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ABSTRACT: This study investigates the influence of the initial X-ray system setting on patient doses and image quality in interventional cardiology procedures. Two dedicated interventional cardiology systems were studied: a system with image intensifier (II) and a flat detector (FD) system. Entrance surface air kerma (ESAK) rates in fluoroscopy and ESAK per frame in the acquisition mode were measured on the surface of a PMMA phantom for the field of views (FOV) of 23 and 17 cm (II system) and 25 and 20 cm (FD system). Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were estimated using DICOM images obtained during the measurements. System performances were compared using a figure of merit combining SNR and ESAK. The influence of system setting on patient doses was investigated analysing the information for air kerma area product (KAP) and cumulative dose (CD) at the patient entrance reference point, for a sample of coronary angiography examinations. ESAK rates in fluoroscopy modes were a factor of 2 higher in the FD system for the similar FOVs, resulting in a factor of 1.9 higher median values of KAP and CD for patients with FD system than for the II system. SNR and CNR for the FD system were better than the equivalent FOVs with II. The resulting FOM was better for the FD system in both FOVs. Potential for optimisation was suggested by adjusting system settings.
Radiation Protection Dosimetry 02/2013; · 0.82 Impact Factor
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J Malone,
P Baldelli,
S Balter,
N Bischof,
H Bosmans,
A Dowling,
S Edyvean,
A Gallagher,
K Faulkner,
K Horner,
L Malone,
I D McLean,
U O'Connor,
A Schreiner,
J Vassileva, E Vano,
J Zoetelief
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ABSTRACT: The EC (European Council) Directive on radiation protection of patients requires that criteria for acceptability of equipment in diagnostic radiology, nuclear medicine and radiotherapy be established throughout the member states. This study reviews the background to this requirement and to its implementation in practice. It notes and considers parallel requirements in the EC medical devices directive and International Electrotechnical Commission standards that it is also important to consider and that both sets of requirements should ideally be harmonised due to the global nature of the equipment industry. The study further reviews the types of criteria that can be well applied for the above purposes, and defines qualitative criteria and suspension levels suitable for application. Both are defined and relationships with other acceptance processes are considered (including acceptance testing at the time of purchase, commissioning and the issue of second-hand equipment). Suspension levels are divided into four types, A, B, C and D, depending on the quality of evidence and consensus they are based on. Exceptional situations involving, for example, new or rapidly evolving technology are also considered. The publication and paper focuses on the role of the holder of the equipment and related staff, particularly the medical physics expert and the practitioner. Advice on how the criteria should be created and implemented is provided for these groups and how this might be coordinated with the supplier. Additional advice on the role of the regulator is provided.
Radiation Protection Dosimetry 11/2012; · 0.82 Impact Factor
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ABSTRACT: BACKGROUND AND PURPOSE:Radiation exposure from neurointerventional procedures can be substantial, with risk of radiation injuries. We present the results of a follow-up program applied to potential skin injuries in interventional neuroradiology based on North American and European guidelines.MATERIALS AND METHODS:The following guidelines approved in 2009 by SIR and CIRSE have been used over the last 2 years to identify patients with potential skin injuries requiring clinical follow-up: peak skin dose >3 Gy, air kerma at the patient entrance reference point >5 Gy, kerma area product >500 Gy · cm(2), or fluoroscopy time >60 minutes.RESULTS:A total of 708 procedures (325 in 2009 and 383 in 2010) were included in the study. After analyzing each dose report, 19 patients (5.9%) were included in a follow-up program for potential skin injuries in 2009, while in 2010, after introducing several optimizing actions and refining the selection criteria, only 4 patients (1.0%) needed follow-up. Over the last 2 years, only 3 patients required referral to a dermatology service.CONCLUSIONS:The application of the guidelines to patient radiation dose management helped standardize the selection criteria for including patients in the clinical follow-up program of potential skin radiation injuries. The peak skin dose resulted in the most relevant parameter. The refinement of selection criteria and the introduction of a low-dose protocol in the x-ray system, combined with a training program focused on radiation protection, reduced the number of patients requiring clinical follow-up.
American Journal of Neuroradiology 08/2012; · 2.93 Impact Factor
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Journal of Radiological Protection 09/2011; 31(3):285-7. · 1.39 Impact Factor
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ABSTRACT: In most of its publications, the International Commission on Radiological Protection has highlighted the importance of education and training in radiation protection (RP) for medical exposures. Spain, like other Member States of the European Union, has implemented the Directive and the Guidelines in the medical area. The purpose of this paper is to present the Spanish experience in RP education and training in medicine, the different objectives established according to professional levels, existing regulations and feedback obtained from various RP actions.
