Patient radiation doses in paediatric interventional cardiology procedures: a review

Current status of diagnostic reference levels in interventional cardiology

Interventional cardiology provides indisputable benefits for patients but uses a substantial amount of ionising radiation. The diagnostic reference level (DRL) is the tool recommended by the International Commission on Radiological Protection to optimise imaging procedures. In this work, a review of studies dealing with radiation dose or recommending DRL values for interventional cardiology since 2010 is presented, providing quantitative and qualitative results. There are many published papers on coronary angiography (CA) and percutaneous coronary intervention. The DRL values compiled for different continental regions are different: the DRL for CA is about 35 Gy cm²for Europe and 83 Gy cm²for North America. These differences emphasise the need to establish national DRLs considering different social and/or economic factors and the harmonisation of the survey methodology. Surveys with a large amount of data collected with the help of dose management systems provide more reliable information with less chance of statistical bias than those with a small amount of data. The complexity of procedures and improvements in technology are important factors that affect the radiation dose delivered to patients. There is a need for additional data on structural and electrophysiological procedures. The analysis of paediatric procedures is especially difficult because some studies present results split into age bands and others into weight bands. Diagnostic procedures are better described, but there is a great variety of therapeutic procedures with different DRL values (up to a factor of nine) and these require a dedicated review.

RADIATION DOSE FOR PATIENTS WITH KAWASAKI DISEASE UNDERGOING FLUOROSCOPICALLY GUIDED CARDIAC CATHETERIZATION

The goal of the present study was to estimate the radiation dose for a group of 45 Kawasaki disease (KD) patients undergoing fluoroscopically guided cardiac catheterization. The sample of procedures corresponds to a single hospital and was collected in 10 years. Anthropometric characteristics and the quantities of air kerma-area product (PKA) among others were recorded for each procedure. Monte Carlo PCXMC 2.0 software was used to estimate organ and effective doses. The PKA value of 7.2 Gy cm2 was proposed as the local Diagnostic Reference Level for KD. For organ absorbed doses, median values for thyroid, heart, lungs, esophagus, skin, active bone and breast were 1.2; 2.2; 4.6; 2.7; 1.1; 1.2 and 2.7 mGy, respectively. For effective dose, the mean value was 2.7 ± 2.5 mSv. This paper presents the first patient dose values for the KD using catheterization techniques, in Latin America and the Caribbean Region.

Potential risks of cardiovascular and cerebrovascular disease and cancer due to cumulative doses received from diagnostic CT scans?

Potential risks from radiation exposure on the development of cardiovascular and cerebrovascular disease are indicated by epidemiological studies. Medical exposures give the largest dose to the population from artificial sources, with cumulative doses from multiple CT scans being significant. Data on doses from scans performed on 12 CT scanners in three hospitals over a period of 5½ years, derived using Radimetrics^TMsoftware, have been reviewed for 105 757 patients. Data have been downloaded for heart, brain, thyroid, and effective doses, and cumulative doses analysed using Excel^TMspreadsheets. 2.4% of patients having body CT scans received cumulative doses to the heart over 100 mSv, 9% of whom were under 50 years. 9.6% of patients having head CT scans received cumulative doses to the brain over 100 mSv with 0.08% over 500 mSv from whom 41% were under 50 years, but only 1.3% of patients scanned had thyroid/carotid artery doses over 100 mSv. An approximate evaluation of potential risks from exposures of the heart above 100 mSv and brain over 500 mSv for patients under 60 years would suggest that at most only one patient would demonstrate any excess risk from vascular disease resulting from the exposures. 0.67% of patients scanned received effective doses over 100 mSv, in line with results from European studies, with 8.4% being under 50 years. The application of age and sex specific risk coefficients relating to excess cancer incidence suggests that two or three patients with effective doses over 100 mSv and five patients with effective doses between 50 and 100 mSv, from those examined, might develop cancer as a result of exposure. However, this will be an overestimate, since it does not take patients' health into account. Exposure management software can aid in evaluating cumulative doses and identifying individual patients receiving substantial doses from repetitive imaging.

