50 research outputs found

    Analyse de la relation entre l’exposition aux rayonnements ionisants lors d’examens de scanographie et la survenue de pathologie tumorale, au sein de la cohorte « Enfant Scanner »

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    Computed tomography (CT) is a powerful imaging technique that provides great benefits for diagnosis and medical management of patients. Nonetheless, the widespread use of this procedure raises many concerns about the potential adverse effects induced by X-rays exposure, both in clinical practice and in terms of public health. First epidemiological studies have suggested an increased risk of cancer associated with CT scan exposures in childhood or adolescence. The interpretation of these results is, however, controversial, and evidence about radiation-induced risks of cancer is still limited at this level of exposure and during childhood.In France, the "Enfant Scanner" cohort was set up by IRSN to study the incidence of cancer among more than 100,000 children who received CT scans before the age of 10 in 21 university hospitals. This study is part of the European Epi-CT project – coordinated by the International Agency for Research on Cancer – which includes nine national cohorts set up on the basis of a common protocol. The current thesis, based on the French cohort, focuses on characterizing the exposure of children receiving diagnostic CT scans and quantifying the risk of cancer associated with these exposures.Dosimetric assessment was performed from the radiological protocols used in paediatrics between 2000 and 2011 in the participating hospitals. This study presents the evolution of the exposures during the period and the variability of practices in the radiology departments. The results show that there is a leeway for optimizing the procedures and limiting the exposure of patients, especially for scans of the head that account for most of the examinations in paediatrics.From these exposure measurements, a quantitative assessment of cancer risk potentially induced by CT scans in paediatrics was performed – on the basis of estimates of risk in other contexts of ionizing radiation exposure. The results show that each CT scan could be associated with an excess risk of tumours of the central nervous system, breast cancer, thyroid cancer or leukaemia ranging from 0.01‰ to 5‰. Cancer risks may be up to 7 times higher for patients aged 1 year compared to 10 year olds. Uncertainties attached to these risk predictions were quantified by simulations.From the follow-up of cancer incidence in the cohort, the dose-response relation was studied between the risk of tumors of the central nervous system, leukaemia and lymphoma, and cumulative X-ray doses to the organs of interest from CT scans. No significant increased risk was observed. Indeed, in 2011, the duration of the follow-up, i.e. 4 years on average, was very short. The analyzes have nevertheless characterized the impact of (acquired or hereditary) immunodeficiencies and other genetic factors predisposing to cancer on the risk estimates, and highlighted the importance of considering the indication of examinations in studies on CT scans.The follow-up of the cohort should be extended to provide more robust risk estimates. Extension of this study as well as expected results from other cohorts, particularly within the Epi-CT project, would provide, in the next 5 years, significant progresses on the issue of the potential adverse effects of CT. To date, risk predictions from quantitative risk assessment are still uncertain, especially for cerebral tumours, but should help to guide the use of CT. In addition, efforts for optimizing the radiological procedures are still needed to reduce the doses delivered in paediatrics and the potential associated risks.La scanographie est une technique d’imagerie mĂ©dicale performante offrant des bĂ©nĂ©fices considĂ©rables pour le diagnostic et le suivi mĂ©dical des patients. NĂ©anmoins, la question des effets adverses potentiels induits par l’exposition aux rayons-X se pose, tant au niveau individuel qu’en termes de santĂ© publique du fait de la frĂ©quence du recours Ă  cette procĂ©dure. Des premiĂšres Ă©tudes Ă©pidĂ©miologiques suggĂšrent une augmentation du risque de cancer associĂ©e Ă  l’exposition Ă  la scanographie durant l’enfance ou l’adolescence. NĂ©anmoins, l’interprĂ©tation de ces rĂ©sultats reste controversĂ©e et les connaissances sur le risque de cancer radio-induit Ă  ce niveau d’exposition et pendant l’enfance demeurent limitĂ©es.En France, la cohorte « Enfant Scanner » est mise en place par l’IRSN pour Ă©tudier l’incidence de cancer dans une population de prĂšs de 110 000 enfants ayant reçu des examens par scanographie avant l’ñge de 10 ans dans 21 centres hospitaliers universitaires. Cette Ă©tude participe au projet europĂ©en Epi-CT, coordonnĂ© par le Centre International de Recherche sur le Cancer, intĂ©grant neuf cohortes nationales sur la base d’un protocole commun. A partir de la cohorte française, cette thĂšse s’intĂ©resse Ă  caractĂ©riser les expositions des enfants recevant des examens diagnostiques par scanographie et Ă  fournir des Ă©lĂ©ments de quantification du risque de cancer associĂ©.Une Ă©valuation dosimĂ©trique est rĂ©alisĂ©e Ă  partir des protocoles radiologiques utilisĂ©s en pĂ©diatrie entre 2000 et 2011 dans les services hospitaliers participant. Cette Ă©tude prĂ©sente l’évolution des expositions au cours de la pĂ©riode ainsi que la variabilitĂ© des pratiques dans les services. Les rĂ©sultats montrent l’existence d’une marge d’optimisation des protocoles utilisĂ©s pour limiter l’exposition des patients, en particulier pour des explorations de la tĂȘte qui sont les examens les plus frĂ©quents en pĂ©diatrie.Une Ă©valuation du risque de cancer potentiellement induit par des actes de scanographie pĂ©diatrique a Ă©tĂ© rĂ©alisĂ©e, sur la base d’estimations de risque obtenues pour d’autres contextes d’exposition aux rayonnements ionisants. Les rĂ©sultats montrent que chaque examen pourrait ĂȘtre associĂ© Ă  un excĂšs de risque de tumeur du systĂšme nerveux central (SNC), de cancer du sein, de la thyroĂŻde ou de leucĂ©mies compris entre 0,01‰ et 5‰. Le risque de cancer serait jusqu’à 7 fois supĂ©rieur pour des patients ĂągĂ©s de 1 an par rapport Ă  des enfants de 10 ans. Les incertitudes attachĂ©es Ă  ces prĂ©dictions de risque ont Ă©tĂ© quantifiĂ©es par simulations.A partir du suivi d’incidence de la cohorte, la relation dose-rĂ©ponse a Ă©tĂ© Ă©tudiĂ©e entre le risque de tumeurs du SNC, de leucĂ©mies et de lymphome, et les doses cumulĂ©es aux organes d’intĂ©rĂȘt reçues lors d’examens par scanographie. Aucune augmentation significative de risque n’a Ă©tĂ© mise en Ă©vidence. En 2011, le suivi dans la cohorte – 4 ans en moyenne– Ă©tait en effet trĂšs court. Les analyses ont nĂ©anmoins caractĂ©risĂ© l’impact de syndromes d’immunodĂ©ficiences et d’autres facteurs gĂ©nĂ©tiques de prĂ©disposition au cancer sur les estimations de risque, et mis en Ă©vidence l’importance de prendre en compte l’indication des examens dans ce type d’étude.Le suivi de la cohorte doit ĂȘtre poursuivi afin de fournir des estimations de risque plus robustes. L’extension de la durĂ©e de suivi de cette population ainsi que les rĂ©sultats attendus Ă  partir d’autres Ă©tudes, notamment dans le cadre du projet Epi-CT, devraient constituer, dans les 5 prochaines annĂ©es, une avancĂ©e tout Ă  fait significative sur la question des risques associĂ©s Ă  la scanographie. A ce jour, les prĂ©dictions rĂ©alisĂ©es dans le cadre d’évaluations de risque demeurent incertaines, en particulier pour les tumeurs du SNC, mais constituent une aide pour orienter le recours Ă  la scanographie. Des efforts d’optimisation des procĂ©dures radiologiques demeurent, par ailleurs, encore nĂ©cessaires pour rĂ©duire les doses dĂ©livrĂ©es en pĂ©diatrie ainsi que les risques possiblement associĂ©

