Experimental evaluation of seven quality control phantoms for digital breast tomosynthesis.

PURPOSES: The introduction of digital breast tomosynthesis (DBT) into the French breast cancer screening program is forecast by the authorities. The aim of the present study was to evaluate image quality phantoms to be used as internal quality controls. METHODS: Seven breast phantoms dedicated to quality control in mammography were evaluated on reconstructed DBT images: ACR Model 015, BR3D, DBT QC model 021, Mam/Digi-EPQC, MTM100, TOMOMAM® and TOMOPHAN®. Two representative image parameters of DBT images were studied: image score and z-resolution, when inserts were included in the phantom, on five DBT systems of three different brands. Three observers were involved. RESULTS: The MTM100, Mam/Digi-EPQC, BR3D, DBT QC model 021 phantoms' images presented artefacts affecting the image score. The ACR Model 015, TOMOMAM® and TOMOPHAN® phantoms appeared to be pertinent for DBT image score analysis. Due to saturation artefacts, Z-resolution results were not coherent with the theory for all phantoms except by using aluminium beads in the TOMOMAM® phantom. CONCLUSIONS: Phantom manufacturers should be encouraged to collaborate with DBT system manufacturers in order to design universal phantoms suitable for all systems for more complete quality control. From our study we can propose several specifications for an ideal and universal phantom designed for internal quality control in DBT. Phantoms should allow sensitive image score measurements. The background structure should be realistic to avoid artefacts. Phantoms should have a standard breast-like shape and size.

Radiation Doses to Patients in Interventional Coronary Procedures-Estimation of Updated National Reference Levels by Dose Audit.

The objective of this study was to estimate the French national updated reference levels (RLs) for coronary angiography (CA) and percutaneous coronary intervention (PCI) by a dose audit from a large data set of unselected procedures and in standard-sized patients. Kerma-area product (PKA), air kerma at interventional point (Ka,r), fluoroscopy time (FT), and the number of registered frames (NFs) and runs (NRs) were collected from 51 229 CAs and 42 222 PCIs performed over a 12-month period at 61 French hospitals. RLs estimated by the 75th percentile in CAs and PCIs performed in unselected patients were 36 and 78 Gy.cm² for PKA, 498 and 1285 mGy for Ka,r, 6 and 15 min for FT, and 566 and 960 for NF, respectively. These values were consistent with the RLs calculated in standard-sized patients. The large difference in dose between sexes leads us to propose specific RLs in males and females. The results suggest a trend for a time-course reduction in RLs for interventional coronary procedures.

Low-dose computed tomography screening for lung cancer in populations highly exposed to tobacco: A systematic methodological appraisal of published randomised controlled trials.

Low-dose computed tomography (LDCT) screening recommendations for lung cancer are contradictory. The French National Authority for Health commissioned experts to carry a systematic review on the effectiveness, acceptability and safety of lung cancer screening with LDCT in subjects highly exposed to tobacco. We used MEDLINE and Embase databases (2003-2014) and identified 83 publications representing ten randomised control trials. Control arms and methodology varied considerably, precluding a full comparison and questioning reproducibility of the findings. From five trials reporting mortality results, only the National Lung Screening Trial found a significant decrease of disease-specific and all-cause mortality with LDCT screening compared to chest X-ray screening. None of the studies provided all information needed to document the risk-benefit balance. The lack of statistical power and the methodological heterogeneity of European trials question on the possibility of obtaining valid results separately or by pooling. We conclude, in regard to the lack of strong scientific evidence, that LDCT screening should not be recommended in subjects highly exposed to tobacco.

[Exposure to CT scans in childhood and long-term cancer risk: A review of epidemiological studies]. / Exposition à la scanographie dans l'enfance et risque de cancer à long terme. Une synthèse des études épidémiologiques récentes.

Amongst medical exams requiring ionizing radiation, computed tomography (CT) scans are used more frequently, including in children. These CT examinations are associated with absorbed doses that are much higher than those associated with conventional radiology. In comparison to adults, children have a greater sensitivity to radiation and a longer life span with more years at cancer risks. Five epidemiological studies on cancer risks after CT scan exposure during childhood were published between 2012 and 2015. The results of these studies are consistent and show an increase of cancer risks in children who have been exposed to several CT scans. However, methodological limits due to indication bias, retrospective assessment of radiation exposure from CT scans and lack of statistical power are to be taken into consideration. International projects such as EPI-CT (Epidemiological study to quantify risks for pediatric computerized tomography and to optimize dose), with a focus on dosimetric reconstruction and minimization of bias will provide more precise results. In the meantime, available results reinforce the necessity of justification and optimization of doses.

