Management of pregnant or potentially pregnant patients undergoing diagnostic and interventional radiology procedures: Investigation of clinical routine practice.

It is well known that foetuses are highly sensitive to ionising radiation and special attention to justification and optimisation of radiological procedures involving a pregnant patient is required. A task to review, validate and compare different approaches to managing the pregnant patient and to estimating the associated foetal doses arising from a diagnostic or interventional radiology (DIR) procedure was designed in the framework of EURADOS working group 12. As a first step, a survey of radiation protection practice including dosimetry considerations among EURADOS members was performed using online questionnaire. Then, to evaluate the possible differences in the estimated foetal doses, a comparison of assessed dose values was made for three cases of pregnant patients that underwent different CT procedures. More than 120 professionals from 108 institutions and 17 countries that are involved in managing pregnant patients undergoing DIR procedures answered the questionnaire. Most of the respondents use national or hospital guidelines on the management of pregnant patients undergoing DIR procedures. However, the guidelines differ considerably among respondents. Comparison of foetal dose assessments performed by dosimetry experts showed the variety of methods used as well as large variability of estimated foetal doses in all three cases. Although European and International commission on radiation protection guidelines already exist, they are more than 20 years old and, in some aspects, they are obsolete. This paper shows that there is a need to revise and update these guidelines.

Lympho-hematopoietic malignancies risk after exposure to low dose ionizing radiation during cardiac catheterization in childhood.

Pediatric patients with congenital heart disease (CHD) often undergo low dose ionizing radiation (LDIR) from cardiac catheterization (CC) for the diagnosis and/or treatment of their disease. Although radiation doses from a single CC are usually low, less is known about the long-term radiation associated cancer risks. We aimed to assess the risk of lympho-hematopoietic malignancies in pediatric CHD patients diagnosed or treated with CC. A French cohort of 17,104 children free of cancer who had undergone a first CC from 01/01/2000 to 31/12/2013, before the age of 16 was set up. The follow-up started at the date of the first recorded CC until the exit date, i.e., the date of death, the date of first cancer diagnosis, the date of the 18th birthday, or the 31/12/2015, whichever occurred first. Poisson regression was used to estimate the LDIR associated cancer risk. The median follow-up was 5.9 years, with 110,335 person-years. There were 22,227 CC procedures, yielding an individual active bone marrow (ABM) mean cumulative dose of 3.0 milligray (mGy). Thirty-eight incident lympho-hematopoietic malignancies were observed. When adjusting for attained age, gender and predisposing factors to cancer status, no increased risk was observed for lympho-hematopoietic malignancies RR/mGy = 1.00 (95% CI: 0.88; 1.10). In summary, the risk of lympho-hematopoietic malignancies and lymphoma was not associated to LDIR in pediatric patients with CHD who undergo CC. Further epidemiological studies with greater statistical power are needed to improve the assessment of the dose-risk relationship.

Childhood cancer risks estimates following CT scans: an update of the French CT cohort study.

OBJECTIVES: Increased risks of central nervous system (CNS) tumors and leukemia associated with computed tomography (CT) exposure during childhood have been reported in recent epidemiological studies. However, no evidence of increased risks was suggested in a previous analysis of the French CT cohort. This study benefits from an updated cohort with a longer follow-up and a larger sample size of patients. METHODS: The patients were followed from the date of their first CT (between 2000 and 2011) until their date of cohort exit defined as the earliest among the following: 31 December 2016, date of death, date of first cancer diagnosis or date of their 18th birthday. Cancer incidence, vital status, cancer predisposing factors (PFs), and additional CT scans were collected via external national databases. Hazard ratios (HRs) associated to cumulative organ doses and sex were estimated from Cox models. RESULTS: At the end of follow-up, mean cumulative doses were 27.7 and 10.3 mGy for the brain and the red bone marrow (RBM), respectively. In patients without PFs, an HR per 10 mGy of 1.05 (95% CI: 1.01-1.09) for CNS tumors, 1.17 (95% CI: 1.09-1.26) for leukemia, and 0.96 (95% CI: 0.63-1.45) for lymphoma was estimated. These estimates were not modified by the inclusion of CT scans performed outside the participating hospitals or after the inclusion period. CONCLUSIONS: This study shows statistically significant dose-response relationships for CNS tumors and leukemia for patients without PFs. KEY POINTS: • Computed tomography is the most important contributor to the collective dose for diagnostic imaging to the French population. • Concerns have been raised about possible cancer risks, particularly after exposure to CT in childhood, due to the greater radiation sensitivity of children and to their longer life expectancy. • Analysis of the updated French CT cohort shows statistically significant dose-response relationships for CNS tumors and leukemia.

