CHRU Morvan

Baguer-Morvan, France

CHRU Morvan

Baguer-Morvan, France
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Benhalouche S.,Brest University Hospital Center | Bert J.,Brest University Hospital Center | Visvikis D.,Brest University Hospital Center | Pradier O.,CHRU Morvan | Nicolas B.,Brest University Hospital Center
Medical Physics | Year: 2013

Purpose: In radiotherapy treatment, it is necessary to position the patient before each session to ensure that the beams target the tumor while sparing the surrounding healthy tissue. This step is made possible via different imaging techniques like the “electronic portal imaging device” (EPID) which is the most common approach. In this configuration, the imaging source is the same as the treatment source, while a flat panel detector is automatically placed under the patient via an articulated arm. In this context, our study was focused on the Monte Carlo modeling of such an EPID in order to simulate both planar and 3D CBCT images. Methods: The work presented here follows a preliminary study in which the treatment part of a clinical LINAC (Siemens Oncor) was modeled in GATE v6.2. The objective was to calculate the dose delivered by complex treatments like IMRT. The objective of the study is to extend this model by incorporating the imaging part of the LINAC, which consists of a flat panel detector (Perkin Elmer XRD1640). For this purpose, geometrical and physical data provided by the manufacturer were first accurately modeled in GATE. As a second step, 2D and 3D images simulations were performed according to clinical protocols: projections over a 200° arc, 1° increments, and 41cm square field of view. IMRT QA and, RANDO anthropomorphic phantom and head‐and‐neck patient CT were used as input objects for simulations. Results: From the obtained series of 2D projections a 3D reconstruction was performed in each case, and the dimensions of the reconstructed structures were compared with actual objects. Conclusion: We have developed within the GATE platform a complete and detailed model of a 160MLC LINAC with its MVCBCT flat panel. Future work will consist in simulating epid‐based transit dosimetry. © 2013, American Association of Physicists in Medicine. All rights reserved.


Benhalouche S.,CHRU Morvan | Bert J.,CHRU Morvan | Visvikis D.,CHRU Morvan | Pradier O.,CHRU Morvan | Nicolas B.,CHRU Morvan
Medical Physics | Year: 2013

Purpose: In radiotherapy treatment, it is necessary to position the patient before each session to ensure that the beams target the tumor while sparing the surrounding healthy tissue. This step is made possible via different imaging techniques like the “electronic portal imaging device” (EPID) which is the most common approach. In this configuration, the imaging source is the same as the treatment source, while a flat panel detector is automatically placed under the patient via an articulated arm. In this context, our study was focused on the Monte Carlo modeling of such an EPID in order to simulate both planar and 3D CBCT images. Methods: The work presented here follows a preliminary study in which the treatment part of a clinical linear accelerator LINAC (Siemens Oncor Impression) was modeled in GATE v6.2. The objective was to calculate the dose delivered by complex treatments like IMRT. The objective of the present study is to extend this model by incorporating the imaging part of the LINAC, which consists of a flat panel detector (Perkin Elmer XRD1640). For this purpose, geometrical and physical data provided by the manufacturer were first accurately modeled in GATE. As a second step, 2D and 3D images simulations were performed according to clinical protocols: projections over a 200° arc, 1° increments, and 41cm square field of view. IMRT QA and, RANDO anthropomorphic phantom and head‐and‐neck patient CT were used as input objects for simulations. Results: From the obtained series of 2D projections a 3D reconstruction was performed in each case, and the dimensions of the reconstructed structures were compared with actual objects. Conclusion: We have developed within the GATE platform a complete and detailed model of a 160 MLC LINAC with its MVCBCT flat panel. Future work will consist in simulating epid‐based transit dosimetry. © 2013, American Association of Physicists in Medicine. All rights reserved.


Nouel A.,Brest University Medical School Hospital | Segalen I.,Brest University Medical School Hospital | Jamin C.,Brest University Medical School Hospital | Jamin C.,Laboratory of Immunology | And 8 more authors.
Kidney International | Year: 2014

In kidney transplantation, the composition of the B-cell compartment is increasingly identified as an important determinant for graft outcome. Whereas naive and transitional B cells have been associated with long-term allograft survival and operational tolerance, memory B cells have been linked to graft rejection and graft loss. Chronic antibody-mediated rejection now represents a major complication in transplantation and is a challenge in current therapeutics. Here, we show that patients with chronic antibody-mediated rejection display a unique B-cell phenotype with a reduced ratio of activated to memory B cells associated with an impaired immunosuppressive activity. The regulatory functions of the B cells depended on their maturation status. Thus, phenotypic and functional analyses of the B-cell compartment may be indicated for appropriate follow-up after transplantation and drive therapy in the establishment of transplant tolerance processes. © 2013 International Society of Nephrology.