Exposure of the French paediatric population to ionising radiation from diagnostic medical procedures in 2010.

BACKGROUND: Medical examination is the main source of artificial radiation exposure. Because children present an increased sensitivity to ionising radiation, radiology practices at a national level in paediatrics should be monitored. OBJECTIVE: This study describes the ionising radiation exposure from diagnostic medical examinations of the French paediatric population in 2010. MATERIALS AND METHODS: Data on frequency of examinations were provided by the French National Health Insurance through a representative sample including 107,627 children ages 0-15 years. Effective doses for each type of procedure were obtained from the published French literature. Median and mean effective doses were calculated for the studied population. RESULTS: About a third of the children were exposed to at least one examination using ionising radiation in 2010. Conventional radiology, dental exams, CT scans and nuclear medicine and interventional radiology represent respectively 55.3%, 42.3%, 2.1% and 0.3% of the procedures. Children 10-15 years old and babies from birth to 1 year are the most exposed populations, with respectively 1,098 and 734 examinations per 1,000 children per year. Before 1 year of age, chest and pelvis radiographs are the most common imaging tests, 54% and 32%, respectively. Only 1% of the studied population is exposed to CT scan, with 62% of these children exposed to a head-and-neck procedure. The annual median and mean effective doses were respectively 0.03 mSv and 0.7 mSv for the exposed children. CONCLUSION: This study gives updated reference data on French paediatric exposure to medical ionising radiation that can be used for public health or epidemiological purposes. Paediatric diagnostic use appears much lower than that of the whole French population as estimated in a previous study.

Chest X-ray screening examinations among French uranium miners: exposure estimation and impact on radon-associated lung cancer risk.

BACKGROUND: Medical surveillance of uranium miners can include periodic chest X-ray examinations. This study aimed to assess the X-ray exposure due to occupational health monitoring in the French cohort of uranium miners, and to test whether consideration of this additional radiation exposure impacts the excess risk of lung cancer death associated with radon exposure. METHOD: X-ray exposure due to occupational health monitoring was estimated retrospectively based on review of a sample of miners' medical records and bibliographic data. Four exposure scenarios were designed, differing in their assumptions about the type of procedures performed, their frequency, and the lung dose delivered. Radon exposure and lung doses from exposure to α-particle emitters and external γ rays have previously been individually assessed. Exposure-risk and dose-risk relations were estimated by Poisson regression with a linear excess relative risk (ERR) model. RESULTS: The cohort included 5086 miners with a mean follow-up duration of 30.1 years. The mean number of chest X-ray examinations ranged from 15.1 in the lowest to 34 in the highest-exposure scenario, and produced a mean cumulative lung dose ranging from 4.6 to 34.2 mGy. The role of occupation-related imaging screening X-ray procedures in total equivalent lung dose appeared insignificant compared to α-emitter exposure. X-ray exposure was not associated with lung cancer mortality risk. The ERR associated with radon remained significantly positive when X-ray exposure was included in the multivariate analysis. CONCLUSIONS: X-ray exposure did not confound the exposure-risk relation between radon and lung cancer.

Characterization of MOSFET detectors for in vivo dosimetry in interventional radiology and for dose reconstruction in case of overexposure.

As MOSFET (Metal Oxide Semiconductor Field Effect Transistor) detectors allow dose measurements in real time, the interest in these dosimeters is growing. The aim of this study was to investigate the dosimetric properties of commercially available TN-502RD-H MOSFET silicon detectors (Best Medical Canada, Ottawa, Canada) in order to use them for in vivo dosimetry in interventional radiology and for dose reconstruction in case of overexposure. Reproducibility of the measurements, dose rate dependence, and dose response of the MOSFET detectors have been studied with a Co source. Influence of the dose rate, frequency, and pulse duration on MOSFET responses has also been studied in pulsed x-ray fields. Finally, in order to validate the integrated dose given by MOSFET detectors, MOSFETs and TLDs (LiF:Mg,Cu,P) were fixed on an Alderson-Rando phantom in the conditions of an interventional neuroradiology procedure, and their responses have been compared. The results of this study show the suitability of MOSFET detectors for in vivo dosimetry in interventional radiology and for dose reconstruction in case of accident, provided a well-corrected energy dependence, a pulse duration equal to or higher than 10 ms, and an optimized contact between the detector and the skin of the patient are achieved.