Radiation dose management for pediatric cardiac computed tomography: a report from the Image Gently ‘Have-A-Heart’ campaign

Abstract

Children with congenital or acquired heart disease can be exposed to relatively high lifetime cumulative doses of ionizing radiation from necessary medical imaging procedures including radiography, fluoroscopic procedures including diagnostic and interventional cardiac catheterizations, electrophysiology examinations, cardiac computed tomography (CT) studies, and nuclear cardiology examinations. Despite the clinical necessity of these imaging studies, the related ionizing radiation exposure could pose an increased lifetime attributable cancer risk. The Image Gently "Have-A-Heart" campaign is promoting the appropriate use of medical imaging studies in children with congenital or acquired heart disease while minimizing radiation exposure. The focus of this manuscript is to provide a comprehensive review of radiation dose management and CT performance in children with congenital or acquired heart disease.

Cardiovascular CT in Cyanotic Congenital Heart Disease

“…However, effective doses still vary widely, and recently published pediatric cardiac-specific dose-length product conversion or "k-"factors suggest that k-factors, and therefore effective cardiac radiation doses, in children are considerably higher than previously believed [32,36]. In an effort to minimize radiation doses and standardize imaging parameters across pediatric centers, the Image Gently alliance's "Have-a-Heart" campaign recently published radiation management guidelines for pediatric cardiovascular CT [32]. Several large congenital cardiac centers have also recently established an international congenital cardiovascular CT registry to establish best practice guidelines for radiation exposure and anesthesia use in CHD patients [37].…”

“…Another group reported that single ventricle patients received on average 10 mSv per year during the first 3-4 years of life [31]. Older CT scanners, using a retrospectively electrocardiogram (ECG)-gated scan mode, have been reported to expose CHD patients to effective doses of up to 28 mSv per cardiac scan [32]. Since then, innovations such as prospective ECG gating, ECG-controlled tube current modulation, high-pitch helical scanning, lower tube potentials, wider detector coverage, and iterative reconstruction techniques have dramatically lowered radiation exposure [33,34].…”

“…Today, sub-milliSievert scans are achievable in many children [35]. However, effective doses still vary widely, and recently published pediatric cardiac-specific dose-length product conversion or "k-"factors suggest that k-factors, and therefore effective cardiac radiation doses, in children are considerably higher than previously believed [32,36]. In an effort to minimize radiation doses and standardize imaging parameters across pediatric centers, the Image Gently alliance's "Have-a-Heart" campaign recently published radiation management guidelines for pediatric cardiovascular CT [32].…”

“…Performing cardiovascular CT in patients with cyanotic cardiac defects, who span the spectrum of neonates to adults and may be unrepaired, palliated, or fully repaired, requires careful individualization of the exam to the patient, the physiology of the defect, and the clinical question being addressed. Detailed guidelines addressing scan protocols and radiation dose reduction in pediatric and congenital heart disease have been published elsewhere, but we will briefly review a few considerations pertinent to cyanotic CHD patients [28,29,32,[94][95][96]. Fig.…”

“…The effective radiation dose is affected by x-ray tube potential and current, scan mode, exposure time, z-axis coverage, and imaging settings used when bolus tracking. The literature suggests that most congenital CHD scanning can be performed at 70 or 80 kV [32,57]. While the use of iterative reconstruction techniques allows lower tube currents to be selected for a given patient size, the clinical question to be addressed should primarily determine tube potential.…”