EFFECTIVE DOSE IN PEDIATRIC INTERVENTIONAL CARDIOLOGY

The aim of this study was to estimate the effective doses (EDs) to children undergoing pediatric interventional cardiology examinations in hospitals of St.-Petersburg, to calculate associated dose conversion coefficients (DCCs) and to investigate their dependence of different parameters of the various procedures. Basic parameters of pediatric cardiology examinations and patient doses were studied in three main pediatric city hospitals. More than 300 examinations were under consideration. The technical, geometrical and dosimetric parameters, as well as patients' parameters, for each individual procedure were collected. All cardiac examinations were divided into five age groups (newborn, 1, 5, 10 and 15 y old). The EDs and the corresponding DCCs from the dose-area product to ED were calculated using PCXMC 2.0 software and based on the collected data. The study included the evaluation of the relations between the DCCs, patient age and parameters of examinations. The results of the study indicated significant dependence of the DCCs on the patients' age and the beam quality. The DCCs for the newborns and 15-year old groups differed by a factor of 10. The maximum estimated ED of 26 mSv was found in the newborn age group.

Ultra-Dense Denoising Network: Application to Cardiac Catheter-Based X-Ray Procedures

Reducing radiation dose in cardiac catheter-based X-ray procedures increases safety but also image noise and artifacts. Excessive noise and artifacts can compromise vital image information, which can affect clinical decision-making. Developing more effective X-ray denoising methodologies will be beneficial to both patients and healthcare professionals by allowing imaging at lower radiation dose without compromising image information. This paper proposes a framework based on a convolutional neural network (CNN), namely Ultra-Dense Denoising Network (UDDN), for low-dose X-ray image denoising. To promote feature extraction, we designed a novel residual block which establishes a solid correlation among multiple-path neural units via abundant cross connections in its representation enhancement section. Experiments on synthetic additive noise X-ray data show that the UDDN achieves statistically significant higher peak signal-to-noise ratio (PSNR) and structural similarity index measure (SSIM) than other comparative methods. We enhanced the clinical adaptability of our framework by training using normally-distributed noise and tested on clinical data taken from procedures at St. Thomas' hospital in London. The performance was assessed by using local SNR and by clinical voting using ten cardiologists. The results show that the UDDN outperforms the other comparative methods and is a promising solution to this challenging but clinically impactful task.

The 2019 Bo Lindell Laureate Lecture: On the use of interdisciplinary, stakeholder-driven, radiation protection research in support of medical uses of ionising radiation

Medical exposures form the largest manmade contributor to total ionising radiation exposure of the UK population. In recent years, new technologies have been developed to improve treatment and prognosis of individuals treated with radiation for diseases such as cancer. However, there is evidence of public, patient, and medical professional concern that radiation protection regulations and practices, as well as understanding of potential long-term adverse health effects of radiation exposure (in the context of other health risks), have not always 'kept pace' with technological developments in this field. This is a truly complex, multi-disciplinary problem for the modern world.The 'Radiation Theme' of the Public Health England and Newcastle University Health Protection Research Unit on 'Chemical and Radiation Threats and Hazards' is addressing this need, with a key focus on a genuinely interdisciplinary approach bringing together world-leading epidemiologists, radiation biologists, clinicians, statisticians, and artists. In addition, the project has a strong grounding in public, patient, and medical professional involvement in research. Similarly, the EU-CONCERT-funded LDLensRad project seeks to understand the mechanisms of action of low-dose ionising radiation in the lens of the eye, and the potential contribution to the development of cataract - in contemporary research, such projects will only be considered successful when they make use of expertise from a variety of fields and when they are able to demonstrate that the outputs are not only of benefit to society, but that society understands and welcomes the benefits. Finally, successful engagement, training, and retention of early career scientists within this field is crucial for sustainability of the research. Herein, the contribution of embedded interdisciplinary working, stakeholder involvement, and training of early career scientists to recent advancements in the field of medical (and wider) radiation protection research is discussed and considered.