Exposure to low-dose ionising radiation from cardiac catheterisation and risk of cancer: the COCCINELLE study cohort profile.

PURPOSE: The COCCINELLE study is a nationwide retrospective French cohort set up to evaluate the risk of cancer in patients who undergone cardiac catheterisation (CC) procedures for diagnosis or treatment of congenital heart disease during childhood. PARTICIPANTS: Children who undergone CC procedures from 1 January 2000 to 31 December 2013, before the age of 16 in one of the 15 paediatric cardiology departments which perform paediatric CC in mainland France were included. The follow-up started at the date of the first recorded CC procedure until the exit date, that is, the date of death, the date of first cancer diagnosis, the date of the 18th birthday or the 31 December 2015, whichever occurred first. The cohort was linked to the National Childhood Cancer Registry to identify patients diagnosed with cancer and with the French National Directory for the Identification of Natural Persons to retrieve the patients' vital status. FINDINGS TO DATE: A total of 17 104 children were included in the cohort and followed for 110 335 person-years, with 22 227 CC procedures collected. Among the patients, 81.6% received only one procedure. Fifty-nine cancer cases were observed in the cohort. Standardised incidence ratios (SIRs) were increased for all-cancer (SIR=3.8, 95% CI: 2.9 to 4.9), leukaemia (SIR=3.3, 95% CI: 2.0 to 5.4), lymphoma (SIR=14.9, 95% CI: 9.9 to 22.5) and solid cancers excluding central nervous system (CNS) tumours (SIR=3.3, 95% CI: 2.0 to 5.5) compared with the general population. FUTURE PLANS: Dose reconstruction is currently underway to estimate individual cumulative doses absorbed to relevant organs, including red bone marrow and brain for respectively haematologic disorders and CNS tumours risk estimation. A dose-response analysis will be conducted with consideration to confounding factors such as age at exposure, gender, predisposing factors to cancer and other sources of medical diagnostic low-dose ionising radiation.

Surgivisio® and O-arm®O2 cone beam CT mobile systems for guidance of lumbar spine surgery: Comparison of patient radiation dose.

PURPOSE: To compare patient radiation doses in cone beam computed tomography (CBCT) of two mobile systems used for navigation-assisted mini-invasive orthopedic surgery: O-arm®O2 and Surgivisio®. METHODS: The study focused on imaging of the spine. Thermoluminescent dosimeters were used to measure organs and effective doses (ED) during CBCT. An ionization-chamber and a solid-state sensor were used to measure the incident air-kerma (Ki) at the center of the CBCT field-of-view and Ki during 2D-imaging, respectively. The PCXMC software was used to calculate patient ED in 2D and CBCT configurations. The image quality in CBCT was evaluated with the CATPHAN phantom. RESULTS: The experimental ED estimate for the low-dose 3D-modes was 2.41 and 0.35 mSv with O-arm®O2 (Low Dose 3D-small-abdomen) and Surgivisio® (3DSU-91 images), respectively. PCXMC results were consistent: 1.54 and 0.30 mSv. Organ doses were 5 to 12 times lower with Surgivisio®. Ki at patient skin were comparable on lateral 2D-imaging (0.5 mGy), but lower with O-arm®O2 on anteroposterior (0.3 versus 0.9 mGy). Both systems show poor low contrast resolution and similar high contrast spatial resolution (7 line-pairs/cm). CONCLUSIONS: This study is the first to evaluate patient ED and organ doses with Surgivisio®. A significant difference in organs doses was observed between the CBCT systems. The study demonstrates that Surgivisio® used on spine delivers approximately five to six times less patient ED, compared to O-arm®O2, in low dose 3D-modes. Doses in 2D-mode preceding CBCT were higher with Surgivisio®, but negligible compared to CBCT doses under the experimental conditions tested.

The HARMONIC project: study design for the assessment of radiation doses and associated cancer risks following cardiac fluoroscopy in childhood.

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.

Patient dose evaluation in computed tomography: A French national study based on clinical indications.

