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Purpose Helical Tomotherapy (HT) appears as a valuable technique for total body irradiation (TBI) to create highly homogeneous and conformal dose distributions with more precise repositioning than conventional TBI techniques. The aim of this work is to describe the technique implementation, including treatment preparation, planning and dosimetric monitoring of TBI delivered in our institution from October 2016 to March 2019. Material and method Prior to patient care, irradiation protocol was set up using physical phantoms. Gafchromic films were used to assess dose distribution homogeneity and evaluate imprecise patient positioning impact. Sixteen patients’ irradiations with a prescribed dose of 12 Gy were delivered in 6 fractions of 2 Gy over 3 days. Pre-treatment quality assurance (QA) was performed for the verification of dose distributions at selected positions. In addition, in-vivo dosimetry was carried out using optically stimulated luminescence dosimeters (OSLD). Results Planning evaluation, as well as results of pre-treatment verifications, are presented. In-vivo dosimetry showed the strong consistency of OSLD measured doses. OSLD mean relative dose differences between measurement and calculation were respectively +0,96% and −2% for armpit and hands locations, suggesting better reliability for armpit OSLD positioning. Repercussion of both longitudinal and transversal positioning inaccuracies on phantoms is depicted up to 2 cm shifts. Conclusion The full methodology to set up TBI protocol, as well as dosimetric evaluation and pre-treatment QA, were presented. Our investigations reveal strong correspondence between planned and delivered doses shedding light on the dose reliability of OSLD for HT based TBI in-vivo dosimetry.

Resume Propos L’amelioration des traitements des cancers de l’enfant a permis une augmentation de la survie a 80 % a 5 ans. La radiotherapie, parfois indispensable au traitement, est associee a des effets indesirables a long terme. L’objectif de cette etude etait d’analyser les complications a long terme de patients ayant eu un cancer dans l’enfance et traite par radiotherapie. Methodes L’etude SALTO, basee sur les registres de cancers de l’enfant en Rhone-Alpes-Auvergne, concernait les enfants traites pour un cancer solide ou un lymphome avant 15 ans, diagnostique entre 1987 et 1992, et majeurs au moment de l’etude. Une consultation par un oncopediatre et un interniste a ete proposee entre 2011 et 2014. Les enfants traites par radiotherapie ont ete compares aux patients traites sans irradiation. Les sequelles ont ete classees en moderees (grade 1–2) ou severes (grade 3–4) selon la CTCAE. Resultats Cinquante-neuf patients ayant recu de la radiotherapie ont participe a ces consultations et 91 sans radiotherapie. Cinquante-huit patients avec radiotherapie (98,3 %) ont presente au moins une complication. Les principaux effets secondaires a long terme tous grades confondus etaient orthopediques (37 %), endocriniens (32 %), thyroidiens (31 %) et l’obesite (31 %). Les principales complications de grade 3–4 etaient endocriniennes, renales, une obesite et les cancers secondaires. On retrouvait significativement plus de complications endocriniennes, thyroidiennes, orthopediques, cutanees, de surdite et de cancers secondaires chez les patients irradies compares aux patients non irradies. Conclusion Ces elements doivent etre integres dans le suivi a long terme des enfants ayant eu un cancer pour une meilleure prevention et/ou un traitement precoce de ces complications.

Resume Les metastases cerebrales sont les tumeurs les plus frequentes du systeme nerveux central. Le bilan IRM doit comporter des sequences ponderees en T1 sans et avec injection, en T2/FLAIR. Elles apparaissent le plus souvent comme des lesions multiples prenant le contraste de facon annulaire ou nodulaire et sont entourees d’œdeme. Elles sont hypervascularisees, ne presentent pas de restriction du coefficient de diffusion dans leur zone necrotique, contiennent des lipides en spectroscopie 1 H. L’absence d’infiltration peritumorale par des cellules malignes permet de differencier metastases et tumeurs primitives. La radiotherapie stereotaxique peut induire une augmentation du volume tumoral transitoire sans valeur pejorative d’un point de vue carcinologique. Plus rares, les atteintes medullaires peuvent etre asymptomatiques et sont a rechercher par IRM.

Resume Introduction En quelques annees, l’IRM a evolue d’une exploration morphologique vers une exploration metabolique et fonctionnelle. Etat des connaissances L’IRM est la pierre angulaire du bilan des tumeurs cerebrales. Elle a un role lors du bilan initial et permet souvent une bonne caracterisation tissulaire du processus lesionnel. Toutefois, elle ne suffit pas a differencier abces, gliome malin et metastase unique, a apprecier le grade histologique des gliomes, a definir les limites tumorales, a caracteriser les tumeurs meningees. Elle a un role lors du suivi pour controler le geste operatoire, apprecier la reponse au traitement, rechercher des signes de recidive. Neanmoins, l’interpretation ne repose que sur des donnees volumetriques qui peuvent etre prises en defaut. Perspectives La spectroscopie 1 H, la diffusion et la perfusion, techniques disponibles sur la plupart des appareils cliniques apportent des informations complementaires sur le metabolisme et la vascularisation des tumeurs. Elles permettent une meilleure caracterisation tissulaire et une meilleure comprehension des modifications post-therapeutiques. Actuellement, aux donnees morphologiques du bilan IRM d’une tumeur cerebrale doivent s’ajouter des informations metaboliques et fonctionnelles.

