Radiation exposure to children during coil occlusion of the patent ductus arteriosus

Effect of Different Anthropometric Body Indexes on Radiation Exposure in Patients Undergoing Cardiac Catheterisation and Percutaneous Coronary Intervention

Background: Patient factors, such as sex and body mass index (BMI), are known to influence patient radiation exposure. Body surface area (BSA) and its association with patient radiation exposure has not been well studied. Methods and Results: We analysed height, weight, BMI and BSA in consecutive patients undergoing cardiac catheterisation and percutaneous coronary intervention (PCI) at a high-volume Australian centre between September 2016 and April 2020 to assess their association with dose–area product (DAP, Gycm²). The mean age of the cohort was 64.5 ± 12.3 years with males comprising 68.8% (n = 8100, 5124 diagnostic cardiac catheterisation cases and 2976 PCI cases). Median male BMI was 28.4 kg/m² [IQR 25.2–32.1] versus 28.8 kg/m² [24.7–33.7] for females, p = 0.01. Males had higher BSA (2.0 ± 0.2 m²) than females (1.78 ± 0.2 m²), p = 0.001. Each 0.4 m² increase in BSA conferred a 1.32x fold change in DAP (95% CI 1.29–1.36, p ≤ 0.001). Each 5 kg/m² increase in BMI was linked to a 1.13x DAP fold change (1.12–1.14, p ≤ 0.001). Male sex conferred a 1.23x DAP fold change (1.20–1.26, p ≤ 0.001). Multivariable modelling with BMI or BSA explained 14% of DAP variance (R² 0.67 vs. 0.53 for both, p ≤ 0.001). Conclusions: BSA is an important anthropometric measure between the sexes and a key predictor of radiation dose and radiation exposure beyond sex, BMI, and weight.

A Study on the Use of Radiation-Protective Apron among Interventionists in Radiology

Objective

Radiation-protective aprons are commonly used by interventionists to protect against the harmful effects of ionizing radiation. Choice of appropriate aprons with respect to lead equivalence and weight is necessary for effective protection and reduced physical strain. This study evaluates the knowledge and practice of using radiation-protective aprons by interventionists.

Materials and Methods

Ninety-one interventional radiologists who attended an annual interventional conference were provided with a questionnaire which included age, years of experience, area of expertise, type and weight of apron used, and physical strain caused due to the use of apron.

Results

About 14.3% of the interventionists practiced in an angiographic suite for less than an hour a day, 45% for 2-4 h, 21% for 4-6 h, 10% for 6-10 h, and the rest above 10 h/day. About 68% of the interventionists wore 0.5 mm lead-equivalent (Pb_eq) aprons; 15.4% with 0.25 mm Pb_eq; about 5.5% with 0.35 mm Pb_eq aprons, and the remaining were not aware of the lead equivalence. About 47% reported that they had body aches due to wearing single-sided aprons. Interventionists working more than 10 h/day wearing single-sided lead apron predominantly complained of shoulder pain and back pain.

Conclusion

A large fraction of interventionists reported that they had physical strain. It is suggestive for interventionists to wear correct fit and light-weight aprons with appropriate lead equivalence.

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.

Substantial radiation reduction in pediatric and adult congenital heart disease interventions with a novel X-ray imaging technology

Background

Pediatric catheterization exposes patients to varying radiation doses. Concerns over the effects of X-ray radiation dose on the patient population have increased in recent years. This study aims at quantifying the patient radiation dose reduction after the introduction of an X-ray imaging technology using advanced real time image noise reduction algorithms and optimized acquisition chain for fluoroscopy and exposure in a pediatric and adult population with congenital heart disease.

Methods

Patient and radiation dose data was retrospectively collected (July 2012–February 2013) for 338 consecutive patients treated with a system using state of the art image processing and reference acquisition chain (referred as “reference system”). The same data was collected (March–October 2013) for 329 consecutive patients treated with the new imaging technology (Philips AlluraClarity, referred as “new system”). Patients were divided into three weight groups: A) below 10 kg, B) 10–40 kg, and C) over 40 kg. Radiation dose was quantified using dose area product (DAP), while procedure complexity using fluoroscopy time, procedure duration and volume of contrast medium.