    Thyroid dysfunction and breast cancer risk among women in the UK Biobank cohort.

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    This study aimed to evaluate the association between thyroid dysfunction and breast cancer risk. We included 239,436 females of the UK Biobank cohort. Information on thyroid dysfunction, personal and family medical history, medications, reproductive factors, lifestyle, and socioeconomic characteristics was retrieved from baseline self-reported data and hospital inpatient databases. Breast cancer diagnoses were identified through population-based registries. We computed Cox models to estimate hazard ratios (HRs) of breast cancer incidence for thyroid dysfunction diagnosis and treatments, and examined potential confounding and effect modification by comorbidities and breast cancer risk factors. In our study, 3,227 (1.3%) and 20,762 (8.7%) women had hyper- and hypothyroidism prior to the baseline. During a median follow-up of 7.1 years, 5,326 (2.2%) women developed breast cancer. Compared to no thyroid dysfunction, there was no association between hypothyroidism and breast cancer risk overall (HR = 0.93, 95% confidence interval (CI): 0.84-1.02, 442 cases), but we found a decreased risk more than 10 years after hypothyroidism diagnosis (HR=0.85, 95%CI 0.74-0.97, 226 cases). There was no association with hyperthyroidism overall (HR=1.08, 95%CI 0.86-1.35, 79 cases) but breast cancer risk was elevated among women with treated hyperthyroidism (HR=1.38, 95%CI: 1.03-1.86, 44 cases) or aged 60 years or more at hyperthyroidism diagnosis (HR=1.74, 95%CI: 1.01-3.00, 113 cases), and 5-10 years after hyperthyroidism diagnosis (HR=1.58, 95%CI: 1.06-2.33, 25 cases). In conclusion, breast cancer risk was reduced long after hypothyroidism diagnosis, but increased among women with treated hyperthyroidism. Future studies are needed to determine whether the higher breast cancer risk observed among treated hyperthyroidism could be explained by hyperthyroidism severity, type of treatment or aetiology

    Recommendations for the organisation of care in paediatric radiation oncology across Europe:a SIOPE-ESTRO-PROS-CCI-Europe collaborative project in the framework of the JARC

