Local Diagnostic Reference Levels for Pediatric Interventional Cardiology Procedures in Argentina.

The aim of this work was to propose a preliminary local diagnostic reference levels (DRL) for pediatric interventional cardiology (PIC) procedures in Argentina, for different ranges of age and weight. This work has been conducted in the framework of the "Optimization of Protection in Pediatric Interventional Radiology in Latin America and the Caribbean" (OPRIPALC) program coordinated by the World Health Organization and the Pan American Health Organization in cooperation with the International Atomic Energy Agency to ensuring that radiation exposures of pediatric patients are the minimum necessary during fluoroscopy-guided interventional procedures. The local DRL values presented in this paper by weight group and age group were 7.1 Gy·cm2 (<5 kg), 10.7 Gy·cm2 (5-15 kg), 18.0 Gy·cm2 (15-30 kg), 15.9 Gy·cm2 (30-50 kg), and 28.2 Gy·cm2 (50-80 kg) and 5.3 Gy·cm2 (<1), 11.2 Gy·cm2 (1 to 5<), 19.6 Gy·cm2 (5 to 10<), and 21.4 Gy·cm2 (10 to 16<), respectively. Our dose results are among the values found in other international studies; however, there is great potential for dose optimization.

Correlation between scatter radiation dose at height of operator's eye and dose to patient for different angiographic projections.

Studies have reported cases of radiation-induced cataract among cardiology professionals. In view of the evidence of epidemiological studies, the ICRP recommends a new threshold for opacities and a new radiation dose to eye lens limit of 20mSv per year for occupational exposure. The aim of this paper is to report scattered radiation doses at the height of the operator's eye in an interventional cardiology facility without considering radiation protection devices and to correlate these values with different angiographic projections and operational modes. Measurements were taken in a cardiac laboratory with an angiography X-ray system equipped with flat-panel detector. PMMA plates of 30×30×5cm were used with a thickness of 20cm. Measurements were taken in two fluoroscopy modes (low and normal, 15pulses/s) and in cine mode (15frames/s). Four angiographic projections were used: anterior posterior; lateral; left anterior oblique caudal (spider); and left anterior oblique cranial, with a cardiac protocol for patients weighing between 70 and 90kg. Measurements of phantom entrance dose rate and scatter dose rate were performed with two Unfors Xi plus detectors. The detector measuring scatter radiation was positioned at the usual distance of the cardiologist's eyes during working conditions. There is a good linear correlation between the kerma area product and scatter dose at the lens. Experimental correlation factors of 2.3, 12.0, 12.2 and 17.6µSv/Gycm2 were found for different projections. PMMA entrance dose rates for low and medium fluoroscopy and cine modes were 13, 39 and 282mGy/min, respectively, for AP projection.

TEMPORAL DEPENDENCE OF THE RADIATION MONITORING INSTRUMENTS FOR AREA MONITORING USED AT RADIODIAGNOSTIC AND INTERVENTION FACILITIES.

Area monitoring is a fundamental test at radiodiagnostic facilities to maintain an acceptable level of radiation exposure for employees and members of the public. Experimental measurements were taken in an ionising radiation calibration laboratory. Four area monitor instruments were used. Dose and dose rate measurements were measured in integrated and rate operating modes. The results show that precautions are necessary where the area monitor uses exposure times of ≤2 s. When taking measurements in rate mode for times ≤2 s, the area monitors evaluated show a tendency to underestimate dose rate, the inaccuracy was 41 %, and varied between 34 and 45 % for different energies. It is highly recommendable to work in integrated mode, inaccuracy varied from 2 to 35 %. For measurements taken with exposure times of ≥3 s, the average inaccuracy was 15 % and the range was between 2 and 41 %.

Mean glandular dose in six digital mammography services in Santiago, Chile: preliminary reference levels.

The purpose of this paper was to estimate mean glandular dose levels (DG) in six digital mammography systems in Santiago, Chile, and to propose preliminary reference levels to execute mammography in Chile. The study was carried out assessing two direct digital systems and four computer-based radiography (CR) systems. Estimates of DG were calculated for different thicknesses of polymethyl methacrylate according to the quality control protocol in digital mammography of the Spanish Society of Medical Physics and NHSBSP Equipment Report 0604 Version 3. DG values ranged between 0.64 and 7.26 mGy for a range of 20- to 70-mm thickness, respectively. Thirty-six per cent of DG was higher than the acceptable dose level and 100 % of DG was higher than the desirable level. It is therefore necessary to optimise doses. The initial proposal to establish dose reference levels for DG would range between 0.90 and 6.40 mGy for a thickness range of 20 to 70 mm.

Latin American dose survey results in mammography studies under IAEA programme: radiological protection of patients in medical exposures (TSA3).

