Radiography of scoliosis: Comparative dose levels and image quality between a dynamic flat-panel detector and a slot-scanning device (EOS system).

PURPOSE: To compare radiation dose and image quality between a slot-scanning system (SSS) and a dynamic flat-panel detector (DFD) in assessing scoliosis in children. METHODS: An experimental study was first performed with a phantom to assess the quality of each device. The clinical part included a prospective observational dosimetric and qualitative comparative study with acquisition of whole-spine X-ray: SSS (31 children), DFD (26 children). Institutional review board approval and informed consent were obtained. Dosimetric statistical analysis was performed from dose area product (DAP) and entrance skin dose measured by thermo-luminescent dosimeters localized in the cervical, thoracic and sacral areas. Assessment of the diagnostic quality (phantom and clinical) was realized by independent evaluation by 3 observers, using statistical analysis of quality score and inter-observer reproducibility. RESULTS: DAP was equivalent with the 2 systems. Entrance skin dose was significantly higher with DFD in thoracic and pelvic regions (P<0.05). Image quality scores of the SSS were significantly better than DFD for a majority of criteria, in both phantom and clinical evaluations. CONCLUSION: For scoliosis evaluation, the SSS, compared to the DFD system, offers enhanced image quality while reducing the entrance skin dose in the most radiosensitive areas.

Follow-up of children exposed to ionising radiation from cardiac catheterisation: the Coccinelle study.

Cardiac catheterisation has become an essential tool in the diagnosis and treatment of children with a wide variety of congenital and acquired forms of cardiovascular disease. Despite the clear clinical benefit to the patient, radiation exposure from paediatric cardiac catheterisation procedures (CCPs) may be substantial. Given children's greater sensitivity to radiation and the longer life span during which radiation health effects can develop, an epidemiological cohort study, named Coccinelle or 'Ladybird' (French acronym for 'Cohorte sur le risque de cancer après cardiologie interventionnelle pédiatrique'), is carried out in France to evaluate the risks of leukaemia and solid cancers in this population. A total number of 8000 included children are expected. Individual CCP-related doses will be assessed for each child included in the cohort. For each CCP performed, dosimetric parameters (dose-area product, fluoroscopy time and total number of cine frames) are retrieved retrospectively. Organ doses, especially to the lung, the oesophagus and the thyroid, are calculated with PCXMC software. The cohort will be followed up through linkage with French paediatric cancer registries.

Are the studies on cancer risk from CT scans biased by indication? Elements of answer from a large-scale cohort study in France.

BACKGROUND: Recent epidemiological results suggested an increase of cancer risk after receiving computed tomography (CT) scans in childhood or adolescence. Their interpretation is questioned due to the lack of information about the reasons for examination. Our objective was to estimate the cancer risk related to childhood CT scans, and examine how cancer-predisposing factors (PFs) affect assessment of the radiation-related risk. METHODS: The cohort included 67,274 children who had a first scan before the age of 10 years from 2000 to 2010 in 23 French departments. Cumulative X-rays doses were estimated from radiology protocols. Cancer incidence was retrieved through the national registry of childhood cancers; PF from discharge diagnoses. RESULTS: During a mean follow-up of 4 years, 27 cases of tumours of the central nervous system, 25 of leukaemia and 21 of lymphoma were diagnosed; 32% of them among children with PF. Specific patterns of CT exposures were observed according to PFs. Adjustment for PF reduced the excess risk estimates related to cumulative doses from CT scans. No significant excess risk was observed in relation to CT exposures. CONCLUSIONS: This study suggests that the indication for examinations, whether suspected cancer or PF management, should be considered to avoid overestimation of the cancer risks associated with CT scans.

Establishment of diagnostic reference levels in cardiac CT in France: a need for patient dose optimisation.

The objective of this study was to propose diagnostic reference levels (DRLs) for coronary computed tomography angiography (CCTA), in the context of a large variability in patient radiation dose, and the lack of European recommendations. Volume Computed Tomography Dose Index (CTDIvol) and dose-length product (DLP) were collected from 460 CCTAs performed over a 3-month period at eight French hospitals. CCTAs (∼50 per centre) were performed using the routine protocols of the centres, and 64- to 320-detector CT scanners. ECG gating was prospective (n = 199) or retrospective (n = 261). The large gap in dose between these two modes required to propose specific DRLs: 26 and 44 mGy for CTDIvol, and 370 and 970 mGy cm for DLP, respectively. This study confirms the large variability in patient doses during CCTA and underlines the need for the optimisation of cardiac acquisition protocols. Availability of national DRLs should be mandatory in this setting.

Local reference levels and organ doses from pediatric cardiac interventional procedures.