Longitudinal Improvements in Radiation Exposure in Cardiac Catheterization for Congenital Heart Disease

Background:

The C3PO-QI (Congenital Cardiac Catheterization Project on Outcomes – Quality Improvement), a multicenter registry launched in 2015, instituted quality improvement (QI) initiatives to reduce patient radiation exposure. Through regular collaboration, this initiative would allow for harmony among active participants, maximizing efforts and efficiency at achieving radiation best practices. This study sought to report these efforts with a detailed methodology for which institutions can target initiatives, reducing radiation exposure, and increasing patient safety.

Methods:

Data were collected prospectively by 8 C3PO-QI institutions between January 1, 2015 and December 31, 2017. Radiation exposure was measured in dose area product per body weight (dose area product/kg; µGy*m 2 /kg) and reported by expected radiation exposure categories (REC) and institution for 40 published unique procedure types. Targeted interventions addressing selected strategic domains for radiation reduction were implemented in the pediatric catheterization labs of the C3PO-QI institutions.

Results:

The study consisted of 15 257 unique cases. Median exposure (dose area product/kg) was decreased by 30% for all procedures. Dose area product/kg was reduced in all 3 REC, with the greatest improvement observed in REC I (REC I, −37%; REC II, −23%; REC III, −27%). Although the baseline radiation exposures and exact percent decrease varied across all C3PO-QI sites, each institution demonstrated improvements in radiation dose over time. These improvements occurred with the implementation of institution-specific QI interventions accelerated by participation in the C3PO-QI multicenter collaborative.

Conclusions:

Substantial radiation dose reductions can be achieved using targeted QI methodology and interventions. Participation in a multicenter QI collaborative may accelerate improvement across all centers due to enhanced engagement and shared learning between sites.

Assessment of Patient Dose with Special Look at Pediatrics during Cardiovascular Imaging

Background

During interventional cardiology processes, patients especially women and children receive high radiation doses due to their sensitivity.

Objective

In this study, we evaluated a pediatric patient dose separately in those undergone intervention cardiac procedure.

Material and Methods

In this cross sectional study, a public hospital with 252 patients, Entrance Skin Dose (ESD) and Dose-Area Product (DAP) were recorded. Prior to the beginning of fluoroscopic procedure, the chest thickness and Body Mass Index (BMI) of patients were measured. Furthermore, kV, mAs, angle of tube and time of angiography and angioplasty were recorded.

Results

Children ratio to all patients underwent the cardiovascular imaging was 1.8. The means of patients' ESD, DAP and fluoroscopy time were 178.3±17 mGy, 1123.6±11 μGycm² and 281.4±181.2 s, respectively for coronary angiography. The females were 96.8 under 30 years and their dose mean was 276±37 mGy, 368±24 μGycm² for ESD and DAP received, respectively with 376s fluoroscopy time. Mean mAs was 359±34 and kV was 71.23±2.7. Above all, a direct and significant correlation was found between the patients' chest thickness with kV (p=0.037, r = 0.11) and mAs (p<0.001, r = 0.28) variations.

Conclusion

The results demonstrated that the number of children referred to the cardiology department and also the dose rate received by them during this test was higher than the data provided for children in developing countries. Paying attention to the children's perception of high-fluorescence time is necessary in comparison with total angiography time in order to reduce the number of radiation injuries among pediatrics.