Latin American countries (Argentina, Brazil, Chile, Costa Rica, Cuba, Ecuador, El Salvador, Guatemala, Mexico, Nicaragua, Paraguay, Uruguay and Venezuela) working under the International Atomic Energy Agency (IAEA) Technical Cooperation Programme: TSA3 Radiological Protection of Patients in Medical Exposures have joined efforts in the optimisation of radiation protection in mammography practice. Through surveys of patient doses, the region has a unique database of diagnostic reference levels for analogue and digital equipment that will direct future optimisation activities towards the early detection of breast cancer among asymptomatic women. During RLA9/057 (2007-09) 24 institutions participated with analogue equipment in a dose survey. Regional training on methodology and measurement equipment was addressed in May 2007. The mean glandular dose (DG) was estimated using the incident kerma in air and relevant conversion coefficients for both projections craneo caudal and mediolateral oblique (CC and MLO). For Phase 2, RLA9/067 (2010-11), it was decided to include also digital systems in order to see their impact in future dose optimisation activities. Any new country that joined the project received training in the activities through IAEA expert missions. Twenty-nine new institutions participated (9 analogue and 20 digital equipment). A total of 2262 patient doses were collected during this study and from them D(G) (mGy) for both projections were estimated for each institution and country. Regional results (75 percentile in mGy) show for CC and MLO views, respectively: RLA9/057 (analogue) 2.63 and 3.17; RLA/067: 2.57 and 3.15 (analogue) and 2.69 and 2.90 (digital). Regarding only digital equipment for CC and MLO, respectively, computed radiography systems showed 2.59 and 2.78 and direct digital radiography (DDR) systems 2.78 and 3.04. Based on the IAEA Basic Safety Standard (BSS) reference dose (3 mGy), it can be observed that there is enough room to start optimisation processes in Latin America (LA); several countries or even particular institutions have values much higher than the 3 mGy. The main issues to address are lack of well-established quality assurance programmes for mammography, not enough medical physicists with training in mammography, an increase in patient doses with the introduction of digital equipment and to create awareness on radiation risk and optimisation strategies.

Riscos da Radiação X e a Importância da Proteção Radiológica na Cardiologia Intervencionista: Uma Revisão Sistemática / Radiation Risks and the Importance of Radiological Protection in Interventional Cardiology: A Systematic Review

Discutimos aqui aspectos vinculados ao enquadramento legal, a recomendações internacionais e a programas de formação em proteção radiológica; ao angiógrafo e à qualidade da imagem; aos efeitos biológicos e aos riscos das radiações ionizantes; às lesões em operadores e pacientes; aos níveis de referência do paciente; ao limite de dose ocupacional e a suas medidas de prevenção. O uso das radiações ionizantes acarreta riscos, que, contudo, justificam-se em procedimentos diagnósticos e terapêuticos. A consciência e o conhecimento desses riscos minimizam o dano, otimizando a qualidade da imagens e o uso seguro das radiações ionizantes. Tem-se demonstrado a ocorrência de cataratas radioinduzidas em trabalhadores de laboratórios de cateterismo. Diversos estudos sugerem que pode haver um risco significativo de opacidade do cristalino, caso não se utilizem adequadamente os dispositivos de proteção radiológica. Adicionalmente, esses tipos de procedimentos intervencionistas são realizados na América Latina, geralmente por médicos especialistas, com a colaboração de enfermeiros, tecnólogos e técnicos, que, muitas vezes, não têm formação adequada em proteção radiológica.

We discuss some aspects related to the legal framework, international recommendations and training programs on radiological protection; image quality and equipment; the biological effects and risks of ionizing radiation; lesions in patients and operators; patient's reference levels; occupational dose limit and preventive actions. The use of ionizing radiation involves risks that are justified in diagnostic and therapeutic procedures. The awareness and knowledge of these risks minimizes the damage, optimizing the quality of images and safe use of ionizing radiation. There is evidence of radiation-induced cataracts in individuals who work in catheterization laboratories. Several studies suggest there may be a significant risk of lens opacity, if radiological protection devices are not properly used. Additionally, these interventional procedures are performed in Latin America, usually by medical specialists in collaboration with nurses, technologists and technicians, who often do not have adequate training in radiological protection.

Pilot program on patient dosimetry in pediatric interventional cardiology in Chile.

PURPOSE: The aim of this study was to present the results of a pilot program on patient dosimetry carried out in Chile during the last 5 yr, using a biplane x-ray angiography system settled for pediatrics. This research was conducted in Latin America under the auspices of the International Atomic Energy Agency (IAEA) supporting programs on radiological protection (RP) of patients. METHODS: Patient age, gender, weight, height, number of cine series, total number of cine frames, fluoroscopy time, and two dosimetric quantities [air kerma-area product (P(ka)) and cumulative dose (CD) at the patient entrance reference point] were recorded for each procedure. RESULTS: The study includes 544 patients grouped into four age groups. The distributions by age group were 150 for <1 yr; 203 for 1 to <5 yr; 97 for 5 to <10 yr; and 94 for 10 to <16 yr. Median values of P(ka) and CD for the four age groups were 0.94, 1.46, 2.13, and 5.03 Gy cm(2) and 23.9, 26.8, 33.5, and 51.6 mGy, respectively. No significant statistical differences were found between diagnostic and therapeutic procedures. A moderate correlation (r = 0.64) was seen between P(ka) and patient weight. CONCLUSIONS: The dose values reported in this paper were lower than those published in the previous work for the same age groups as a result of the optimization actions carried out by cardiologists and medical physicists with the support of the IAEA. Methodology and results will be used as a starting point for a wider survey in Chile and Latin America with the goal to obtain regional diagnostic reference levels as recently recommended by the International Commission on Radiological Protection for interventional procedures.

