Effective dose conversion factors in paediatric interventional cardiology

Age-specific Dose Catalog for Diagnostic Fluoroscopy and Fluoroscopically Guided Interventional Procedures from a Pediatric Hospital

Background Fluoroscopy is an imaging modality associated with a wide range of dose levels, characterized using a variety of dose metrics, including effective dose. However, for clinical procedures, effective dose is a seldom-used and unregulated metric in the United States, and thus, it is not extensively studied in radiology despite potentially large clinical implications for patients, especially children and infants. Purpose To formulate and report a dose catalog across all diagnostic and interventional radiology (IR) fluoroscopy examination or procedure types at a specialized tertiary care pediatric hospital. Materials and Methods In this retrospective study, dose metrics taken from radiation dose structured reports of fluoroscopy between October 2014 and March 2023 were analyzed. The reports included fluoroscopy across 18 diagnostic examination types and 24 IR procedure types. The National Cancer Institute dosimetry system for Radiography and Fluoroscopy Monte Carlo software was used to estimate age-specific effective dose from dose-area product (DAP). The DAP-to-effective dose conversion factors were estimated per IR procedure type and diagnostic fluoroscopy examination type based on age. Results A total of 11 536 individual diagnostic fluoroscopy examinations (18 types) and 8017 individual IR procedures (24 types) were analyzed. Median effective dose values per diagnostic fluoroscopy examination type ranged from 0.0010 to 0.44 mSv (mean, 0.0808 mSv ± 0.0998 [SD]). Calculated DAP-to-effective dose conversion factors ranged from 0.04 to 2.48 mSv/Gy · cm2 (mean, 0.758 mSv/Gy · cm2 ± 0.614) across all diagnostic fluoroscopy examination types. Median effective dose values per IR procedure type ranged from 0.0007 to 3.90 mSv (mean, 0.6757 mSv ± 0.8989). Calculated DAP-to-effective dose conversion factors ranged from 0.001 to 0.87 mSv/Gy · cm2 (mean, 0.210 mSv/Gy · cm2 ± 0.235) across all IR procedure types. Conclusion A pediatric fluoroscopy dose catalog was created, including age-specific effective dose, using a repeatable robust method based on accurate clinical data. © RSNA, 2024 Supplemental material is available for this article. See also the editorial by Borrego and Balter in this issue.

Use of ionizing radiation in a Norwegian cohort of children with congenital heart disease: imaging frequency and radiation dose for the Health Effects of Cardiac Fluoroscopy and Modern Radiotherapy in Pediatrics (HARMONIC) study

BACKGROUND

The European-funded Health Effects of Cardiac Fluoroscopy and Modern Radiotherapy in Pediatrics (HARMONIC) project is a multicenter cohort study assessing the long-term effects of ionizing radiation in patients with congenital heart disease. Knowledge is lacking regarding the use of ionizing radiation from sources other than cardiac catheterization in this cohort.

OBJECTIVE

This study aims to assess imaging frequency and radiation dose (excluding cardiac catheterization) to patients from a single center participating in the Norwegian HARMONIC project.

MATERIALS AND METHODS

Between 2000 and 2020, we recruited 3,609 patients treated for congenital heart disease (age < 18 years), with 33,768 examinations categorized by modality and body region. Data were retrieved from the radiology information system. Effective doses were estimated using International Commission on Radiological Protection Publication 60 conversion factors, and the analysis was stratified into six age categories: newborn; 1 year, 5 years, 10 years, 15 years, and late adolescence.

RESULTS

The examination distribution was as follows: 91.0% conventional radiography, 4.0% computed tomography (CT), 3.6% diagnostic fluoroscopy, 1.2% nuclear medicine, and 0.3% noncardiac intervention. In the newborn to 15 years age categories, 4-12% had ≥ ten conventional radiography studies, 1-8% underwent CT, and 0.3-2.5% received nuclear medicine examinations. The median effective dose ranged from 0.008-0.02 mSv and from 0.76-3.47 mSv for thoracic conventional radiography and thoracic CT, respectively. The total effective dose burden from thoracic conventional radiography ranged between 28-65% of the dose burden from thoracic CT in various age categories (40% for all ages combined). The median effective dose for nuclear medicine lung perfusion was 0.6-0.86 mSv and for gastrointestinal fluoroscopy 0.17-0.27 mSv. Because of their low frequency, these procedures contributed less to the total effective dose than thoracic radiography.

