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Aim To evaluate the different techniques used for liver metastases Stereotactic Body Radiation Therapy (SBRT) planning. We especially focused on immobilization devices, motion management and imaging used for contouring. Background Although some guidelines exist, there is no consensus regarding the minimal requirements for liver SBRT treatments. Materials and methods We reviewed the main liver metastases SBRT publications and guidelines; and compared the techniques used for immobilization, motion management, margins and imaging. Results There is a wide variety of techniques used for immobilization, motion management and planning imaging. Conclusions We provide a subjective critical analysis of minimal requirements and ideal technique for liver SBRT planning.

International audience; The aim was to analyze arc therapy techniques according to the number and position of the brain lesions reported by comparing dynamic noncoplanar conformal arcs (DCA), two coplanar full arcs (RAC) with volumetric-modulated arc therapy (VMAT), multiple noncoplanar partial arcs with VMAT (RANC), and two full arcs with VMAT and 10° table rotation (RAT). Patients with a single lesion (n= 10), multiple lesions (n = 10) or a single lesion close to organs at risk (n = 5) and previously treated with DCA were selected. For each patient, the DCA treatment was replanned with all VMAT techniques. All DCA plans were compared with VMAT plans and evaluated in regard to the different quality indices and dosimetric parameters. For single lesion, homogeneity index (HI) better results were found for the RANC technique (0.17 ± 0.05) compared with DCA procedure (0.27± 0.05). Concerning conformity index (CI), the RAT technique gave higher and better values (0.85 ± 0.04) compared with those obtained with the DCA technique (0.77 ± 0.05). DCA improved healthy brain protection (8.35 ± 5.61 cc vs. 10.52 ± 6.40 cc for RANC) and reduced monitor unit numbers (3046 ± 374 MU vs. 4651 ± 736 for RANC), even if global room occupation was higher. For multiple lesions, VMAT techniques provided better HI (0.16) than DCA (0.24 ± 0.07). The CI was improved with RAT (0.8 ± 0.08 for RAT vs. 0.71 ± 0.08 for DCA). The V10Gy healthy brain was better protected with DCA (9.27 ± 4.57 cc). Regarding the MU numbers: RANC < RAT< RAC < DCA. For a single lesion close to OAR, RAT achieved high degrees of homogeneity (0.27 ± 0.03 vs. 0.53 ± 0.2 for DCA) and conformity (0.72± 0.06vs. 0.56 ± 0.13 for DCA) while sparing organs at risk (Dmax = 12.36 ± 1.05Gyvs. 14.12 ± 0.59 Gy for DCA, and Dmean = 3.96 ± 3.57Gyvs. 4.72 ± 3.28Gy for DCA). On the other hand, MU numbers were lower with DCA (2254 ± 190 MUvs. 3438 ± 457 MU for RANC) even if overall time was inferior with RAC. For a single lesion, DCA provide better plan considering low doses to healthy brain even if quality indexes are better for the others techniques. For multiple lesions, RANC seems to be the best compromise, due to the ability to deliver a good conformity and homogeneity plan while sparing healthy brain tissue. For a single lesion close to organs at risk, RAT is the most appropriate technique.

Introduction Intravenous contrast agent injection during the patient CT simulation facilitates radiotherapy contouring in the case of head and neck cancers. However, the image contrast enhancement may introduce discrepancy between the planned and delivered dose. The aim of this retrospective study is to quantify the variations of Hounsfield unites (HU) and to investigate their effect on Volumetric Modulated Arc Therapy (VMAT) dose distributions. Material and methods Ten patients previously treated by VMAT techniques with identical dose levels (70/60/50 Gy) were selected. For each patient, two CT scans were performed, 2 min. (CT inj ) and 12 min. (CT delay ) after Iomeron® 350 biphasic intravenous injection (60 mL, 1 mL/s followed by 90 mL, 2 mL/s after 30 s). The treatment planning (optimization and calculation) was performed with CT inj using the Eclipse TPS and Acuros XB® algorithm. Two other treatment plans were recalculated with the same parameters and CT delay . The mean HU and the iodine distribution were compared between the two scan images in the PTV50, the parotids and the thyroid. A dosimetric comparison using dose-volume histograms in target volumes and OAR (thyroid, parotids) was performed. The maximum (D 2% ), minimum (D 98% ) and median (D 50% ) doses were registered. Results The maximum HU average difference over all the patients was observed in the thyroid (81.37 ± 36.01 HU) followed by the PTV50 (10.76 pm 15.70 HU) and the parotids (9.39 ± 16.01 HU). The differences observed with Acuros® algorithm were below 0.2% for D 2% , D 98% et D 50% in target volumes and 0.31% in OAR. Conclusion This study shows that the use of intravenous contrast during CT simulation does not significantly affect dose calculation in head and neck VMAT plans using Acuros® algorithm.