Radiation Protection Dosimetry 08/2011; 147(1-2):338-42. · 0.82 Impact Factor
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ABSTRACT: Radiochromic XR-RV2 films are considered as one of the best dosemeters to measure patient skin doses in fluoroscopy-guided interventional procedures. To fulfil this purpose, they need to be calibrated with diagnostic energies and doses beyond several Gray. The vendor provides a visual calibration strip to estimate the absorbed dose. Differences between visual dose estimation versus film digitisation were investigated. The influence of backscatter radiation on film sensitivity was also investigated and the sources of uncertainty were analysed when skin doses were measured with these films. When based on the visual comparison with the strip, the estimation of the dose resulted in an error of 50 % (2 Gy in the region around 4 Gy). However, when using numerical methods after film digitisation, the uncertainty in dose measurement fell to 7-14 % in the dose range of interest. Calibration under backscatter conditions demonstrates that the 'in air' calibration underestimates the doses by 7 %. When the dose was measured with a calibration method based on 16 bits grey digitisation, uncertainty was twice higher than when the red channel from red, green, blue digitised images was used.
Radiation Protection Dosimetry 07/2011; 147(1-2):94-8. · 0.82 Impact Factor
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ABSTRACT: The aim of this work was to investigate the differences in dose settings and image quality among 10 X-ray systems used for interventional cardiology in Chile. Entrance surface air kerma (ESAK) was measured on a phantom of 20 cm thickness of polymethyl methacrylate slabs. Image quality was evaluated using DICOM images of a test object Leeds TOR 18-FG for cine mode acquisition, through the numerical parameters signal-to-noise ratio (SNR), high-contrast spatial resolution (HCSR) and figure of merit. ESAK rate values for fluoroscopy modes ranged between 7.1 and 121.7 mGy min(-1). For cine mode, ESAK values per frame ranged from 63 to 400 µGy fr(-1). SNR and HCSR parameters for cine mode varied from 4.8 to 8.6 and 0.4 to 10, respectively. FOM values resulted from 6.9 to 64.5 among the different X-ray systems. Results show important differences between systems and point out the need to launch an optimisation programme.
Radiation Protection Dosimetry 07/2011; 147(1-2):90-3. · 0.82 Impact Factor
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R Sánchez, E Vano,
J M Fernández,
J Sotil,
F Carrera,
J Armas,
F Rosales,
X Pifarre,
J Escaned,
J Angel,
J F Diaz,
F Bosa,
J R Saez,
J Goicolea
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ABSTRACT: A national programme on patient and staff dose evaluation in interventional cardiology made in cooperation with the haemodynamic section of the Spanish Society of Cardiology has recently been launched. Its aim is to propose a set of national diagnostic reference levels (DRLs) for patients as recommended by the International Commission on Radiological Protection and to initiate several optimisation actions to improve radiological protection of both patients and staff. Six hospitals have joined the programme and accepted to submit their data to a central database. First to be acquired were the quality control data of the X-ray systems and radiation doses of patients and professionals. The results from 9 X-ray systems, 1467 procedures and staff doses from 43 professionals were gathered. Provisional DRLs resulted in 44 Gy cm(2) for coronary angiography and 78 Gy cm(2) for interventions. The X-ray systems varied up to a factor of 5 for dose rates in reference conditions. Staff doses showed that 50 % of interventional cardiologists do not use their personal dosemeters correctly.
Radiation Protection Dosimetry 07/2011; 147(1-2):57-61. · 0.82 Impact Factor
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ABSTRACT: The aim of this study was to evaluate patient doses in two interventional cardiology laboratories over a period of 1 y in which the imaging devices were changed from image intensifier (II) to flat detector (FD). Dosimetric data from a total of 1040 coronary angiography (CA) procedures and 1087 percutaneous transluminal coronary angioplasty (PTCA) procedures were gathered. During the period studied with II imaging, median values of dose area product were 28 Gy cm(2) for CA and 57 Gy cm(2) for PTCA. In the first half of the year with FD imaging, median values were 37 Gy cm(2) for CA and 89 Gy cm(2) for PTCA. A significant increase in patient doses was noticed in the early stages of use of FD technology for imaging IC procedures, while fluoroscopy time and number of images remained similar. A careful setting of the X-ray systems, after upgrading the imaging system, is essential to avoid unjustified increases in patient doses.