CONCLUSION

This study shows that CT made the largest contribution to the radiation dose from imaging (excluding cardiac intervention). However, although the dose per conventional radiograph was low, the large number of examinations resulted in a substantial total effective dose. Therefore, it is important to consider the frequency of conventional radiography while calculating cumulative dose for individuals. The findings of this study will help the HARMONIC project to improve risk assessment by minimizing the uncertainty associated with cumulative dose calculations.

DOSE EVALUATION AND PROPOSAL OF LOCAL DIAGNOSTIC REFERENCE LEVELS FOR PAEDIATRIC CARDIAC CATHETERIZATIONS PERFORMED ON A HIGH-SENSITIVITY ANGIOGRAPHIC SYSTEM ALLOWING LOW-DOSE IMAGING

Radiation doses from paediatric cardiac catheterizations were analysed based on procedure type and patient weight, and local diagnostic reference levels (LDRLs) were proposed. The procedures were performed on a Siemens Artis Q.zen biplane system with high-sensitivity detectors allowing low-dose imaging. Good radiological practice, e.g. adapting dose level and frame rate continuously and minimizing the x-ray field with collimators, was routine during procedures. The median total dose-area-product (DAP) value was 58 μGym2 for diagnostic catheterizations, 48 μGym2 for interventional catheterizations and 33 μGym2 for myocardial biopsies. The median DAP per body weight was 4.0 μGym2 kg-1. The median total fluoroscopy time varied from 6.0 min for myocardial biopsies, to 9.7 and 10.5 min, respectively, for diagnostic and interventional catheterizations. The third quartile of the DAP values in each weight group was proposed as LDRL. LDRLs for fluoroscopy time were determined solely based on procedure type, due to the absence of weight dependence.

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.

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.

Effect of Exposure Angulation on the Occupational Radiation Exposure during Cardiac Angiography: Simulation Study

Cardiac angiography to visualize the cardiac coronary artery for lesions causes a lot of radiation exposure dose to the interventional cardiologist. We evaluated the occupational radiation exposure to the interventional cardiologist based on changes to the angle of the X-ray tube used in cardiac angiography and calculated the conversion factor for effective dose in this study. To evaluate the occupational radiation exposure resulting from scattered radiation to interventional cardiologists, organ doses for eyeball, thyroid, and heart were calculated using Monte Carlo simulation with korean typical man(KTMAN) phantom at the left anterior oblique (LAO)30/cranial (CRAN)30, CRAN40, right anterior oblique (RAO)30/CRAN30, RAO30/caudal(CAUD)20, CAUD39, LAO40/CAUD35, and LAO40 positions in the femoral and the radial artery puncture. In this study, analysis of the different angles showed the highest radiation exposure on LAO30/CRAN30 and CRAN40 position, which were 150.65% and 135.3%, respectively, compared to AP angles. Therefore, to reduce occupational dose for interventional cardiologists, it is recommended that radiation protection, such as using radiation shield and personal protective equipment (PPE), be used at LAO30/CRAN30 and CRAN40 angulation, and the conversion factor for calculating the organ dose received by the interventional cardiologists based on patient dose can be applied for improved occupational dose management.

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.

Radiation dose in paediatric cardiac catheterisation: A systematic literature review

OBJECTIVES

It is believed that children are more sensitive to ionising radiation than adults. This work reviewed the reported radiation dose estimates for paediatric cardiac catheterisation. A systematic literature review was performed by searching healthcare databases for studies reporting radiation dose using predetermined key words relating to children having cardiac catheterisation. The quality of publications was assessed using relevant Critical Appraisal Skills Programme questions and their reported radiation exposures were evaluated.

KEY FINDINGS

It is only in recent years that larger cohort observations have been undertaken. Although radiation dose from paediatric cardiac catheterisation has decreased in recent years, the literature indicated that it remains varied and potentially substantial.

CONCLUSION

Standardisation of weight categories and procedure types such as those recommended by the PiDRL project could help compare current and future radiation dose estimates.