Objectif Comparer les parametres dosimetriques de trois methodes de radiotherapie stereotaxique pulmonaire par accelerateur lineaire : tracking (1), gating (2) et respiration libre (3). Patients et methodes Une etude retrospective a ete menee chez dix patients. Le volume tumoral macroscopique, le volume cible previsionnel (volume tumoral macroscopique + 3 mm) et le poumon homolateral sain ont ete definis sur chaque phase du cycle respiratoire sur une scanographie quadridimensionnelle. La dose prescrite etait de 60 Gy en quatre seances. Pour le tracking (1), dix plans de traitement, correspondant aux dix phases, ont ete crees a partir de neuf champs statiques puis additionnes. Tous les plans ont ete normalises tels que 99 % de la dose couvre 99 % du volume cible previsionnel pulmonaire homolateral et ont respecte les contraintes de l’etude ROSEL. Le gating (2) a ete analyse lors de trois phases expiratoires (40, 50 et 60 %). Pour la respiration libre (3), un volume cible interne (somme des volumes tumoraux macroscopiques) et un volume cible previsionnel (volume cible interne + 3 mm) ont ete generes. Le volume cible previsionnel a ete reporte sur chaque scanographie et la distribution de dose a ete calculee. La normalisation et les contraintes de doses sont identiques a celles utilisees pour le tracking. Enfin, les dix plans ont ete additionnes. Les trois modalites ont ete evaluees a partir des histogrammes dose-volume des volumes tumoraux macroscopiques, de l’indice d’homogeneite ( 1 H = dose maximale − dose minimale dose moyenne ) et des doses recues par le poumon sain (dose moyenne et volume recevant 20 Gy : V20 Gy). Resultats En depit de dose maximale et d’indices d’homogeneite similaires (dose maximale : tracking 80,44 Gy ; gating 80,47 Gy ; respiration libre 81,29 Gy ; IH : tracking et gating 0,17 ; respiration libre 0,15), l’irradiation en respiration libre ameliorait la couverture du volume tumoral macroscopique en augmentant les dose minimales et moyennes (dose minimale : tracking 67,5 Gy ; gating 67,35 Gy ; respiration libre 69,95 Gy ; dose moyenne : tracking 75,87 Gy ; gating 75,91 Gy ; respiration libre 77,49 Gy). En revanche, le poumon sain etait mieux protege avec le tracking (V20 Gy : tracking 3,69 % ; gating 3,89 % ; respiration libre 6,17 % et dose moyenne : tracking 3,41 Gy ; gating 3,63 Gy ; respiration libre 4,9 Gy), meme si les contraintes de doses ont ete respectees dans tous les cas (V20 Gy de moins de 10 %). Conclusion Une irradiation en respiration libre delivre plus de dose au volume tumoral macroscopique tandis que le tracking et gating epargnent d’avantage le poumon sain mais complexifient aussi le traitement.

Resume La conductivite de solutions aqueuses de chlorure de plomb PbCl 2 a ete mesuree a 25°C entre 0,5 × 10 −3 et 36 × 10 −3 mol dm −3 . Les donnees sont interpretees en prenant en compte la presence des especes Pb 2+ , Cl − , PbCl + , PbCl 2 . On obtient les conductivities equivalentes limite des ions Pb 2+ et PbCl + : Les constantes thermodynamiques de formation de PbCl + et PbCl 2 , dans l'echelle des molarites sont