Radiation Protection Dosimetry 07/2011; 147(1-2):83-5. · 0.82 Impact Factor
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E Vano
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ABSTRACT: When planning good management of ionising radiation in medicine, key factors such as ensuring that health professionals work together and convincing them that radiation protection (RP) represents a substantial part of the quality management system in their clinical practice are of utmost importance. The United Nations Scientific Committee on the Effects of Atomic Radiation has decided that one of the thematic priorities will be medical radiation exposure of patients. The International Commission on Radiological Protection has recently updated the report on RP in medicine and continues to work on focused documents centred on specific areas where advice is needed. The roles of the International Atomic Energy Agency, World Health Organization and the European Commission, in the area of RP in medicine, are described in the present document. The industry, the standardisation organisations as well as many scientific and professional societies are also dedicating significant effort to radiation safety aspects in medicine. Some of the efforts and priorities contemplated in RP in medicine over the coming years are suggested. The best outcome will be accomplished when all the actors, i.e. medical doctors, other health professionals, regulators, health authorities and the industry manage to work together.
Radiation Protection Dosimetry 07/2011; 147(1-2):3-7. · 0.82 Impact Factor
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ABSTRACT: The evaluation of a new occupational Dose Aware System (DAS) showing staff radiation doses in real time has been carried out in several angiography rooms in our hospital. The system uses electronic solid-state detectors with high-capacity memory storage. Every second, it archives the dose and dose rate measured and is wirelessly linked to a base-station screen mounted close to the diagnostic monitors. An easy transfer of the values to a data sheet permits further analysis of the scatter dose profile measured during the procedure, compares it with patient doses, and seeks to find the most effective actions to reduce operator exposure to radiation.
The cumulative occupational doses measured per procedure (shoulder-over lead apron) ranged from 0.6 to 350 μSv when the ceiling-suspended screen was used, and DSA (Digital Subtraction Acquisition) runs were acquired while the personnel left the angiography room. When the suspended screen was not used and radiologists remained inside the angiography room during DSA acquisitions, the dose rates registered at the operator's position reached up to 1-5 mSv/h during fluoroscopy and 12-235 mSv/h during DSA acquisitions. In such case, the cumulative scatter dose could be more than 3 mSv per procedure.
Real-time display of doses to staff members warns interventionists whenever the scatter dose rates are too high or the radiation protection tools are not being properly used, providing an opportunity to improve personal protection accordingly.
CardioVascular and Interventional Radiology 12/2010; 33(6):1210-4. · 2.09 Impact Factor
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ABSTRACT: Entrance surface air kerma (ESAK) values and image quality parameters were measured and compared for two biplane angiography x-ray systems dedicated to paediatric interventional cardiology, one equipped with image intensifiers (II) and the other one with dynamic flat detectors (FDs). Polymethyl methacrylate phantoms of different thicknesses, ranging from 8 to 16 cm, and a Leeds TOR 18-FG test object were used. The parameters of the image quality evaluated were noise, signal-difference-to-noise ratio (SdNR), high contrast spatial resolution (HCSR) and three figures of merit combining entrance doses and signal-to-noise ratios or HCSR. The comparisons showed a better behaviour of the II-based system in the low contrast region over the whole interval of thicknesses. The FD-based system showed a better performance in HCSR. The FD system evaluated would need around two times more dose than the II system evaluated to reach a given value of SdNR; moreover, a better spatial resolution was measured (and perceived in conventional monitors) for the system equipped with flat detectors. According to the results of this paper, the use of dynamic FD systems does not lead to an automatic reduction in ESAK or to an automatic improvement in image quality by comparison with II systems. Any improvement also depends on the setting of the x-ray systems and it should still be possible to refine these settings for some of the dynamic FDs used in paediatric cardiology.
Physics in Medicine and Biology 12/2010; 55(23):7287-97. · 2.83 Impact Factor
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ABSTRACT: Within the Information System on Occupational Exposure in Medicine, Industry and Research (ISEMIR), a new International Atomic Energy Agency initiative, a Working Group on interventional cardiology, aims to assess staff radiation protection (RP) levels and to propose an international database of occupational exposures. A survey of regulatory bodies (RBs) has provided information at the country level on RP practice in interventional cardiology (IC). Concerning requirements for wearing personal dosemeters, only 57 % of the RB specifies the number and position of dosemeters for staff monitoring. Less than 40 % of the RBs could provide occupational doses. Reported annual median effective dose values (often <0.5 mSv) were lower than expected considering validated data from facility-specific studies, indicating that compliance with continuous individual monitoring is often not achieved in IC. A true assessment of annual personnel doses in IC will never be realised unless a knowledge of monitoring compliance is incorporated into the analysis.