Interventional cardiology (IC) procedures can be responsible for relatively high radiation doses compared to conventional radiology especially for young patients. The aim of this study was to assess current exposure levels in a French reference centre of pediatric IC. Dosimetric data including dose area product (DAP), fluoroscopy time (FT) and number of cine frame (NF) were analysed taking into account patient weight. Doses to the lungs, esophagus, breast and thyroid were evaluated using anthropomorphic phantoms and thermoluminescent dosimeters. Finally, effective doses (E) were calculated using DAP and conversion factors calculated with PCXMC 2.0 software. 801 IC procedures performed between 2010 and 2011 were analysed. Large variations were observed for DAP, FT and NF values for a given procedure and a given weight group. The assessment of organ doses showed high levels of dose to the lungs and esophagus especially in new-born babies. For diagnostic procedures, E varied from 0.3 to 23 mSv with a mean value of 4.8 mSv and for therapeutic procedures, values ranged from 0.1 to 48.4 mSv with a mean value of 7.3 mSv. The highest values were recorded for angioplasty procedures (mean 13 mSv, range 0.6-48.4 mSv). The increasing use of IC in pediatric population stresses the need of setting up reference levels and keeping doses to children as low as possible.

Radiation exposure from CT in early childhood: a French large-scale multicentre study.

OBJECTIVES: The increasing use of CT scans in the paediatric population raises the question of a possible health impact of ionising radiation exposure associated with CT scans. The aim of this study was to describe the pattern of CT use in early childhood. METHODS: In 14 major French paediatric radiology departments, children undergoing at least 1 CT scan before age 5, between 2000 and 2006, were included. For each examination, absorbed organ doses were calculated. RESULTS: 43% of the 27 362 children in the cohort were aged less than 1 year during their first exposure, with 9% being aged less than 1 month. The mean number of examinations per child was 1.6 (range 1-43). The examinations included: head in 63% of the cases, chest in 21%, abdomen and pelvis in 8% and others in 8%. Brain and eye lenses received the highest cumulative doses from head examinations, with mean organ dose values of 22 mGy (maximum 1107 mGy) and 26 mGy (maximum 1392 mGy), respectively. The mean cumulative effective dose was 3.2 mSv (range 0.1-189 mSv). CONCLUSION: CT scan exposure in childhood is responsible for relatively high doses to radiosensitive organs. The rather large dose range according to the protocols used requires their optimisation. The cohort follow-up will study the risk of long-term radiation-induced cancer.

[Patient dose during interventional neuroradiology procedures: Results from a multi-center study]. / Dose patient en neuroradiologie interventionnelle : bilan d'une enquête multicentrique.

PURPOSE: The purpose of this multicenter study was to determine the doses received by patients during interventional neuroradiology procedures and to consider establishing reference standards. MATERIALS AND METHODS: A retrospective study of nine interventional neuroradiology departments was conducted. Seven diagnostic (cerebral and spinal angiography) and therapeutic (embolization and vertebroplasty) procedures were reviewed. For each procedure, three dosimetric parameters were recorded: dose-area product (DAP), fluoroscopy time, and number of images. RESULTS: Results showed interdepartment variations, up to four-fold for diagnostic procedures and seven-fold for therapeutic procedures. However, applying the 75th percentile method to the entire dataset, reference standards can be proposed for six types of procedures including diagnostic cerebral angiography (230 Gycm(2)), follow-up selective cerebral angiography (80 Gycm(2)), aneurysm embolization (350 Gycm(2)), AVM embolization (440 Gycm(2)). Reference standards are also proposed with regards to fluoroscopy time and number of images. CONCLUSION: Such standards are useful for clinicians to evaluate and improve their practices.

[Duties of the radiologist for the radiation protection of radiation workers]. / Obligations du radiologue pour la radioprotection des travailleurs.

After a risk analysis has been completed by the radiation safety officer, all entities where a source of ionizing radiation is present must established a monitored or controlled zone containing the source. When exposure exceeds the maximum regulatory dose, a dedicated color-coded controlled (yellow or orange) or restricted zone must be established. All assessments performed by the RSO should reflect normal working conditions. From these results, workers can be divided into two categories, A or B, based on their level of exposure. The workers should undergo medical and dosimetric follow-up with the use of passive dosimetry. The use of operational dosimetry should be added when working in a controlled zone. A radiation dosimetry report for each worker should be available to the occupational medicine provider to ensure appropriate dosimetric monitoring.

IRSN methodological guide to conducting workplace studies in compliance with French regulations.

Under French regulations governing radiation protection of workers, dosimetric workplace studies are mandatory. However, their practical implementation is not described. IRSN has developed a guide to help stakeholders in the radiological protection of workers conduct such studies. It proposes a general methodology applicable to most cases and 'workplace sheets', which apply this methodology to specific occupational settings. At present, two sheets are available: conventional radiology and interventional radiology.

[Organ doses from CT examinations in children]. / Evaluation des doses d'irradiation aux organes en scanographie pédiatrique.

PURPOSE: To estimate radiation doses from routine pediatric CT scans (body) and to propose dose reduction protocols. MATERIAL AND METHODS: [corrected] Study performed with a phantom equivalent to the body of 5 year old child with evaluation of doses delivered to breast, gonads, bone marrow (sternum, T12) and thyroid for CT examinations of the chest, abdomen, pelvis and spine. Extrapolation is made to estimate the doses for 1 year old and 10 year old children. Finally, dose reduction protocols are evaluated. RESULTS: CT of the chest delivers significant doses to breast tissue and bone marrow, CT of the abdomen and pelvis delivers significant doses to the ovaries and CT pf the spine delivers significant doses to thyroid and bone marrow. Optimization can be achieved without degradation of the image quality, by reducing Kv and mAs within reasonable limits. This study may be used in order to evaluate the doses delivered by multi-detector CT units.