Objectifs L’irradiation de la sphere ORL avec une technique d’arctherapie volumetrique genere plusieurs questions des lors que le calcul dosimetrique est realise sur une scanographie de simulation apres injection. Ainsi, il n’est pas possible de choisir des portes d’entrees de faisceaux evitant le rehaussement de contraste du a l’injection. L’objectif de ce travail etait d’analyser cet impact et de determiner s’il est necessaire de realiser deux acquisitions de preparation, l’une apres injection pour la definition des volumes, et une autre pour le calcul dosimetrique. Patients et methodes L’etude a porte sur les dossiers de neuf patients traites, pris en charge pour des cancers de la sphere ORL avec la technique d’arctherapie volumetrique (Varian Medical Systems). Deux acquisitions scanographiques ont ete realisees, une avec et une sans injection. L’optimisation et le calcul de dose ont ete realises sur la scanographie apres injection, au moyen du systeme de planification des traitements TPS Eclipse ® (VMS) et des algorithmes AAA et PRO (v.10). Le meme plan de traitement a ete recalcule dans un second temps sur la scanographie sans injection. Les differences entre les histogrammes doses–volumes obtenus des doses moyennes, des doses maximales et minimales ainsi que les volumes recevant 20, 30 et 45 Gy pour les organes a risque ont ete relevees et comparees. Resultats L’etude montre que la dose moyenne delivree dans le volume cible previsionnel de haute dose etait en moyenne superieure de 0,028 ± 0,038 %, la dose minimale superieure de 0,975 ± 2,06 % et la dose maximale de 0,389 ± 0,562 %. Des resultats similaires ont ete retrouves pour les volumes cibles previsionnels de dose intermediaire et de basse dose. Les ecarts sur les organes a risque etaient legerement plus importants mais inferieurs a 1,5 %. Conclusion L’effet du produit de contraste sur des traitements des cancers de la sphere ORL avec une technique d’arctherapie volumetrique s’est traduit par des ecarts inferieurs a 1 % sur les volumes cibles previsionnels et inferieurs a 1,5 % sur les organes a risque. Ces resultats ne permettent pas la remise en cause du protocole de dosimetrie sur scanographie apres injection.

Objectifs Le controle du mouvement est un defi majeur en radiotherapie stereotaxique abdominale. Nous presentons notre etude de radiotherapie stereotaxique pour des tumeurs primaires et des metastases hepatiques utilisant le systeme « intrafraction motion review » (IMR), qui permet d’obtenir des informations simultanees par imagerie de basse (kV) et de haute (MV) energies afin de synchroniser le faisceau pendant la seance d’arctherapie volumetrique modulee. Patients et methodes Entre mai 2012 et mars 2015, 42 patients consecutifs ont recu une irradiation stereotaxique hepatique avec intention curative. Tous les patients ont beneficie d’une technique d’arctherapie volumetrique modulee asservie a la respiration avec un accelerateur lineaire Varian Novalis Truebeam STx®. Ce systeme adapte en temps reel la zone de traitement au cycle respiratoire du patient, le jour de la seance et pendant le traitement. Les huit derniers patients ont beneficie du declenchement automatique du faisceau synchronise a l’imagerie pendant les fractions (« auto beam hold », ABH). Une marge de 5 mm autour du volume cible interne a ete utilisee pour creer le volume cible previsionnel, qui etait en moyenne de 117,81 cm3. La dose prescrite etait de 40 a 50 Gy en cinq a dix fractions. La dose prescrite et le nombre de fractions ont ete choisis en fonction du volume de foie irradie, de la fonction hepatique et des resultats d’histogrammes dose–volume. La toxicite a ete analysee chez tous les patients, le controle local chez 34 apres un suivi minimal de quatre mois. Resultats Avec un suivi median de 13 mois, le traitement a ete bien tolere et aucun patient n’a souffert d’hepatopathie radio-induite, ni de perforation ou hemorragie digestive. Pour ce qui concerne la toxicite aigue, trois patients ont souffert de douleurs abdominales de grade 1, un de nausees de grade 1, huit d’une asthenie de grade 1 et un d’une asthenie de grade 2. Aucun patient n’a souffert de complication biliaire secondaire a la radiotherapie. Le taux controle local « dans le champ d’irradiation » etait de 90 %, avec huit reponses completes (23,5 %), 14 reponses partielles (41 %) et huit stabilisations (20 %), deux tumeurs ont evolue « dans le champ », quatre « hors champ ». Conclusion La tolerance clinique et les resultats oncologiques semblent favorables pour l’irradiation stereotaxique hepatique asservie a la respiration et guidee par l’image avec adaptation en temps reel.