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    Disparities in survival and long-term side-effects from paediatric cancer are observed across European Society for Paediatric Oncology (SIOPE) eaffiliated countries. The Joint Action on Rare Cancers (JARC) is a project supported by the European Union and member states aiming to formulate recommendations on rare cancers, including paediatric malignancies, to reduce inequalities and to improve health outcomes. Most paediatric cancers are treated by a combination of systemic agents, surgery and/or radiotherapy. Radiotherapy for children is becoming increasingly complex because of the growing availability of new modalities and techniques and the evolution in molecular biology. These added challenges have the potential to enhance disparities in survival and side-effects between countries, but also among centres in the same country. To tackle radiotherapy-related inequalities, representatives of SIOPE, European SocieTy for Radiotherapy and Oncology, Paediatric Radiation Oncology Society and Childhood Cancer InternationaleEurope defined 'standard' and 'optional' levels to deliver Good Clinical Practiceecompliant treatment in paediatric radiation oncology with a focus on patient-related care, education and training. In addition, more than 250 paediatric radiotherapy centres across the SIOPE-affiliated countries have been mapped. For a better understanding of resources in paediatric radiotherapy, JARC representatives are working on an online survey for paediatric radiation oncologists of each centre in SIOPE-affiliated countries. The outcome of this survey will give an insight into the strengths and weaknesses of paediatric radiotherapy across SIOPE-affiliated countries and can be relevant for European Reference Networks in terms of collaboration pathways and referrals in paediatric radiotherapy. (C) 2019 The Authors. Published by Elsevier Ltd

    Risk of subsequent gliomas and meningiomas among 69,460 5-year survivors of childhood and adolescent cancer in Europe:the PanCareSurFup study

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    BACKGROUND: Childhood cancer survivors are at risk of subsequent gliomas and meningiomas, but the risks beyond age 40 years are uncertain. We quantified these risks in the largest ever cohort.METHODS: Using data from 69,460 5-year childhood cancer survivors (diagnosed 1940-2008), across Europe, standardized incidence ratios (SIRs) and cumulative incidence were calculated.RESULTS: In total, 279 glioma and 761 meningioma were identified. CNS tumour (SIR: 16.2, 95% CI: 13.7, 19.2) and leukaemia (SIR: 11.2, 95% CI: 8.8, 14.2) survivors were at greatest risk of glioma. The SIR for CNS tumour survivors was still 4.3-fold after age 50 (95% CI: 1.9, 9.6), and for leukaemia survivors still 10.2-fold after age 40 (95% CI: 4.9, 21.4). Following cranial radiotherapy (CRT), the cumulative incidence of a glioma in CNS tumour survivors was 2.7%, 3.7% and 5.0% by ages 40, 50 and 60, respectively, whilst for leukaemia this was 1.2% and 1.7% by ages 40 and 50. The cumulative incidence of a meningioma after CRT in CNS tumour survivors doubled from 5.9% to 12.5% between ages 40 and 60, and in leukaemia survivors increased from 5.8% to 10.2% between ages 40 and 50.DISCUSSION: Clinicians following up survivors should be aware that the substantial risks of meningioma and glioma following CRT are sustained beyond age 40 and be vigilant for symptoms.</p

    Complete patient exposure during paediatric brain cancer treatment for photon and proton therapy techniques including imaging procedures

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    BackgroundIn radiotherapy, especially when treating children, minimising exposure of healthy tissue can prevent the development of adverse outcomes, including second cancers. In this study we propose a validated Monte Carlo framework to evaluate the complete patient exposure during paediatric brain cancer treatment.Materials and methodsOrgan doses were calculated for treatment of a diffuse midline glioma (50.4 Gy with 1.8 Gy per fraction) on a 5-year-old anthropomorphic phantom with 3D-conformal radiotherapy, intensity modulated radiotherapy (IMRT), volumetric modulated arc therapy (VMAT) and intensity modulated pencil beam scanning (PBS) proton therapy. Doses from computed tomography (CT) for planning and on-board imaging for positioning (kV-cone beam CT and X-ray imaging) accounted for the estimate of the exposure of the patient including imaging therapeutic dose. For dose calculations we used validated Monte Carlo-based tools (PRIMO, TOPAS, PENELOPE), while lifetime attributable risk (LAR) was estimated from dose-response relationships for cancer induction, proposed by Schneider et al.ResultsOut-of-field organ dose equivalent data of proton therapy are lower, with doses between 0.6 mSv (testes) and 120 mSv (thyroid), when compared to photon therapy revealing the highest out-of-field doses for IMRT ranging between 43 mSv (testes) and 575 mSv (thyroid). Dose delivered by CT ranged between 0.01 mSv (testes) and 72 mSv (scapula) while a single imaging positioning ranged between 2 ΌSv (testes) and 1.3 mSv (thyroid) for CBCT and 0.03 ΌSv (testes) and 48 ΌSv (scapula) for X-ray. Adding imaging dose from CT and daily CBCT to the therapeutic demonstrated an important contribution of imaging to the overall radiation burden in the course of treatment, which is subsequently used to predict the LAR, for selected organs.ConclusionThe complete patient exposure during paediatric brain cancer treatment was estimated by combining the results from different Monte Carlo-based dosimetry tools, showing that proton therapy allows significant reduction of the out-of-field doses and secondary cancer risk in selected organs

    Analyse de la relation entre l’exposition aux rayonnements ionisants lors d’examens de scanographie et la survenue de pathologie tumorale, au sein de la cohorte « Enfant Scanner »

