The Image Gently Alliance Have-A-Heart campaign has prepared a detailed report on radiation dose management and cardiac computed tomography (CT) performance in children with congenital or acquired heart disease. These children undergo a variety of clinically necessary imaging examinations that may expose them to relatively high lifetime cumulative doses of ionizing radiation. The report in the January issue of Pediatric Radiology offers expert opinions on radiation dose metrics and dose consideration, techniques to optimize the performance of cardiac CT, implementation of institutional CT dose monitoring, and communicating with parents.
The DICOM structured dose report produced by CT scanners includes volumetric CT dose index (CTDIvol) and dose-length product (DLP) data. These scanner output data should not be used as a radiation dose metric for a pediatric patient. Effective dose estimation methodologies are not standardized for pediatric cardiac CT, and no consensus has been established for a standard calculation method for cardiac CT effective dose for children.
The authors recommend the use of recently published American Association of Physicists in Medicine (AAPM)-approved pediatric conversion factors prepared by members of the Image Gently campaign.1 They caution that individual patient metrics, such as age-related sensitivities and/or variations in organ sizes and locations, are not accounted for in all effective dose calculations. They compiled a detailed table of effective dose ranges for pediatric CT from12 peer-reviewed journal articles.
The authors state that echocardiography has excellent diagnostic accuracy and is the primary imaging modality for children with heart disease. When echocardiography yields an incomplete examination, cardiac magnetic resonance imaging (MRI) is often used. Cardiac MRI provides excellent visualization and no exposure to ionizing radiation. Its negatives include potential lack of availability, high cost, use of gadolinium-based contrast agents, time to perform, and potential need to sedate the patient.
The advantages of cardiac CT include excellent spatial resolution and visualization of the airways, pulmonary parenchyma, bones, and soft tissues. It is also a very fast exam to perform. It is the current optimal study for coronary imaging, specifically for the visualization of coronary artery origins, proximal through distal courses including evidence of anomalous origins, acute origin angulations, or intramural segments in congenital or acquired anomalies, and in infants with complex anomalies. Cardiac CT can also identify areas of coronary artery dilation or stenosis in patients with acquired coronary disease. The authors state that cardiac CT is also excellent for imaging patients with suspected thoracic arterial abnormalities or thromboembolism. It provides clear imaging of vascular rings, branch pulmonary artery and pulmonary vein assessment, and evaluation for aortopulmonary collaterals.
The report provides detailed recommendations on optimizing cardiac CT techniques, including scan protocols specifically for each patient to achieve the goals for each study, contrast agent administration, and special requirements for children with the Fontan circulation.
The authors also discuss informed decision making with respect to cardiac CT scanning and children, in terms of which clinicians should be involved and what information should be shared with the family. They also provide practical advice on implementing a CT dose management program. No matter how detailed or comprehensive facility’s program, the authors caution that constant vigilance, as well as regular review of radiation exposure data, is required to ensure that quality and dose are optimal for every child who has a cardiac CT examination.
Image Gently Have-A-Heart campaign offers pediatric cardiac CT report/recommendations . Appl Radiol.