Objectifs Analyser l’information issue de trois methodes d’acquisition d’images pour des tissus situes entre deux protheses metalliques. Patients et methodes Six patients possedant des protheses de hanche bilaterales ont ete selectionnes pour cette etude. Pour chaque patient, trois series d’images ont ete comparees. Les deux premieres ont ete realisees sur un scanographe GE Optima CT580, l’une en utilisant l’algorithme de reduction des artefacts metalliques (MAR), l’autre sans. La troisieme serie a ete realisee par tomographie conique lors de la premiere seance de traitement (CBCT). Pour chaque serie, une meme region d’interet rectangulaire a ete tracee sur une coupe frontale, dans les tissus mous situes entre les deux protheses. Le nombre Hounsfield moyen (HUm) et l’ecart-type (σ), correspondant au bruit dans l’image, ont ete releves. Selon la meme methodologie, les images de 12 patients sans protheses ont ete etudiees afin d’avoir une reference du nombre Hounsfield moyen (HUref) dans cette region anatomique et de la comparer aux valeurs obtenues pour les series d’images des patients avec protheses. Resultats Pour la cohorte de patients sans prothese, la reference du nombre Hounsfield moyen etait de 11,2 ± 43,5 HU. Pour la cohorte avec protheses bilaterales, l’algorithme de reduction des artefacts metalliques donnait la valeur de nombre Hounsfield moyen la plus proche de la reference du nombre Hounsfield moyen (HUm (MAR) = –37,1 HU ; HUm (CBCT) = –262,6 HU ; HUm (no MAR) = –409,5 HU). Il permettait egalement de reduire le bruit par comparaison aux images sans reconstruction avec l’algorithme de reduction des artefacts metalliques et a la tomographie conique (σ (MAR) = 104,9 HU ; σ (CBCT) = 153,2 HU ; σ (no MAR) = 211 HU) Conclusion La qualite de reconstruction des tissus entre deux protheses metalliques est amelioree avec l’algorithme de reduction des artefacts metalliques en reduisant les artefacts, le bruit et en augmentant la precision des nombre de Hounsfield.

Introduction In order to select the best one according to the number and the position of the lesions we compare in this study dynamic conformal arc (DCA), coplanar VMAT (RAC), noncoplanar VMAT (RANC) and entire arc VMAT with table rotations of 10° and 350° (RAT). Material and methods 5 single lesions (case 1), 5 multiple lesions (case 2) and 5 single lesions close to organs at risk (case 3) were analyzed. Each technique was evaluated in regard to conformity and homogeneity indexes for PTV (CI = [[(PTV covered by prescription isodose)tˆ2/(V*PTV*V_(prescription isodose)) and HI=(D_max- D_min)/D_mean), the healthy brain tissue dose (V10Gy), Dmax (OAR) and the number of monitor units (MU). Results For case 1, HI and CI are better for RANC (HI: 0.17 RANC – 0.22 RAT – 0.23 RAC _0.27 DCA and CI: 0.86 RAT – 0.85 RANC _0.83 RAC – 0.76 DCA) but DCA reduces brain tissue V10Gy (11.97 cc DCA – 14.51 cc RANC – 15.9 cc RAT – 18.34 cc RAC) and MU (3092 DCA – 4573 RAC – 4639 RANC – 5250 RAT). In case 2, HI is similar for VMAT (0.17 RANC and RAT – 0.18 RAC – 0.22 DCA) and CI is top with RAT (0.72 RAT – 0.68 RAC – 0.67 RANC – 0.65 DCA). The healthy brain is as well protected with DCA as with RANC (10.5 DCA and RANC – 15.08 RAT – 18.12 RAC) but MU decrease with RANC (4250 RANC – 4802 RAT – 4841 RAC – 7908 DCA). For case 3, RAT improves HI and CI (HI: 0.27 RAT – 0.3 RANC – 0.31 RAC – 0.57DCA and CI: 0.74 RAT – 0.65 RAC – 0.59 RANC _0.5 DCA) and spares brain tissue and OAR (V10Gy: 1.31 RAT – 1.56 RAC – 2 RANC – 2.31 DCA and Dmax (OAR): 12.17 RAT – 12.59 RAC – 12.77 RANC – 14.15 Gy DCA). The MU numbers decrease with DCA (2184 DCA – 3533 RANC – 3714 RAT – 3840 RAC). Conclusion For simple case 1, DCA provide better plan considering low doses to healthy brain. For case 2, RANC is the best compromise ‘‘PTV cover- brain protection”. For case 3, results are significantly better with RAT.

