X-Ray to DRR Images Translation for Efficient Multiple Objects Similarity Measures in Deformable Model 3D/2D Registration.

The robustness and accuracy of the intensity-based 3D/2D registration of a 3D model on planar X-ray image(s) is related to the quality of the image correspondences between the digitally reconstructed radiographs (DRR) generated from the 3D models (varying image) and the X-ray images (fixed target). While much effort may be devoted to generating realistic DRR that are similar to real X-rays (using complex X-ray simulation, adding densities information in 3D models, etc.), significant differences still remain between DRR and real X-ray images. Differences such as the presence of adjacent or superimposed soft tissue and bony or foreign structures lead to image matching difficulties and decrease the 3D/2D registration performance. In the proposed method, the X-ray images were converted into DRR images using a GAN-based cross-modality image-to-images translation. With this added prior step of XRAY-to-DRR translation, standard similarity measures become efficient even when using simple and fast DRR projection. For both images to match, they must belong to the same image domain and essentially contain the same kind of information. The XRAY-to-DRR translation also addresses the well-known issue of registering an object in a scene composed of multiple objects by separating the superimposed or/and adjacent objects to avoid mismatching across similar structures. We applied the proposed method to the 3D/2D fine registration of vertebra deformable models to biplanar radiographs of the spine. We showed that the XRAY-to-DRR translation enhances the registration results, by increasing the capture range and decreasing dependence on the similarity measure choice since the multi-modal registration becomes mono-modal.

Toward Automated 3D Spine Reconstruction from Biplanar Radiographs Using CNN for Statistical Spine Model Fitting.

To date, 3D spine reconstruction from biplanar radiographs involves intensive user supervision and semi-automated methods that are time-consuming and not effective in clinical routine. This paper proposes a new, fast, and automated 3D spine reconstruction method through which a realistic statistical shape model of the spine is fitted to images using convolutional neural networks (CNN). The CNNs automatically detect the anatomical landmarks controlling the spine model deformation through a hierarchical and gradual iterative process. The performance assessment used a set of 68 biplanar radiographs, composed of both asymptomatic subjects and adolescent idiopathic scoliosis patients, in order to compare automated reconstructions with ground truths build using multiple experts-supervised reconstructions. The mean (SD) errors of landmark locations (3D Euclidean distances) were 1.6 (1.3) mm, 1.8 (1.3) mm, and 2.3 (1.4) mm for the vertebral body center, endplate centers, and pedicle centers, respectively. The clinical parameters extracted from the automated 3D reconstruction (reconstruction time is less than one minute) presented an absolute mean error between 2.8° and 4.7° for the main spinal parameters and between 1° and 2.1° for pelvic parameters. Automated and expert's agreement analysis reported that, on average, 89% of automated measurements were inside the expert's confidence intervals. The proposed automated 3D spine reconstruction method provides an important step that should help the dissemination and adoption of 3D measurements in clinical routine.

Importance of whole genome sequencing for the assessment of outbreaks in diagnostic laboratories: analysis of a case series of invasive Streptococcus pyogenes infections.

Outbreaks of Streptococcus pyogenes hypervirulent clones are constant public health threats. In western Switzerland, an increase of severe cases of S. pyogenes invasive infections was observed between December 2015 and March 2016. Our aim was (i) to investigate these cases by the use of Whole Genome Sequencing (WGS) and (ii) to determine the specific virulome and resistome of each isolate in order to undertake adequate public health measures. Eleven Streptococcus pyogenes strains isolated from 11 patients with severe invasive infections between December 13, 2015 and March 12, 2016 were included in our study. Practically, emm-typing, MLST and WGS were used to investigate the relatedness between the isolates. The presence of virulence and antibiotic resistance genes as well as mutations in transcriptional regulators of virulence and in genes encoding for antibiotic targets were assessed. Three and two groups of isolates shared the same emm-type and ST type, respectively. Single Nucleotide Polymorphism (SNP) analysis revealed 14 to 32 SNPs between the strains of the same emm-type group, ruling out the possibility of a clonal outbreak. Mutations found in covS and rocA could partially explain an increased virulence. As these reassuring results were obtained in less than 10 days, no specific hospital hygiene and no dedicated public health measures had to be undertaken. WGS is a powerful technique to discriminate between closely related strains, excluding an outbreak in less than 10 days. Moreover, WGS provided extensive data on the virulome and resistome of all these strains.

[Implementing new technology in radiation oncology: The French agency for nuclear safety (ASN) report]. / Conditions de mise en œuvre des « nouvelles techniques et pratiques ¼ en radiothérapie. Synthèse du rapport du groupe de travail issu du groupe permanent d'experts en radioprotection médicale de l'Autorité de sûreté nucléaire.

