Patient-Specific Dose and Radiation Risk Estimation in Pediatric Cardiac Catheterization

Implementing Patient Protection Radiation Dose Alerts for Pediatric Cardiac Catheterization Examinations

Background

Advancements in cardiac catheterization have improved survival for pediatric congenital heart disease patients, but the associated ionizing radiation risks necessitate ethical consideration.

Methods

This study presents an empirical model, developed from 3131 unique pediatric procedures, to establish alert levels based on a patient's lateral thickness of the thorax for various procedural categories during diagnostic or interventional cardiac catheterization. The model uses linear regression of logarithmic reference air kinetic energy released per unit mass (KERMA) and air KERMA area product, also referred to as dose area product, to set alert levels at the top 95% and 99% of patient data.

Results

Coefficients of the regression fits are provided for diagnostic and interventional procedural groups and fluoroscopic plane allowing any facility to scale the results of this study's single facility data to model their practice's unique procedural dose levels.

Conclusions

The proposed method allows institutions to tailor dose alert levels to their specific pediatric populations to reduce overexposure events.

Standardized diagnostic reference levels for paediatric interventional cardiology: Data from an Italian referral centre

PURPOSE

To provide data on radiation exposure in paediatric interventional cardiology procedures, addressing the scarcity of valuable Local Diagnostic Reference Levels (LDRLs),established according to the standardized approach proposed by the Radiation Protection 185 report (RP185).

METHODS

Paediatric catheterization procedures conducted at the University-Hospital of Padua from September 2019 to December 2022 were stratified by body weight (BW) classes and procedure type. LDRLs were calculated for groups with at least 20 patients as the 75th percentile of Kerma-Area Product (PKA) and Air Kerma at reference point (Ka,r) values. Kruskal-Wallis test was applied to evaluate differences in the dose-related quantities among BW groups for a selected procedure and among procedures for the same BW class. Results were compared with recent literature.

RESULTS

A total of 838 procedures were analysed. LDRL were provided for five therapeutic procedures. The 75th percentile of PKA and Ka,r increases with weight, regardless procedure type. PKA and Ka,r are generally statistically different between BW groups, for both diagnostic and therapeutic procedures, and between different procedures at fixed weight group. Angioplasty and Right Ventricular Outflow Tract treatments (PVR) showed exposure values approximately doubled then other procedures. PKA/(BW·FT) is not statistically different among procedures except for Atrial Septal Defect (ASD) closures. LDRL values from this study are generally lower than the published ones.

CONCLUSIONS

The study stands out as one of the few that presents a considerable number of LDRLs for weight categories and procedure types with a sample size of at least 20 patients per group, in agreement with RP185. PKA shows strong correlation with the product BW·FT.

The effect of electro-anatomical mapping on the success rate and fluoroscopy time in supra-ventricular tachycardia ablation in children: single centre retrospective study

AIMS

To evaluate the effect of electro-anatomical mapping on success rate and fluoroscopy time in ablation of supraventricular tachycardia substrates in a large group of children.

METHODS

Patients referred from multiple centres in the Netherlands and who received a first ablation for supraventricular tachycardia substrates in the Leiden University Medical Center between 2014 and 2020 were included in this retrospective cohort study. They were divided in procedures in patients with fluoroscopy and procedures in patients using electro-anatomical mapping.

RESULTS

Outcomes of ablation of 373 electro-anatomical substrates were analysed. Acute success rate in the fluoro-group (n = 170) was 95.9% compared to 94.5% in the electro-anatomical mapping group (n = 181) (p = 0.539); recurrence rate was 6.1% in the fluoro-group and 6.4% in the electro-anatomical mapping group (p = 0.911) after a 12-months follow-up. Redo-ablations were performed in 12 cases in the fluoro-group and 10 cases in the electro-anatomical mapping group, with a success rate of 83.3% versus 80.0%, resulting in an overall success rate of 95.9% in the fluoro-group and 92.8% in the electro-anatomical mapping group (p = 0.216) after 12 months. Fluoroscopy time and dose area product decreased significantly from 16.00 ± 17.75 minutes (median ± interquartile range) to 2.00 ± 3.00 minutes (p = 0.000) and 210.5 µGym2 ± 249.3 to 32.9 µGym2 ± 78.6 (p = 0.000), respectively. In the fluoro-group, four complications occurred (2.0%) and in the electro-anatomical mapping group no complications occurred.

CONCLUSION

These results demonstrate that ablations of supraventricular tachycardia substrates in children remain a highly effective and safe treatment after the introduction of electro-anatomical mapping as a standard of care, while significantly reducing fluoroscopy time and dose area product.

X-ray Doses in Relation to Body Mass, Indication, and Substrate During Pediatric Electrophysiological Procedures on the Heart

The main goal of this study is to determine typical values of dose area product (DAP) and difference in the effective dose (ED) for pediatric electrophysiological procedures on the heart in relation to patient body mass. This paper also shows DAP and ED in relation to the indication, the arrhythmia substrate determined during the procedure, and in relation to the reason for using radiation. Organ doses are described as well. The subjects were children who have had an electrophysiological study done with a 3D mapping system and X-rays in two healthcare institutions. Children with congenital heart defects were excluded. There were 347 children included. Significant difference was noted between mass groups, while heavier children had higher values of DAP and ED. Median DAP in different mass groups was between 4.00 (IQR 1.00-14.00) to 26.33 (IQR 8.77-140.84) cGycm2. ED median was between 23.18 (IQR 5.21-67.70) to 60.96 (IQR 20.64-394.04) µSv. The highest DAP and ED in relation to indication were noted for premature ventricular contractions and ventricular tachycardia-27.65 (IQR 12.91-75.0) cGycm2 and 100.73 (IQR 53.31-258.10) µSv, respectively. In arrhythmia substrate groups, results were similar, and the highest doses were in ventricular substrates with DAP 29.62 (IQR 13.81-76.0) cGycm2 and ED 103.15 (IQR 60.78-266.99) µSv. Pediatric electrophysiology can be done with very low doses of X-rays when using 3D mapping systems compared to X-rays-based electrophysiology, or when compared to pediatric interventional cardiology or adult electrophysiology.

Multimodality 3D image fusion with live fluoroscopy reduces radiation dose during catheterization of congenital heart defects

Introduction

Imaging fusion technology is promising as it is radiation and contrast sparing. Herein, we compare conventional biplane angiography to multimodality image fusion with live fluoroscopy using two-dimensional (2D)-three-dimensional (3D) registration (MMIF2D-3D) and assess MMIF2D-3D impact on radiation exposure and contrast volume during cardiac catheterization of patients with congenital heart disease (CHD).

Methods

We matched institutional MMIF2D-3D procedures and controls according to patient characteristics (body mass index, age, and gender) and the seven procedure-type subgroups. Then, we matched the number of tests and controls per subgroup using chronological ordering or propensity score matching. Subsequently, we combined the matched subgroups into larger subgroups of similar procedure type, keeping subgroups with at least 10 test and 10 control cases. Air kerma (AK) and dose area product (DAP) were normalized by body weight (BW), product of body weight and fluoroscopy time (BW × FT), or product of body weight and number of frames (BW × FR), and stratified by acquisition plane and irradiation event type (fluoroscopy or acquisition). Three senior interventionists evaluated the relevance of MMIF2D-3D (5-point Likert scale).