Introduction Two Lung Stereotactic techniques with tumor control position during irradiation are compared. Material and methods The Rapidarc technology allows to homogenize the dose in the PTV while reducing the dose delivered in the OAR. For Lung stereotactic treatment, it creates a decrease of the average dose in the ITV not in compliance with the recommendations and the practices based on an important heterogeneity of dose in the target volume. Besides, the leafs movement does not allow any more the ‘‘on-line” follow-up by the portal imager made during the previous treatments realized by means of static fields. An kV intrafraction imaging technique (IMR) available on Truebeam allows to deliver these treatments while following in a continuous way the tumor position in every respiratory cycle. We analyse the dosimetrics results obtained whith an approach who consist of modulate the homogeneity of dose in the PTV so that the prescription is similar to the previous treatments realized by means of static fields. Results The concerned populations are similar with average volumes (±standard deviation) of PTV of ±9 (15) cc in Rapidarc (20 patients) and 17 (11) cc in static fields (35 patients). The dose heterogeneity imposed inside the PTV generates an increase of 5 % of the conformity index (Viso100 %/VPTV100 %) who remains however slightly better in RA, 1.15 (±0.1) vs 1.17 (±0.1). The average dose in the ITV, 117 (±3)% and in the PTV, 113 (±3)% are identical. The maximal doses in organs at risks are globally reduced by 20% with the possibility to reach more than 40% on the most critical volume. Conclusion A prescription on the average dose in the ITV associated with a coverage of the PTV by an isodose superior to 99% allows in Rapidarc to manage the heterogeneity of dose wished in the target volumes. The intra fraction follow-up by imaging kV without implanted markers allows to control the target position during the duration of the session.

Purpose In this paper, we used the Intrafration Motion Review technique (IMR, Varian medical system), which allows simultaneous kV/MV utilization to analyse the liver motion during gated RapidArc stereotactic treatment. Materials and methods Eight liver cancer patients with implanted fiducial markers were treated using the gated RapidArc technique with a Varian Novalis Truebeam linear accelerator. Four 4D computed tomography (CT) scans were acquired using Real time Position Management (RPM) system to study the reproducibility of liver motion. The cine 4D CT images were separated into 10 phases CT series based on respiratory motion information. A Maximum Intensity Projection (MIP) and an Average Intensity Projection (Ave-IP) CT series were generated. The Internal Target Volume (ITV) was outlined in the MIP CT series. The Planning Target Volume (PTV) was created by adding a 5 mm margin from the ITV. The fiducials were marked in the exhalation and/or in the inhalation phase making possible the intrafraction verification. The treatment planning is realized in the Ave-IP CT series. The patient's alignment is set based on markers using daily cone beam CT (CBCT). During the treatment, kV images were acquired at each exhalation or inhalation phase when the respiratory signal cross the upper and lower gating threshold defined during the respiratory learning process. The positions of the fiducials markers were compared with their expected positions. Results The average (±SD) conformity index CIPTV = (VPTV95% (cc)/ VPTV (cc)) * (VPTV95% (cc)/ Viso95% (cc)) was 0.93 ± 0.02 and homogeneity index HIPTV = (D2% - D98%)/Dmedian was 0.09 ± 0.02. The average MU/Gy was 147 ± 25. The room occupation's time was 53, 30, 20, 24, 24 min respectively for the five first fractions. The average kV images acquired per fraction were 35 with a maximum of 74 images and a minimum of 12 images. The average gating errors of the fiducials in the Superior–Inferior (SI) direction during the intrafraction was 0,91 mm with a maximum of 6 mm. Conclusion For tumor motion, monitoring intra-fraction by IMR ensures with certainty the PTV irradiation estimates with a systematic checking of the position of the target volume (fiducials) when this one come inside the region of treatment.

Objectif Nous presentons ici les premiers resultats de toxicite associes a une technique d’arctherapie volumetrique modulee (VMAT) dans le cas du cancer du sein bilateral. Patientes et methode Les dossiers d’une serie continue de 20 patientes atteintes d’un cancer du sein bilateral, allant du stade I a IV et necessitant une radiotherapie locoregionale ont ete analyses. Les doses prescrites etaient de 63,2 Gy en 29 fractions dans le volume cible previsionnel du boost , 52,2 Gy en 29 fractions dans celui du sein et la chaine mammaire interne et 49,3 Gy en 29 fractions dans celle sus-claviculaire. Les objectifs a atteindre etaient d’un volume recevant 95 % de la dose prescrite (V95 %) d’au moins 99 % pour le volume cible anatomoclinique du sein (representant la glande et respectant 0,5 cm de revetement cutane) et d’un V95 % de plus de 95 % pour les autres volume cibles, d’une dose moyenne pulmonaire de moins de 15 Gy, d’un volume recevant 20 Gy (V20) pulmonaire de moins de 22 % et d’une dose moyenne cardiaque de moins de 12 Gy. Pour la gradation des reactions secondaires, l’echelle CTCAE v. 3 (Common Terminology Criteria for Adverse Events Version 3) a ete utilisee. Resultats Aucune patiente n’a souffert de reaction de grade 3 ou plus, dix sur 20 d’une toxicite cutanee aigue de grade 1 ou 2 et une seule d’une œsophagite de grade 2. Le V95 % anatomoclinique du sein obtenu etait a 98,92 ± 0,94 a droite et 98,92 % ± 1,09 a gauche. En ce qui concerne les poumons, le V20 droit etait de 18,6 % ± 4,92 et le gauche de 17,05 % ± 6,11. La dose moyenne cardiaque delivree etait a 10,75 Gy ± 4,63. Conclusion L’arctherapie volumetrique modulee constitue une solution dosimetrique optimale pour l’irradiation des volumes complexes, notamment dans le cas des cancers du sein bilateral. L’etude presente n’a enregistre aucune toxicite aigue severe. Un suivi de plus longue duree s’impose afin de detecter la toxicite a distance.

