Abstract
The HARMONIC project (Health Effects of Cardiac Fluoroscopy and Modern Radiotherapy in Paediatrics) is a European study aiming to improve our understanding of the long-term health risks from radiation exposures in childhood and early adulthood. Here, we present the study design for the cardiac fluoroscopy component of HARMONIC. A pooled cohort of approximately 100 000 patients who underwent cardiac fluoroscopy procedures in Belgium, France, Germany, Italy, Norway, Spain or the UK, while aged under 22 years, will be established from hospital records and/or insurance claims data. Doses to individual organs will be estimated from dose indicators recorded at the time of examination, using a lookup-table-based dosimetry system produced using Monte Carlo radiation transport simulations and anatomically realistic computational phantom models. Information on beam geometry and x-ray energy spectra will be obtained from a representative sample of radiation dose structured reports. Uncertainties in dose estimates will be modelled using 2D Monte Carlo methods. The cohort will be followed up using national registries and insurance records to determine vital status and cancer incidence. Information on organ transplantation (a major risk factor for cancer development in this patient group) and/or other conditions predisposing to cancer will be obtained from national or local registries and health insurance data, depending on country. The relationship between estimated radiation dose and cancer risk will be investigated using regression modelling. Results will improve information for patients and parents and aid clinicians in managing and implementing changes to reduce radiation risks without compromising medical benefits.
Highlights
Survival rates for congenital heart disease have improved markedly in recent decades [1,2,3], leading to increased focus on the long-term complications of treatment
HARMONIC will involve dose estimation for procedures performed as far back as the 1990s, i.e. well before the introduction of radiation dose structured reports (RDSR) in 2005. It is not clear if the typical beam angles used for cardiac fluoroscopy have changed over time and, whether RDSRs are an appropriate source of information for pre-RDSR era examinations
For pre-RDSR era examinations, for which detailed exposure data are not available, probability density functions (PDFs) will be wider, reflecting greater uncertainty. 2D Monte Carlo (2DMC) methods have been applied to studies of radiation doses from computed tomography (CT) [42] occupational exposures [43] and environmental exposures [44, 45] but not paediatric cardiac fluoroscopy, where information on uncertainties in dose estimates is currently very limited
Summary
Survival rates for congenital heart disease have improved markedly in recent decades [1,2,3], leading to increased focus on the long-term complications of treatment. [7]) and, at high doses, impairment of tissue function through the effects of excessive cell killing [8]. These risks may be justified, if outweighed by the diagnostic or therapeutic advantage of the exposure. The project addresses exposures not covered by existing or recently completed European paediatric radiation research programs including MEDIRAD (childhood CT and radioiodine and breast radiotherapy in adults) and EPI-CT (childhood CT). We will highlight a number of challenges faced by the study (and other similar studies) and the proposed methods for addressing them
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