[Exposure to ionizing radiation from computed tomography (CT) in childhood and cancer risk]. / Esposizione a radiazioni ionizzanti da tomografia computerizzata (TC) in età infantile e rischio di tumore.

A recent US cohort study estimated 500 cancer cases attributable to exposure to CT out of 600,000 children aged <15 years who underwent a computed tomography (CT) to head or abdomen. This review synthetizes the evidence on the association between exposure to ionizing radiation through CT and cancer risk. Five cohort studies were identified. Three studies show clear increases in cancer risk among children and adolescents who underwent at least one CT. All studies had methodological limits, among which the lack of an individual level estimate of dose-organ specific absorbed by patient and problems of statistical power. Results from on-going large international studies will allow a more accurate risk estimation.

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.

Paediatric CT scan usage and referrals of children to computed tomography in Germany--a cross-sectional survey of medical practice and awareness of radiation related health risks among physicians.

BACKGROUND: Computed tomography (CT) is a major source of ionizing radiation exposure in medical diagnostic. Compared to adults, children are supposed to be more susceptible to health risks related to radiation. The purpose of a cross-sectional survey among office-based physicians in Germany was the assessment of medical practice in paediatric CT referrals and to investigate physicians' knowledge of radiation doses and potential health risks of radiation exposure from CT in children. METHODS: A standardized questionnaire was distributed to all paediatricians and surgeons in two defined study areas. Furthermore, the study population included a random sample of general practitioners in the two areas. The questionnaire covered the frequency of referrals for paediatric CT examinations, the medical diagnoses leading to paediatric CT referrals, physicians' knowledge of radiation doses and potential health risks of radiation exposure from CT in children. RESULTS: A total of 295 (36.4%) physicians responded. 59% of the doctors had not referred a child to CT in the past year, and approximately 30% referred only 1-5 children annually. The most frequent indications for a CT examination in children were trauma or a suspected cancer. 42% of the referrals were related to minor diagnoses or unspecific symptoms. The participants underestimated the radiation exposure due to CT and they overestimated the radiation exposure due to conventional X-ray examinations. CONCLUSIONS: In Germany, the frequency of referrals of children to computed tomography is moderate. The knowledge on the risks from radiation exposure among office-based physicians in our sample varied, but there was a tendency to underestimate potential CT risks. Advanced radiological training might lead to considerable amendments in terms of knowledge and practice of CT referral.

Computed tomographies and cancer risk in children: a literature overview of CT practices, risk estimations and an epidemiologic cohort study proposal.

Radiation protection is a topic of great public concern and of many scientific investigations, because ionizing radiation is an established risk factor for leukaemia and many solid tumours. Exposure of the public to ionizing radiation includes exposure to background radiation, as well as medical and occupational exposures. A large fraction of the exposure from diagnostic procedures comes from medical imaging. Computed tomography (CT) is the major single contributor of diagnostic radiation exposure. An increase in the use of CTs has been reported over the last decades in many countries. Children have smaller bodies and lower shielding capacities, factors that affect the individual organ doses due to medical imaging. Several risk models have been applied to estimate the cancer burden caused by ionizing radiation from CT. All models predict higher risks for cancer among children exposed to CT as compared to adults. However, the cancer risk associated with CT has not been assessed directly in epidemiological studies. Here, plans are described to conduct an historical cohort study to investigate the cancer incidence in paediatric patients exposed to CT before the age of 15 in Germany. Patients will be recruited from radiology departments of several hospitals. Their individual exposure will be recorded, and time-dependent cumulative organ doses will be calculated. Follow-up for cancer incidence via the German Childhood Cancer Registry will allow computation of standardized incidence ratios using population-based incidence rates for childhood cancer. Dose-response modelling and analyses for subgroups of children based on the indication for and the result of the CT will be performed.

Pediatric computed tomography practice in Japanese university hospitals from 2008-2010: did it differ from German practice?

Computed tomography (CT) is an essential tool in modern medicine and is frequently used to diagnose a wide range of conditions, particularly in industrial countries, such as Japan and Germany. However, markedly higher doses of ionizing radiation are delivered during CT imaging than during conventional X-ray examinations. To assess pediatric CT practice patterns, data from three university hospital databases (two in Japan and one in Germany) were analyzed. Anonymized data for patients aged 0 to 14 years who had undergone CT examinations between 2008 and 2010 were extracted. To assess CT practice, an interdisciplinary classification scheme for CT indications, which incorporated the most common examination types and radiosensitive tissues, was developed. The frequency of CT examinations was determined according to sex, age at examination, and indications. A total of 5182 CT examinations were performed in 2955 children. Overall, the frequency of CT examinations at the Japanese university hospitals did not differ significantly from that at the German hospital. However, differences were detected in the age distribution of the patients who underwent CT examinations (the proportion of patients <5 years of age was significantly higher in Japan than in Germany) and in the indications for CT. Substantial practice differences regarding the use of CT in pediatric health care were detected between the three hospitals. The results of this study point towards a need for approaches such as clinical guidelines to reduce unwarranted medical radiation exposures, particularly abdominal and head CT, in the Japanese health system.