PURPOSE: A national survey was performed to assess patient dose indicators based on clinical indication and on patient morphology for most common adult computed tomography (CT) examinations in France. METHODS: Seventeen groups of clinical indications (GCIs) for diagnostic CT in adult patients were considered based on their frequency and on image quality requirements. Data was collected for 15-30 consecutive examinations performed between 2015 and 2017, per CT scanner and GCI. Distributions of total examination Dose-Length Product (DLP) and Volume CT Dose Index (CTDIvol) were assessed for each GCI as a function of patient gender or patient Body Mass Index (BMI) for head/neck and trunk examinations, respectively. RESULTS: 6610 examinations were analysed. Median total exam DLP values were higher for men compared to women patients for head and neck examinations: difference ranged from 6% for ear trauma indication (577 vs 543 mGy·cm, p = 0.01) to 35% for brain tumour GCI (1472 vs 1093 mGy·cm, p < 0.01). For trunk examinations, total exam DLP increased consistently with patient's BMI. For normal-BMI patients, median CTDIvol and DLP differed significantly between different GCIs for single-phase CT of the chest (3 mGy and 112 mGy·cm, respectively, for chronic obstructive pulmonary disease group vs 5.8 mGy and 207 mGy·cm for pulmonary embolism group, p < 0.05) and of the abdomen-pelvis (5.6 mGy and 284 mGy·cm, respectively, in renal colic group vs 9.5 mGy and 463 mGy·cm in occlusive syndrome group, p < 0.05). CONCLUSION: This study provides morphological- and clinical-based patient dose indicators in CT as a practical tool for clinical practices optimisation.

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.

SESAME: A TOOL FOR NUMERICAL DOSIMETRIC RECONSTRUCTION OF PATIENTS OVEREXPOSURES IN INTERVENTIONAL RADIOLOGY.

Radiation overexposure accidents are rare but can have severe health consequences. Evaluating the dose received by the patient is a crucial step in the medical management. For that purpose, for more than 15 years, IRSN has been developing an in-house tool named SESAME for the numerical reconstruction of radiological accidents due to external sources. Recently, two new functionalities were implemented in SESAME to allow accurate reconstructions of interventional radiology (IR) overexposures. The experimental validation of SESAME for the reconstruction of overexposures in IR is presented. First, an anthropomorphic dummy equipped with dosemeters was irradiated following conditions similar to a fluoroscopically guided interventional procedure. Then the procedure was simulated using SESAME. Finally measured doses were compared to calculated doses. Even with a limited amount of data available, SESAME can provide valuable dose information for the medical team in charge of the patient, such as skin dose mapping and dose distribution in depth.

Projected Future Cancer Risks in Children Treated With Fluoroscopy-Guided Cardiac Catheterization Procedures.

Background Children treated with cardiac catheterization procedures have now a long life expectancy and consequently potential long-term radiation-induced risks. We projected lifetime attributable risks (LARs) of cancer incidence from the most frequent procedures in pediatrics: atrial septal defect closure, patent ductus arteriosus occlusion, or pulmonary valvuloplasty. Methods and Results Organ equivalent doses were estimated for 1251 procedures performed in children aged ≤15 years at 2 reference catheterization centers in France from 2009 to 2013. Sex-specific LARs were projected in lifelong nonsmokers using extended Committee on Biological Effects of Ionizing Radiation VII risk models and considering various sources of risk projection uncertainties and dose variability (Radiation Risk Assessment Tool software). Median LARs ranged between 0.3 and 1.4 (atrial septal defect closure), 0.6 and 5.0 (patent ductus arteriosus occlusion), and 1.0 and 12.0 (pulmonary valvuloplasty) per 1000 procedures, depending on patient sex and age at treatment. These radiation-related risks would represent 0.4% to 6.0% of children's total lifetime cancer risk. For the 10% of procedures (all types combined) with highest exposures, LARs reached 4.2 per 1000 (95% uncertainty interval, 0.8-13.1) in boys and 22.2 per 1000 (95% uncertainty interval, 7.4-45.6) in girls. In boys, lung cancer accounted for 70% to 80% of the projected LARs, whereas in girls it accounted for 20% to 60% and breast cancer for 30% to 80% of the excess risks, depending on the type of procedure and patient age. Conclusions Radiation exposure may lead to substantial radiation doses and increased cancer risks in some cases. This suggests the need for dose reporting to support recommendations for long-term surveillance and prevention strategies when it is necessary.

Individual radiation exposure from computed tomography: a survey of paediatric practice in French university hospitals, 2010-2013.

