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Purpose Automated planning techniques aim to reduce manual planning time and inter-operator variability without compromising the plan quality which is particularly challenging for head-and-neck (HN) cancer radiotherapy. The objective of this study was to evaluate the performance of an a priori-multicriteria plan optimization algorithm on a cohort of HN patients. Methods A total of 14 nasopharyngeal carcinoma (upper-HN) and 14 “middle-lower indications” (lower-HN) previously treated in our institution were enrolled in this study. Automatically generated plans (autoVMAT) were compared to manual VMAT or Helical Tomotherapy planning (manVMAT-HT) by assessing differences in dose delivered to targets and organs at risk (OARs), calculating plan quality indexes (PQIs) and performing blinded comparisons by clinicians. Quality control of the plans and measurements of the delivery times were also performed. Results For the 14 lower-HN patients, with equivalent planning target volume (PTV) dosimetric criteria and dose homogeneity, significant decrease in the mean doses to the oral cavity, esophagus, trachea and larynx were observed for autoVMAT compared to manVMAT-HT. Regarding the 14 upper-HN cases, the PTV coverage was generally significantly superior for autoVMAT which was also confirmed with higher calculated PQIs on PTVs for 13 out of 14 patients, whereas PQIs calculated on OARs were generally equivalent. Number of MUs and total delivery time were significantly higher for autoVMAT compared to manVMAT. All plans were considered clinically acceptable by clinicians. Conclusions Overall superiority of autoVMAT compared to manVMAT-HT plans was demonstrated for HN cancer. The obtained plans were operator-independent and required no post-optimization or manual intervention.

International audience; Nasopharyngeal cancers are a rarity in France. Radiotherapy is the cornerstone of treatment, frequently combined with chemotherapy. The technical modality of radiotherapy is complex in this disease, which is located in the vicinity of numerous organs at risk. In this article, we will present the updated guidelines of the French society for radiation oncology (Société française de radiothérapie oncologique, SFRO) on the indications, and technical details of radiotherapy in nasopharyngeal cancers.

We present the update of the recommendations of the French society of radiation oncology on soft tissue sarcomas. Currently, the initial management of sarcomas is very important as it may impact on patients' quality of life, especially in limb soft tissue sarcomas, and on overall survival in trunk sarcomas. Radiotherapy has to be discussed within a multidisciplinary board meeting with results of biopsy, eventually reexamined by a dedicated sarcoma pathologist. The role of radiotherapy varies according to localization of soft tissue sarcoma. It is part of the standard treatment in grade 2 and 3 sarcomas of the extremities and superficial trunk5cm. In case of R1 or R2 resection, reexcision should be discussed. In such cases, it may be delivered preoperatively (50Gy/25 fractions of 2Gy) or postoperatively. In retroperitoneal sarcomas, preoperative conformal radiotherapy with or without modulated intensity cannot be proposed systematically in daily practice. Concomitant chemoradiotherapy cannot be considered a standard treatment. Intensity-modulated radiotherapy has become widely available. Other soft tissue sarcoma sites such as trunk, head and neck and gynaecological soft tissue sarcomas will be addressed, as well as other techniques that may be used such as brachytherapy and proton therapy.

Modern radiotherapy treatment planning is a complex and time-consuming process that requires the skills of experienced users to obtain quality plans. Since the early 2000s, the automation of this planning process has become an important research topic in radiotherapy. Today, the first commercial automated treatment planning solutions are available and implemented in a growing number of clinical radiotherapy departments. It should be noted that these various commercial solutions are based on very different methods, implying a daily practice that varies from one center to another. It is likely that this change in planning practices is still in its infancy. Indeed, the rise of artificial intelligence methods, based in particular on deep learning, has recently revived research interest in this subject. The numerous articles currently being published announce a lasting and profound transformation of radiotherapy planning practices in the years to come. From this perspective, an evolution of initial training for clinical teams and the drafting of new quality assurance recommendations is desirable.