Objectif Nous presentons ici les resultats dosimetriques chez 20 patientes consecutives traitees pour un cancer du sein bilateral entre juillet 2011 et decembre 2013. Patientes et methodes Les volumes cibles ont ete definis selon les criteres du Radiation Therapy Oncology Group (RTOG) (en particulier, le volume cible previsionnel etait egal au volume cible anatomoclinique plus 7 mm). La dose prescrite a ete de 63,2 Gy dans le volume cible previsionnel du boost (n = 17), 52,2 Gy dans le volume cible previsionnel du sein (n = 20) et la chaine mammaire interne (n = 9) et 49,3 Gy dans le volume cible previsionnel sus-claviculaire (n = 9) en 29 fractions. Les contraintes de prescription etaient les suivantes : volume recevant cible anatomoclinique recevant 95 % (V95 %) de la dose prescrite d’au moins 95 %, sauf pour sein, dans lequel il devait etre d’au moins 99 %. Un recueil systematique de la dose delivree dans les organes a risque a ete realise. Resultats Les moyennes droites et gauches (deviation standard) etaient ; volume cible anatomoclinique recevant 95 % de la dose prescrite : sein = 98,92 (0,94) ; 98,92 (1,09) ; boost = 99,4 % (1,6) ; 98,9 % (2,3) ; chaine mammaire interne = 98 % (5,2) ; 98,8 % (2,4) ; aire sus-claviculaire = 98,8 % (0,2) ; 99,7 % (0,6). Volume cible previsionnelle recevant 95 % de la dose prescrite ; sein = 92,43 % (6,31) ; 92,14 % (6,21) ; boost = 94 % (7,8) ; 92,3 % (12,8) ; chaine mammaire interne = 80,5 % (15,8) ; 84,7 % (17) ; aire sus-claviculaire = 96,2 % (2,8) ; 94,2 %. Poumons droit et gauche : dose moyenne = 12,7 Gy (2,2) ; 12,0 Gy (2,2) ; volume recevant 30 Gy (V30) = 8,9 % (2,9) ; 8,3 % (3,9) ; volume recevant 20 Gy (V20) = 18,6 % (4,92) ; 17,05 % (6,11) ; volume recevant 10 Gy (V10) = 43,6 % (12,6) ; 38,8 % (11,4) ; volume recevant 5 Gy (V5) = 79,6 % (14,4) ; 77,7 % (16,1). Cœur : dose moyenne = 10,75 Gy (4,63). Conclusion L’arctherapie volumetrique modulee des cancers du sein bilateraux permet une excellente couverture des volumes cibles avec une exposition des organes a risque acceptable.

blocks, which could open the way to improved CTV definition and planning. Materials/Methods: An in-house, spectral domain OCT system was developed for this study. A pair of tilting galvanometer mirrors permits lateral scanning of the infrared beam resulting in a 5x5x3-mm image volume. Paraffin blocks (40x25x4 mm) containing formalin-fixed mouse mammary glands with tumor were imaged. Other than removing the plastic mount, the blocks were not manipulated in any way in preparation for imaging. After each scan, the blockswere translated on amoveable stage until the entire samplewas imaged. Blocks were scanned through both sides in order to image their full thickness. Individual scans were stitched together to generate a final, complete image volume. For comparison, sections at multiple depths were obtained from the blocks, stained with hematoxylin and eosin (H&E), and photographed at high magnification and resolution. Results: Complete 3D images of the tissue blocks were obtained. The scan time for a single 5x5x3-mm image was about 15 seconds. A lateral resolution of 16 mm and a 6-mm resolution in the depth direction permitted visualization of tissue micro-architecture that correlated with the H&E section images. Images from consecutive blocks could be stitched together, allowing reconstruction of larger specimens over multiple blocks. Because of the paraffin medium, both micro-CT and small animal MRI were unable to visualize any features within the blocks. Conclusions: Optical coherence tomography is a fast, non-invasive, highresolution imaging modality capable of volumetric reconstruction of paraffin tissue blocks. As such, it could greatly facilitate the imaging and analysis of microscopic disease needed to study and improve CTV design and treatment. Author Disclosure: L. Kim: None. R. Droz-Rosario: None. E. Hwuang: None. L. Higgins: None. M. Pierce: None.