PEDIATRIC RADIATION DOSE DURING CARDIAC CATHETERIZATION PROCEDURES IN SUDAN

Children are more radio sensitive than adult. This study aims to assess radiation doses and the associated hazards to pediatric during cardiac catheterization procedures. Radiation dose for 112 patients was estimated in the biggest cardiac center in Sudan. The median KAP in Gy cm2, CK in mGy, number of frames and fluoroscopy time in minutes were (4.6, 29.0, 340.4, 13.5) and (6.0, 35.0, 318, 9.8) for the diagnostic and therapeutic cardiac procedures, respectively. The median (KAP in Gy cm2, effective dose in mSv) for different age groups in the intervals of less than 1 year, 1-<5 years, 5-<10 years and 10-15 years old were (2.2, 4.4), (2.5, 5.0), (4.2, 5.1) and (8.5, 4.1) respectively. Including all the procedures using the multiplicative model of ICRP 60, the mean attributable lifetime risk for stochastic effect was 0.08 and 0.05% for girls and boys, respectively. Training is needed to raise staff awareness about radiation protection.

CONTEMPORARY AUSTRALIAN DOSE AREA PRODUCT LEVELS IN THE FLUOROSCOPIC INVESTIGATION OF PAEDIATRIC CONGENITAL HEART DISEASE

This study examines radiation dose levels delivered to children from birth to 15 y of age in the investigation of congenital heart disease (CHD) at a major Sydney children's hospital. The aims are to compare values with those derived from similar studies, to provide a template for more consistent dose reporting, to establish local and national diagnostic reference levels and to contribute to the worldwide paediatric dosimetry database. A retrospective review of 1007 paediatric procedural records was undertaken. The cohort consisted of 795 patients over a period from January 2007 to December 2012 who have undergone cardiac catheterisation for the investigation of CHD. The age range included was from the day of birth to 15 y. Archived dose area product (DAP) and fluoroscopy time (FT) readings were retrieved and analysed. The mean, median, 25th and 75th percentile DAP levels were calculated for six specific age groupings. The 75th percentile DAP values for the specific age categories were as follows: 0-30 d-1.9 Gy cm2, 1-12 months-2.9 Gy cm2, 1-3 y-5.3 Gy cm2, 3-5 y-6.2 Gy cm2, 5-10 y-7.5 Gy cm2 and 10-15 y-17.3 Gy cm2. These levels were found to be lower than the values reported in comparable overseas studies. Individual year-specific levels were determined, and it is proposed that these are more useful than the common grouping method. The age-specific 75th percentile DAP levels outlined in this study can be used as baseline local diagnostic reference levels. The needs for the standardisation of DAP reporting and for a greater range of age-specific diagnostic reference levels have been highlighted. For the first time, Australian dose values for paediatric cardiac catheterisation are presented.

Patient radiation doses and reference levels in pediatric interventional radiology

OBJECTIVES

To describe, in a multicentric paediatric population, reference levels (RLs) for three interventional radiological procedures.

METHODS

From January 2012 to March 2015, children scheduled for an interventional radiological procedure in two French tertiary centres were retrospectively included and divided into four groups according to age: children younger than 2 years (A1), aged 2-7 years (A5), 8-12 years (A10) and 13-18 years (A15). Three procedures were identified: cerebral digital subtraction angiography (DSA), brain arteriovenous malformation (bAVM) embolization, and head and neck superficial vascular malformation (SVM) percutaneous sclerotherapy. Demographic and dosimetric data, including dose area product (DAP), were collected.

RESULTS

550 procedures were included. For DSA (162 procedures), the proposed RL values in DAP were 4, 18, 12 and 32 Gy∙cm² in groups A1, A5, A10 and A15, respectively. For bAVM embolization (258 procedures), values were 33, 70, 105 and 88 Gy∙cm² in groups A1, A5, A10 and A15, respectively. For SVM sclerotherapy (130 procedures), values were 350, 790, 490 and 248 mGy∙cm² in groups A1, A5, A10 and A15, respectively.

CONCLUSION

Consecutive data were available to permit a proposal of reference levels for three major paediatric interventional radiology procedures.

KEY POINTS

• We determined reference levels (RLs) for bAVM embolization, DSA and SVM sclerotherapy. • The proposed RLs will permit benchmarking practice with an external standard. • The proposed RLs by age may help to develop paediatric dose guidelines.