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    Computed tomography (CT) is a powerful imaging technique that provides great benefits for diagnosis and medical management of patients. Nonetheless, the widespread use of this procedure raises many concerns about the potential adverse effects induced by X-rays exposure, both in clinical practice and in terms of public health. First epidemiological studies have suggested an increased risk of cancer associated with CT scan exposures in childhood or adolescence. The interpretation of these results is, however, controversial, and evidence about radiation-induced risks of cancer is still limited at this level of exposure and during childhood.In France, the "Enfant Scanner" cohort was set up by IRSN to study the incidence of cancer among more than 100,000 children who received CT scans before the age of 10 in 21 university hospitals. This study is part of the European Epi-CT project – coordinated by the International Agency for Research on Cancer – which includes nine national cohorts set up on the basis of a common protocol. The current thesis, based on the French cohort, focuses on characterizing the exposure of children receiving diagnostic CT scans and quantifying the risk of cancer associated with these exposures.Dosimetric assessment was performed from the radiological protocols used in paediatrics between 2000 and 2011 in the participating hospitals. This study presents the evolution of the exposures during the period and the variability of practices in the radiology departments. The results show that there is a leeway for optimizing the procedures and limiting the exposure of patients, especially for scans of the head that account for most of the examinations in paediatrics.From these exposure measurements, a quantitative assessment of cancer risk potentially induced by CT scans in paediatrics was performed – on the basis of estimates of risk in other contexts of ionizing radiation exposure. The results show that each CT scan could be associated with an excess risk of tumours of the central nervous system, breast cancer, thyroid cancer or leukaemia ranging from 0.01‰ to 5‰. Cancer risks may be up to 7 times higher for patients aged 1 year compared to 10 year olds. Uncertainties attached to these risk predictions were quantified by simulations.From the follow-up of cancer incidence in the cohort, the dose-response relation was studied between the risk of tumors of the central nervous system, leukaemia and lymphoma, and cumulative X-ray doses to the organs of interest from CT scans. No significant increased risk was observed. Indeed, in 2011, the duration of the follow-up, i.e. 4 years on average, was very short. The analyzes have nevertheless characterized the impact of (acquired or hereditary) immunodeficiencies and other genetic factors predisposing to cancer on the risk estimates, and highlighted the importance of considering the indication of examinations in studies on CT scans.The follow-up of the cohort should be extended to provide more robust risk estimates. Extension of this study as well as expected results from other cohorts, particularly within the Epi-CT project, would provide, in the next 5 years, significant progresses on the issue of the potential adverse effects of CT. To date, risk predictions from quantitative risk assessment are still uncertain, especially for cerebral tumours, but should help to guide the use of CT. In addition, efforts for optimizing the radiological procedures are still needed to reduce the doses delivered in paediatrics and the potential associated risks.La scanographie est une technique d’imagerie mĂ©dicale performante offrant des bĂ©nĂ©fices considĂ©rables pour le diagnostic et le suivi mĂ©dical des patients. NĂ©anmoins, la question des effets adverses potentiels induits par l’exposition aux rayons-X se pose, tant au niveau individuel qu’en termes de santĂ© publique du fait de la frĂ©quence du recours Ă  cette procĂ©dure. Des premiĂšres Ă©tudes Ă©pidĂ©miologiques suggĂšrent une augmentation du risque de cancer associĂ©e Ă  l’exposition Ă  la scanographie durant l’enfance ou l’adolescence. NĂ©anmoins, l’interprĂ©tation de ces rĂ©sultats reste controversĂ©e et les connaissances sur le risque de cancer radio-induit Ă  ce niveau d’exposition et pendant l’enfance demeurent limitĂ©es.En France, la cohorte « Enfant Scanner » est mise en place par l’IRSN pour Ă©tudier l’incidence de cancer dans une population de prĂšs de 110 000 enfants ayant reçu des examens par scanographie avant l’ñge de 10 ans dans 21 centres hospitaliers universitaires. Cette Ă©tude participe au projet europĂ©en Epi-CT, coordonnĂ© par le Centre International de Recherche sur le Cancer, intĂ©grant neuf cohortes nationales sur la base d’un protocole commun. A partir de la cohorte française, cette thĂšse s’intĂ©resse Ă  caractĂ©riser les expositions des enfants recevant des examens diagnostiques par scanographie et Ă  fournir des Ă©lĂ©ments de quantification du risque de cancer associĂ©.Une Ă©valuation dosimĂ©trique est rĂ©alisĂ©e Ă  partir des protocoles radiologiques utilisĂ©s en pĂ©diatrie entre 2000 et 2011 dans les services hospitaliers participant. Cette Ă©tude prĂ©sente l’évolution des expositions au cours de la pĂ©riode ainsi que la variabilitĂ© des pratiques dans les services. Les rĂ©sultats montrent l’existence d’une marge d’optimisation des protocoles utilisĂ©s pour limiter l’exposition des patients, en particulier pour des explorations de la tĂȘte qui sont les examens les plus frĂ©quents en pĂ©diatrie.Une Ă©valuation du risque de cancer potentiellement induit par des actes de scanographie pĂ©diatrique a Ă©tĂ© rĂ©alisĂ©e, sur la base d’estimations de risque obtenues pour d’autres contextes d’exposition aux rayonnements ionisants. Les rĂ©sultats montrent que chaque examen pourrait ĂȘtre associĂ© Ă  un excĂšs de risque de tumeur du systĂšme nerveux central (SNC), de cancer du sein, de la thyroĂŻde ou de leucĂ©mies compris entre 0,01‰ et 5‰. Le risque de cancer serait jusqu’à 7 fois supĂ©rieur pour des patients ĂągĂ©s de 1 an par rapport Ă  des enfants de 10 ans. Les incertitudes attachĂ©es Ă  ces prĂ©dictions de risque ont Ă©tĂ© quantifiĂ©es par simulations.A partir du suivi d’incidence de la cohorte, la relation dose-rĂ©ponse a Ă©tĂ© Ă©tudiĂ©e entre le risque de tumeurs du SNC, de leucĂ©mies et de lymphome, et les doses cumulĂ©es aux organes d’intĂ©rĂȘt reçues lors d’examens par scanographie. Aucune augmentation significative de risque n’a Ă©tĂ© mise en Ă©vidence. En 2011, le suivi dans la cohorte – 4 ans en moyenne– Ă©tait en effet trĂšs court. Les analyses ont nĂ©anmoins caractĂ©risĂ© l’impact de syndromes d’immunodĂ©ficiences et d’autres facteurs gĂ©nĂ©tiques de prĂ©disposition au cancer sur les estimations de risque, et mis en Ă©vidence l’importance de prendre en compte l’indication des examens dans ce type d’étude.Le suivi de la cohorte doit ĂȘtre poursuivi afin de fournir des estimations de risque plus robustes. L’extension de la durĂ©e de suivi de cette population ainsi que les rĂ©sultats attendus Ă  partir d’autres Ă©tudes, notamment dans le cadre du projet Epi-CT, devraient constituer, dans les 5 prochaines annĂ©es, une avancĂ©e tout Ă  fait significative sur la question des risques associĂ©s Ă  la scanographie. A ce jour, les prĂ©dictions rĂ©alisĂ©es dans le cadre d’évaluations de risque demeurent incertaines, en particulier pour les tumeurs du SNC, mais constituent une aide pour orienter le recours Ă  la scanographie. Des efforts d’optimisation des procĂ©dures radiologiques demeurent, par ailleurs, encore nĂ©cessaires pour rĂ©duire les doses dĂ©livrĂ©es en pĂ©diatrie ainsi que les risques possiblement associĂ©