Purpose In this study we report the first clinical results of monitoring the prostate movement during a VMAT radiation through the use of MIR system (Motion Intrafraction Review, Varian Medical Systems). This method allows using a kV irradiation during treatment delivery and verifying real-time internal displacement volumes. Materials and methods Seven patients with prostatic carcinoma were treated using RapidArc technique on a TrueBeam Novalis accelerator. Before the simulation, three gold markers were implanted in the prostate and a hyaluronic acid injection was performed to remove the anterior wall of the rectum. Each patient received an MRI acquisition in radiotherapy position and a fusion was performed with CT simulation in order to improve the quality of the irradiated volume definition. Algorithm PRO3 (version V 10.0.28) was used for the preparation of the treatment plan on the Eclipse console and two arcs were delivered with a 600 MU/ min dose rate. A schema 20 * 3.1 Gy equivalent to 84 Gy with 5 fractions per week was used. The irradiation was delivered in gated mode required to operate MIR on TrueBeam version 1.6. During the treatment, kV images were automatically acquired at each exhale. The actual position of the markers was directly compared with their expected position represented by a green circle on the acquired image. Results The treatment time was 16 ± 6 min. The number of kV images acquired during irradiation was 26 ± 15 with a maximum of 64. After retrospective analysis, the average deviation of the markers in the superior-inferior direction was 0.29 [0–1.4] mm. The anterior- posterior and lateral offsets are difficult to analyze retrospectively because markers are not visible on all the images. However, a live correction of the fiducials positions has been applied only for two sessions out of 120. Conclusion Verification by kV imaging of intrafraction prostate motion is now possible simultaneously with the delivery of treatment. This online tracking will certainly reduce the PTV margins for hypofractionated treatment with strong dose per fraction. The MIR system available on the TrueBeam will allow in version 2.0 to get rid of the respiratory cycle by producing an image on a request related to the number of seconds, the number of UM or the gantry position.

Introduction The quality of a treatment performed by intensity modulation is based on the positioning accuracy of the multileaf collimator leaves (MLC, 120 leaves). The dosimetric impact achieved by the introduction of systematic errors on the leaves positioning has been studied to assess the generated effects. Materials and methods The study was performed on 8 patients treated for prostate localization with 80 Gy prescribed dose in dynamic arc therapy. Original treatment plans clinically approved were exported in DICOM RT to be processed using Matlab ® software. Systematic errors of magnitude between 0.5 mm and 5 mm were introduced by opening the MLC leaves, or by closing and shifting. The 128 revised plans were then introduced into the treatment planning system (TPS). They were recalculated keeping the same optimization constraints than the original plan. Geometric and dosimetric index (SFRO and ICRU used index) were calculated using the Artiview ® software, Aquilab. Results Changes introduced to the original plans are significantly impacting dosimetric treatment planning validation index. Among these index, the near maximum dose D_2%(Gy) received by the target volume (PTV) differs from 12%, 15% and 20% to the original treatment plan for maximum openings, shifts and closures respectively. For the same index and amplitude errors of up to 2 mm, an offset MLC error is less penalizing ( 5%) systematic error. Other dosimetric and geometric index complete the analysis as the Dice similarity coefficient (DSC), which is more sensitive to errors introduction in treatment plans. Conclusion Dosimetric validation is based on calculated and measured doses distributions comparison, thanks to tolerances (generally 3%/3 mm). This study allows us to understand the impact of potential MLC positioning errors on planned treatment and to discuss about the validity of quality assurance tolerance values.

Mass transfer between a free moving drop and a continuous liquid has been studied for the case when the resistance to mass transfer lies in the continuous phase. A new representation of results using Galilei number is suggested when the liquid is stationary. The authors have measured the average rate of fall and mean mass transfer coefficient when the continuous phase is subjected to sinusoidal pulsations. It has been shown that pulsation increase efficiency not only by increasing the residence time but also by increasing the mass transfer (roughly 20% for some values of amplitude and frequency). At constant diameter of droplet, the product of mass-transfer coefficient and average velocity vary linearly with the product of amplitude and frequency of pulsation.