Results

The Overall group consisted of 54 MMIF2D-3D cases. The combined and matched subgroups were pulmonary artery stenting (StentPUL), aorta angioplasty (PlastyAO), pulmonary artery angioplasty (PlastyPUL), or a combination of the latter two (Plasty). The FT of the lateral plane reduced significantly by 69.6% for the Overall MMIF2D-3D population. AKBW and DAPBW decreased, respectively, by 43.9% and 39.3% (Overall group), 49.3% and 54.9% (PlastyAO), and 36.7% and 44.4% for the Plasty subgroup. All the aforementioned reductions were statistically significant except for DAPBW in the Overall and Plasty (sub)groups. The decrease of AKBW and DAPBW in the StentPUL and PlastyPUL subgroups was not statistically significant. The decrease in the median values of the weight-normalized contrast volume (CMCBW) in all five subgroups was not significant. Cardiologists considered MMIF2D-3D very useful with a median score of 4.

Conclusion

In our institution, MMIF2D-3D overall enabled significant AKBW reduction during the catheterization of CHD patients and was mainly driven by reduced FT in the lateral plane. We observed significant AKBW reduction in the Plasty and PlastyAO subgroups and DAPBW reduction in the PlastyAO subgroup. However, the decrease in CMCBW was not significant.

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.

Optimization of Radiation Protection in Pediatric Interventional Radiology in Latin America and the Caribbean: Development, Advancements, Challenges and Achievements of the OPRIPALC Program

This article presents the development, advancements, challenges and achievements of the "Optimization of Protection in Pediatric Interventional Radiology in Latin America and the Caribbean" (OPRIPALC) program. This international initiative is led by the World Health Organization, the Pan American Health Organization and the International Atomic Energy Agency. The main objectives of OPRIPALC are to foster a culture of radiological protection in pediatric interventions, enhance these procedures' quality, and define optimization strategies such as the use of diagnostic reference levels (DRLs). Currently, 33 centers from 12 countries participate actively in the program. Significant progress has been made towards the proposed objectives, overcoming the challenges posed by the COVID-19 pandemic. Through many virtual meetings for coordination, planning, training and follow-up, a comprehensive set of DRLs for both diagnostic and therapeutic procedures, categorized by weight and age, have been established and are in use. A consensus document on good practices is in the final stage of development. The program's continuation into at least a second phase is essential to address pending issues, including the integration of automatic dose management systems, the levels of occupational radiation doses, their correlation with pediatric patient doses, and strategies to reduce them.

Percutaneous closure of simple congenital heart diseases under echocardiographic guidance

Congenital heart disease (CHD), birth defect with the highest incidence rates worldwide, and is mainly characterized by the abnormal internal structure of the heart or/and the anatomical structure of great vessels. In the past few decades, CHD repair surgery through standard median sternotomy incision combined with cardiopulmonary bypass (CPB) technology has been considered the gold standard for surgical correction of heart and great vessels. With the promotion and clinical application of interventional catheterization technology, transcatheter closure of CHD under radioactive radiation has gradually been recognized and applied. However, its radiation exposure and potential complications related to arteriovenous vessels still face challenges. In recent years, an increasing number of surgeons have explored new surgical procedures, for the safe and effective treatment of CHD, as far as possible to reduce surgical trauma, avoid radiation exposure, and improve the cosmetic effect. Therefore, on the premise of satisfactory exposure or guidance, how to integrate ultrasound and percutaneous interventional technology remained the focus of the exploration. This mini-review highlights and summarizes the signs of progress of ultrasound intervention in the last decade that have proven the effectiveness and operability of a well-established procedure for percutaneous closure of congenital heart diseases under echocardiographic guidance only. We discuss potential diseases that will benefit from this emerging procedure based on this progress. Owing to the crucial advantages played by this strategy in the treatment of CHD, better understanding and promotion of this less exploited field may contribute to the development of therapeutics targeting CHD, improve medical utilization rate, promote the optimization of medical resources, and ultimately achieve precise and efficient medical treatment.

Radiation dose analysis of computed tomography coronary angiography in Children with Kawasaki disease

BACKGROUND

There is evolving role of computed tomography coronary angiography (CTCA) in non-invasive evaluation of coronary artery abnormalities in children with Kawasaki disease (KD). Despite this, there is lack of data on radiation dose in this group of children undergoing CTCA.

AIM

To audit the radiation dose of CTCA in children with KD.

METHODS

Study (December 2013-February 2018) was performed on dual source CT scanner using adaptive prospective electrocardiography-triggering. The dose length product (DLP in milligray-centimeters-mGy.cm) was recorded. Effective radiation dose (millisieverts-mSv) was calculated by applying appropriate age adjusted conversion factors as per recommendations of International Commission on Radiological Protection. Radiation dose was compared across the groups (0-1, 1-5, 5-10, and > 10 years).

RESULTS

Eighty-five children (71 boys, 14 girls) with KD underwent CTCA. The median age was 5 years (range, 2 mo-11 years). Median DLP and effective dose was 21 mGy.cm, interquartile ranges (IQR) = 15 (13, 28) and 0.83 mSv, IQR = 0.33 (0.68, 1.01) respectively. Mean DLP increased significantly across the age groups. Mean effective dose in infants (0.63 mSv) was significantly lower than the other age groups (1-5 years 0.85 mSv, 5-10 years 1.04 mSv, and > 10 years 1.38 mSv) (P < 0.05). There was no significant difference in the effective dose between the other groups of children. All the CTCA studies were of diagnostic quality. No child required a repeat examination.

CONCLUSION

CTCA is feasible with submillisievert radiation dose in most children with KD. Thus, CTCA has the potential to be an important adjunctive imaging modality in children with KD.

New Optimization Strategies on Radiation Protection in Fluoroscopy-Guided Interventional Procedures in Pediatrics

The term fluoroscopically guided interventional procedure describes a clinical practice in medicine, where fluoroscopic systems are used to conduct diagnostic procedures or provide image guidance for therapeutic interventional procedures performed via percutaneous or other access routes [...].