Patient radiation doses in paediatric interventional cardiology procedures: a review

A large number of investigations into the radiation doses from x-ray guided interventional cardiology procedures in children have been carried out in recent years. A review was conducted of these studies, gathering data on kerma area product (P KA), fluoroscopic screening time (FT), air kerma, and estimates of effective dose and organ doses. The majority of studies focus on P KA and FT with no estimation of dose to the patient. A greater than ten-fold variation in average P KA was found between different studies, even where data were stratified by patient age or weight. Typical values of P KA were 0.6-10 Gy · cm2 (<1 year/10 kg), 1.5-30 Gy · cm2 (1-5 years), 2-40 Gy · cm2 (5-10 years), 5-100 Gy · cm2 (10-16 years) and 10-200 Gy · cm2 (>16 years). P KA was lowest for heart biopsy (0.3-10 Gy · cm2 for all ages combined) and atrial septostomy (0.4-4.0 Gy · cm2), and highest for pulmonary artery angioplasty (1.5-35 Gy · cm2) and right ventricular outflow tract dilatation (139 Gy · cm2). Most estimates of patient dose were in the form of effective dose (typically 3-15 mSv) which is of limited usefulness in individualised risk assessment. Few studies estimated organ doses. Despite advances in radiation protection, recent publications have reported surprisingly large doses, as represented by P KA and air kerma. There is little indication of a fall in these dose indicators over the last 15 years. Nor is there much suggestion of a fall in doses associated with the use of flat panel detectors, as opposed to image intensifiers. An assessment of the impact of radiation dose in the context of overall patient outcome is required.

Estimation of Organ and Effective Doses for Neonate and Infant Diagnostic Cardiac Catheterizations

OBJECTIVE

Radiation exposure to neonates and infants during cardiac catheterizations is an important issue. Smaller patient size and higher heart rate in these patients result in a greater need for magnification modes and higher frame rates, all of which contribute to a significant increase in radiation doses. The aims of our study were to evaluate organ and effective doses for neonates and infants during diagnostic cardiac catheterizations on the basis of in-phantom dosimetry and conversion factors from dose-area product (DAP) to the effective dose.

MATERIALS AND METHODS

Organ doses for 0- and 1-year-old children during diagnostic cardiac catheterizations were measured by radiophotoluminescence glass dosimeters implanted in neonate and infant anthropomorphic phantoms. The effective doses were evaluated according to recommendations of the International Commission on Radiologic Protection (ICRP) publication 103.

RESULTS

The mean effective doses evaluated according to ICRP 103 were 7.7 mSv (range, 0.1-18.4 mSv) for a neonate and 7.3 mSv (range, 1.9-18.6 mSv) for an infant. Conversion factors from DAP to the effective dose were 2.2 and 4.0 in posteroanterior and lateral cine angiography, respectively, for a neonate and 1.4 and 2.7 in posteroanterior and lateral cine angiography, respectively, for an infant.

CONCLUSION

The dose data and conversion factors evaluated in this study could be useful for the estimation of radiation exposure in neonates and infants during diagnostic cardiac catheterization.

Radiation dose and mortality risk to children undergoing therapeutic interventional cardiology

BACKGROUND

Children undergoing interventional cardiology procedures deserve special concern due to the greater radiation sensitivity of their tissues and more remaining years of life during which a radiation-induced cancer may develop.

PURPOSE

To determine the patient radiation dose for pediatric therapeutic interventional cardiology and to estimate the patient effective dose and lifetime mortality risk to children associated with five common procedures.

MATERIAL AND METHODS

Ninety children with congenital heart defects undergoing interventional therapy were enrolled in this study. Data regarding fluoroscopy and radiography time, dose-area product (DAP) and peak skin dose (PSD) for each case were measured. Patients were divided into five groups. The patient effective dose (E) was calculated using a multiplicative model of ICRP 60. The overall lifetime mortality risk was evaluated using appropriate risk coefficients.

RESULTS

The mean, median, standard deviation, and range of time, PSD, DAP, and E were presented for the five study groups. When these metrics were considered, there were wide variations for different cases within the same group and statistically significant differences between the five groups. The PSD correlated significantly with DAP (Pearson r = 0.70; P < 0.01), but the correlation in individual cases was poor. For all cases, the range of E was found to be between 0.44 and 66.7 mSv. The corresponding risk of lifetime mortality was 1.16 per thousand.

CONCLUSION

The current study provides overall data on the time, PSD, E, and lifetime mortality risk for pediatric therapeutic interventional cardiology. Radio frequency ablation showed the highest radiation risk.