Results

The new system provides significant patient dose reduction compared to the reference system. Median DAP values were reduced in group A) from 140.6 cGy·cm² to 60.7 cGy·cm², in group B) from 700.0 cGy·cm² to 202.2 cGy·cm² and in group C) from 4490.4 cGy·cm² to 1979.8 cGy·cm² with reduction of 57%, 71% and 56% respectively (p < 0.0001 for all groups).

Conclusions

Despite no other changes in procedural approach, the novel X-ray imaging technology provided substantial radiation dose reduction of 56% or higher.

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x-ray radiation dose in pediatric patients is of specific concern as congenital heart disease is more often treated by interventional measures.

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the effect of advanced real time image noise reduction algorithms and optimized acquisition chain for fluoroscopy and exposure was studied.

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A state of the art image processing and reference acquisition chain was compared to the new imaging technology in 338 vs 329 consecutive patients.

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Patients were divided into three weight groups: A) below 10 kg, B) 10-40 kg, and C) over 40 kg according to clinical practice and procedure complexity.

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the novel X-ray imaging technology provided substantial radiation dose reduction of 56% or higher.

Estimation of radiation dose and risk to children undergoing cardiac catheterization for the treatment of a congenital heart disease using Monte Carlo simulations

BACKGROUND

Children diagnosed with congenital heart disease often undergo cardiac catheterization for their treatment, which involves the use of ionizing radiation and therefore a risk of radiation-induced cancer.

OBJECTIVE

The purpose of this study was to calculate the effective and equivalent organ doses (H(T)) in those children and estimate the risk of exposure-induced death.

MATERIALS AND METHODS

Fifty-three children were divided into three groups: atrial septal defect (ASD), ventricular septal defect (VSD) and patent ductus arteriosus (PDA). In all procedures, the exposure conditions and the dose-area product meters readings were recorded for each individual acquisition. Monte Carlo simulations were run using the PCXMC 2.0 code and mathematical phantoms simulating a child's anatomy. The H(T) values to all irradiated organs and the resulting E and risk of exposure-induced death values were calculated.

RESULTS

The average dose-area product values were, respectively, 40 ± 12 Gy·cm(2) for the ASD, 17.5 ± 0.7 Gy·cm(2) for the VSD and 9.5 ± 1 Gy·cm(2) for the PDA group. The average E values were 40 ± 12, 22 ± 2.5 and 17 ± 3.6 mSv for ASD, VSD and PDA groups, respectively. The respective estimated risk of exposure-induced death values per procedure were 0.109, 0.106 and 0.067%.

CONCLUSION

Cardiac catheterizations in children involve a considerable risk for radiation-induced cancer that has to be further reduced.

Estimation of children's radiation dose from cardiac catheterisations, performed for the diagnosis or the treatment of a congenital heart disease using TLD dosimetry and Monte Carlo simulation

Entrance surface radiation doses were measured with thermoluminescent dosimeters for 98 children who were referred to a cardiology department for the diagnosis or the treatment of a congenital heart disease. Additionally, all the radiographic parameters were recorded and Monte Carlo simulations were performed for the estimation of entrance surface dose to effective dose conversion factors, in order to further calculate the effective dose for each child. For diagnostic catheterisations the values ranged from 0.16 to 14.44 mSv, with average 3.71 mSv, and for therapeutic catheterisations the values ranged from 0.38 to 25.01 mSv, with average value 5 mSv. Effective doses were estimated for diagnostic procedures and interventional procedures performed for the treatment of five different heart diseases: (a) atrial septal defect (ASD), (b) ventricular septal defect (VSD), (c) patent ductus arteriosus (PDA), (d) aorta coarctation and (e) pulmonary stenosis. The high levels of radiation exposure are, however, balanced with the advantages of cardiac catheterisations such as the avoidance of surgical closure and the necessity of shorter or even no hospitalisation.