Setting up regional diagnostic reference levels for pediatric interventional cardiology in Latin America and the Caribbean countries: preliminary results and identified challenges

The goal of the present study was to propose a set of preliminary regional diagnostic reference levels (DRLs) for pediatric interventional cardiology (IC) procedures in Latin America and the Caribbean countries, classified by age and weight groups. The study was conducted in the framework of the Optimization of Protection in Pediatric Interventional Radiology in Latin America and the Caribbean program coordinated by the World Health Organization and the Pan American Health Organization in cooperation with the International Atomic Energy Agency. The first step of the program was focused on pediatric IC. Dose data from diagnostic and therapeutic procedures were collected between December 2020 and December 2021. Regional DRLs were set as the third quartile of patient dose data (kerma area product) collected in 18 hospitals from 10 countries in an initial sample of 968 procedures. DRLs were set for four age bands and five weight ranges. The values obtained for the four age bands (<1 yr, 1 to <5 yr, 5 to <10 yr and 10 to <16 yr) were 2.9, 6.1, 8.8 and 14.4 Gy cm²for diagnostic procedures, and 4.0, 5.0, 10.0 and 38.1 Gy cm²for therapeutic procedures, respectively. The values obtained for the five weight bands (<5 kg, 5 to <15 kg, 15 to <30 kg, 30 to <50 kg and 50 to <80 kg) were 3.0, 4.5, 8.1, 9.2 and 26.8 Gy cm²for diagnostic procedures and 3.7, 4,3, 7.3, 16.1 and 53.4 Gy cm²for therapeutic procedures, respectively. While initial data were collected manually as patient dose management systems (DMSs) were not available in most of the hospitals involved in the program, a centralized automatic DMS for the collection and management of patient dose indicators has now been introduced and is envisaged to increase the sample size. The possibility of alerting on high dose values and introducing corrective actions will help in optimization.

Improved catheter tracking during cardiovascular magnetic resonance-guided cardiac catheterization using overlay visualization

INTRODUCTION

Cardiovascular magnetic resonance (CMR)-guided cardiac catheterization is becoming more widespread due to the ability to acquire both functional CMR measurements and diagnostic catheterization data without exposing patients to ionizing radiation. However, the real-time imaging sequences used for catheter guidance during these procedures are limited in resolution and the anatomical detail they can provide. In this study, we propose a passive catheter tracking approach which simultaneously improves catheter tracking and visualization of the anatomy.

METHODS

60 patients with congenital heart disease underwent CMR-guided cardiac catheterization on a 1.5T CMR scanner (Ingenia, Philips Healthcare, Best the Netherlands) using the Philips iSuite system. The proposed T1-overlay technique uses a commercially available heavily T1-weighted sequence to image the catheter, and overlays it on a high-resolution 3D dataset within iSuite in real-time. Suppressed tissue in the real-time images enables the use of a thick imaging slab to assist in tracking of the catheter. Improvement in catheter visualization time was compared between T1-overlay and the conventional invasive CMR (iCMR) balanced steady state free precession (bSSFP) sequence. This technique also enabled selective angiography visualization for real-time evaluation of blood flow dynamics (such as pulmonary transit time), similar to direct contrast injection under standard fluoroscopy. Estimates of pulmonary transit time using iCMR were validated using x-ray fluoroscopy in 16 patients.

RESULTS

The T1-overlay approach significantly increased the time that the catheter tip was kept in view by the technologist compared to the bSSFP sequence conventionally used for iCMR. The resulting images received higher ratings for blood/balloon contrast, anatomy visualization, and overall suitability for iCMR guidance by three cardiologists. iCMR selective angiography using T1-overlay also provided accurate estimates of pulmonary transit time that agreed well with x-ray fluoroscopy.

CONCLUSION

We demonstrate a new passive catheter tracking technique using the iSuite platform that improves visualization of the catheter and cardiac anatomy. These improvements significantly increase the time that the catheter tip is seen throughout the procedure. We also demonstrate the feasibility of iCMR selective angiography for the measurement of pulmonary transit time.

Fluoroscopy-free ablation in congenital heart disease of moderate or great complexity

BACKGROUND

Fluoroscopy-free (FF) ablation has been demonstrated to be safe and successful in patients with structurally normal hearts, but has not been systematically evaluated in patients with congenital heart disease (CHD) of moderate or great (M/G) complexity. This study aimed to evaluate and compare feasibility, safety, and outcomes of FF ablation in patients with or without M/G-CHD.

METHODS

Consecutive patients undergoing electrophysiologic study and intended catheter ablation over a 24-month period were included. Subgroups were created based on presence and complexity of CHD-M/G-CHD or simple complexity/no CHD (S/N-CHD). Cases with total radiation dose of zero qualified as FF. Demographic and peri-procedural variables and outcome data were analyzed.

RESULTS

A total of 89 procedures were included with 62 comprising the S/N-CHD group and 27 comprising the M/G-CHD group. Of the M/G-CHD patients, 13 had CHD of great complexity (including 6 single ventricle/Fontan and 2 atrial switch patients). Patients with M/G-CHD were older, had higher BMI, had higher incidence of ventricular dysfunction, and greater incidence of complex arrhythmias. Fluoroscopy-free ablation was achieved in 59% of M/G-CHD and 69% of S/N-CHD patients. Both groups had similar rates of acute procedural success, recurrence, and complications. Fluoroscopy was primarily used to visualize pre-existing transvenous leads and peripheral venous anomalies or to guide transbaffle/transseptal puncture.

CONCLUSIONS

A fluoroscopy-free ablation approach is feasible, safe, and successful even in patients with M/G-CHD with comparable outcomes to those with S/N-CHD.

Model-based iterative reconstruction for 320-detector row CT angiography reduces radiation exposure in infants with complex congenital heart disease

PURPOSE

We investigated the impact of model-based iterative reconstruction (MBIR) on 320-detector row computed tomography angiography (CTA) in infants with complex congenital heart disease (CHD).

METHODS

Seventy infants with complex CHD who underwent 320-detector row CTA (40 boys and 30 girls; age range, 0-22 months; median age, 60 days) were retrospectively evaluated. First, the images were reconstructed by filtered back projection (FBP), hybrid iterative reconstruction (HIR), or MBIR in 20 cases, and variables were compared among the three iterative reconstruction methods (IR test). Second, the variables were compared between 25 cases scanned using HIR and 25 cases scanned using MBIR, with a 20 standard deviation noise level for both. Attenuation values and contrast-to-noise ratios (CNRs) of the great vessels and heart chambers were calculated. Total dose-length products were recorded for all patients (radiation dose: RD test).

RESULTS

In the IR test, the mean CNR values were 4.8±1.3 for FBP, 6.9±1.4 for HIR, and 8.2±1.7 for MBIR (P < 0.0001). The best subjective image qualities in the great vessels and heart chambers were obtained with MBIR. In RD testing, no significant differences between HIR and MBIR in image quality (CNR: HIR, 8.4±2.4; MBIR, 8.3±2.4) were observed. The effective dose was significantly lower for MBIR than for HIR (0.7±0.2 vs. 1.1±0.3 mSv; P < 0.001).

CONCLUSION

The MBIR algorithm significantly improved image quality and decreased radiation exposure in 320-row CTA of infants with complex CHD, providing an alternative to FBP or HIR that is both safer and produces better results.

Radiation Exposure in Pediatric Interventional Procedures

The article is part of the series of articles on radiation protection. You can find further articles in the special section of the CVIR issue. The expanding applications of interventional procedures coupled with the potential harmful effects of ionizing radiation highlight the need to assess the delivered radiation dose and establish an effective radiation protection program, particularly in the radiosensitive pediatric population. Given the complexity and heterogeneity of interventional procedures as well as the unique characteristics of children, the management of radiation dose is proving to be quite challenging. The aim of the current article is to provide an overview of the radiation exposure in pediatric patients during interventional procedures focusing on the importance of radiation protection in the pediatric population, the reported radiation doses and the techniques of minimizing radiation dose.