Trends in the utilization of computed tomography and cardiac catheterization among children with congenital heart disease

Background/Purpose

Pediatric cardiac computed tomography (CT) is a noninvasive imaging modality used to clearly demonstrate the anatomical detail of congenital heart diseases. We investigated the impact of cardiac CT on the utilization of cardiac catheterization among children with congenital heart disease.

Methods

The study sample consisted of 2648 cardiac CT and 3814 cardiac catheterization from 1999 to 2009 for congenital heart diseases. Diagnoses were categorized into 11 disease groups. The numbers of examination, according to the different modalities, were compared using temporal trend analyses. The estimated effective radiation doses (mSv) of CT and catheterization were calculated and compared.

Results

The number of CT scans and interventional catheterizations had a slight annual increase of 1.2% and 2.7%, respectively, whereas that of diagnostic catheterization decreased by 6.2% per year. Disease groups fell into two categories according to utilization trend differences between CT and diagnostic catheterization. The increased use of CT reduces the need for diagnostic catheterization in patients with atrioventricular connection disorder, coronary arterial disorder, great vessel disorder, septal disorder, tetralogy of Fallot, and ventriculoarterial connection disorder. Clinicians choose either catheterization or CT, or both examinations, depending on clinical conditions, in patients with semilunar valvular disorder, heterotaxy, myocardial disorder, pericardial disorder, and pulmonary vein disorder. The radiation dose of CT was lower than that of diagnostic cardiac catheterization in all age groups.

Conclusion

The use of noninvasive CT in children with selected heart conditions might reduce the use of diagnostic cardiac catheterization. This may release time and facilities within the catheterization laboratory to meet the increasing demand for cardiac interventions.

Local reference levels and organ doses from pediatric cardiac interventional procedures

Interventional cardiology (IC) procedures can be responsible for relatively high radiation doses compared to conventional radiology especially for young patients. The aim of this study was to assess current exposure levels in a French reference centre of pediatric IC. Dosimetric data including dose area product (DAP), fluoroscopy time (FT) and number of cine frame (NF) were analysed taking into account patient weight. Doses to the lungs, esophagus, breast and thyroid were evaluated using anthropomorphic phantoms and thermoluminescent dosimeters. Finally, effective doses (E) were calculated using DAP and conversion factors calculated with PCXMC 2.0 software. 801 IC procedures performed between 2010 and 2011 were analysed. Large variations were observed for DAP, FT and NF values for a given procedure and a given weight group. The assessment of organ doses showed high levels of dose to the lungs and esophagus especially in new-born babies. For diagnostic procedures, E varied from 0.3 to 23 mSv with a mean value of 4.8 mSv and for therapeutic procedures, values ranged from 0.1 to 48.4 mSv with a mean value of 7.3 mSv. The highest values were recorded for angioplasty procedures (mean 13 mSv, range 0.6-48.4 mSv). The increasing use of IC in pediatric population stresses the need of setting up reference levels and keeping doses to children as low as possible.

Computed tomographic versus catheterization angiography in tetralogy of Fallot

AIM

To compare multidetector computed tomographic angiography with the gold standard cardiac catheterization and angiography in tetralogy of Fallot.

METHODS

In 40 consecutive patients over 5 years of age with tetralogy of Fallot, multidetector computed tomographic angiography and catheterization angiography studies were compared for intracardiac anatomy, pulmonary anatomy and indices, coronaries and collaterals. Safety parameters, relative advantages and limitations were also analyzed.

RESULTS

All catheterization studies required hospitalization whereas all tomographic studies were performed as outpatient procedures. The need for sedation and amount of contrast used were significantly greater in catheterization than in tomographic studies. Complications noted during catheterization were access site complications in 4 patients, cyanotic spells in 2, transient complete heart block requiring temporary pacing in 2, and air embolism in one. No complication was observed during tomographic studies. All tomographic studies were adequate, but 2 catheterization studies were inadequate. Ventricular septal defects, aortic override, level of right ventricular outflow tract obstruction, and pulmonary artery anatomy were equally assessed by both imaging modalities. However, tomographic studies missed additional small muscular ventricular septal defects. There was a linear correlation between tomographic and catheterization studies for pulmonary annulus size, artery sizes, Z-score, and Nakata index. There was complete concordance with respect to side of aortic arch and detection of collaterals. Coronary anatomy was better delineated in tomographic studies.

CONCLUSIONS

For preoperative evaluation of tetralogy of Fallot patients, multidetector computed tomographic angiography can be used as a reliable noninvasive alternative to cardiac catheterization angiography.