Cerebral metastases are the commonest central nervous system tumors. The MR assessment should include T1-weighted images with and without enhancement and T2/FLAIR images. They usually appear as multiple lesions with nodular or annular enhancement and are surrounded by edema. They are hypervascularized and have no restriction of their diffusion coefficient in their necrotic area and contain lipids on 1H spectroscopy. Metastases can be distinguished from primary tumors by the lack of malignant cell infiltration around the tumor. Stereotactic radiotherapy may temporarily increase tumor volume, although this is not of adverse oncological value. Less commonly, spinal disease may be asymptomatic and should be examined by MR.

Radiotherapy and chemotherapy may induce neurological toxicities with different appearances on CT and MRI scans. While optimized radiotherapy techniques have reduced some complications, new unwanted effects have occurred on account of therapeutic protocols involving the simultaneous use of radiotherapy and chemotherapy. Advances in radio-surgery, innovative anti-angiogenic therapies, as well as prolonged patient survival have led to the emergence of new deleterious side effects. In this report, we describe the early, semi-delayed, and late encephalic complications, while specifying how to identify the morphological lesions depending on the therapeutic protocol.

International audience; OBJECTIVE: The purpose of this study was to evaluate retrospectively whether cerebral blood volume measurement based on pretreatment perfusion MRI is a prognostic biomarker for survival in patients with oligodendroglioma or mixed oligoastrocytoma. PATIENTS AND METHODS: Between 1998 and 2004, 54 patients (23 females and 31 males), aged 21-73 years, with oligodendroglioma (or mixed tumour) were examined prior to beginning treatment with dynamic susceptibility-weighted contrast (DSC) perfusion MRI during gadolinium first-pass. The relative cerebral blood volume (rCBV) was calculated by dividing the measurement within the tumour by the measurement of the normal-appearing contralateral region. Patients were classified in two groups, grade A and grade B, according to the Saint-Anne Hospital classification and followed-up clinically and by means of MRI until their death or for a minimum of 5 years. Patients were also classified in grade II and grade III-IV, according to the World Health Organisation (WHO) classification, and were analysed with the same methods. Age, sex, treatment, tumour grade, contrast agent uptake, and rCBV were tested using survival curves with Kaplan-Meier's method, and their differences were analysed using the log-rank test. RESULTS: In this population, median survival was 3 years. A rCBV threshold value of 2.2 was validated as a prognostic factor, for survival in these patients with oligodendrogliomas. Age, sex, contrast uptake, and maximum rCBV were found to be prognostic factors in univariate analysis. Multivariate analysis revealed that tumour grade (grade A/grade B), rCBV, age, and sex were prognostic factors independent of the other factors. The tumour grade according to the WHO classification (II versus III-IV) was also detected as an independent prognostic factor. CONCLUSION: Pretreatment rCBV measured by DSC perfusion MRI was found to be a prognostic factor for survival in patients with oligodendroglioma or mixed tumour, by using the Saint-Anne Hospital classification, which separate the IIB from the IIA.

International audience; To characterize peritumoral BOLD contrast disorders, 25 patients referred for resection of primary frontal or parietal neoplasms (low-grade glioma (LGG) (n=8); high-grade glioma (HGG) (n=7); meningioma (n=10)) without macroscopic tumoral infiltration of the primary sensorimotor cortex (SM1) were examined preoperatively using BOLD fMRI during simple motor tasks. Overall cerebral BOLD signal was estimated using vasoreactivity to carbogen inhalation. Using bolus of gadolinium, cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transit time (MTT) were estimated. In a 1cm(3) region-of-interest centered on maximal T-value in SM1 contralateral to movements, interhemispheric asymmetry was evaluated using interhemispheric ratios for BOLD and perfusion parameters. During motor tasks contralateral to the tumor, ipsitumoral sensorimotor activations were decreased in HGG and meningiomas, correlated to the distance between the tumor and SM1. Whereas CBV was decreased in ipsitumoral SM1 for HGG, it remained normal in meningiomas. Changes in basal perfusion could not explain motor activation impairment in SM1. Decreased interhemispheric ratio of the BOLD response to carbogen was the best predictor to model the asymmetry of motor activation (R=0.51). Moreover, 94.9+/-4.9% of all motor activations overlapped significant BOLD response to carbogen inhalation.

International audience; PURPOSE: To present the imaging and perfusion data obtained in nine patients with pilocytic astrocytomas (PA) and to discuss the original functional issues of this technique. METHOD: Nine patients with pathologically proven PA underwent conventional and perfusion MR imaging. Various areas of relative cerebral blood volume (rCBV) within the tumors were obtained. The maximum rCBV ratios were identified and considered as representative of the tumor. The results were compared with the pathological findings. RESULTS: In all patients, rCBV was

In a few years, magnetic resonance imaging (MRI) has evolved from a morphology-based examination to one that encompasses metabolism and function.MRI is a well-established tool for the initial evaluation of brain tumors, but conventional MR sequences have some limitations. Conventional MRI is unable to distinguish high-grade glioma from metastasis and abscess, to define precisely the histopathological grade of gliomas, to determine exactly the limits of tumor extension, to characterize meningeal tumors. Differentiation of tumor recurrence from treatment-related changes may be difficult with standard MR imaging because the interpretation is essentially based on volume analysis.1H Spectroscopy, diffusion and perfusion imaging become possible with the development of MR imagers and can be routinely performed in clinical settings. They give complementary information about tumor metabolism and vascularity and allow a better analysis of post-treatment modifications. Functional and metabolic explorations should be used to characterize brain tumors.