Monte Carlo-based patient internal dosimetry in fluoroscopy-guided interventional procedures: A review

PURPOSE

This systematic review aims to understand the dose estimation approaches and their major challenges. Specifically, we focused on state-of-the-art Monte Carlo (MC) methods in fluoroscopy-guided interventional procedures.

METHODS

All relevant studies were identified through keyword searches in electronic databases from inception until September 2020. The searched publications were reviewed, categorised and analysed based on their respective methodology.

RESULTS

Hundred and one publications were identified which utilised existing MC-based applications/programs or customised MC simulations. Two outstanding challenges were identified that contribute to uncertainties in the virtual simulation reconstruction. The first challenge involves the use of anatomical models to represent individuals. Currently, phantom libraries best balance the needs of clinical practicality with those of specificity. However, mismatches of anatomical variations including body size and organ shape can create significant discrepancies in dose estimations. The second challenge is that the exact positioning of the patient relative to the beam is generally unknown. Most dose prediction models assume the patient is located centrally on the examination couch, which can lead to significant errors.

CONCLUSION

The continuing rise of computing power suggests a near future where MC methods become practical for routine clinical dosimetry. Dynamic, deformable phantoms help to improve patient specificity, but at present are only limited to adjustment of gross body volume. Dynamic internal organ displacement or reshaping is likely the next logical frontier. Image-based alignment is probably the most promising solution to enable this, but it must be automated to be clinically practical.

Percutaneous closure of ventricular septal defects in children: key parameters affecting patient radiation exposure

BACKGROUND

Ventricular septal defect (VSD) transcatheter closure is gaining worldwide popularity despite its complexity. Reports on key factors affecting radiation exposure in children are scarce.

AIMS

This clinical study is the first to comprehensively analyze the impact of all relevant parameters on children's radiation exposure during VSD interventional closures.

METHODS

Between March 2016 and August 2019, all pediatric VSD cases percutaneously treated at a reference center for interventional congenital cardiology and equipped with a single-plane Innova 2100 X-ray unit were retrospectively reviewed. Multiple linear regression was performed to investigate the impact of clinical, technical, and procedural parameters on patients' radiation exposure assessed using total air kerma area product (PKA,T).

RESULTS

A total of 85 patients were included in this study and 82.4% had perimembranous defects. Device implantation was successful in 96.5% of cases. The procedure lasted for a median of 60 min with a median PKA,T of 19.6 Gy.cm2 (range, 1.1 to 244.8 Gy.cm2). Patients' weight (B = 1.679, P = 0.01), number of operators (B = 1.561, P = 0.02), device positioning complexity (B = 2.381, P = 0.002), and procedural incidents (B = 2.096, P = 0.008) significantly increased PKA,T. Patients' age (B = 1.053, P = 0.784), device design (B = -1.216, P = 0.780) and approach of delivery (B = -1.119, P = 0.511) did not significantly affect PKA,T.

CONCLUSIONS

Radiation exposure in children undergoing VSD percutaneous closure was highly variable. A higher patient's weight, numbers of operators, complexity in device positioning, and procedural incidents, were identified as key factors increasing patient dose for this kind of intervention.

Reducing the Breast Cancer Risk and Radiation Dose of Radiography for Scoliosis in Children: A Phantom Study

Full-spinal radiographs (FRs) are often the first choice of imaging modality in the investigation of scoliosis. However, FRs are strongly related to breast cancer occurrence due to multiple large-field radiographic examinations taken during childhood and adolescence, which may increase the risk for breast cancer in adulthood among women with scoliosis. The purpose of this study was to consider various technical parameters to reduce the patient radiation dose of FRs for scoliosis. To evaluate breast surface doses (BSDs) in FRs, radio photoluminescence dosimeters were placed in contact with a child phantom. Using the PC-based Monte Carlo (PMC) program for calculating patient doses in medical X-ray examinations, the breast organ dose (BOD) and the effective dose were calculated by performing Monte Carlo simulations using mathematical phantom models. The BSDs in the posteroanterior (PA) view were 0.15-0.34-fold those in the anteroposterior (AP) view. The effective dose in the PA view was 0.4-0.61-fold that in the AP view. BSD measurements were almost equivalent to the BODs obtained using PMC at all exposure settings. During FRs, the PA view without an anti-scatter grid significantly reduced the breast dose compared to the AP view with an anti-scatter grid.

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.

Increased Cancer Incidence Following up to 15 Years after Cardiac Catheterization in Infants under One Year between 1980 and 1998-A Single Center Observational Study

OBJECTIVE

To evaluate the incidence of cancer within the first 15 years of life in children who underwent cardiac catheterization under the age of one year.

METHODS

In this retrospective, single center study, 2770 infants (7.8% with trisomy 21) were studied. All infants underwent cardiac catheterization under one year of age between January 1980 and December 1998. Newly diagnosed cancer in the first 15 years of life was assessed through record linkage to the German Childhood Cancer Registry (GCCR). Cancer risk in study patients was compared to the GCCR population of children less than 15 years. Patients with trisomy 21 were compared to the Danish Cytogenic Register for trisomy 21. Effective radiation doses were calculated for each tumor patient and 60 randomly selected patients who did not develop cancer.

RESULTS

In total, 24,472.5 person-years were analyzed. Sixteen children developed cancer, while 3.64 were expected (standardized incidence ratio (SIR) = 4.4, 95% confidence interval (CI): 2.5-7.2, p < 0.001). There was no preferred cancer type. The observed incidence of leukemia and solid tumors in trisomy 21 was only slightly higher (1 in 476 py) than expected (1 in 609 py, p = 0.64). There was no direct relationship between the radiation dose and the incidence of cancer.

CONCLUSION

Cardiac catherization in the first year of life was associated with a significantly increased cancer risk in a population with congenital heart disease.

Oval stenting in left pulmonary artery stenosis: a novel double balloon technique to prevent airway compression in single ventricle

AIMS

Left pulmonary artery (LPA) stenosis is common in patients with cavopulmonary connections. Stent implantation is the treatment of choice but may be complicated or contraindicated by left main bronchus (LMB) compression due to limited retro-aortic space after a Damus-Kaye-Stansel (DKS) or Norwood operation. This study describes a novel double balloon technique of LPA stenting in patients at risk of LMB compression.

METHODS AND RESULTS

A cohort study was performed in 11 patients who underwent LPA stenting with an oval stent technique between 2015 and 2018. Retro-aortic anatomy was evaluated periprocedurally by three-dimensional rotational angiography (3DRA). Pre-existing LMB compression was demonstrated by 3DRA in seven out of eight patients who had undergone previous LPA stenting and in one patient without stenting. Primary ovalisation with immediate stent implantation on double balloons was performed in one patient. Ten patients had secondary ovalisation with single balloon stent implantation followed by the double balloon technique for ovalisation. The procedures were successful in all patients and guaranteed LMB patency without increasing pre-existing compression.

CONCLUSIONS

The 3DRA-guided oval stent technique with double balloon inflation is successful in treating LPA stenosis after a DKS or Norwood operation in patients at risk of bronchial compression, guaranteeing LMB patency without increasing pre-existing compression.