In August 2013, the French nuclear safety agency (ASN) requested the permanent group of experts in radiation protection in medicine (GPMED) to propose recommendations on the implementation of new technology and techniques in radiation oncology. These recommendations were finalized in February 2015 by the GPMED. In April 2015, the ASN sent a letter to the French ministry of health (DGS/DGOS), and its national health agencies (ANSM, INCa, HAS). In these letters, ASN proposed that, from the 12 recommendations made by the GPMED, an action plan should be established, whose control could be assigned to the French national cancer institute (INCa), as a pilot of the national committee for radiotherapy and that this proposal has to be considered at the next meeting of the national committee of radiotherapy.

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.

Impact of neoadjuvant chemotherapy cycles prior to interval surgery in patients with advanced epithelial ovarian cancer.

OBJECTIVES: Complete surgery with no macroscopic residual disease (RD) at primary (PDS) or interval debulking surgery (IDS) is the main objective of surgery in advanced epithelial ovarian cancer (EOC). The aim of this work was to evaluate the impact on survival of the number of neoadjuvant chemotherapy (NAC) cycles before IDS in EOC patients. METHODS: Data from EOC patients (stages IIIC-IV), operated on between 1995 and 2010 were consecutively recorded. NAC/IDS patients were analyzed according to the number of preoperative cycles (<4=group B1; >4=group B2) and compared with patients receiving PDS (group A). Patients with complete resection were specifically analyzed. RESULTS: 367 patients were analyzed, 220 received PDS and 147 had IDS/NAC. In group B, 37 patients received more than 4 NAC cycles (group B2). Group B2 patients presented more frequently stage IV disease at diagnosis (p<0.01) compared to groups A and B1. The rate of complete cytoreduction was higher in group B (p<0.001). Patients with no RD after IDS and who had received more than 4 NAC cycles had poor survival (p<0.001) despite complete removal of their tumor (relative risk of death after multivariate analysis of 3 (p<0.001)) with an independent impact from disease stage and WHO performance status. CONCLUSIONS: Patients with advanced EOC receiving complete IDS after more than 4cycles of NAC have poor prognosis. Despite worse prognostic factors observed in this group of patients, our study reinforces the concept of early and complete removal of all macroscopic tumors in the therapeutic sequence of EOC.

Day-care for breast cancer: ambulatory surgery and intra-operative radiation. Techniques and preliminary results of the Centre Val-d'Aurelle--Montpellier.

One-day breast carcinoma treatment is defined as association of ambulatory surgery and intra-operative irradiation. Selection and rigorous process of patients is the key to success. The surgical technique is not changed by the radiotherapy. Patient's satisfaction index is very high. Financial loss should not be a hurdle to its implementation.

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.

[Impact of surgery in the management of pancreatic metastases of renal cell cancer]. / Place de la chirurgie dans la prise en charge des métastases pancréatiques des cancers du rein.

INTRODUCTION: Incidence of renal cell carcinoma (RCC) is increasing over the 25 last years. Pancreatic metastases of RCC are rare. The aim of this work was to study overall survival of patients operated for pancreatic metastases of RCC in Montpellier cancer institute. PATIENTS AND METHODS: Between 2000 and 2012, a retrospective monocentric study was performed at Montpellier cancer institute. We evaluated the outcomes of curative pancreatic metastases from renal primary and the impact of targeted therapies. RESULTS: Thirty-eight patients were treated in our center for pancreatic metastases of RCC. Twelve patients had a curative surgery of metachronous pancreatic metastases. Four patients were without recurrence after pancreatic resection (33.3%). None had adjuvant therapy. Six patients were treated by targeted therapies, because of metastatic progression. Five of 6 died, the sixth evolved with targeted therapies by thyrosine kinase inhibitor. Average deadline between appearance of metastases and death was 89.9 months for operated patients. Average deadline between appearance of c metastases and death was 33.1 months for the others (P=0.004). CONCLUSION: Surgical treatment of pancreatic metastases should increase life expectancy of patients. Others studies are necessary to prove the impact of targeted therapies in metastatics patients in this indication. LEVEL OF EVIDENCE: 5.

Three-dimensional reconstruction of the lower limb from biplanar calibrated radiographs.

Three-dimensional (3D) reconstruction of lower limbs is essential for surgical planning and clinical outcome evaluation. 3D reconstruction from biplanar calibrated radiographs may be an alternative to irradiation issues of CT-scan. A previous study proposed a two-step reconstruction method based on parametric models and statistical inferences leading to a fast Initial Solution (IS) followed by manual adjustments. This study aims to improve the IS using a new 3D database, a novel parametric model of the tibia and a different regression approach. The IS was evaluated in terms of shape accuracy on 9 lower limbs and reproducibility of clinical measurements on 22 lower limbs. Reconstruction time was also evaluated. Comparison to the previous method showed an improvement of the IS in terms of shape accuracy (1.3 vs. 1.6 and 2 mm respectively for both femur and tibia) and reproducibility of clinical measurements (i.e. 3.1° vs. 8.3° for neck-shaft-angle; 4.2° and 5° vs. 5° and 6° for tibial and femoral torsion respectively). The proposed approach constitutes a considerable step towards an automatic 3D reconstruction of lower limb.