Cardiac catheterization procedures in children with congenital heart disease: Increased chromosomal aberrations in peripheral lymphocytes

Cardiac catheterization procedures are performed on about 20,000 children with congenital heart disease (CHD) annually in China. The procedure, which involves exposure to ionizing radiation, causes DNA damage and may lead to increased cancer risk. We have studied chromosomal aberrations (CA) in peripheral lymphocytes of CHD children. CA frequencies were assessed in an interventional group of 70 children who underwent cardiac catheterization and a control group of 51 children receiving open-heart surgery. Total CA and all chromosome-type aberrations were higher in the exposed children than in the control group. With respect to the type of septal defect, the translocation frequency was higher in patients with ventricular rather than atrial defects. Cardiac catheterization procedures increase CA frequencies and may also increase the risk of cancer.

Diagnostic Reference Levels, Deterministic and Stochastic Risks in Pediatric Interventional Cardiology Procedures

To establish diagnostic reference levels (DRLs) and investigate deterministic and stochastic risks in pediatric interventional cardiology (IC) procedures. Exposure parameters were retrospectively reviewed for 373 patients treated between May 2016 and November 2018 at a single specialized hospital. Weight specific DRLs were derived for pediatric IC procedures. Additionally, peak skin dose (Dskin,max) was measured using thermoluminescent dosimeters for a sample of 7 diagnostic and 43 therapeutic procedures. Finally, using PCXMC software, organ doses were computed and the risk of exposure-induced cancer death (REID) was estimated using the risk models of the Biological Effects of Ionizing Radiation VII committee. DRLs for ventricular septal defect (VSD) occlusions, lacking in the literature, in terms of air kerma at patient entrance reference point (388 and 629 mGy) and total air kerma-area product (28 and 61 Gycm) were proposed for patients weight-groups 5 - < 15 kg and 15 - < 30 kg, respectively. The mean (range) Dskin,max was 15 (1-30) mGy and 94 (1-491) mGy for diagnostic and therapeutic procedures, respectively. Meanwhile, VSD occlusion involved the highest organ doses where the lungs, liver, stomach, and breasts mean doses were 57, 37, 6, and 10 mGy, respectively, and the associated REID were 0.5% and 0.3% in female and male patients, respectively. DRLs were proposed for pediatric IC procedures; these will help optimize patient exposure. Dskin,max values were lower than the 2 Gy threshold for skin injuries. Pediatric organ doses and the REID were the highest during VSD occlusion and may be critical for repetitive procedures.

Local DRLs and automated risk estimation in paediatric interventional cardiology

Introduction

Cardiac catheterization procedures result in high radiation doses and often multiple procedures are necessary for congenital heart disease patients. However, diagnostic reference levels (DRL) remain scarce. Our first goal was finding the optimal DRL parameter and determining appropriate DRLs. The second goal was to calculate organ doses (OD), effective doses (ED) and lifetime attributable risks (LAR) per procedure and to provide conversion factors based on dose area product (DAP).

Materials and methods

DRLs are calculated for each procedure type, as the 75^th percentile of the cumulative value per procedure from the corresponding parameter. All irradiation events in the DICOM Structured Reports were automatically processed and simulated using PCXMC, resulting in OD, ED and LAR. Using a Kruskal Wallis H test and subsequent pairwise comparisons, differences in median values of the DRL parameter between procedure types were assessed.

Results

Linear regression showed a strong correlation and narrow confidence interval between DAP and product of body weight and fluoroscopy time (BWxFT), even when all procedures (diagnostic and interventional) are combined. Only 15% of the pairwise comparisons were statistically significant for DAP normalized to BWxFT (DAP_BWxFT). The latter pairs contained less frequent procedure types with significant outliers. For DAP normalized to BW (DAP_BW), 38% of the pairwise comparisons showed statistically significant differences. Conversion factors from DAP_BW to OD and ED were reported for various weight groups, due to the higher correlation between DAP_BW and both OD and ED than between DAP and both OD and ED.

Conclusions

The P75 of DAP_BWxFT for all procedures combined serves as an appropriate DRL value. This facilitates local DRL determination in smaller paediatric centres, which often have insufficient data to produce appropriate DRLs for different procedure types. Conversion factors are more reliable starting from DAP_BW instead of DAP and should be used according to the appropriate BW group.