The transfer of iodine from a drop of carbon tetrachloride falling in water has been studied in the presence of two surface-active agents, Teepol and sodium dodecylsulfate. The presence of Teepol is found to decrease the drop's terminal velocity more than that of sodium dodecylsulfate, this effect being more pronounced for larger drops. Small amounts of these surfactants reduce the internal circulation and consequently the mass transfer rates. Efficiencies can even fall below those for rigid spheres when the surfactant concentration is high. The maximum reduction for the individual mass transfer coefficient is about 77% with both surface-active agents. Results are compared with the model of Vermeulen and the model of Calderbank and Korchinski. These results are also expressed using the Galileo number and diffusivity effective factor R .

A study was made of the effect of a surface-active agent, on mass transfer of Iodine from an aqueous phase to a falling drop of carbon tetrachloride. The size of drops was varied from 0.2 to 0.4 cm equivalent spherical diameters and the concentrations of Teepol ranged from 0 to 0.5 cm 3 /l. The experimental falling velocities have been compared with various correlations proposed by several workers. It has been found that the experimental results for the pure or slightly contaminated system (0.05 cm 3 /l) agree well with Vignes' correlation. In case of mass transfer, a maximum reduction in the mass transfer coefficient of 58% due to the presence of Teepol has been observed. Results have been expressed in dimensionless form using the Galileo and Sherwood numbers.

The purpose of this paper is to give a complete analysis of the influence of mass transfer direction on the performance of a pulsed perforated plate-column. The ternary system studied was water—iodine—carbon tetrachloride. Both mass transfer directions were considered, i.e. iodine transfering from continuous aqueous phase to dispersed organic phase and vice versa. Parameters considered are overall efficiency, hold up, true number of transfer units, Peclet number for both phases, drop size, interfacial area and overall mass transfer coefficient.

A study was made of the fall of a single drop of carbon tetrachloride through pure or contaminated water. Results are presented for the variations of the shape of the drop and of the frequency of oscillation with diameter and Teepol concentration. It has been found that presence of surface active agents, increases the deformation of drops but reduces the frequency of oscillations. The comparison between these experimental data and several relations has shown that no previous correlations of either the eccentricity or the frequency of oscillation are satisfactory when the system is contaminated by some surfactants. Les auteurs ont etudie le comportement d'une goutte isolee de tetrachlorure de carbone en chute libre dans une colonne remplie d'eau pure ou contaminee par un agent tensio-actif. Ils presentent les variations de la forme de la goutte et de la frequence d'oscillation en fonction du diametre et de la concentration en Teepol. La presence d'impuretes augmente la deformation mais reduit les oscillations de forme. La comparaison entre ces resultats experimentaux et diverses relations empiriques montre que celles-ci ne sont pas valables pour les systemes contamines.

Resume Dans la premiere partie de cette etude, les auteurs comparent les courbes experimentales representant le mouvement d'une bille spherique indeformable evoluant dans un liquide soumis a l'action d'une pulsation sinusoidale, aux courbes calculees a partir de la theorie. Les courbes experimentales ont ete obtenues a partir des films de la chute d'une bille dans une colonne dans laquelle circule un liquide visqueux. Les courbes theoriques ont ete tracees en explicitant une equation proposee dans la litterature [8] et valable en regime laminaire. Cette comparaison permet de conclure que l'equation est applicable si l'on tient compte de l'influence eventuelle des parios et de l'amplitude reelle du liquide. La deuxieme partie concerne le regime turbulent. Le rapport de la vitesse moyenne avec pulsation a la vitesse moyenne sans pulsation ( u/u f=0 ) mis en evidence experimentalement est compare au resultat fourni par une equation theorique de Houghton [4].

Si l'on superpose une agitation rotative a l'agitation produite par la pulsation dans une coloune a plateaux perfores on obtient de meilleures efficacites surtout pour des valeurs du produit A.f assez faibles. Les auteurs ont mesure experimentalement la retention et le nombre de Peclet dans ce nouvel extracteur afin d'en deduire le coefficient de melange en retour de la phase continue. En comparant leurs resultats avec ceux que l'on obtient dans une colonne pulsee standard ils montrent que l'amelioration d'efficacite doit ětre attribuee a l'augmentation de retention et non pas, comme on pouvait le penser, a la diminution du melange en retour. The efficiency of a pulsed perforated plate extraction column can be improved, particularly at low values of A.f, by superimposing a rotary agitation. The hold up and the Peclet number have been measured in such a column in order to calculate the coefficient of backmixing of the continuous phase. A comparison of the results with those for a conventional pulsed column has indicated that the improved performance is due to an increase in hold up and not, as might have been supposed, to reduced backmixing.