels in standard X-ray examinations. RADIATION PROTECTION DOSIMETRY 2004; 113:54-63. [PMID: 15572400 DOI: 10.1093/rpd/nch432] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The national diagnostic reference levels (NDRLs) form an efficient, concise and powerful standard for optimising radiation protection of a patient. However, in a large hospital, where many radiological departments are present, it is also possible to calculate and define lower dose values as local diagnostic reference levels (LDRLs). In our hospital there are eight radiological departments; in each of these, the entrance skin dose (ESD) distributions were determined for 10 standard projections (AP Abdomen, PA and LAT Chest, AP and LAT Lumbar Spine, LAT Lumbo-Sacral Joint, AP Pelvis, PA and LAT Skull and AP Urinary tract) and then the ESDs were compared with data previously published and with Italian NDRLs. All ESD values were below the corresponding NDRLs. The maximum/minimum ratio of ESDs ranged from 3.9 (LAT Skull) to 34.3 (AP Abdomen) for individual adult patients and from 2.1 (PA Skull) to 6.5 (Urinary tract) across the mean values of the radiological departments. Finally, it is shown how LDRLs can be proposed to obtain a more fully optimised radiation protection of patients.
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Affiliation(s)
- Gaetano Compagnone
- Medical Physics Department, S. Orsola-Malpighi Hospital, Via Massarenti 9, 40138 Bologna, Italy.
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42
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Rill LN, Brateman L, Arreola M. Evaluating radiographic parameters for mobile chest computed radiography: Phantoms, image quality and effective dose. Med Phys 2003; 30:2727-35. [PMID: 14596311 DOI: 10.1118/1.1611291] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Conventional chest radiography is technically difficult because of wide variations in tissue attenuations in the chest and limitations of screen-film systems. Mobile chest radiography, performed bedside on hospital inpatients, presents additional difficulties due to geometric and equipment limitations inherent in mobile x-ray procedures and the severity of illness in the patients. Computed radiography (CR) offers a different approach for mobile chest radiography by utilizing a photostimulable phosphor. Photostimulable phosphors overcome some image quality limitations of mobile chest imaging, particularly because of the inherent latitude. Because they are more efficient in absorbing lower-energy x-rays than rare-earth intensifying screens, this study evaluated changes in kVp for improving mobile chest CR. Three commercially available systems were tested, with the goal of implementing the findings clinically. Exposure conditions (kVp and grid use) were assessed with two acrylic-and-aluminum chest phantoms which simulated x-ray attenuation for average-sized and large-sized adult chests. These phantoms contained regions representing the lungs, heart and subdiaphragm to allow proper CR processing. Signal-to-noise ratio (SNR) measurements using different techniques were obtained for acrylic and aluminum disks (1.9 cm diameter) superimposed in the lung and heart regions of the phantoms, where the disk thicknesses (contrast) were determined from disk visibility. Effective doses to the phantoms were also measured for these techniques. The results indicated that using an 8:1, 33 lines/cm antiscatter grid improved the SNR by 60-300 % compared with nongrid images, depending on phantom and region; however, the dose to the phantom also increased by 400-600%. Lowering x-ray tube potential from 80 to 60 kVp improved the SNR by 30-40%, with a corresponding increase in phantom dose of 40-50%. Increasing the potential from 80 to 100 kVp reduced both the SNR and the phantom dose by approximately 10%. The most promising changes in technique for trial in clinical implementation include using an antiscatter grid, especially for large patients, and potentially increasing kVp.
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Affiliation(s)
- Lynn N Rill
- Department of Radiology, University of Florida, Gainesville, Florida 32610, USA
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van Soldt RTM, Zweers D, van den Berg L, Geleijns J, Jansen JTM, Zoetelief J. Survey of posteroanterior chest radiography in The Netherlands: patient dose and image quality. Br J Radiol 2003; 76:398-405. [PMID: 12814926 DOI: 10.1259/bjr/76222078] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
Council Directive 97/43/Euratom (Medical Exposure Directive) states that member States of the European Union shall promote the establishment and use of diagnostic reference levels for radio-diagnostic examinations. Dose surveys can form the basis for the establishment of diagnostic reference levels. In view of the implementation of the Medical Exposure Directive in the Netherlands, a survey of dose and image quality has been performed for posteroanterior (PA) chest radiography in 2001. In this survey, 25 participants were selected from a list of 175 Dutch hospitals, whereas in a previous PA chest survey (about 10 years ago) participation was voluntary and participants came predominantly from the south-western part of the Netherlands. For conventional screen-film PA chest radiography, the present results for patient dose and image quality are quite similar to those results from the previous survey. The fraction of conventional X-ray systems utilizing lung compensation filters has remained approximately the same. For dedicated digital chest radiography systems, image quality is better than for conventional systems, but doses vary and can assume relatively high values. The results indicate that there are still possibilities for dose reduction, without loss of image quality. The 75 percentile value of the entrance surface dose distribution is approximately 0.13 mGy.