RADIATION DOSE TO PATIENTS IN CORONARY INTERVENTIONAL PROCEDURES: A SURVEY

The objective of this study was to evaluate dose-area product (DAP) and peak skin dose (PSD) for coronary angiography (CA) and percutaneous coronary intervention (PCI). The DAP and PSD of 300 randomly selected patients who were referred to CA and/or PCI, over a period of 3 months were recorded and analyzed. The mean DAP of 32 Gy cm2 and mean PSD of 412 mGy for CA were lower than 118 Gy cm2 and 857 mGy, respectively, for PCI. The DAP range of 2-84 Gy cm2 for CA and 12-378 mGy for PCI were also established. The maximum value of PSD for PCI procedures reached above the 2 Gy threshold for erythema. However, these values are similar to those available in literature. Periodic surveys may be required to monitor and/or reduce radiation doses in coronary interventional procedures.

Organ and effective doses detriment to paediatric patients undergoing multiple interventional cardiology procedures

The aims of the present study were to present the frequency of multiple interventional cardiac procedures for a certain group of patients obtained at one of the largest paediatric hospitals in Chile. In addition it has been analysed cumulative kerma area product (KAP) and cumulative air kerma (CAK), and calculated organ doses for the patient groups undergoing 2, 3 and ≥ 4 procedures, using Monte Carlo software. Effective doses were also estimated for epidemiological purposes and to permit comparison with other imaging procedures. The sample used corresponds to the last 9 years and refers to a total of 1521 paediatric patients and 1824 interventional cardiac procedures. The results for frequency were: 13.7% of patients underwent 2 procedures, 4.1% underwent 3 procedures and 1.4% underwent 4 or more procedures. The median KAP and CAK values measured for the cumulative procedures in these three groups of patients were 3.7, 5.4 and 10.8 Gy·cm² and 59.9, 83.2 and 147.6 mGy, respectively. In terms of the most irradiated organs during interventional cardiac procedures, the highest median values (for the group of ≥4 procedures) were: active bone marrow 5.0 mGy, lungs 23.5 mGy, oesophagus 15.2 mGy, thyroid 7.8 mGy and breast 11.0 mGy. Median dose value to the heart (for the group of ≥4 procedures) was 12.7 mGy. Median values in terms of calculated effective dose for the three patient groups (with 2, 3 and ≥4 procedures) were 3.4, 5.9 and 8.7 mSv, respectively.

Reducing Radiation Exposure in Cardiac Catheterizations for Congenital Heart Disease

Ionizing radiation exposure is a necessary risk entailed during congenital cardiac catheterizations. The congenital catheterization lab at Yale New Haven Children's Hospital employed quality improvement strategies to minimize radiation exposure in this vulnerable population. In two phases, we implemented six interventions, which included adding and utilizing lower fluoroscopy and digital angiography (DA) doses, increasing staff and physician radiation awareness, focusing on tighter collimation, and changing the default fluoroscopy and DA doses to lower settings. Post-intervention data were collected prospectively for all procedures in the congenital catheterization lab and compared to pre-intervention radiation data collected retrospectively. Radiation exposure was measured in total air kerma (mGy), dose area product per body weight (DAP/kg) (µGy m²/kg), and fluoroscopy time (min). Data were collected for a total of 312 cases. In considering all procedures, the DAP/kg decreased by 67.6% and air kerma decreased by 63%. Fluoroscopy time did not change over the study period. Significant decreases in radiation exposure (DAP/kg) by procedure type were seen for atrial septal defect, patent ductus arteriosus, and transcatheter pulmonary valve procedures with a 45%, 42% and 83% decrease, respectively. Air kerma decreased significantly for ASD and PDA procedures with an 80% and 72% decrease, respectively. When compared to national benchmarks, the median DAP/kg and air kerma for these procedures are lower at our institution. The decreases continue to be sustained 2 years post-interventions. Systems-based interventions can be readily implemented in the congenital cardiac catheterization lab with dramatic and sustainable radiation dose reduction for patients.