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.

Cancer Risk in Congenital Heart Disease-What Is the Evidence?

As life expectancy in patients with congenital heart disease (CHD) has improved, the risk for developing noncardiac morbidities is increasing in adult patients with CHD (ACHD). Among these noncardiac complications, malignancies significantly contribute to the disease burden of ACHD patients. Epidemiologic studies of cancer risk in CHD patients are challenging because they require large numbers of patients, extended follow-up, detailed and validated clinical data, and appropriate reference populations. However, several observational studies suggest that cancer risks are significantly elevated in patients with CHD compared with the general population. CHD and cancer share genetic and environmental risk factors. An association with exposure to low-dose ionizing radiation secondary to medical therapeutic or diagnostic procedures has been reported. Patients with Down syndrome, as well as, to a lesser extent, deletion of 22q11.2 and renin-angiotensin system pathologies, may manifest both CHD and a predisposition to cancer. Such observations suggest that carcinogenesis and CHD may share a common basis in some cases. Finally, specific conditions, such as Fontan circulation and cyanotic CHD, may lead to multisystem consequences and subsequently to cancer. Nonetheless, there is currently no clear consensus regarding appropriate screening for cancer and surveillance modalities in CHD patients. Physicians caring for patients with CHD should be aware of this potential predisposition and meet screening recommendations for the general population fastidiously. An interdisciplinary and global approach is required to bridge the knowledge gap in this field.

Diagnostic Accuracy of Noncontrast Self-navigated Free-breathing MR Angiography versus CT Angiography: A Prospective Study in Pediatric Patients with Suspected Anomalous Coronary Arteries

RATIONALE AND OBJECTIVES

To evaluate the diagnostic accuracy of a prototype noncontrast, free-breathing, self-navigated 3D (SN3D) MR angiography (MRA) technique for the assessment of coronary artery anatomy in children with known or suspected coronary anomalies, using CT angiography (CTA) as the reference standard.

MATERIALS AND METHODS

Twenty-one children (15 male, 12.3 ± 2.6 years) were prospectively enrolled between July 2014 and August 2016 in this IRB-approved, HIPAA-compliant study. Patients underwent same-day unenhanced SN3D-MRA and contrast-enhanced CTA. Two observers rated the visualization of coronary artery segments and diagnostic confidence on a 3-point scale and assessed coronary arteries for anomalous origin, as well as interarterial and intramural course. Sensitivity, specificity, positive (PPV) and negative predictive values (NPV) of SN3D-MRA for the detection of coronary artery abnormalities were calculated. Interobserver agreement was assessed using Intraclass Correlation Coefficients (ICC).

RESULTS

Fourteen children showed coronary artery abnormalities on CTA. The visualization of coronary segments was rated significantly higher for CTA compared to MRA (p <0.015), except for the left main coronary artery (p = 0.301), with good to excellent interobserver agreement (ICC = 0.62-0.94). Diagnostic confidence was higher for CTA (p = 0.046). Sensitivity, specificity, PPV, and NPV of MRA were 92%, 92%, 96%, and 87% for the detection of coronary artery anomalies, 85%, 85%, 74%, and 92% for high origin, 71%, 92%, 82%, and 87% for interarterial, and 41%, 96%, 87%, and 80% for intramural course.

CONCLUSIONS

Noncontrast SN3D-MRA is highly accurate for the detection of coronary artery anomalies in pediatric patients while diagnostic confidence and coronary artery visualization remain superior with CTA.

Echocardiography-guided percutaneous closure of perimembranous ventricular septal defects without arterial access and fluoroscopy

Background

Traditional percutaneous device closure of perimembranous ventricular septal defects (PmVSDs) is a minimally invasive technique, but can result in high radiation exposure and can result in potential arterial complications. Here, we aimed to assess the safety and feasibility of device closure of PmVSDs via the femoral vein approach under transesophageal echocardiography (TEE) guidance in children.

Methods

From January 2014 to December 2017, a total of 46 PmVSD patients (mean age, 6.5 ± 2.3 years [range, 4.2–12.0 years]; mean body weight 22.1 ± 6.6 kg [range, 16.0–38.5 kg]; VSD diameter, 4.1 ± 0.6 mm [range, 3.2–5.0 mm]) underwent attempted transcatheter closure via the femoral vein approach under the guidance of TEE without fluoroscopy.

Results

The transcatheter occlusion procedure under TEE guidance was successful in 44 (95.7%) patients. Surgery was necessary in 2 (4.3%) patients. The procedure duration was 28.2 ± 8.7 min (range, 12.0–42.0 min). One patient had immediate post-operative trivial residual shunt and three patients had immediate incomplete right bundle branch block (IRBBB) after operation; the new IRBBB in 1 case was noted in the first postoperative month. No residual shunt was noted at 3 months after the procedure, and no intervention related complications were detected at 1–24 months follow-up.

Conclusions

Percutaneous device closure of PmVSDs under TEE guidance solely by femoral vein approach is effective and safe, avoids radiation exposure, potential arterial complications and a surgical incision.

Electronic supplementary material

The online version of this article (10.1186/s12887-019-1687-0) contains supplementary material, which is available to authorized users.

Flexible Modeling of the Association Between Cumulative Exposure to Low-Dose Ionizing Radiation From Cardiac Procedures and Risk of Cancer in Adults With Congenital Heart Disease

Adults with congenital heart disease are increasingly being exposed to low-dose ionizing radiation (LDIR) from cardiac procedures. In a recent study, Cohen et al. (Circulation. 2018;137(13):1334-1345) reported an association between increased LDIR exposure and cancer incidence but did not explore temporal relationships. Yet, the impact of past exposures probably accumulates over years, and its strength may depend on the amount of time elapsed since exposure. Furthermore, LDIR procedures performed shortly before a cancer diagnosis may have been ordered because of early symptoms of cancer, raising concerns about reversal causality bias. To address these challenges, we combined flexible modeling of cumulative exposures with competing-risks methodology to estimate separate associations of time-varying LDIR exposure with cancer incidence and all-cause mortality. Among 24,833 patients from the Quebec Congenital Heart Disease Database, 602 had incident cancer and 500 died during a follow-up period of up to 15 years (1995-2010). Initial results suggested a strong association of cancer incidence with very recent LDIR exposures, likely reflecting reverse causality bias. When exposure was lagged by 2 years, an increased cumulative LDIR dose from the previous 2-6 years was associated with increased cancer incidence, with a stronger association for women. These results illustrate the importance of accurate modeling of temporal relationships between time-varying exposures and health outcomes.

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 75th 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 (DAPBWxFT). The latter pairs contained less frequent procedure types with significant outliers. For DAP normalized to BW (DAPBW), 38% of the pairwise comparisons showed statistically significant differences. Conversion factors from DAPBW to OD and ED were reported for various weight groups, due to the higher correlation between DAPBW and both OD and ED than between DAP and both OD and ED.

CONCLUSIONS

The P75 of DAPBWxFT 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 DAPBW instead of DAP and should be used according to the appropriate BW group.