Comparison of organs' shapes with geometric and Zernike 3D moments.

The morphological similarity of organs is studied with feature vectors based on geometric and Zernike 3D moments. It is particularly investigated if outliers and average models can be identified. For this purpose, the relative proximity to the mean feature vector is defined, principal coordinate and clustering analyses are also performed. To study the consistency and usefulness of this approach, 17 livers and 76 hearts voxel models from several sources are considered. In the liver case, models with similar morphological feature are identified. For the limited amount of studied cases, the liver of the ICRP male voxel model is identified as a better surrogate than the female one. For hearts, the clustering analysis shows that three heart shapes represent about 80% of the morphological variations. The relative proximity and clustering analysis rather consistently identify outliers and average models. For the two cases, identification of outliers and surrogate of average models is rather robust. However, deeper classification of morphological feature is subject to caution and can only be performed after cross analysis of at least two kinds of feature vectors. Finally, the Zernike moments contain all the information needed to re-construct the studied objects and thus appear as a promising tool to derive statistical organ shapes.

French diagnostic reference levels in diagnostic radiology, computed tomography and nuclear medicine: 2004-2008 review.

After 5 y of collecting data on diagnostic reference levels (DRLs), the Nuclear Safety and Radiation Protection French Institute (IRSN) presents the analyses of this data. The analyses of the collected data for radiology, computed tomography (CT) and nuclear medicine allow IRSN to estimate the level of regulatory application by health professionals and the representativeness of current DRL in terms of relevant examinations, dosimetric quantities, numerical values and patient morphologies. Since 2004, the involvement of professionals has highly increased, especially in nuclear medicine, followed by CT and then by radiology. Analyses show some discordance between regulatory examinations and clinical practice. Some of the dosimetric quantities used for the DRL setting are insufficient or not relevant enough, and some numerical values should also be reviewed. On the basis of these findings, IRSN formulates recommendations to update regulatory DRL with current and relevant examination lists, dosimetric quantities and numerical values.

[Recommendation of the working group commissioned by the French Nuclear Safety Authority on stereotactic radiation therapy]. / Avis du groupe de travail missionné par l'Autorité de sûreté nucléaire concernant la radiothérapie stéréotaxique.

PURPOSE: At the request of the French nuclear safety authority (Autorité de Sûreté Nucléaire, ASN) a working party of multidisciplinary experts was initiated to elaborate a report regarding propositions for the clinical practice of stereotactic radiation therapy and the related medical physics. MATERIAL AND METHODS: Several stereotactic radiation therapy experts were audited by the working party, especially neurosurgeons and neuroradiologists, as well as radiation oncologists, medical physicists and radiation technologists. An international survey was conducted looking at legal requirements and guidelines concerning stereotactic radiation therapy. A national survey was conducted in France among 29 departments performing stereotactic radiation therapy. The working party report was submitted for advice to the permanent group of medical experts of ASN. RESULTS: Among the 13 countries who responded, very few have legal documents. Some of them are stating that stereotactic radiation therapy must be performed in a radiotherapy department and only by well-trained professionals. Guidelines describing the role of each participant have been published in the USA. In France, stereotactic radiation therapy is performed with dedicated machines or adapted linear accelerators. In 2009, within the 29 departments, 4247 patients were treated with stereotactic radiation therapy representing 4% of the patients treated with external beam radiation therapy. Intracranial lesions were: 3383 and extracranial: 864. The working party of multidisciplinary experts made 7 recommendations. The first one saying that stereotactic radiation therapy must be considered as a radiotherapy. The permanent group of medical experts is asking to modify the "décret du 19 mars 2007" regarding "radiosurgery". CONCLUSION: The medical benefit of stereotactic radiation therapy is well admitted and it is an increasingly used technique. This work through practical guidelines and legal propositions intends to promote a well-controlled development of this radiotherapy technique.

Semi-automated stereoradiographic upper limb 3D reconstructions using a combined parametric and statistical model: a preliminary study.