Radiation Protection Dosimetry 11/2010; 144(1-4):437-41. · 0.82 Impact Factor
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J. F. Malone,
A. Schreiner,
H. Zoetelief,
I. D. Mclean,
S. Balter, E. Vano,
H. Bosmans,
N. Bischof,
R. Klausz,
A. Dowling,
U. O’Connor,
C. Walsh,
A. Gallagher,
K. Faulkner
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ABSTRACT: In 2007, the European Commission has commissioned a group of Experts to undertake the revision of Report RP91 on “Criteria
for Acceptability of Radiological (including Radiotherapy) and Nuclear Medicine Installations”, which will be published soon.
This paper introduces some of the concerns encountered in the diagnostic radiology section of the report and the approach
adopted to establishing the criteria.
KeywordsDiagnostic Radiology-Criteria of Acceptability-Suspension Levels-Ionising Radiation
12/2009: pages 211-214;
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E Vano,
R Sanchez,
J M Fernandez,
F Rosales,
M A Garcia,
J Sotil,
J Hernandez,
F Carrera,
J Ciudad,
M M Soler,
T Ballester
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ABSTRACT: The purpose of this work was to investigate the differences in dose settings among the X-ray units involved in a national survey of patient doses in interventional radiology (IR). The survey was promoted by the National Society of IR and involved 10 centers. As part of the agreed quality control for the survey, entrance doses were measured in a 20-cm-thick acrylic phantom simulating a medium-sized patient. A standard digital subtraction angiography (DSA) imaging protocol for the abdomen was used at the different centers. The center of the phantom was placed at the isocenter of the C-arm system during the measurements to simulate clinical conditions. Units with image intensifiers and flat detectors were involved in the survey. Entrance doses for low, medium, and high fluoroscopy modes and DSA acquisitions were measured for a field of view of 20 cm (or closest). A widespread range of entrance dose values was obtained: 4.5-18.6, 9.2-28.4, and 15.4-51.5 mGy/min in low, medium, and high fluoroscopy mode, respectively, and 0.7-5.0 mGy/DSA image. The ratios between the maximum and the minimum values measured (3-4 for fluoroscopy and 7 for DSA) suggest an important margin for optimization. The calibration factor for the dose-area product meter was also included in the survey and resulted in a mean value of 0.73, with a standard deviation of 0.07. It seems clear that the dose setting for the X-ray systems used in IR requires better criteria and approaches.
CardioVascular and Interventional Radiology 01/2009; 32(1):121-6. · 2.09 Impact Factor
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ABSTRACT: The purpose of the paper is to define predictors of the kerma-area product (KAP) in percutaneous coronary intervention (PCI). Two new digital X-ray interventional cardiology systems recently installed were included. A total of 398 PCI procedures were carried out by 6 board-certified senior interventional cardiologists with more than 15 years' experience and good knowledge of radiation protection measures. Clinical, radiation and procedural data were collected based on a detailed protocol developed by the SENTINEL cardiology subgroup. Correlation with clinical and procedure factors was then investigated. A significant correlation was found between fluoroscopy time and (i) lesion classification, (ii) the level of tortuosity and (iii) the number of vessels treated. No statistically significant differences were observed in the complexity of the case between operators. However, large differences were found in the KAP among operators, which were mostly attributed to the different number of frames taken by each operator. There was no statistically significant correlation between complexity and the total number of frames. The study showed that, in certain circumstances, the clinical need to successfully perform PCI takes precedence over radiation safety concerns.
The British journal of radiology 10/2008; 81(972):940-5. · 2.11 Impact Factor
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ABSTRACT: Radiation dose and image quality for paediatric protocols in a biplane x-ray system used for interventional cardiology have been evaluated. Entrance surface air kerma (ESAK) and image quality using a test object and polymethyl methacrylate (PMMA) phantoms have been measured for the typical paediatric patient thicknesses (4-20 cm of PMMA). Images from fluoroscopy (low, medium and high) and cine modes have been archived in digital imaging and communications in medicine (DICOM) format. Signal-to-noise ratio (SNR), figure of merit (FOM), contrast (CO), contrast-to-noise ratio (CNR) and high contrast spatial resolution (HCSR) have been computed from the images. Data on dose transferred to the DICOM header have been used to test the values of the dosimetric display at the interventional reference point. ESAK for fluoroscopy modes ranges from 0.15 to 36.60 microGy/frame when moving from 4 to 20 cm PMMA. For cine, these values range from 2.80 to 161.10 microGy/frame. SNR, FOM, CO, CNR and HCSR are improved for high fluoroscopy and cine modes and maintained roughly constant for the different thicknesses. Cumulative dose at the interventional reference point resulted 25-45% higher than the skin dose for the vertical C-arm (depending of the phantom thickness). ESAK and numerical image quality parameters allow the verification of the proper setting of the x-ray system. Knowing the increases in dose per frame when increasing phantom thicknesses together with the image quality parameters will help cardiologists in the good management of patient dose and allow them to select the best imaging acquisition mode during clinical procedures.