    Analyse de la relation entre l’exposition aux rayonnements ionisants lors d’examens de scanographie et la survenue de pathologie tumorale, au sein de la cohorte « Enfant Scanner »

    No full text
    Computed tomography (CT) is a powerful imaging technique that provides great benefits for diagnosis and medical management of patients. Nonetheless, the widespread use of this procedure raises many concerns about the potential adverse effects induced by X-rays exposure, both in clinical practice and in terms of public health. First epidemiological studies have suggested an increased risk of cancer associated with CT scan exposures in childhood or adolescence. The interpretation of these results is, however, controversial, and evidence about radiation-induced risks of cancer is still limited at this level of exposure and during childhood.In France, the "Enfant Scanner" cohort was set up by IRSN to study the incidence of cancer among more than 100,000 children who received CT scans before the age of 10 in 21 university hospitals. This study is part of the European Epi-CT project – coordinated by the International Agency for Research on Cancer – which includes nine national cohorts set up on the basis of a common protocol. The current thesis, based on the French cohort, focuses on characterizing the exposure of children receiving diagnostic CT scans and quantifying the risk of cancer associated with these exposures.Dosimetric assessment was performed from the radiological protocols used in paediatrics between 2000 and 2011 in the participating hospitals. This study presents the evolution of the exposures during the period and the variability of practices in the radiology departments. The results show that there is a leeway for optimizing the procedures and limiting the exposure of patients, especially for scans of the head that account for most of the examinations in paediatrics.From these exposure measurements, a quantitative assessment of cancer risk potentially induced by CT scans in paediatrics was performed – on the basis of estimates of risk in other contexts of ionizing radiation exposure. The results show that each CT scan could be associated with an excess risk of tumours of the central nervous system, breast cancer, thyroid cancer or leukaemia ranging from 0.01‰ to 5‰. Cancer risks may be up to 7 times higher for patients aged 1 year compared to 10 year olds. Uncertainties attached to these risk predictions were quantified by simulations.From the follow-up of cancer incidence in the cohort, the dose-response relation was studied between the risk of tumors of the central nervous system, leukaemia and lymphoma, and cumulative X-ray doses to the organs of interest from CT scans. No significant increased risk was observed. Indeed, in 2011, the duration of the follow-up, i.e. 4 years on average, was very short. The analyzes have nevertheless characterized the impact of (acquired or hereditary) immunodeficiencies and other genetic factors predisposing to cancer on the risk estimates, and highlighted the importance of considering the indication of examinations in studies on CT scans.The follow-up of the cohort should be extended to provide more robust risk estimates. Extension of this study as well as expected results from other cohorts, particularly within the Epi-CT project, would provide, in the next 5 years, significant progresses on the issue of the potential adverse effects of CT. To date, risk predictions from quantitative risk assessment are still uncertain, especially for cerebral tumours, but should help to guide the use of CT. In addition, efforts for optimizing the radiological procedures are still needed to reduce the doses delivered in paediatrics and the potential associated risks.La scanographie est une technique d’imagerie mĂ©dicale performante offrant des bĂ©nĂ©fices considĂ©rables pour le diagnostic et le suivi mĂ©dical des patients. NĂ©anmoins, la question des effets adverses potentiels induits par l’exposition aux rayons-X se pose, tant