Radiation dose to the brain and subsequent risk of developing brain tumors in pediatric patients undergoing interventional neuroradiology procedures

Radiation dose to the brain and subsequent lifetime risk of diagnosis of radiation-related brain tumors were estimated for pediatric patients undergoing intracranial embolization. Average dose to the whole brain was calculated using dosimetric data from the Radiation Doses in Interventional Radiology Study for 49 pediatric patients who underwent neuroradiological procedures, and lifetime risk of developing radiation-related brain tumors was estimated using published algorithms based on A-bomb survivor data. The distribution of absorbed dose within the brain can vary significantly depending on field size and movement during procedures. Depending on the exposure conditions and age of the patient, organ-averaged brain dose was estimated to vary from 6 to 1600 mGy. The lifetime risk of brain tumor diagnosis was estimated to be increased over the normal background rates (57 cases per 10,000) by 3 to 40% depending on the dose received, age at exposure, and gender. While significant uncertainties are associated with these estimates, we have quantified the range of possible dose and propagated the uncertainty to derive a credible range of estimated lifetime risk for each subject. Collimation and limiting fluoroscopy time and dose rate are the most effective means to minimize dose and risk of future induction of radiation-related tumors.

Radiation dose survey in a paediatric cardiac catheterisation laboratory equipped with flat-panel detectors

Flat-panel X-ray detectors for fluoroscopy represent a modern imaging equipment that is being implemented in paediatric cardiac catheterisation laboratories. Infants and children represent a group of patients with a high radiosensitivity. A survey of 273 (126 diagnostic and 147 therapeutic) paediatric catheterisations was performed to investigate the radiation doses delivered by the new X-ray system. Statistical parameters (75th, 50th and 25th percentiles) of dose-area product (DAP) and fluoroscopy time are reported for patients divided into six age groups: 0-30 d, >1-12 m, >1-3, >3-5, >5-10 and >10-15 y. For accurate risk estimation, effective dose (E) has been determined for all patients using the PCXMC software. For diagnostic procedures, the third quartile of E ranges from 11.3 mSv for newborns to 7 mSv for children of 10-15 y. Therapeutic procedures are more complex than diagnostic. Consequently, the third quartile of E is 22.6 mSv (0-30 d), 18.6 (>1-12 m), 13.3 (>1-3 y), 21.5 (>3-5 y), 17.8 (>5-10 y) and 34.1 mSv (>10-15 y). Dose conversion factors, which relate the DAP and E, have been estimated for each age group. The results of this study may serve as a first step in the optimisation process, in order to make full use of the dose reduction potential of flat-panel systems.

Real-time magnetic resonance imaging-guided stenting of aortic coarctation with commercially available catheter devices in Swine

BACKGROUND

Real-time MR imaging (rtMRI) is now technically capable of guiding catheter-based cardiovascular interventions. Compared with x-ray, rtMRI offers superior tissue imaging in any orientation without ionizing radiation. Translation to clinical trials has awaited the availability of clinical-grade catheter devices that are both MRI visible and safe. We report a preclinical safety and feasibility study of rtMRI-guided stenting in a porcine model of aortic coarctation using only commercially available catheter devices.

METHOD AND RESULTS

Coarctation stenting was performed wholly under rtMRI guidance in 13 swine. rtMRI permitted procedure planning, device tracking, and accurate stent deployment. "Active" guidewires, incorporating MRI antennas, improved device visualization compared with unmodified "passive" nitinol guidewires and shortened procedure time (26+/-11 versus 106+/-42 minutes; P=0.008). Follow-up catheterization and necropsy showed accurate stent deployment, durable gradient reduction, and appropriate neointimal formation. MRI immediately identified aortic rupture when oversized devices were tested.

CONCLUSIONS

This experience demonstrates preclinical safety and feasibility of rtMRI-guided aortic coarctation stenting using commercially available catheter devices. Patients may benefit from rtMRI in the future because of combined device and tissue imaging, freedom from ionizing radiation, and the ability to identify serious complications promptly.