Technical and anatomical factors affecting intra-arterial chemotherapy fluoroscopy time and radiation dose for intraocular retinoblastoma

BACKGROUND

Intra-arterial chemotherapy has an increasingly prominent role in the management of retinoblastoma. One concern regarding this technique is procedural radiation exposure.

OBJECTIVES

To examine the effects of our institution's procedural technique on fluoroscopy parameters for patients undergoing intra-arterial chemotherapy infusions for intraocular retinoblastoma. Secondary goals included describing the effect of anatomical variations of the carotid siphon and ophthalmic artery on radiation dose.

METHODS

A retrospective review of pediatric patients with retinoblastoma referred to interventional neuroradiology for chemosurgery was performed. Techniques were classified as: A (1.2 Fr or 1.5 Fr microcatheter with continuous verapamil flush, advanced without guide through a 2 Fr sheath) or B (1.5 Fr or 1.7 Fr microcatheter advanced within a 4 Fr base catheter, through a 4 Fr sheath). Statistical analysis was performed to determine if there was a significant difference in fluoroscopy parameters based on technique or due to anatomical variation.

RESULTS

26 patients were treated with 94 intra-arterial chemotherapy infusions. 34 procedures were performed using technique A and 60 using technique B. Mean fluoroscopy time (4.75 min), fluoroscopy dose (23.3 mGy), and dose-area product (DAP; 85.2 μGy.m²) for technique A were significantly lower (p value <0.05) than for technique B, 14.0 min., 191 mGy, and 586 μGy.cm², respectively.

CONCLUSIONS

Microcatheter-only technique with continuous verapamil infusion resulted in decreased fluoroscopy times, DAP, and radiation doses at our institution for the treatment of intraocular retinoblastoma. Furthermore, our fluoroscopy times using this technique are the lowest reported in the current literature. Additionally, our anatomical analysis has demonstrated a positive correlation between increasing vessel tortuosity and fluoroscopy times.

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.

Radiation Risk Categories in Cardiac Catheterization for Congenital Heart Disease: A Tool to Aid in the Evaluation of Radiation Outcomes

To stratify diverse procedure types into categories with similar radiation exposure in cardiac catheterization for congenital heart disease. Radiation exposures for a comprehensive list of specific procedure types and stratification of outcomes based on radiation risk are not currently available. Data between January 2014 and December 2015 were collected on all cases performed at sites participating in C3PO-QI (Congenital Cardiac Catheterization Outcomes Project-Quality Improvement Initiative) and 9 centers were included. Using expert consensus, 40 unique procedure types were defined by diagnostic characteristics or the intervention(s) performed, and dose area product (DAP) per kilogram of body weight (µGy × m²/kg) was summarized. Using empiric and consensus methods, three radiation risk categories were created. A total of 11,735 cases were included for analysis. Thirteen (n = 7918) procedure types with median DAP/kg < 100 were categorized in the low radiation exposure category (median DAP/kg 39). The medium exposure category (n = 1807) consisted of 16 procedure types with median DAP/kg values ranging 100 to < 200 (overall median DAP/kg 131). Finally, the high radiation exposure category (n = 1073) consisted of 11 procedure types with median DAP/kg ≥ 200 (overall median DAP/kg of 231). The radiation exposure risk categories created in this multi-center dataset are a critical step towards the development of a robust risk adjustment methodology for radiation exposure in catheterization for congenital heart disease.

Dramatic Dose Reduction in Three-Dimensional Rotational Angiography After Implementation of a Simple Dose Reduction Protocol

Previously, median effective dose (ED) of 1.6 mSv per three-dimensional rotational angiography (3DRA) has been reported. This study evaluated ED and image quality in 3DRA after implementation of a simple dose reduction protocol in pediatric catheterizations. Simple conversion factors between 3DRA ED and readily available parameters at the cathlab were determined. The dose reduction protocol consisted of frame reduction (60-30 frames/s (f/s)), active collimation of the X-ray beam, usage of a readily available low dosage program, and a pre-3DRA run check. EDs were calculated with Monte Carlo PCXMC 2.0. Three observers blindly assessed 3DRA image quality of the dose reduction and normal-dose cohort. Between October 2014 and October 2015, 84 patients (median age 4.3 years) underwent 100 3DRAs with a median ED of 0.54 mSv (0.12-2.2) using the dose reduction protocol. Median ED in the normal-dose cohort (17 3DRAs) was 1.6 mSv (1.2-4.9). Image quality in the dose reduction cohort remained excellent. Correlations between ED and dose area product (DAP) and ED and skin dose were found with a ρ of 0.82 and 0.83, respectively. ED exposure of the entire catheterization was reduced to 2.64 mSv. Introduction of a simple protocol led to 66% dose reduction in 3DRA and 79% in the entire catheterization. 3DRA image quality in this group remained excellent. In 3DRA ED correlates well with DAP and skin dose, parameters readily available at the cathlab.

Equivalent thicknesses of beam hardening filters consisting of aluminium, copper, Al/Cu and Al/Gold combinations and plumbiferous acrylic for 40 to 150 kVp diagnostic spectra

PURPOSE

Beam hardening filters used to reduce patient doses typically consist of aluminium, copper, or a combination of both. Optically transparent filters containing lead in plumbiferous acrylic became available. One vendor also uses a combination of aluminium and gold. Data is provided to compare filter thicknesses in terms of half-value layer (HVL) for clinically relevant kVp.

METHODS

Equivalent filter thicknesses were defined by identical kVp and 1st HVL. Equivalent copper filter thicknesses were calculated for aluminium and typical filters found in radiographic and interventional systems. A verified semi-empirical spectrum calculation programme and National Institute of Standards and Technology (NIST) mass attenuation coefficients were applied. Lead acrylic filters were simulated by a two-component model of acrylic plus lead with mass thicknesses determined by matching 1 HVLs in Al at RQR5 using filter specifications.

RESULTS

Coefficients are provided to convert mm Cu to mm Al and vice versa for tube potentials from 40 to 150 kVp. 1 mm Al corresponds to 27.8 ± 1 μm Cu over the entire energy range simulated. Using this simple model as opposed to simulations of all individual filters made from Al/Cu combinations (1 and 2 mm Al, 1 Al + 0.1 and 0.2 Cu, 1.5 Al plus 0.3 and 0.6 Cu, 2 Al plus 0.1 Cu) for the entire energy range results in differences in equivalent Cu thicknesses below 4 μm Cu (3 μm for 50-150 kVp). kVp dependence is larger for filters containing larger Z elements. 1 mm Al plus 10 μm gold used by Shimadzu corresponds to 75-80 μm Cu, depending on kVp; plumbiferous acrylic with nominal filtrations of 1 Al plus 0.1 Cu, and 1 Al plus 0.2 Cu corresponded to 124-132 μm, and 206-232 μm Cu, respectively.

CONCLUSIONS

Experimental verification of the equivalence of aluminium and combined aluminium plus copper filters showed excellent agreement between calculated copper equivalent thickness and measurements with copper filters for clinical beams from 40 to 150 kVp.