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Affiliation(s)
- R T M van Soldt
- Interfaculty Reactor Institute Delft University of Technology, Mekelweg 15, 2629 JB Delft , The Netherlands
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44
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Preston-Martin S, Pogoda JM. Estimation of radiographic doses in a case-control study of acute myelogenous leukemia. HEALTH PHYSICS 2003; 84:245-259. [PMID: 12553655 DOI: 10.1097/00004032-200302000-00013] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Radiation exposure from dental and medical radiography is inherently difficult to estimate. Because no single resource is available for this type of data, gathering the information needed to estimate exposure in epidemiologic studies is a labor-intensive, imprecise process. For a case-control study of adult-onset acute myelogenous leukemia in Los Angeles County and radiography, a database was created of estimates of dose to the red bone marrow for each radiographic procedure reported by subjects in interviews and recorded in subjects' medical records. Resources used included the medical literature as well as personal communications with radiology experts. Dose estimates for each procedure based on this database are reported. Methods and complications are contrasted with a past effort to estimate dose from dental radiography for a case-control study of parotid gland tumors. Among the more difficult aspects of medical radiography dose estimation are the wide variety of examinations performed, the continually-changing environment of diagnostic imaging, and the number of variables that contribute to the delivered dose to an individual from a specific imaging procedure.
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Affiliation(s)
- Susan Preston-Martin
- Keck School of Medicine, University of Southern California (USC), Department of Preventive Medicine, USC/Norris Comprehensive Cancer Center, 1441 Eastlake Avenue, MS 44, P.O. Box 33800, Los Angeles, CA 90033-0800, USA
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Abstract
Optimization in chest radiography requires evaluation of patient dose and image quality. This study is aimed at proposing a simple geometrical phantom that realistically simulates the important anatomical regions of the thorax. For this purpose, the standard LucAl chest phantom is modified by adding an "anthropomorphic" insert and image quality test plate. Different test objects are arranged on the plate in three important anatomical areas; lung, cardiac, and subdiaphragmal regions. The aim is to simultaneously find two types of image quality index, objective and subjective, which can be used to compare different images in order to select the better image. Two objective indices are proposed, areal contrast index DeltaC(a) and scatter fraction P(s) and two subjectively estimated, a low contrast visualization index P(low) and a high contrast visualization index P(high). To demonstrate the potential of this phantom method it was applied to an X-ray unit to find the optical film density that ensures optimal visualization in different anatomical areas. It was found for the X-ray system under investigation that the automatic exposure control could be set to produce an optical density of about 1.8 in the lung field. The reported method is easily implemented in any clinical situation where optimization of chest radiography is needed.
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Affiliation(s)
- J Vassileva
- Applied Physics Department, Konstantin Preslavsky University, 9712 Shumen, Bulgaria
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Kaczmarek RV, Conway BJ, Slayton RO, Suleiman OH. Results of a nationwide survey of chest radiography: comparison with results of a previous study. Radiology 2000; 215:891-6. [PMID: 10831717 DOI: 10.1148/radiology.215.3.r00jn43891] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
PURPOSE To provide public health information by means of measurement of the radiation exposures that patients undergoing chest radiography would receive and to compare the results with those of a similar previous survey. MATERIALS AND METHODS Surveyed facilities were randomly selected from each state. Patient exposure was evaluated along with film processing, half-value layer, and image quality. Additional information obtained concerned type of equipment, facility work load, radiographic technique, screen-film system, and grid type. RESULTS Mean entrance air kerma in all facilities was 141 microGy (16.1 mR). Mean kilovoltage in all facilities was 101 kV. In 1994, 140 (90%) of 156 hospitals (vs 71% in 1984) and 92 (58%; nearly double the percentage in 1984) of 159 nonhospital sites were using grids. Scoring with the imaging test tool resulted in a mean spatial resolution of 2.3 cycles per millimeter, and a mean low-contrast sensitivity of about 3%. Two hundred fifty-three (80%) of 315 facilities surveyed were processing film at minimum acceptable performance levels. CONCLUSION Mean entrance air kerma for all facilities did not substantially change. Although increased grid usage would lead to the expectation of higher measured exposures, this was offset by an increase in the use of faster screen-film combinations.
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Affiliation(s)
- R V Kaczmarek
- U.S. Food and Drug Administration, Center for Devices and Radiological Health, Rockville, MD 20850, USA.