Towards the definition of Institutional diagnostic reference levels in paediatric interventional cardiology procedures in Greece

This study aimed to evaluate paediatric radiation doses in a dedicated cardiology hospital, with the objective of characterising patterns in dose variation. The ultimate purpose was to define Local (Institutional) Diagnostic Reference Levels (LDRLs) for different types of paediatric cardiac interventional procedures (IC), according to patient age. From a total of 710 cases performed during three consecutive years, by operators with more than 15 years of experience, the age was noted in only 477 IC procedures. The median values obtained for Fluoroscopy Time (FT), Number of Frames (N) and Kerma Area Product (P_KA) by age range were 5.8 min, 1322 and 2.0 Gy.cm² for <1 y; 6.5 min, 1403 and 3.0 Gy.cm² for 1 to <5 y; 5.9 min, 950 and 7.0 Gy.cm² for 5 to <10 y; 5.7 min, 940 and 14.0 Gy.cm² for 10 to <16 y, respectively. A large range of patient dose data is observed, depending greatly on procedure type and patient age. In all age groups the range of median FT, N and P_KA values was 3.1-15.8 min, 579-1779 and 1.0-20.8 Gy.cm² respectively. Consequently, the definition of LDRLs presents challenges mainly due to the multiple clinical and technical factors affecting the outcome. On the other hand the lack of paediatric IC DRLs makes the identification of good practices more difficult. A consensus is needed on IC procedures nomenclature and grouping in order to allow a common assessment and comparison of doses.

THE IMPACT OF DIGITAL TECHNOLOGY ON DOSE REDUCTION IN PAEDIATRIC CARDIAC CATHETERISATION WITHIN A LARGE METROPOLITAN CHILDREN'S HOSPITAL

This study examines the kerma-area product (PKA) levels from paediatric cardiac catheterisations at a major Children's Hospital over three different time periods in order to gain an understanding of the causation of dose variations over time and to present a model for dose reduction. A retrospective review of 1245 paediatric procedural records was undertaken. This cohort consisted of patients that were catheterised over a period from November 2007 to July 2009, October 2009 to November 2011 and January 2016 to December 2016. The age distribution was from newborn to 18 years. Archived (PKA) readings were retrieved and analysed. The 75th percentile PKA values for the specific age categories over time periods (1, 2, 3) were 0-30 days-(5.47, 1.37, 1.37) Gy cm2; 1-12 months-(6.42, 2.03, 1.06) Gy cm2; 1-3 years-(11.25, 3.20, 1.25) Gy cm2; 3-5 years-(12.65, 3.72, 2.88) Gy cm2; 5-10 years-(12.80, 8.53, 3.52) Gy cm2; 10-15 years-(27.92, 10.85, 2.97) Gy cm2; >15 years-(29.09, 27.81, 11.65) Gy cm2. Using newer imaging technologies, optimising dose reduction strategies and regular dose auditing can transform radiation dose delivery for paediatric x-ray examinations. Our centre provides a template for dose reduction success worldwide.

Radiation exposure in transcatheter patent ductus arteriosus closure: time to tune?

OBJECTIVES

The aims of this study were to describe radiation level at our institution during transcatheter patent ductus arteriosus occlusion and to evaluate the components contributing to radiation exposure.

BACKGROUND

Transcatheter occlusion relying on X-ray imaging has become the treatment of choice for patients with patent ductus arteriosus. Interventionists now work hard to minimise radiation exposure in order to reduce risk of induced cancers.

METHODS

We retrospectively reviewed all consecutive children who underwent transcatheter closure of patent ductus arteriosus from January 2012 to January 2016. Clinical data, anatomical characteristics, and catheterisation procedure parameters were reported. Radiation doses were analysed for the following variables: total air kerma, mGy; dose area product, Gy.cm2; dose area product per body weight, Gy.cm2/kg; and total fluoroscopic time.