PURPOSE: Quantitative assessment of 3D clinical indices may be crucial for elbow surgery planning. 3D parametric modeling from bi-planar radiographs was successfully proposed for spine and lower limb clinical investigation as an alternative for CT-scan. The aim of this study was to adapt this method to the upper limb with a preliminary validation. METHODS: CT-scan 3D models of humerus, radius and ulna were obtained from 20 cadaveric upper limbs and yielded parametric models made of geometric primitives. Primitives were defined by descriptor parameters (diameters, angles...) and correlations between these descriptors were found. Using these correlations, a semi-automated reconstruction method of humerus using bi-planar radiographs was achieved: a 3D personalized parametric model was built, from which clinical parameters were computed [orientation and projections on bone surface of trochlea sulcus to capitulum (CTS) axis, trochlea sulcus anterior offset and width of distal humeral epiphysis]. This method was evaluated by accuracy compared to CT-scan and reproducibility. RESULTS: Points-to-surface mean distance was 0.9 mm (2 RMS = 2.5 mm). For clinical parameters, mean differences were 0.4-1.9 mm and from 1.7° to 2.3°. All parameters except from angle formed by CTS axis and bi-epicondylar axis in transverse plane were reproducible. Reconstruction time was about 5 min. CONCLUSIONS: The presented method provides access to morphological upper limb parameters with very low level of radiation. Preliminary in vitro validation for humerus showed that it is fast and accurate enough to be used in clinical daily practice as an alternative to CT-scan for total elbow arthroplasty pre operative evaluation.

Fast 3D reconstruction of the lower limb using a parametric model and statistical inferences and clinical measurements calculation from biplanar X-rays.

In clinical routine, lower limb analysis relies on conventional X-ray (2D view) or computerised tomography (CT) Scan (lying position). However, these methods do not allow 3D analysis in standing position. The aim of this study is to propose a fast and accurate 3D-reconstruction-method based on parametric models and statistical inferences from biplanar X-rays with clinical measurements' (CM) assessment in standing position for a clinical routine use. For the reproducibility study, the 95% CI was under 2.7° for all lower limbs' angular measurements except for tibial torsion, femoral torsion and tibiofemoral rotation ( < 5°). The 95% CI were under 2.5 mm for lower limbs' lengths and 1.5 to 3° for the pelvis' CM. Comparisons between X-rays and CT-scan based 3D shapes in vitro showed mean differences of 1.0 mm (95% CI = 2.4 mm). Comparisons of 2D lower limbs' and 3D pelvis' CM between standing 'Shifted-Feet' and 'Non-Shifted-Feet' position showed means differences of 0.0 to 1.4°. Significant differences were found only for pelvic obliquity and rotation. The reconstruction time was about 5 min.

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.

[Debate: Pro intraoperative radiation therapy in breast cancer]. / Débat : pour la radiothérapie peropératoire dans le cancer du sein.

The use of intraoperative radiation therapy in breast cancer patients started about 20 years ago. Several retrospective and prospective studies have been published. Intraoperative radiation therapy was initially given as a boost to the tumour bed, followed by whole-breast irradiation. These studies have demonstrated the feasibility of the technique, with local control rates and cosmetic results similar to those obtained with standard treatments. Accelerated partial breast irradiation yields local recurrence rates as low as those observed after whole-breast irradiation. Intraoperative radiation therapy as a single irradiation modality with a unique dose has been investigated in recent prospective studies showing satisfactory local results. Intraoperative radiation therapy can be proposed either as a boost or as a unique treatment in selected cases (tumour size, nodal and hormonal status, patient's age). Intraoperative radiation therapy can be delivered by orthovoltage (50 kV) X-rays from mobile generators, or by electrons from linear accelerators, mobile or fixed, dedicated or not to intraoperative radiation therapy.

[Typical patient radiation doses in diagnostic imaging]. / Ordre de grandeur des doses délivrées en radiodiagnostic.

Radiologists should be able to appreciate the radiation dose delivered to patients for routine diagnostic procedures. The radiology report should include data necessary to calculate the patient dose in Gray. Using the effective dose, it is possible to compare with other source of radiation exposure. Simple formulas, taking into account different anatomical regions, derived from dose-area product (conventional radiography) or dose-length product (CT) are provided to calculate the effective dose in Sievert. For conventional (non-interventional) radiography, the effective dose for a given exam is inferior or equal to the yearly background radiation. For CT, the effective dose corresponds to 1 to 10 years of yearly background radiation.

[The framework of radiation protection in France]. / Organisation de la radioprotection en France.

Over the last 10 years, the framework of radiation protection in France has undergone significant modifications. This has mainly been the result of implementation of European directives, which are based on new data and evolving concepts at the international level. As a practical matter, public health laws and labor laws have evolved to strengthen the radiation protection to both patients and workers. For patients, the indication for the examination must be better justified and the exposure should be optimized and recorded. For workers, the maximum exposure limits have been reduced while monitoring and risk assessment have been reinforced. In addition, the equipment is subject to additional quality control evaluations while the facilities are assessed for safety.