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Suleiman OH, Stern SH, Spelic DC. Patient dosimetry activities in the United States: the nationwide evaluation of X-ray trends (NEXT) and tissue dose handbooks. Appl Radiat Isot 1999; 50:247-59. [PMID: 10028641 DOI: 10.1016/s0969-8043(98)00073-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
In the United States the Food and Drug Administration (FDA) in collaboration with the Conference of Radiation Control Program Directors (CRCPD) and state and local government agencies surveys clinical facilities about X-ray system air kerma and ancillary data related to patient dosimetry for a variety of diagnostic X-ray examinations. The survey program is known as the Nationwide Evaluation of X-ray Trends (NEXT). The survey utilizes reference patient-equivalent phantoms in the collection of comprehensive technical information. With knowledge of the skin-entrance air kerma, specific tissue doses can be calculated. An overview of NEXT and previously published FDA tissue dose handbooks for diagnostic X-ray examinations is presented.
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Affiliation(s)
- O H Suleiman
- U.S. Food and Drug Administration, Center for Devices and Radiological Health, Rockville, MD 20850, USA
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Abstract
The aim in radiology is to obtain images which are adequate for the clinical purpose with the minimum radiation dose to the patient. If optimum performance is to be achieved, assessments of image quality must be made to balance against patient dose. The subjective nature of image interpretation makes an objective approach to such assessment difficult. Methods widely applied involve the use of test objects, which although providing a measure of imaging performance may be difficult to link to clinical image formation. The ideal method for evaluation of imaging techniques is through clinical trials and this should be used to address major questions. Scoring of quality criteria, relating to features observed in a normal clinical radiograph, provides a simple method through which image quality can be assessed in every hospital department.
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Affiliation(s)
- C J Martin
- Department of Clinical Physics and Bio-Engineering, West Glasgow Hospitals University NHS Trust, Scotland, U.K
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Leyenaar HJ, Abolfathi AH, Bakalyar DM, Conlin CH, Wieting DW, Chandler JG. A working cardiac valve phantom for radiographic assessment of prosthetic heart valves. Acad Radiol 1995; 2:896-901. [PMID: 9419657 DOI: 10.1016/s1076-6332(05)80070-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
RATIONALE AND OBJECTIVES A working valve phantom (WVP) that both exercises the valve occluder and simulates movements of the mitral annulus is described. It was designed to develop a method for radiographic detection of a single broken leg of the two-legged Björk-Shiley convexo-concave (C/C) heart valve outlet strut. METHODS The WVP consists of a pneumatically driven left ventricular assist device immersed in 22 cm of water. Left ventricular assist device annulus movements are generated by systolic turgor and diastolic relaxation of the aortic outflow graft within limits set by the holding fixture design. RESULTS WVP images were comparable in attenuation, valve motion, and diagnostic sensitivity to clinical C/C valve images and were effective in assessing leaflet excursions in another valve model. Techniques developed in the WVP have proved successful in the clinical detection of C/C valves that have a single broken leg but that show normal function in all other tests. CONCLUSION The WVP can be a useful tool for developing refined radiographic assessments of prosthetic heart valves.
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Affiliation(s)
- H J Leyenaar
- Shiley Heart Valve Research Center, Irvine, CA, USA
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Sandborg M, Dance DR, Carlsson GA, Persliden J. Monte Carlo study of grid performance in diagnostic radiology: factors which affect the selection of tube potential and grid ratio. Br J Radiol 1993; 66:1164-76. [PMID: 8293262 DOI: 10.1259/0007-1285-66-792-1164] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
A Monte Carlo computational model has been developed for the study of the performance of anti-scatter grids in diagnostic radiology. It is used here to estimate the scatter in the image plane from soft tissue phantoms (representing the patient) and to calculate image contrast and the mean absorbed dose in the phantom. Different scattering conditions, representative of various examinations, have been investigated: adult lumbar spine; small field radiography and fluoroscopy; adult chest and paediatric pelvis and chest. For each scattering condition, the combinations of tube potential and grid ratio have been found which, for a well designed grid, result in the lowest mean absorbed dose in the phantom for a fixed contrast level. In examinations which generate large amounts of scatter, the use of high grid ratios in combination with high tube potentials is favourable with regard to both mean absorbed dose in the phantom and tube charge. When less scatter is generated, either the grid ratio or the tube potential can be varied to achieve the desired contrast level. High grid ratios require shorter exposure times, but need careful alignment in the beam to prevent primary radiation cut-off. It is shown that the air gap technique can be used to reduce patient dose in examinations with small amounts of scatter, but in combinations with a lower tube potential than when a grid is used.
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Affiliation(s)
- M Sandborg
- Department of Radiation Physics, Linköping University, Faculty of Health Sciences, Sweden
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