Real-time magnetic resonance imaging to guide pediatric endovascular procedures

Although x-ray fluoroscopy (XRF) has guided diagnostic and therapeutic transcatheter procedures for decades, certain limitations still exist. XRF still visualizes tissue poorly and relies on projection of shadows that do not convey depth information. Adjunctive echocardiography overcomes some of these limitations but still suffers suboptimal or unreliable imaging windows. Furthermore, ionizing radiation exposure in children imparts a cancer risk. An interventional platform using real-time magnetic resonance imaging (MRI) may offer superior image guidance without radiation. Although there are many remaining challenges, but real-time MRI has the potential to revolutionize transcatheter therapeutics.

Assessment of patient radiation doses during transcatheter closure of ventricular and atrial septal defects with Amplatzer devices

The purpose of this study was to estimate the radiation dose to which children are exposed during cardiac catheterizations for the treatment of ventricular and atrial septal defects. Radiation doses were estimated for 46 children aged 1-18 years. These children were treated for secundum atrial septal defects (ASD group) for perimembranous ventricular septal defects (VSD group) or underwent a routine diagnostic catheterization (diagnostic group). Thermoluminescent dosimeters (TLDs) were attached in locations, representing the lateral entrance dose, the posterior entrance dose, the thyroid dose, and the gonad dose, respectively. A dose area product (DAP) meter was also attached externally on the posterior-anterior (PA) tube to give a direct value in cGy cm(2) for each procedure. The patient's entrance dose from the PA field ranged from 1.5 to 185.0 mGy for all patients, while the lateral entrance dose varied from 0.9 to 204 mGy. Radiation exposure to the thyroid and the gonads was found to vary from 0.4 to 8.3 and 0.1 to 2.1 mGy, respectively. The DAP meter recorded DAP values for the posterior tube, between 46 and 3,700 cGy cm(2). The mean effective dose was found to be 7.7, 16.2, and 33.3 mSv for the diagnostic, the ASD, and the VSD group, respectively. Very strong correlation was found between the DAP values and the entrance radiation dose measured with TLDs. The mean entrance dose received from therapeutic cardiac catheterizations using the Amplatzer devices was found approximately twice the dose received from a diagnostic one. Even for the most complex procedures, the maximum entrance dose was at least 10 times lower than the threshold, associated with skin erythema.

Magnetic Resonance–Guided Cardiac Catheterization in a Swine Model of Atrial Septal Defect

Background— Radiation exposure during cardiac catheterization, limited image planes, and poor soft tissue definition are disadvantages of x-ray fluoroscopy that could be overcome with the use of MRI. This study evaluates the feasibility of real-time MRI (MR fluoroscopy) to guide left and right heart catheterization.

Methods and Results— Anesthetized pigs (n=7) with defects of the atrial septum were catheterized using venous and arterial access. A prototype active tracking catheter was used to obtain blood pressures and samples from cardiac chambers and great vessels using antegrade, transseptal, and retrograde approaches. MR fluoroscopy was used for catheter steering. Velocity-encoded cine MRI was used to measure pulmonary and aortic blood flow to calculate vascular resistances. Image planes used during catheter manipulation used rapid sequencing to planes directed by the operator to include the tip of the catheter and the chamber to be entered. All areas of interest were effectively entered, and samples were obtained. In the presence of an acute atrial septal defect, a Q p /Q s ratio of 1.3±0.2 was measured, and no significant differences in pressure between inferior vena cava, right atrium, and left atrium were found. Pulmonary and aortic flow were 4.9±0.6 and 3.7±0.4 L/min, and pulmonary and systemic vascular resistance were 312±134 and 2006±336 dyne · s · cm −5 .

Conclusions— Left and right heart catheterization using MR guidance is feasible. The combination of hemodynamic catheterization data with anatomic and functional MRI may significantly improve the evaluation of patients with congenital heart disease while avoiding radiation exposure.