Practical ways to reduce radiation dose for patients and staff during device implantations and electrophysiological procedures

Despite the advent of non-fluoroscopic technology, fluoroscopy remains the cornerstone of imaging in most interventional electrophysiological procedures, from diagnostic studies over ablation interventions to device implantation. Moreover, many patients receive additional X-ray imaging, such as cardiac computed tomography and others. More and more complex procedures have the risk to increase the radiation exposure, both for the patients and the operators. The professional lifetime attributable excess cancer risk may be around 1 in 100 for the operators, the same as for a patient undergoing repetitive complex procedures. Moreover, recent reports have also hinted at an excess risk of brain tumours among interventional cardiologists. Apart from evaluating the need for and justifying the use of radiation to assist their procedures, physicians have to continuously explore ways to reduce the radiation exposure. After an introduction on how to quantify the radiation exposure and defining its current magnitude in electrophysiology compared with the other sources of radiation, this position paper wants to offer some very practical advice on how to reduce exposure to patients and staff. The text describes how customization of the X-ray system, workflow adaptations, and shielding measures can be implemented in the cath lab. The potential and the pitfalls of different non-fluoroscopic guiding technologies are discussed. Finally, we suggest further improvements that can be implemented by both the physicians and the industry in the future. We are confident that these suggestions are able to reduce patient and operator exposure by more than an order of magnitude, and therefore think that these recommendations are worth reading and implementing by any electrophysiological operator in the field.

Estimation of dose-area product-to-effective dose conversion factors for neonatal radiography using PCXMC

Dose-area product-to-effective dose (E) conversion factors for chest, abdomen and abdomen-chest neonatal radiographs were computed. Seven patient models in the Monte Carlo software, PCXMC, were defined, representing neonates ranging in weight from 0.5 to 6.0 kg. Conversion factors for a tube potential range of 50-80 kVp at two beam filtrations (3.0 mm Al and 3.0 mm Al+0.1 mm Cu) were calculated. For 133 neonatal radiographs, effective dose values determined using these conversion factors were compared with those obtained from PCXMC simulations customised for each radiograph. For a 3.0-kg newborn irradiated at 60 kVp/3.0 mm Al beam filtration, the conversion factors were 2.58, 1.90 and 1.91 μSv (mGy cm(2))(-1) for chest, chest-abdomen and abdomen radiographs, respectively. Average dose difference between the conversion factors and customised dose calculations was 16 %. Disagreement in effective dose was most strongly correlated with under-collimation in the lateral direction.

Conversion factors for estimation of effective dose in paediatric chest tomosynthesis

For chest tomosynthesis in adults, a conversion factor of 0.26 mSv/Gy cm² has been reported for calculating the effective dose from the registered dose-area-product. The aim of this study was to determine conversion factors for chest tomosynthesis in children. Using the Monte Carlo-based computer software PCXMC 2.0, simulations were performed on modified phantoms for males and females aged 8-19 y, in the posteroanterior and anteroposterior projection, with energies 80-140 kV and copper filtration 0.1-0.3 mm. Resulting conversion factors ranged between 0.23 and 1.09 mSv/Gy cm², decreased with patient age, were significantly higher in the anteroposterior projection and increased with increased energy or copper filtration. To avoid an underestimation of effective dose in children, it is recommended to use age-dependent conversion factors. As a simplified approach, three conversion factors might be used for posteroanterior chest tomosynthesis and radiography in children, namely 0.6 (8-10 y), 0.4 (11-14 y) and 0.3 mSv/Gy cm² (15-19 y).

Detection of pulmonary arterial morphology in tetralogy of Fallot with pulmonary atresia by computed tomography: 12 years of experience