A Cost-Effective Analysis of Systematically Using Mapping Systems During Catheter Ablation Procedures in Children and Teenagers

The aim of this study is to evaluate the cost-effectiveness of an extended use of 3D non-fluoroscopic mapping systems (NMSs) during paediatric catheter ablation (CA) in an adult EP Lab. This study includes 58 consecutive patients (aged between 8 and 18) who underwent CA from March 2005 to February 2015. We compare the fluoroscopy data of two groups: group I, patients who underwent CA from 2005 to 2008 using only fluoroscopy, and group II, patients who underwent CA from 2008 to 2015 performed also using NMSs. Two cost-effectiveness analyses were carried out: the first method was based on the alpha value (AV), and the second one was based on the value of a statistical life (VSL). For both methods, a children's correction factor was also considered. The reduction cost estimated from all these methods was compared to the real additional cost of using NMSs. The use of an NMS during a CA procedure has led to an effective dose reduction (ΔE) of 2.8 milli-Sievert. All presented methods are based on parameters with a wide range of values. The use of an NMS, applying directly AV values or VSL values, is not cost-effective for most countries. Only considering the children's correction factor, the CA procedure using an NMS seems to be cost-effective. The cost-effectiveness of a systematic use of NMSs during CA procedures in children and teenagers remains a challenging task. A positive result depends on which value of AV or VSL is considered and if the children's correction factor is applied or not.

PRELIMINARY INVESTIGATION OF RADIATION DOSE TO PATIENTS FROM CARDIOVASCULAR INTERVENTIONAL PROCEDURES IN TANZANIA

Although contemporary cardiac X-ray exams are typically set so benefits outweighs the risk, the growing use and increasing complexity of the cardiovascular interventional radiological (CVIR) procedures does increase the risk of radiation-related tissue effects and stochastic effects to the individual patients and the population. In view of these radiological concerns there is a need to investigate factors that influence the doses received by the patients and enable optimisation needed. The air kerma area product (KAP), cumulative air kerma (CAK) and fluoroscopy time (FT) to patients from two major CVIR procedures: coronary angiography (CA) and percutaneous coronary interventions (PCI), were obtained from two major hospitals in Tanzania. The CAK and KAP were determined using ionisation chambers equipped in each angiographic unit. The median values of the KAP, CAK and FT for the CA procedures were 37.8 Gy cm2, 425.5 mGy and 7.6 min, respectively, while for the PCI were 86.5 Gy cm2, 1180.3 mGy and 19.0 min, respectively. The overall differences among individual KAP, CAK and FT values across the two hospitals investigated differed by factors of up to 33.5, 58.7 and 26.3 for the CA, while for the PCI procedures differed by factors of up to 10.9, 25.3 and 13.8, respectively. The mean values of KAP and FT for both CA and PCI were mostly higher than those reported values for Ireland, Belgium, Greece, France, China and Australia. The third quartiles of the KAP, CAK and FT for both CA and PCI were relatively above the preliminary diagnostic reference levels proposed by the IAEA, DIMOND III and SENTINEL. The observed substantial variations of mean values of technical parameters and patient doses (KAP, CAK and FT values) observed for the CA and PCI procedures inter and intra-hospitals were mainly explained by the complexity of the CVIR procedures, the nature of pathology, patient-specific characteristics, the variation in levels of skills and experiences among IC personnel, and the different procedural protocols employed among interventional cardiologists and hospitals. The observed great variations of procedural protocols and patient doses within and across the hospitals and relative higher dose than reported values from the literature call for the need to optimise radiation dose to patient from IC procedures.

THE RADIATION DOSE PROFILE IN PEDIATRIC INTERVENTIONAL CARDIOLOGY TO ESTIMATE THE STOCHASTIC EFFECT RISK: PRELIMINARY STUDY

Background: The specific characteristic of anatomy and physiology of children cause the risk of radiation effects received when they underwent the interventional cardiology procedures higher than an adult. Purpose: to estimate the stochastic effect risk in a pediatric patient during interventional cardiology procedures. Method: Data collection was performed by placing thermoluminescence dosimeter (TLD) on thyroid, gonad, left and right thoracic areas, and the 5th thoracic vertebrae during interventional cardiology. Result: The results showed that the greatest exposure was received around vertebrae (bone marrow) because of the superimpose X-ray on the vertebrae during the procedures. Conclusion: The greatest probability of stochastic effect that happened was leukemia. Estimation risk ratio of leukemia was 0, 9 % and thyroid cancer was 0,037%. 

Evaluation of patient and staff exposure with state of the art X-ray technology in cardiac catheterization: A randomized controlled trial

INTRODUCTION

Cardiac catheterization procedures result in high patient radiation exposure and corresponding staff doses are reported to be among the highest for medical staff. The purpose of current randomized controlled study was to quantify the potential radiation dose reduction for both patient and staff, enabled by recent X-ray technology. This technology is equipped with advanced image processing algorithms, real-time dose monitoring, and an acquisition chain optimized for cardiac catheterization applications.

METHODS

A total of 122 adult patients were randomly assigned to one of two cath labs, either the reference X-ray modality (Allura Xper FD10, Philips Healthcare, the Netherlands) or the new X-ray system (AlluraClarity FD20/10 Philips Healthcare, the Netherlands). Exposure parameters and staff dosimeter readings were recorded for each exposure. Technical measurements were performed to define the radiation scatter behavior.

RESULTS

With the newer equipment, patient radiation dose is reduced (as total dose-area product) by 67% based on geometric means with 95%CI of 53%, 77% for diagnostic and interventional procedures. The C-arm and leg dosimeter readings were both reduced with 65% (P < 0.001), while for the collar and chest dosimeter readings no statistically significant reduction was noticed.

CONCLUSION

The new x-ray and image processing technology, significantly reduces patient dose in coronary angiographies, and PCIs by 67%. In general, scatter dose was also reduced, yet for some dosimeters the reduction was limited and not statistically significant. This study clearly indicates that the scatter behavior is highly dependent on C-arm rotation, operator movement and height, dosimeter position, beam filtration, clinical procedure type and system geometry.

Unresolved questions associated with the management of ventricular preexcitation syndrome

BACKGROUND

Many recent recommendations concern the management of preexcitation syndrome. In clinical practice, they are sometimes difficult to use. The purpose of the authors was to discuss the main problems associated with this management. Three problems are encountered: (1) the reality of the absence of symptoms or the interpretation of atypical symptoms, (2) the electrocardiographic diagnosis of preexcitation syndrome that can be missed, and (3) the exact electrophysiological protocol and its interpretation used for the evaluation of the prognosis. Because of significant progress largely related to the development of curative treatment, it seems easy to propose ablation in many patients despite the related risks of invasive studies and to minimize the invasive risk by only performing ablation for patients with at-risk pathways. However, there is a low risk of spontaneous events in truly asymptomatic patients and the indication of accessory pathway ablation should be discussed case by case.