PubMed | iGo, CHRU Morvan and CHRU Strasbourg
Type: Journal Article | Journal: Kidney international | Year: 2014

In kidney transplantation, the composition of the B-cell compartment is increasingly identified as an important determinant for graft outcome. Whereas naive and transitional B cells have been associated with long-term allograft survival and operational tolerance, memory B cells have been linked to graft rejection and graft loss. Chronic antibody-mediated rejection now represents a major complication in transplantation and is a challenge in current therapeutics. Here, we show that patients with chronic antibody-mediated rejection display a unique B-cell phenotype with a reduced ratio of activated to memory B cells associated with an impaired immunosuppressive activity. The regulatory functions of the B cells depended on their maturation status. Thus, phenotypic and functional analyses of the B-cell compartment may be indicated for appropriate follow-up after transplantation and drive therapy in the establishment of transplant tolerance processes.


Cornec D.,Brest University Hospital Center | Cornec D.,University of Western Brittany | Saraux A.,Brest University Hospital Center | Saraux A.,University of Western Brittany | And 4 more authors.
Immunotherapy | Year: 2013

Primary Sjögren's syndrome is a systemic autoimmune disease characterized by progressive exocrine gland destruction, resulting clinically in eyes and mouth dryness. To date, no treatment has been proven effective to modify the course of this slow-evolving disease. B cells are now considered to play a central role in the pathogenesis of primary Sjögren's syndrome because their functions are not restrained to antibody production. Thus, several B-cell targeting therapies are under clinical investigation. Rituximab, a monoclonal antibody directed to CD20 and leading to transient blood B-cell depletion, has shown partial improvements in subjective and objective sicca symptoms in small studies. However, the results of two large controlled trials are awaited before considering its use in large populations of patients. Several other therapeutic strategies are being studied, targeting other B-cell surface proteins (epratuzumab and anti-CD22) or major cytokines of B-cell homeostasis (e.g., BAFF, IL-6 and lymphotoxin-β). Although great hope is generated by the trials of these specific therapies, another challenge for clinical researchers is the development of reliable tools to assess the activity of Sjögren's syndrome and its response to treatment. © 2013 Future Medicine Ltd.


PubMed | CHRU Morvan and French Institute of Health and Medical Research
Type: Journal Article | Journal: Medical physics | Year: 2016

The objective of this work is to test the advantage of using the surface acquired by two stereo Time-of-Flight (ToF) cameras in comparison of the use of one camera only for patient positioning in radiotherapy.A first step consisted on validating the use of a stereo ToFcamera system for positioning management of a phantom mounted on a linear actuator producing very accurate and repeatable displacements. The displacements between two positions were computed from the surface point cloud acquired by either one or two cameras thanks to an iterative closest point algorithm. A second step consisted on determining the displacements on patient datasets, with two cameras fixed on the ceiling of the radiotherapy room. Measurements were done first on voluntary subject with fixed translations, then on patients during the normal clinical radiotherapy routine.The phantom tests showed a major improvement in lateral and depth axis for motions above 10 mm when using the stereo-system instead of a unique camera (Fig1). Patient measurements validate these results with a mean real and measured displacement differences in the depth direction of 1.5 mm when using one camera and 0.9 mm when using two cameras (Fig2). In the lateral direction, a mean difference of 1 mm was obtained by the stereo-system instead of 3.2 mm. Along the longitudinal axis mean differences of 5.4 and 3.4 mm with one and two cameras respectively were noticed but these measurements were still inaccurate and globally underestimated in this direction as in the literature. Similar results were also found for patient subjects with a mean difference reduction of 35%, 7%, and 25% for the lateral, depth, and longitudinal displacement with the stereo-system.The addition of a second ToF-camera to determine patient displacement strongly improved patient repositioning results and therefore insures better radiation delivery.


PubMed | CHRU Morvan and French Institute of Health and Medical Research
Type: Journal Article | Journal: Medical physics | Year: 2016