Experimental evaluation of a modified Amplatzer duct occluder

The purpose of this study was to evaluate a new device specifically designed for patent ductus arteriosus (PDA) occlusion based on PDA anatomy. Percutaneous closure of aortopulmonary shunts was attempted in 10 dogs. Shunts were surgically created in the location and orientation of PDA. The occlusion prosthesis consisted of a cylindrical frame filled with polyester and a 32 degree angled retention disk. The delivery system of the device included a 6 Fr thin-walled Teflon introducing sheath, an antirotating delivery catheter, and cable. Complete occlusion of the shunt was obtained in nine animals. One animal died before device placement. Temporary hemolysis occurred in one dog after device placement. The disk of device was completely covered by smooth glistening neoendothelium at 1-3 months postmortem examination. None of the devices protruded into the lumen of the aorta. The device is an improvement over the standard Amplatzer duct occluder. The angled retention disk lies flatly against the aortic wall, avoiding turbulence or an aortic pressure gradient.

Gianturco-Grifka vascular occlusion device for closure of patent ductus arteriosus

We retrospectively reviewed the results of catheter closure of patent ductus areteriosus using the Ginaturco-Grifka vascular occlusion device in our institution. All patients in whom it was attempted had successful implantation, complete closure on follow-up, and no complications.

Exposure to ionizing radiation in children undergoing Amplatzer device placement to close atrial septal defects

To evaluate exposure to ionizing radiation during Amplatzer device occlusion, a prospective study was performed to measure surface entrance radiation dose by thermoluminescent dosimetry (TLD). Between June 1998 and April 1999, dosimetry was carried out on 12 patients with Amplatzer device occlusion of atrial septal defects (n = 10) or Fontan fenestration (n =) and 12 age-matched patients who underwent diagnostic catherization. TLD chips were placed at the posterior (PA) and right lateral (LA) chest wall as well as the thyroid (TH) and gonadal (GN) regions. The Amplatzer group had a median age of 6.4 yr (2.4-12.4 yr) and a median weight of 23.7 kg (15.6-28.9 kg), which were similar (p = NS) to those of the control group, who had a median age of 7.9 yr (3.3-16.2 yr) and a median weight of 29.9 kg (10.6-58.0 kg). Device placement was successful in 11 of 12 patients; one device was removed owing to partial obstruction of the right-upper pulmonary vein. Fluoroscopy times were also similar in the Amplatzer group (23.5 +/- 2.1 min) and the control group (16.4 +/- 3.1 min; P = NS). The measured surface entrance doses of the Amplatzer group was similar (p = NS) to those of the control group in all four regions: PA (4.96 +/- 1.88 vs. 6.07 +/- 2.16 cGy), LA (5.22 +/- 1.68 vs. 3.13 +/- 1.25 cGy), TH (0.92 +/- 0.14 vs. 0.69 +/- 0.09 cGy), and GN (0.20 +/- 0.00 vs. 0.22 +/- 0.01cGy). Fluoroscopy times and measured surface entrance doses of ionizing radiation in patients undergoing Amplatzer device occlusion are similar to those in patients undergoing routine diagnostic catheterization.

Interventional catheterization

Several investigations have been performed to evaluate the mid-term results of coil embolization for patent ductus arteriosus. Excellent results were obtained with coils if the minimum diameter of the ductus was less than 4 mm. Balloon dilation of native coarctation and recoarctation may be associated with complications such as aneurysm formation. Stent placement may solve some of the problems of balloon dilation, but the stents currently available are not perfect. Results of transcatheter closure of atrial septal defect using new devices have been were reported. The self-expanding nitinol double-disk device (Amplatzer septal occluder) (AGA Medical Corporation, Golden Valley, Minnesota) is becoming popular because it is easy to implant, is easy to retrieve before its release, can occlude a relatively large defect, and has a low rate of residual leak. Although the immediate results with this device were excellent, surgical closure is still the standard treatment and we need to see the long-term results of transcatheter closure.