A new approach of three-dimensional guidance in paediatric cath lab: segmented and tessellated heart models for cardiovascular interventions in CHD

BACKGROUND

Optimal imaging is essential for catheter-based interventions in CHD. The three-dimensional models in volume-rendering technique currently in use are not standardised. This paper investigates the feasibility and impact of novel three-dimensional guidance with segmented and tessellated three-dimensional heart models in catheterisation of CHD. In addition, a nearly radiation-free two- to three-dimensional registration and a biplane overlay were used.Methods and resultsWe analysed 60 consecutive cases in which segmented tessellated three-dimensional heart models were merged with live fluoroscopy images and aligned using the tracheal bifurcation as a fiducial mark. The models were generated from previous MRI or CT by dedicated medical software. We chose the stereo-lithography format, as this promises advantage over volume-rendering-technique models regarding visualisation. Prospects, potential benefits, and accuracy of the two- to three-dimensional registration were rated separately by two paediatric interventionalists on a five-point Likert scale. Fluoroscopy time, radiation dose, and contrast dye consumption were evaluated. Over a 10-month study period, two- to three-dimensional image fusion was applied to 60 out of 354 cases. Of the 60 catheterisations, 73.3% were performed in the context of interventions. The accuracy of two- to three-dimensional registration was sufficient in all cases. Three-dimensional guidance was rated superior to conventional biplane imaging in all 60 cases. We registered significantly smaller amounts of used contrast dye (p<0.01), lower levels of radiation dose (p<0.02), and less fluoroscopy time (p<0.01) during interventions concerning the aortic arch compared with a control group.

CONCLUSIONS

Two- to three-dimensional image fusion can be applied successfully in most catheter-based interventions of CHD. Meshes in stereo-lithography format are accurate and base for standardised and reproducible three-dimensional models.

Exposure to Low-Dose Ionizing Radiation From Cardiac Procedures and Malignancy Risk in Adults With Congenital Heart Disease

Background:

Adults with congenital heart disease (CHD) are exposed to increasing amounts of low-dose ionizing radiation (LDIR) from cardiac procedures. Cancer prevalence in this population is higher than in the general population. This study estimates the association between LDIR exposure from cardiac procedures and incident cancer in adult patients with CHD.

Methods:

The study population derived from the Quebec Congenital Heart Disease Database. We measured cumulative numbers of LDIR-related cardiac procedures for each patient until 1 year before the time of cancer diagnosis or administrative censoring. To assess the association between LDIR exposure and cancer risk, we conducted a nested case-control study and matched cancer cases with controls on sex, CHD severity, birth year, and age.

Results:

The study included 24 833 adult patients with CHD aged 18 to 64 years from 1995 to 2009. In >250 791 person-years of follow-up, 602 cancer cases were observed (median age, 55.4 years). The cumulative incidence of cancer estimated up to 64 years of age was 15.3% (95% confidence interval [CI], 14.2–16.5). Cases had more LDIR-related cardiac procedures than controls (1410 versus 921 per 1000 adult patients with CHD, P <0.0001). Cumulative LDIR exposure was independently associated with cancer (odds ratio [OR], 1.08 per procedure; 95% CI, 1.04–1.13). Similar results were obtained by using dose estimates for LDIR exposure (OR, 1.10 per 10 mSv; 95% CI, 1.05–1.15) with a possible dose-related response. The effect measure was in the same direction, and the association was persistent for exposure from ≥6 procedures in all sensitivity analyses: after excluding most smoking-related cancer cases (OR, 1.10 per procedure; 95% CI, 1.05–1.16 and OR when exposure from ≥6 procedures, 3.08; 95% CI, 1.77–5.37), and after applying a 3-year lag period (OR, 1.09 per procedure; 95% CI, 1.03–1.14 and OR when exposure from ≥6 procedures: 2.58; 95% CI, 1.43–4.69).

Conclusions:

To our knowledge, this is the first large population-based study to analyze and document the association between LDIR-related cardiac procedures and incident cancer in the population of adults with CHD. Confirmations of these findings by prospective studies are needed to reinforce policy recommendations for radiation surveillance in patients with CHD where no regulation currently exists. Physicians ordering and performing cardiac imaging should ensure that exposure is as low as reasonably achievable without sacrificing quality of care.

Impact of low dose settings on radiation exposure during pediatric fluoroscopic guided interventions

PURPOSE

To evaluate the effects of lowering the detector entrance exposure in children undergoing interventional radiology procedures.

MATERIALS AND METHODS

The study retrospectively investigated radiation dose levels in pediatric patients aged 0-18 years before (n = 39) and after (n = 26) lowering detector entrance dose, undergoing embolization of peripheral Arteriovenous malformations, Portal Vein Interventions or Percutaneous Transhepatic Cholangio Drainage (PTCD) between 2014 and 2017. Patient characteristics, fluoroscopy time, protocols used as well as resulting Skin Dose and Dose Area Product (DAP) were compared in each cohort. Image quality was assessed by two independent readers.

RESULTS

The two patient cohorts did not differ in terms of patient demographics. Similarly, fluoroscopy time did not differ before and after implementation of the low dose settings. An overall reduction of skin dose of 75.1% for AVM embolizations, 80.5% for Portal Vein Interventions and 85.3% for PTCD placement was observed. The DAP decrease was 82.5% for AVM embolizations, 72.2% for Portal Vein Interventions and 79.8% for PTCD placement. Image quality was generally considered to be good with an insignificant difference between pre and post implementation of the low dose approach and good agreement between the two readers. Manual inroom-switching to higher dose levels was possible, however this was not performed more frequently after implementation of the low dose settings.

CONCLUSION

Lowering the detector entrance dose in pediatric interventional radiology procedures results in a significant decrease of the radiation dose burden.

Paediatric interventional cardiology in Costa Rica: diagnostic reference levels and estimation of population dose

The goal of the present study was to propose a set of national diagnostic reference levels (DRLs) in Costa Rica for paediatric interventional cardiology (IC) procedures classified by age and weight and to estimate the collective dose of the paediatric population from these intervention practices. The data collection period was May 2016 to May 2017. The third quartile of patient dose data distributions for kerma-area product (KAP) values was set as the national DRLs. A sample of 154 paediatric IC procedures (collected in the national paediatric hospital with a single x-ray system) was used and divided into four age ranges and five weight ranges. The national DRLs obtained for KAPs by age range were 1.79 Gy cm² (<1 year) to 23.0 Gy cm² (10-15 years). The national DRLs obtained for KAPs by weight range were 1.0 Gy cm² (<10 kg) to 49.6 Gy cm² (50-79 kg). The contribution to the collective dose of the population of Costa Rica amounted to 0.78 person Sv.

Free-breathing 320-row computed tomographic angiography with low-tube voltage and hybrid iterative reconstruction in infants with complex congenital heart disease

We explored the clinical value of low-tube voltage prospective second-generation ECG-triggered 320-row CT angiography in infants with complex CHD (37 male, 23 female, aged 0-2 years). The diagnostic accuracy of 320-row CT in complex CHD was 99.4% for intracardiac cardiovascular malformations, 99.8% for extracardiac cardiovascular malformations, and 100% for other malformations. The average subjective overall image quality score for cardiac structures was 3.7 ± 0.5 points. Second-generation 320-row CT angiography with low-tube voltage and prospective ECG-triggered volume target scanning allows accurate diagnosis of cardiovascular anomalies in infants with complex CHD.