au niveau individuel qu’en termes de santĂ© publique du fait de la frĂ©quence du recours Ă  cette procĂ©dure. Des premiĂšres Ă©tudes Ă©pidĂ©miologiques suggĂšrent une augmentation du risque de cancer associĂ©e Ă  l’exposition Ă  la scanographie durant l’enfance ou l’adolescence. NĂ©anmoins, l’interprĂ©tation de ces rĂ©sultats reste controversĂ©e et les connaissances sur le risque de cancer radio-induit Ă  ce niveau d’exposition et pendant l’enfance demeurent limitĂ©es.En France, la cohorte « Enfant Scanner » est mise en place par l’IRSN pour Ă©tudier l’incidence de cancer dans une population de prĂšs de 110 000 enfants ayant reçu des examens par scanographie avant l’ñge de 10 ans dans 21 centres hospitaliers universitaires. Cette Ă©tude participe au projet europĂ©en Epi-CT, coordonnĂ© par le Centre International de Recherche sur le Cancer, intĂ©grant neuf cohortes nationales sur la base d’un protocole commun. A partir de la cohorte française, cette thĂšse s’intĂ©resse Ă  caractĂ©riser les expositions des enfants recevant des examens diagnostiques par scanographie et Ă  fournir des Ă©lĂ©ments de quantification du risque de cancer associĂ©.Une Ă©valuation dosimĂ©trique est rĂ©alisĂ©e Ă  partir des protocoles radiologiques utilisĂ©s en pĂ©diatrie entre 2000 et 2011 dans les services hospitaliers participant. Cette Ă©tude prĂ©sente l’évolution des expositions au cours de la pĂ©riode ainsi que la variabilitĂ© des pratiques dans les services. Les rĂ©sultats montrent l’existence d’une marge d’optimisation des protocoles utilisĂ©s pour limiter l’exposition des patients, en particulier pour des explorations de la tĂȘte qui sont les examens les plus frĂ©quents en pĂ©diatrie.Une Ă©valuation du risque de cancer potentiellement induit par des actes de scanographie pĂ©diatrique a Ă©tĂ© rĂ©alisĂ©e, sur la base d’estimations de risque obtenues pour d’autres contextes d’exposition aux rayonnements ionisants. Les rĂ©sultats montrent que chaque examen pourrait ĂȘtre associĂ© Ă  un excĂšs de risque de tumeur du systĂšme nerveux central (SNC), de cancer du sein, de la thyroĂŻde ou de leucĂ©mies compris entre 0,01‰ et 5‰. Le risque de cancer serait jusqu’à 7 fois supĂ©rieur pour des patients ĂągĂ©s de 1 an par rapport Ă  des enfants de 10 ans. Les incertitudes attachĂ©es Ă  ces prĂ©dictions de risque ont Ă©tĂ© quantifiĂ©es par simulations.A partir du suivi d’incidence de la cohorte, la relation dose-rĂ©ponse a Ă©tĂ© Ă©tudiĂ©e entre le risque de tumeurs du SNC, de leucĂ©mies et de lymphome, et les doses cumulĂ©es aux organes d’intĂ©rĂȘt reçues lors d’examens par scanographie. Aucune augmentation significative de risque n’a Ă©tĂ© mise en Ă©vidence. En 2011, le suivi dans la cohorte – 4 ans en moyenne– Ă©tait en effet trĂšs court. Les analyses ont nĂ©anmoins caractĂ©risĂ© l’impact de syndromes d’immunodĂ©ficiences et d’autres facteurs gĂ©nĂ©tiques de prĂ©disposition au cancer sur les estimations de risque, et mis en Ă©vidence l’importance de prendre en compte l’indication des examens dans ce type d’étude.Le suivi de la cohorte doit ĂȘtre poursuivi afin de fournir des estimations de risque plus robustes. L’extension de la durĂ©e de suivi de cette population ainsi que les rĂ©sultats attendus Ă  partir d’autres Ă©tudes, notamment dans le cadre du projet Epi-CT, devraient constituer, dans les 5 prochaines annĂ©es, une avancĂ©e tout Ă  fait significative sur la question des risques associĂ©s Ă  la scanographie. A ce jour, les prĂ©dictions rĂ©alisĂ©es dans le cadre d’évaluations de risque demeurent incertaines, en particulier pour les tumeurs du SNC, mais constituent une aide pour orienter le recours Ă  la scanographie. Des efforts d’optimisation des procĂ©dures radiologiques demeurent, par ailleurs, encore nĂ©cessaires pour rĂ©duire les doses dĂ©livrĂ©es en pĂ©diatrie ainsi que les risques possiblement associĂ©

    Analysis of the Relation Between Exposure to Ionising Radiation from Computed Tomography Scans in Childhood and Cancer Incidence within the "Cohorte Enfant Scanner" Study