Radiation protection in pediatric interventional cardiology: An IAEA PILOT program in Latin America.

The aim of this work is to present a methodology and some initial results for a pilot program on radiation protection (RP) in pediatric interventional cardiology under the auspices of the International Atomic Energy Agency. The starting point of the program was a workshop involving several pediatric cardiologists leading this specialty in 11 Latin American countries. The workshop included a pilot RP training course and additional sessions during which the objectives of the program and the methodology to collect and process data on patient and staff radiation doses were discussed. Special attention was dedicated to agree on a common quality control (QC) protocol for the x-ray and imaging systems used in the different catheterization laboratories. The preliminary data showed that only 64% of the cardiologists used their personal dosimeters regularly and that only 36% were aware of their personal dose values. The data on pediatric interventional activity were collected from 10 centers from nine different countries. A total of 2,429 procedures (50% diagnostic and 50% therapeutic) were carried out during 2009 in these centers. Patient dose data were available in only a few centers and were not analyzed on a regular basis in any of the catheterization laboratories involved. Plans were developed for a basic QC protocol of the x-ray systems and construction of a Latin American database on pediatric cardiology with patient and staff dose values with the idea in mind of obtaining distributions of these dose values before promoting several optimization strategies.

Radiation dose and image quality for paediatric interventional cardiology systems. A national survey in Chile.

Radiation dose and image quality for paediatric protocols in all five X-ray fluoroscopy systems used for interventional cardiology procedures existing in Chile have been evaluated. Entrance surface air kerma (ESAK) and image quality using a test object (TO) and polymethyl methacrylate (PMMA) phantoms have been measured for the typical paediatric patient thicknesses (4-16 cm of PMMA). Images from fluoroscopy (low (FL), medium and high) and cine (CI) modes have been archived in DICOM format. Signal-to-noise ratio (SNR), figure of merit (FOM) and high-contrast spatial resolution (HCSR) have been computed from the images. The ratio between the maximum and the minimum value of ESAK per frame for a given fluoroscopy mode between the five systems ranges from 2 to 5 and from 14 to 38 for CI mode. SNR, FOM and HCSR showed a great variability for the different acquisition modes (AMs) and PMMA thickness. In the near future, it is urgent to upgrade Chilean legislation on radiation protection to incorporate quality assurance programmes that will allow us to evaluate and optimise the X-ray systems used in medical applications. Increments in doses per frame when increasing phantom thickness and when used CI runs instead of FL runs can be considered by the cardiologist in the good management of patient dose and allow them to select the best imaging AM during clinical procedures.

Scatter and staff dose levels in paediatric interventional cardiology: a multicentre study.

Interventional cardiology procedures usually imply high doses to the staff, as paediatric cardiologists need to stay closer to the patient than during adult procedures. Also, biplane systems are used that imply an additional source of staff doses. The objective of this paper is to measure scatter doses in four X-ray systems, using polymethyl methacrylate phantoms with thicknesses ranging from 4 to 16 cm to simulate paediatric patients, for the different acquisition modes. Scatter dose rates measured at the position of cardiologist's eyes ranged from 0.8 to 12 mSv h(-1), and about twice the above values at lower extremities, as a linear function of the surface air kerma at the phantom, keeping the irradiated area constant. Therefore, the respective personal dose equivalent for the lens of the eyes may be around 0.5 and 1 mSv throughout the procedure, if additional protection is not used. Simultaneous cine acquisition in biplane systems yielded scatter doses to cardiologists, increased by factors from 5 to 21, compared with a single C-arm acquisition case and depending on geometry. Knowledge of scatter doses for different operation modes, patient thicknesses and the biplane operation should help paediatric cardiologists to adopt conservative attitudes in respect of their occupational radiation risks.

Staff radiation doses in interventional cardiology: correlation with patient exposure.

In pediatric interventional cardiology, cardiologists need to stay closer to the patient than during adult catheterization, and the use of biplane systems increases the scatter radiation. Occupational radiation risk is rather high, and estimation of lens doses becomes necessary. Deriving factors for assessing these doses from the patient doses displayed in catheterization laboratories can help in preserving staff radiation safety. A biplane X-ray system and polymethylmethacrylate plates of 4 to 20 cm to simulate pediatric patients have been used. Patient entrance dose rates, dose-area product, and doses to the eyes of the cardiologists for the typical operation modes have been measured. Correlations between patient and staff doses have been obtained. Scatter dose rates increase by a factor of 92 from low fluoroscopy to cine acquisition when phantom thickness increases from 4 to 20 cm. Scatter doses increase linearly with dose-area product for all the thicknesses. Administration of 1 Gy x cm(2) to the patient involves 7 microSv to the eyes of the cardiologist (without extra protection). In conclusion, the experimental correlation factors found between phantom and scatter doses allow a fairly good estimation of staff doses from the dosimetric patient data.