OBJECTIVES: To describe computed tomography (CT) scanning parameters, volume CT dose index (CTDIvol) and dose-length product (DLP) in paediatric practice and compare them to current diagnostic reference levels (DRLs). METHODS: The survey was conducted in radiology departments of six major university hospitals in France in 2010-2013. Data collection was automatised to extract and standardise information on scanning parameters from DICOM-header files. CTDIvol and DLP were estimated based on Monte Carlo transport simulation and computational reference phantoms. RESULTS: CTDIvol and DLP were derived for 4,300 studies, four age groups and 18 protocols. CTDIvol was lower in younger patients for non-head scans, but did not vary with age for routine head scans. Ratios of 95th to 5th percentile CTDIvol values were 2-4 for most body parts, but 5-7 for abdominal examinations and 4-14 for mediastinum CT with contrast, depending on age. The 75th percentile CTDIvol values were below the national DRLs for chest (all ages) and head and abdominal scans (≥10 years). CONCLUSION: The results suggest the need for a better optimisation of scanning parameters for routine head scans and infrequent protocols with patient age, enhanced standardisation of practices across departments and revision of current DRLs for children. KEY POINTS: • CTDIvol varied little with age for routine head scans. • CTDIvol was lowest in youngest children for chest or abdominal scans. • Individual and inter-department variability warrant enhanced standardisation of practices. • Recent surveys support the need for revised diagnostic reference levels. • More attention should be given to specific protocols (sinuses, neck, spine, mediastinum).

Percutaneous bone biopsies: comparison between flat-panel cone-beam CT and CT-scan guidance.

PURPOSE: This study was designed to compare the accuracy of targeting and the radiation dose of bone biopsies performed either under fluoroscopic guidance using a cone-beam CT with real-time 3D image fusion software (FP-CBCT-guidance) or under conventional computed tomography guidance (CT-guidance). METHODS: Sixty-eight consecutive patients with a bone lesion were prospectively included. The bone biopsies were scheduled under FP-CBCT-guidance or under CT-guidance according to operating room availability. Thirty-four patients underwent a bone biopsy under FP-CBCT and 34 under CT-guidance. We prospectively compared the two guidance modalities for their technical success, accuracy, puncture time, and pathological success rate. Patient and physician radiation doses also were compared. RESULTS: All biopsies were technically successful, with both guidance modalities. Accuracy was significantly better using FP-CBCT-guidance (3 and 5 mm respectively: p = 0.003). There was no significant difference in puncture time (32 and 31 min respectively, p = 0.51) nor in pathological results (88 and 88 % of pathological success respectively, p = 1). Patient radiation doses were significantly lower with FP-CBCT (45 vs. 136 mSv, p < 0.0001). The percentage of operators who received a dose higher than 0.001 mSv (dosimeter detection dose threshold) was lower with FP-CBCT than CT-guidance (27 vs. 59 %, p = 0.01). CONCLUSIONS: FP-CBCT-guidance for bone biopsy is accurate and reduces patient and operator radiation doses compared with CT-guidance.

Variability of bronchial measurements obtained by sequential CT using two computer-based methods.

This study aimed to evaluate the variability of lumen (LA) and wall area (WA) measurements obtained on two successive MDCT acquisitions using energy-driven contour estimation (EDCE) and full width at half maximum (FWHM) approaches. Both methods were applied to a database of segmental and subsegmental bronchi with LA > 4 mm(2) containing 42 bronchial segments of 10 successive slices that best matched on each acquisition. For both methods, the 95% confidence interval between repeated MDCT was between -1.59 and 1.5 mm(2) for LA, and -3.31 and 2.96 mm(2) for WA. The values of the coefficient of measurement variation (CV(10), i.e., percentage ratio of the standard deviation obtained from the 10 successive slices to their mean value) were strongly correlated between repeated MDCT data acquisitions (r > 0.72; p < 0.0001). Compared with FWHM, LA values obtained using EDCE were higher for LA < 15 mm(2), whereas WA values were lower for bronchi with WA < 13 mm(2); no systematic EDCE underestimation or overestimation was observed for thicker-walled bronchi. In conclusion, variability between CT examinations and assessment techniques may impair measurements. Therefore, new parameters such as CV(10) need to be investigated to study bronchial remodeling. Finally, EDCE and FWHM are not interchangeable in longitudinal studies.