Regional Deprivation and Non-Cancer Related Computed Tomography Use in Pediatric Patients in Germany: Cross-Sectional Analysis of Cohort Data.

BACKGROUND: Conflicting findings were observed in recent studies assessing the association between patients' area-level socio-economic status and the received number of computed tomography (CT) examinations in children. The aim was to investigate the association between area-level socio-economic status and variation in CT examination practice for pediatric patients in Germany. METHODS: Data from Radiology Information Systems for children aged 0 to < 15 years without cancer who had at least one CT examination between 2001 and 2010 were extracted in 20 hospitals across Germany. The small-area German Index of Multiple Deprivation (GIMD) was used to assess regional deprivation. The GIMD scores were classified into least, medium and most deprived areas and linked with the patient's last known postal code. A multinomial logistic regression model was used to assess the association between patients' CT numbers and regional deprivation adjusting for age, sex, and location of residence (urban/rural). RESULTS: A total of 37,810 pediatric patients received 59,571 CT scans during the study period. 27,287 (72%) children received only one CT, while n = 885 (2.3%) received six or more. Increasing numbers of CT examinations in non-cancer patients were significantly associated with higher regional deprivation, which increased, although CI overlap, for higher CT categories: '2-3 CT' odds ratio (OR) = 1.45, 95%CI: 1.40-1.50; '4-5 CT' OR = 1.48, 95%CI: 1.38-1.59; '6+CT' OR = 1.54, 95%CI: 1.41-1.69. In addition, male sex, higher age categories, and specific body regions were positively associated with increased numbers of CT examinations. CONCLUSION: We observed a positive association between regional deprivation and CT numbers in non-cancer pediatric patients. Limitations of the ecological approach and the lack of differentiation of CT details have to be acknowledged. More information on CT indications is necessary for a full assessment of this finding. In addition, further work on ways to assess socio-economic status more accurately may be required.

Computed Tomography in Germany.

BACKGROUND: In 2001, calculations in models based on atomic bomb survivors indicated that children exposed to ionizing radiation by computed tomography (CT) would be expected to have an increased risk of cancer. This led to the issuance of new recommendations in Germany concerning CT in children. METHODS: We analyzed data from the German pediatric CT cohort study together with data on children from a large general statutory health insurance provider (AOK) in order to characterize the secular trend in the use of CT in Germany. We used information from the Picture Archiving and Communication System (PACS) to estimate individual organ doses per scan and their development over time. RESULTS: The number of CT scans performed on children in Germany each year declined by 29% from 2006 to 2012. Over the same period, younger children were exposed to lower organ doses during CT scanning, although some organ doses were higher in neonates than in older children. The highest organ doses were in the 7.6 to 12.5-year-old age group and affected the brain (37.12 mGy ± 19.68 mGy) and the lenses (41.24 mGy ± 20.08 mGy). In every age group, the organ doses declined from year to year. With approximately 21 000 children aged 0-13 undergoing CT each year (extrapolated from insurance data of 2008), one can expect 2.3 [-1.7; 6.3] additional new cases of leukemia and 1 [-2.3; 4.0] additional new tumor of the central nervous system to arise each year. CONCLUSION: In view of the risks, children should undergo CT only for the indications listed by the German Commission on Radiological Protection (Strahlenschutzkommission). Further epidemiological studies are needed for estimation of the risk associated with the use of newer CT technology.

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.

Systematic review on physician's knowledge about radiation doses and radiation risks of computed tomography.

BACKGROUND: The frequent use of computed tomography is a major cause of the increasing medical radiation exposure of the general population. Consequently, dose reduction and radiation protection is a topic of scientific and public concern. AIM: We evaluated the available literature on physicians' knowledge regarding radiation dosages and risks due to computed tomography. METHODS: A systematic review in accordance with the Cochrane and PRISMA statements was performed using eight databases. 3091 references were found. Only primary studies assessing physicians' knowledge about computed tomography were included. RESULTS: 14 relevant articles were identified, all focussing on dose estimations for CT. Overall, the surveys showed moderate to low knowledge among physicians concerning radiation doses and the involved health risks. However, the surveys varied considerably in conduct and quality. For some countries, more than one survey was available. There was no general trend in knowledge in any country except a slight improvement of knowledge on health risks and radiation doses in two consecutive local German surveys. CONCLUSIONS: Knowledge gaps concerning radiation doses and associated health risks among physicians are evident from published research. However, knowledge on radiation doses cannot be interpreted as reliable indicator for good medical practice.