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    La scanographie est une technique d’imagerie mĂ©dicale performante offrant des bĂ©nĂ©fices considĂ©rables pour le diagnostic et le suivi mĂ©dical des patients. NĂ©anmoins, la question des effets adverses potentiels induits par l’exposition aux rayons-X se pose, tant au niveau individuel qu’en termes de santĂ© publique du fait de la frĂ©quence du recours Ă  cette procĂ©dure. Des premiĂšres Ă©tudes Ă©pidĂ©miologiques suggĂšrent une augmentation du risque de cancer associĂ©e Ă  l’exposition Ă  la scanographie durant l’enfance ou l’adolescence. NĂ©anmoins, l’interprĂ©tation de ces rĂ©sultats reste controversĂ©e et les connaissances sur le risque de cancer radio-induit Ă  ce niveau d’exposition et pendant l’enfance demeurent limitĂ©es.En France, la cohorte « Enfant Scanner » est mise en place par l’IRSN pour Ă©tudier l’incidence de cancer dans une population de prĂšs de 110 000 enfants ayant reçu des examens par scanographie avant l’ñge de 10 ans dans 21 centres hospitaliers universitaires. Cette Ă©tude participe au projet europĂ©en Epi-CT, coordonnĂ© par le Centre International de Recherche sur le Cancer, intĂ©grant neuf cohortes nationales sur la base d’un protocole commun. A partir de la cohorte française, cette thĂšse s’intĂ©resse Ă  caractĂ©riser les expositions des enfants recevant des examens diagnostiques par scanographie et Ă  fournir des Ă©lĂ©ments de quantification du risque de cancer associĂ©.Une Ă©valuation dosimĂ©trique est rĂ©alisĂ©e Ă  partir des protocoles radiologiques utilisĂ©s en pĂ©diatrie entre 2000 et 2011 dans les services hospitaliers participant. Cette Ă©tude prĂ©sente l’évolution des expositions au cours de la pĂ©riode ainsi que la variabilitĂ© des pratiques dans les services. Les rĂ©sultats montrent l’existence d’une marge d’optimisation des protocoles utilisĂ©s pour limiter l’exposition des patients, en particulier pour des explorations de la tĂȘte qui sont les examens les plus frĂ©quents en pĂ©diatrie.Une Ă©valuation du risque de cancer potentiellement induit par des actes de scanographie pĂ©diatrique a Ă©tĂ© rĂ©alisĂ©e, sur la base d’estimations de risque obtenues pour d’autres contextes d’exposition aux rayonnements ionisants. Les rĂ©sultats montrent que chaque examen pourrait ĂȘtre associĂ© Ă  un excĂšs de risque de tumeur du systĂšme nerveux central (SNC), de cancer du sein, de la thyroĂŻde ou de leucĂ©mies compris entre 0,01‰ et 5‰. Le risque de cancer serait jusqu’à 7 fois supĂ©rieur pour des patients ĂągĂ©s de 1 an par rapport Ă  des enfants de 10 ans. Les incertitudes attachĂ©es Ă  ces prĂ©dictions de risque ont Ă©tĂ© quantifiĂ©es par simulations.A partir du suivi d’incidence de la cohorte, la relation dose-rĂ©ponse a Ă©tĂ© Ă©tudiĂ©e entre le risque de tumeurs du SNC, de leucĂ©mies et de lymphome, et les doses cumulĂ©es aux organes d’intĂ©rĂȘt reçues lors d’examens par scanographie. Aucune augmentation significative de risque n’a Ă©tĂ© mise en Ă©vidence. En 2011, le suivi dans la cohorte – 4 ans en moyenne– Ă©tait en effet trĂšs court. Les analyses ont nĂ©anmoins caractĂ©risĂ© l’impact de syndromes d’immunodĂ©ficiences et d’autres facteurs gĂ©nĂ©tiques de prĂ©disposition au cancer sur les estimations de risque, et mis en Ă©vidence l’importance de prendre en compte l’indication des examens dans ce type d’étude.Le suivi de la cohorte doit ĂȘtre poursuivi afin de fournir des estimations de risque plus robustes. L’extension de la durĂ©e de suivi de cette population ainsi que les rĂ©sultats attendus Ă  partir d’autres Ă©tudes, notamment dans le cadre du projet Epi-CT, devraient constituer, dans les 5 prochaines annĂ©es, une avancĂ©e tout Ă  fait significative sur la question des risques associĂ©s Ă  la scanographie. A ce jour, les prĂ©dictions rĂ©alisĂ©es dans le cadre d’évaluations de risque demeurent incertaines, en particulier pour les tumeurs du SNC, mais constituent une aide pour orienter le recours Ă  la scanographie. Des efforts d’optimisation des procĂ©dures radiologiques demeurent, par ailleurs, encore nĂ©cessaires pour rĂ©duire les doses dĂ©livrĂ©es en pĂ©diatrie ainsi que les risques possiblement associĂ©sComputed tomography (CT) is a powerful imaging technique that provides great benefits for diagnosis and medical management of patients. Nonetheless, the widespread use of this procedure raises many concerns about the potential adverse effects induced by X-rays exposure, both in clinical practice and in terms of public health. First epidemiological studies have suggested an increased risk of cancer associated with CT scan exposures in childhood or adolescence. The interpretation of these results is, however, controversial, and evidence about radiation-induced risks of cancer is still limited at this level of exposure and during childhood.In France, the "Enfant Scanner" cohort was set up by IRSN to study the incidence of cancer among more than 100,000 children who received CT scans before the age of 10 in 21 university hospitals. This study is part of the European Epi-CT project – coordinated by the International Agency for Research on Cancer – which includes nine national cohorts set up on the basis of a common protocol. The current thesis, based on the French cohort, focuses on characterizing the exposure of children receiving diagnostic CT scans and quantifying the risk of cancer associated with these exposures.Dosimetric assessment was performed from the radiological protocols used in paediatrics between 2000 and 2011 in the participating hospitals. This study presents the evolution of the exposures during the period and the variability of practices in the radiology departments. The results show that there is a leeway for optimizing the procedures and limiting the exposure of patients, especially for scans of the head that account for most of the examinations in paediatrics.From these exposure measurements, a quantitative assessment of cancer risk potentially induced by CT scans in paediatrics was performed – on the basis of estimates of risk in other contexts of ionizing radiation exposure. The results show that each CT scan could be associated with an excess risk of tumours of the central nervous system, breast cancer, thyroid cancer or leukaemia ranging from 0.01‰ to 5‰. Cancer risks may be up to 7 times higher for patients aged 1 year compared to 10 year olds. Uncertainties attached to these risk predictions were quantified by simulations.From the follow-up of cancer incidence in the cohort, the dose-response relation was studied between the risk of tumors of the central nervous system, leukaemia and lymphoma, and cumulative X-ray doses to the organs of interest from CT scans. No significant increased risk was observed. Indeed, in 2011, the duration of the follow-up, i.e. 4 years on average, was very short. The analyzes have nevertheless characterized the impact of (acquired or hereditary) immunodeficiencies and other genetic factors predisposing to cancer on the risk estimates, and highlighted the importance of considering the indication of examinations in studies on CT scans.The follow-up of the cohort should be extended to provide more robust risk estimates. Extension of this study as well as expected results from other cohorts, particularly within the Epi-CT project, would provide, in the next 5 years, significant progresses on the issue of the potential adverse effects of CT. To date, risk predictions from quantitative risk assessment are still uncertain, especially for cerebral tumours, but should help to guide the use of CT. In addition, efforts for optimizing the radiological procedures are still needed to reduce the doses delivered in paediatrics and the potential associated risks