Our aim was to evaluate the feasibility of using computed tomography (CT) to define the pulmonary artery anatomy in patients with tetralogy of Fallot and pulmonary atresia (TOF-PA). We retrospectively reviewed 110 patients with TOF-PA between 1995 and 2008. Those who received cardiac catheterization and surgery within 3 months of their CT examinations were enrolled. Based on Dr. Somerville's classification, the pulmonary arterial pattern was determined, including identifiable pulmonary trunk (type I), the presence of both left and right pulmonary arteries without trunk (II), only left or right pulmonary artery present (III), and absent intrapericardial pulmonary arteries (IV). The accuracy of both imaging modalities was evaluated with operation findings as the golden standard. The effective radiation doses and adverse events were also recorded. In the 64 eligible patients (median age, 23 months), CT and catheterization demonstrated accurate pulmonary arterial morphology in 60 (60/64) and 53 (53/64) TOF-PA patients, respectively. Thirty-two of 35 type I patients were correctly identified by CT, whereas 26 were correctly identified by catheterization (p = 0.03). Of the 20 type II TOF-PA patients, 19 were diagnosed by CT, whereas 18 were diagnosed by catheterization. CT and catheterization both successfully defined six type III and three type IV patients. The median calculated radiation doses caused by CT and catheterization were 4.5 and 5.6 mSv, respectively (p > 0.05).

CONCLUSIONS

For patients with TOF-PA, CT could accurately delineate pulmonary arterial morphology with the same level of accuracy as cardiac catheterization. Therefore, CT can be considered a reasonable diagnostic alternative for such patients.

Cardiac computed tomography and conventional angiography in the diagnosis of congenital cardiac disease in children: recent trends and radiation doses

BACKGROUND

The use of imaging that employs ionising radiation is increasing in the setting of paediatric cardiology. Children's high radiosensitivity and the lack of contemporary radiation data warrant a review of the radiation doses from the latest "state-of-the-art" angiography and computed tomography systems.

OBJECTIVES

In children aged less than 16 years with congenital cardiac disease, we aimed to report: recent trends in the use of diagnostic angiography and cardiac dual-source computed tomography; the characteristics, lesions, and imaging histories of patients undergoing these procedures; and the average radiation doses imparted by each modality.

STUDY DESIGN

Retrospective review of consecutive cases undergoing cardiac computed tomography or diagnostic angiography in a teaching hospital between January, 2008 and December, 2009. Radiation doses were converted to effective doses (millisievert) using published conversion factors.

RESULTS

Angiography was performed 3.7 times more often than computed tomography. Computed tomography examinations increased by 92.5%, whereas angiography decreased by 26.4% in 2009 compared with 2008. Patients undergoing computed tomography were younger and weighed less than those undergoing angiography, but lesions were similar between the 2 groups. Multiple lifetime angiography was more prevalent than multiple lifetime computed tomography (p < 0.001). The median procedural dose - range - from angiography and computed tomography was 5 (0.2-27.8) and 1.7 (0.5-9.5) millisieverts, respectively (p < 0.001).

CONCLUSION

Despite not being completely analogous investigations, computed tomography should be considered prior to angiography and not withheld on radiation dose concerns, given that it imparts lower and more consistent doses than conventional angiography.

Accuracy and safety of high pitch computed tomography imaging in young children with complex congenital heart disease

Multidetector computed tomographic angiography defines anatomy in complex congenital heart disease, but radiation exposure and general anesthesia requirements limit its application. The aim of this study was to compare radiation exposure, anesthesia use, and diagnostic accuracy between standard-pitch, single-source computed tomography and high-pitch, dual-source computed tomography for image quality and risk in a clinical pediatric population. Consecutive computed tomographic scans were evaluated in patients aged <2 years with complex congenital heart disease. Two groups were compared on the basis of standard- versus high-pitch scans. High-pitch scans were further divided into variable pitch (2.25 to 3.0) and highest pitch (3.4) groups. Image quality, radiation exposure, anesthesia use, and diagnostic confidence and accuracy were determined. Sixty-one scans were reviewed (29 at standard pitch, 32 at high pitch). Body surface area, scan length, and indications were similar. The median dose-length product for standard-pitch scans was 66 mGy · cm (range 29 to 372) compared to 7 mGy · cm (range 3 to 50) in all high-pitch scans. The median dose-length product was 28 mGy · cm (range 8 to 50) for variable high-pitch scans and 5 mGy · cm (range 3 to 12) for the highest fixed-pitch scans. Diagnostic confidence was similar, although high-pitch scans had higher image noise and lower contrast-to-noise ratios. All high-pitch scans were performed under sedation with free breathing, and all standard-pitch scans required general anesthesia. Diagnostic accuracy was 100% in the 2 groups, with 17 standard-pitch and 16 high-pitch patients undergoing procedural validation. In conclusion, high-pitch, dual-source computed tomography provides excellent diagnostic accuracy and markedly reduces radiation dose, although image quality is mildly reduced.