RESULTS

A total of 324 patients were included (median age=1.51 [Q1-Q3: 0.62-4.23] years; weight=10.3 [6.7-17.0] kg). In all, 322/324 (99.4%) procedures were successful. The median radiation doses were as follows: total air kerma: 26 (14.5-49.3) mGy; dose area product: 1.01 (0.56-2.24) Gy.cm2; dose area product/kg: 0.106 (0.061-0.185) Gy.cm2/kg; and fluoroscopic time: 2.8 (2-4) min. In multivariate analysis, a weight >10 kg, a ductus arteriosus width <2 mm, complications during the procedure, and a high frame rate (15 frames/second) were risk factors for an increased exposure.

CONCLUSION

Lower doses of radiation can be achieved with subsequent recommendations: technical improvement, frame rate reduction, avoidance of biplane cineangiograms, use of stored fluoroscopy as much as possible, and limitation of fluoroscopic time. A greater use of echocardiography might even lessen the exposure.

Radiation dose and risk in children undergoing cardiac interventions performed using flat detector angiography systems

The purpose of the study was to measure radiation doses and estimate risk from various beam projections in children undergoing cardiac interventions. The dose area product (DAP) was measured for eleven patent ductus arteriosus device closures (PDA), four atrial septal defect device closures (ASD), and three balloon pulmonary valvuloplasty (BPV) interventions performed using a flat detector system. The total mean DAPs for PDA, ASD and BPV were 1.9 Gycm², 9.8 Gycm² and 6.2 Gycm² respectively. The fluoroscopic kerma dose rates increased by 10%, 33% and 92% when changing the projection from posterior-anterior to lateral projection for PDA interventions among infants, <5 yrs and >5 yrs respectively. The effective dose (ED) and organ doses were estimated from DAP using Monte Carlo software. Lungs received the highest organ dose of 7.4 mGy (PDA), 20.7 mGy (ASD) and 17.3 mGy (BPV) compared to other organs. The mean EDs from PDA, ASD and BPV were 2.5 mSv, 6.1 mSv and 4.9 mSv respectively. PDA intervention performed in infants had a radiation risk 66% higher than children aged between 3-10 years. Their lifetime attributable risk as per BEIR VII for cancer incidence was 1 in 907 males and 1 in 1047 females.

Organ and effective doses from paediatric interventional cardiology procedures in Chile

The aim of this study was to present the results of organ and effective doses for paediatric patients for different types of interventional cardiology procedures for age and weight groups, derived from a patient dosimetry pilot programme carried out in Chile, under the auspices of the International Atomic Energy Agency. Over seven years, a retrospective collection of demographic and patient dose data was obtained: age, gender, weight, height, number of cine series, total number of cine frames, fluoroscopy time, dose-area product (DAP) and cumulative dose at patient entrance reference point. Monte Carlo software was used to calculate organ and effective doses. 1506 procedures were divided into four age and seven weight groups. Organ doses (median values) for diagnostic and therapeutic procedures were: active bone marrow 0.90 and 0.64mGy; heart 1.99 and 1.46mGy; lungs 3.56 and 2.59mGy; thyroid 1.27 and 0.83; and breast (in the case of females) 1.78 and 1.36mGy. The ranges for effective doses (median values) and weight bands were 1.2-3.9mSv for diagnostic procedures and 1.0-2.5mSv for therapeutic procedures. The resulting conversion factors (median values) to estimate effective dose from DAP (in mSv/Gy.cm2) were: 1.70; 0.89; 0.58; and 0.40, for age groups of <1year, 1-<5years, 5-<10years and 10-<16years, respectively. The obtained set of dose values will enable comparisons with other imaging procedures (comparing the same age bands) for justification and optimization purposes.