Long-term health hazards from diagnostic X-ray exposure

Medical imaging is an important function in the diagnosis and management of disease and its use have been increasing with technological advancements. A large part of medical imaging uses ionizing radiation as medium for imaging although it does pose potential risks to the patient. Computed Tomography (CT) uses a larger radiation dose than conventional X-rays and technological advances has led to more complex examinations increasing radiation doses even higher. The increased availability of CT machines has also facilitated the increased usage. This means that the population as a whole receives an increasing radiation dose and CT is now the most important contributor to radiation dose from medical examinations. The potential damage from ionizing radiation concerns long-term risks and includes cancer but other effects are known and includes cognitive difficulties amongst children. In study I we investigated the relationship between pelvimetry and negative effects from ionizing radiation on cognitive function expressed as changes in school grades. We examined 1 536 children exposed to pelvimetry in utero and compared them to 44 530 unexposed children. We found no negative effect on school grades when controlling for sex, birth order, mother’s education and birth position. In study II and III we examined the risk of ionizing radiation from CT of the head. We gathered data from a radiological archive in Sweden and collected 26 370 patients. Patients were then matched on age, sex and residence to 4 controls, both cohorts were then linked to national registries in order to gather outcome data. The outcome in study II was meningioma and in study III glioma. We found no evidence of increased risk for neither meningioma nor glioma after CT examinations. However, information in national registries were not enough for exclusion of prevalent tumor at time of first CT or radiotherapy, referral notes were necessary in order to minimize bias. Study IV is a method article and is a description of the international EPI-CT study that aims to investigate children who have had a CT examination. As part of EPI-CT we have collected RIS and PACS data from hospitals in order to assemble the Swedish cohort. This data will then be linked to national registries in order to investigate adverse effects from CT examinations. In conclusion we have not found any negative result on school performance after pelvimetry nor have we found any increased risk for meningioma or glial tumors after CT examination of the head

EPI-CT: design, challenges and epidemiological methods of an international study on cancer risk after paediatric and young adult CT

Computed tomography (CT) has great clinical utility and its usage has increased dramatically over the years. Concerns have been raised, however, about health impacts of ionising radiation exposure from CTs, particularly in children, who have a higher risk for some radiation induced diseases. Direct estimation of the health impact of these exposures is needed, but the conduct of epidemiological studies of paediatric CT populations poses a number of challenges which, if not addressed, could invalidate the results. The aim of the present paper is to review the main challenges of a study on the health impact of paediatric CTs and how the protocol of the European collaborative study EPI-CT, coordinated by the International Agency for Research on Cancer (IARC), is designed to address them. The study, based on a common protocol, is being conducted in Belgium, Denmark, France, Germany, the Netherlands, Norway, Spain, Sweden and the United Kingdom and it has recruited over one million patients suitable for long-term prospective follow-up. Cohort accrual relies on records of participating hospital radiology departments. Basic demographic information and technical data on the CT procedure needed to estimate organ doses are being abstracted and passive follow-up is being conducted by linkage to population-based cancer and mortality registries. The main issues which may affect the validity of study results include missing doses from other radiological procedures, missing CTs, confounding by CT indication and socioeconomic status and dose reconstruction. Sub-studies are underway to evaluate their potential impact. By focusing on the issues which challenge the validity of risk estimates from CT exposures, EPI-CT will be able to address limitations of previous CT studies, thus providing reliable estimates of risk of solid tumours and leukaemia from paediatric CT exposures and scientific bases for the optimisation of paediatric CT protocols and patient protection

Assessing Organ Doses from Paediatric CT Scans—A Novel Approach for an Epidemiology Study (the EPI-CT Study)

The increasing worldwide use of paediatric computed tomography (CT) has led to increasing concerns regarding the subsequent effects of exposure to radiation. In response to this concern, the international EPI-CT project was developed to study the risk of cancer in a large multi-country cohort. In radiation epidemiology, accurate estimates of organ-specific doses are essential. In EPI-CT, data collection is split into two time periods—before and after introduction of the Picture Archiving Communication System (PACS) introduced in the 1990s. Prior to PACS, only sparse information about scanner settings is available from radiology departments. Hence, a multi-level approach was developed to retrieve information from a questionnaire, surveys, scientific publications, and expert interviews. For the years after PACS was introduced, scanner settings will be extracted from Digital Imaging and Communications in Medicine (DICOM) headers, a protocol for storing medical imaging data. Radiation fields and X-ray interactions within the body will be simulated using phantoms of various ages and Monte-Carlo-based radiation transport calculations. Individual organ doses will be estimated for each child using an accepted calculation strategy, scanner settings, and the radiation transport calculations. Comprehensive analyses of missing and uncertain dosimetry data will be conducted to provide uncertainty distributions of doses

Cohort Profile:the EPI-CT study: a European pooled epidemiological study to quantify the risk of radiation-induced cancer from paediatric CT

International audience•The multinational EPI-CT study was set-up in 2011 to provide direct estimates of risk of solid tumours and leukaemia among children and young adults who underwent computed tomography (CT) scanning and to consolidate the scientific basis for optimization of paediatric CT protocols and patient protection.•Under a common protocol, cohort studies were conducted in Belgium, Denmark, France, Germany, the Netherlands, Norway, Spain, Sweden and the United Kingdom, coordinated by the International Agency for Research on Cancer (IARC). •The study recruited a total of about 950,000 patients having undergone at least one CT-scan before the age of 22 years. A total of 8.7 million person-years of incidence follow-up were accrued between 1977 and 2014. Cohort members were followed up passively through linkage with population-based cancer and mortality registries. A methodology was developed to reconstruct individual organ doses and estimate associated uncertainties, using data available in electronic archiving systems of the radiology departments of participating hospitals. Description of the cohort and analysis of mortality risk are presented here.•Proposals for possible collaboration in further analyses of the data should be addressed to Dr. Ausrele Kesminiene ([email protected]) and will be reviewed by the EPI-CT steering committe