The objective of this study was to evaluate the necessity to account for the organs at risk (OARs) respiratory induced motion in addition to the tumor displacement when planning a radiotherapy treatment that accounts for tumor motion.For 18 lung cancer patients, conformational radiotherapy treatment plans were generated using 3 different CT volumes: the two extreme respiratory phases corresponding to either the full inspiration (plan 1) or expiration (plan 3), as well as a manually deformed phase consisting in full inspiration combined with the full expiration tumor location (plan 2) simulating a tumor tracking plan without addressing OARs motion. Treatment plans were initially created on plan 1 and then transferred to plan 2 and 3 which represent respectively the tumor displacement only and the whole anatomic variations due to breathing. The dose coverage and the dose delivered to the OARs were compared using conformational indexes and generalized equivalent uniform dose.The worst conformational indexes were obtained for plans with all anatomic deformations (Table 1) with an underestimation of the 95% isodose spreading on healthy tissue compared to plans considering the tumor displacement only. Furthermore, mean doses to the OARs when accounting for all the anatomic changes were always higher than those associated with the tumor displacement only: the mean difference between these two plans was 11.37 Gy (maximum of 3.8 Gy) for the heart and 1.41.42 Gy (maximum of 4.1 Gy) for the lung in which the tumor was located (Figure 1).OARs deformations due to breathing motion should be included in the treatment planning in order to avoid unnecessary OARs dose and/or allow for a tumor dose escalation. This is even more important for treatments like stereotactic radiation therapy which necessitates a high precision ballistic and dose control.


PubMed | CHRU Morvan and French Institute of Health and Medical Research
Type: Journal Article | Journal: Medical physics | Year: 2016

To evaluate the feasibility of delivering a gated Intensity Modulated Radiotherapy (IMRT) treatment using multiple respiratory phases in order to account for all anatomic changes during free breathing and accelerate the gated treatment without increasing the dose per fraction.For 7 patients with lung cancer, IMRT treatment plans were generated on a full inspiration (FI) Computed Tomography (CT) and a Mid Intensity Position (MIP) CT. Moreover, in order to achieve an accelerated gated IMRT, multiple respiratory phase plans were calculated: 2-phase plans including the FI and the full expiration phases, and 3-phase plans by adding the mid-inspiration phase. In order to assess the tolerance limits, plans doses were registered and summed to the FI-based plan. Mean dose received by Organs at Risk (OARs) and target volumes were used to compare obtained plans.The mean dose differences between the FI plans and the multi-phase plans never exceeded 0.4 Gy (Fig. 1). Concerning the clinical target volume these differences were even smaller: less than 0.1 Gy for both the 2-phase and 3-phase plans. Regarding the MIP treatment plan, higher doses in different healthy structures were observed, with a relative mean increase of 0.4 to 1.5 Gy. Finally, compared to the prescribed dose, the FI as well as the multi-phase plans were associated with a mean difference of 0.4 Gy, whereas in the case of MIP a higher mean difference of 0.6 Gy was observed.The doses obtained while planning a multi-phase gated IMRT treatment were within the tolerance limits. Compared to MIP, a better healthy tissue sparing was observed in the case of treatment planning based on one or multiple phases. Future work will consist in testing the multi-phase treatment delivery while accounting for the multileaf collimator speed constraints.


PubMed | Varian Medical Systems, CHRU Morvan, French Institute of Health and Medical Research and Instituto Clinico Humanitas
Type: Journal Article | Journal: Medical physics | Year: 2016

To evaluate the patient positioning accuracy in radiotherapy using a stereo-time of flight (ToF)-camera system.A system using two ToF cameras was used to scan the surface of the patients in order to position them daily on the treatment couch. The obtained point clouds were registered to (a) detect translations applied to the table (intrafraction motion) and (b) predict the displacement to be applied in order to place the patient in its reference position (interfraction motion). The measures provided by this system were compared to the effectively applied translations. The authors analyzed 150 fractions including lung, pelvis/prostate, and head and neck cancer patients.The authors obtained small absolute errors for displacement detection: 0.8 0.7, 0.8 0.7, and 0.7 0.6 mm along the vertical, longitudinal, and lateral axes, respectively, and 0.8 0.7 mm for the total norm displacement. Lung cancer patients presented the largest errors with a respective mean of 1.1 0.9, 0.9 0.9, and 0.8 0.7 mm.The proposed stereo-ToF system allows for sufficient accuracy and faster patient repositioning in radiotherapy. Its capability to track the complete patient surface in real time could allow, in the future, not only for an accurate positioning but also a real time tracking of any patient intrafraction motion (translation, involuntary, and breathing).


PubMed | CHRU Cavale Blanche and CHRU Morvan
Type: Case Reports | Journal: Revue neurologique | Year: 2015

We report a case of inflammatory cerebral amyloid angiopathy (CAA) that led to rapid cognitive decline, seizures, visual hallucinations, hyperproteinorrachia and right hemispheric leukopathy. Brain biopsy gave the diagnosis of CAA. Although no inflammatory infiltrate was found in the biopsy sample, corticosteroids led to a regression of the radiological lesions without significant clinical improvement. CAA is a rare disease, defined by lesions of classical cerebral amyloid angiopathy and perivascular infiltrates in contact with the affected vessels. In cases of rapidly progressive dementia associated with leukopathy, inflammatory amyloid angiopathy should be considered as cognitive disorders may improve after immunosuppressive therapy.

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