Physics in Medicine and Biology 09/2008; 53(15):4049-62. · 2.83 Impact Factor
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ABSTRACT: A methodology to automatically detect potential retakes in digital imaging, using the Digital Imaging and Communications in Medicine (DICOM) header information, is presented. In our hospital, neither the computed radiography workstations nor the picture archiving and communication system itself are designed to support reject analysis. A system called QCOnline, initially developed to help in the management of images and patient doses in a digital radiology department, has been used to identify those images with the same patient identification number, same modality, description, projection, date, cassette orientation, and image comments. The pilot experience lead to 6.6% and 1.9% repetition rates for abdomen and chest images. A thorough analysis has shown that the real repetitions were 3.3% and 0.9% for abdomen and chest images being the main cause of the discrepancy being the wrong image identification. The presented methodology to automatically detect potential retakes in digital imaging using DICOM header information is feasible and allows to detect deficiencies in the department performance like wrong identifications, positioning errors, wrong radiographic technique, bad image processing, equipment malfunctions, artefacts, etc. In addition, retake images automatically collected can be used for continuous training of the staff.
Journal of Digital Imaging 08/2008; 22(4):393-9. · 1.25 Impact Factor
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ABSTRACT: Over the last two years we have evaluated paediatric patient doses in projection radiography derived from exposure level (EL) in computed radiography (CR) in a large university hospital. Entrance surface air kerma (ESAK) for 3501 paediatric examinations was calculated from the EL, which is a dose index parameter related to the light emitted by the phosphor-stimulable plate, archived in the Digital Imaging and Communications in Medicine (DICOM) header of the images and automatically transferred to a database using custom-built dedicated software. Typical mean thicknesses for several age bands of paediatric patients was estimated to calculate ESAK from the EL values, using results of experimental measurements with phantoms for the typical x-ray beam qualities used in paediatric examinations. Mean/median ESAK values (in microGy) for the age bands of <1 year, 1-5 years, 6-10 years and 11-15 years have been obtained for chest without a bucky: 51/41, 57/34, 91/54 and 122/109; chest with a bucky (for only the last three age bands): 114/87, 129/105 and 219/170; abdomen: 119/91, 291/225, 756/600 and 1960/1508 and pelvis: 65/48, 455/314, 943/707 and 2261/1595. Sample sizes of clinical images used for the (indirect) measurements were 1724 for chest without a bucky, 799 for chest with a bucky, 337 for abdomen and 641 for pelvis. The methodology we describe could be applicable to other centres using CR as an imaging modality for paediatrics. Presently, this method is the only practical approach to automatically extract parameters contained in the DICOM header, for the calculation of patient dose values for the CR modality.
Physics in Medicine and Biology 06/2008; 53(12):3365-80. · 2.83 Impact Factor
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A Larkin,
N Sheahan,
U O'Connor,
L Gray,
A Dowling, E Vano,
P Torbica,
D Salat,
A Schreiner,
V Neofotistou,
J F Malone
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ABSTRACT: New developments in dual energy X-ray absorptiometry (DEXA) imaging technology [fan beam and cone beam (CB)] result in higher exposure levels, shorter scan times, increased patient throughput and increased shielding requirements. This study presents the results of a European survey detailing the number and location of DEXA systems in SENTINEL partner states and the QA (quality assurance) currently performed by physicists and operators in these centres. The results of a DEXA equipment survey based on an in-house developed QA protocol are presented. Measurements show that the total effective dose to the patient from a spine and dual femur DEXA examination on the latest generation DEXA systems is comparable with a few microSv at most. Scatter measurements showed that the use of a mobile lead screen for staff protection was necessary for fan and CB systems. Scattered dose from newer generation systems may also exceed the exposure limits for the general public so structural shielding may also be required. Considerable variation in the magnitude and annual repeatability of half value layer was noted between different models of DEXA scanners. A comparative study of BMD (bone mineral density) accuracy using the European Spine Phantom highlighted a deviation of up to 7% in BMD values between scanners of different manufacturers.
Radiation Protection Dosimetry 05/2008; 129(1-3):279-83. · 0.82 Impact Factor