    Cataract risk in a cohort of US radiologic technologists performing nuclear medicine procedures.

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    International audiencePurpose: To estimate the risk of cataract in a cohort of nuclearmedicine (NM) radiologic technologists on the basis of their work histories and radiation protection practices.Materials and In the years 2003—2005 and 2012—2013, 42 545 radio- Methods: logic technologists from a U.S. prospective study com-pleted questionnaires in which they provided information regarding their work histories and cataract histories. Cox proportional hazards models, stratified according to birth- year cohort (born before 1940 or born in 1940 or later) and adjusted for age, sex, and race, were used to estimate hazard ratios (HRs) for the risk of cataract in radiologic technologists according to NM work history practices ac- cording to decade.Results: During the follow-up period (mean follow-up, 7% years),7137 incident cataracts were reported. A significantly in- creased risk of cataract (HR, 1.08; 95% confidence interval [CI]: 1.03, 1.14) was observed among workers who performed an NM procedure at least once—as opposed to never. Risks of cataract were increased in the group who had performed a diagnostic (HR, 1.07; 95% CI: 1.01, 1.12) or therapeutic (HR, 1.10; 95% CI: 1.04, 1.17) NM procedure. Risks were higher for those who had first performed diagnostic NM procedures in the 1980s to early 2000s (HR, 1.30; 95% CI: 1.08, 1.58) and those who had performed therapeutic NM procedures in the 1970s (HR, 1.11; 95% CI: 1.01, 1.23) and in the 1980s to early 2000s (HR, 1.14; 95% CI: 1.02, 1.29). With the exception of a significantly increased risk associated with performing therapeutic NM procedures without shielding the radiation source in the 1980s (HR, 1.32; 95% CI: 1.04, 1.67), analyses revealed no association between cataract risk and specific radiation protection technique used.Conclusion: An increased risk of cataract was observed among U.S.radiologic technologists who had performed an NM procedure at least once. This association should be examined in future studies incorporating estimated lens doses

    ORGAN DOSE ESTIMATION ACCOUNTING FOR UNCERTAINTY FOR PEDIATRIC AND YOUNG ADULT CT SCANS IN THE UNITED KINGDOM

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    International audienceAbstract Since our previous publication of organ dose for the pediatric CT cohort in the UK, there have been questions about the magnitude of uncertainty in our dose estimates. We therefore quantified shared and unshared uncertainties in empirical CT parameters extracted from 1073 CT films (1978–2008) from 36 hospitals in the study and propagated these uncertainties into organ doses using Monte Carlo random sampling and NCICT organ dose calculator. The average of 500 median brain and marrow doses for the full cohort was 35 (95% confidence interval: 30–40) mGy and 6 (5–7) mGy, respectively. We estimated that shared uncertainty contributed ~99% of coefficient of variation of median brain doses in brain scans compared to unshared uncertainty (1% contribution). We found that the previous brain doses were slightly underestimated for 1990 compared to the results in the current study due to the revised CTDI models based on CT films
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