International audience; Continuous improvements have been made in the way to prescribe, record and report dose distributions since the therapeutic use of ionizing radiations. The international commission for radiation units and measurement (ICRU) has provided a common language for physicians and physicists to plan and evaluate their treatments. The PTV concept has been used for more than two decades but is becoming obsolete as the CTV-to-PTV margin creates a static dose cloud that does not properly recapitulate all planning vs. delivery uncertainties. The robust optimization concept has recently emerged to overcome the limitations of the PTV concept. This concept is integrated in the inverse planning process and minimizes deviations to planned dose distribution through integration of uncertainties in the planning objectives. It appears critical to account for the uncertainties that are specific to protons and should be accounted for to better exploit the clinical potential of proton therapy. It may also improve treatment quality particularly in hypofractionated photon plans of mobile tumors and more widely to photon radiotherapy. However, in contrast to the PTV concept, a posteriori evaluation of plan quality, called robust evaluation, using error-based scenarios is still warranted. Robust optimization metrics are warranted. These metrics are necessary to compare PTV-based photon and robustly optimized proton plans in general and in model-based NTCP approaches. Assessment of computational demand and approximations of robust optimization algorithms along with metrics to evaluate plan quality are needed but a step further to better prescribe radiotherapy may has been achieved.

International audience; Recent technological developments in linear accelerators (linacs) and their imaging systems have made it possible to routinely perform stereotactic radiotherapy (SRT) treatments. To ensure the security and quality of the treatments, national and international recommendations have been written. This review focuses on the recommendations of the report 91 of the International Commission on Radiation Units (ICRU) on stereotactic treatments with small photon beams and proposes to answer the question of the eligibility of the commercially available accelerators for the treatment of extra-cranial SRT (SBRT). The ICRU 91 report outlines important features needed to respect the constraints, which are high intensity photon beam, integrated image-guidance, high mechanical accuracy of the linac, multileaf collimator with reduced leaf width, bundled motion management and bundled 6 Dimensional "robotic" couch tabletop. Most of the contemporary linacs meet these recommendations, in particular, stereotactic dedicated linacs, or modern gantry-based linacs equipped with 3 dimensional cone-beam CT imaging and 2D-stereoscopic planar imaging. Commercially available ring-based linacs have some limitations: they offer only coplanar treatments, and couch movements are limited to translations and, some have limited imaging equipment and no ability to manage intrafraction motion. However, for performing SBRT, non-coplanar irradiations are not mandatory, contrarily to intracranial stereotactic irradiations. Furthermore, patients' rotations can be corrected, thanks to real-time adaptive radiotherapy available on MRI-linacs. Finally, significant improvements are expected in the short term to compensate the weaknesses of the current devices.

International audience; Purpose: To evaluate the repositioning accuracy of 4 immobilization devices (ID) used for whole breast Helical Tomotherapy treatments: arm float with VacFix® (Par Scientific, Denmark), all-in-one® (AIO®) system (Orfit, Belgium), MacroCast thermoplastic mask (Macromedics, The Netherlands) and BlueBag® system with Arm-Shuttle (Elekta, Sweden).Materials and methods: Twenty four women with breast cancer with PTV including the breast/chest wall and lymph nodes were involved in this study (6 women per group). Pretreatment registration results were first collected using automatic bone registration + manual adjustment on the vertebra followed by independent registrations on different ROIs representing each treated area (axillary, mammary chain, clavicular, breast/chest wall). The differences in translations and rotations between reference registration and the above mentionned ROIs were calculated. A total of 120 MVCT images were analyzed.Results: Significant differences were found between IDs (p < 0.0001), ROIs (p = 0.0002) and the session number (p < 0.0001) on the observed shifts, when examining 3D translation vectors. 3D-vectors were significantly lower for the BlueBag® than for the VacFix® or for the AIO® (p < 0.0001), but differences were not significant compared to the mask (p = 0.674). Finally, setup margins were overall smaller for the BlueBag® than for other IDs, with values ranging from 1.53 to 1.91 mm on the mammary chain area, 4.52-6.07 mm on the clavicular area, 2.71-4.62 mm on the axillary area, and 3.39-5.10 mm on the breast.Conclusion: We demonstrated in this study that the BlueBag® combined with arm shuttle is a robust solution for breast and nodes immobilization during HT treatments.

International audience; Background and purpose: To compare two in-beam monitoring devices for prostate radiotherapy: intra-prostatic electromagnetic transmitters (EM-T) (RayPilot®, Micropos Medical) and ultrasound imaging using transperineal probe (TP-US) (Clarity®, Elekta) used concomitantly on phantom and on patients.Materials and methods: The phantom study evaluated accuracy in presence of known translations and rotations. Then intra-fraction motions were analyzed for 10 prostate cancer patients implanted with the EM-T 8 days before the simulation CT (171 sessions). The percent time in which the differences between the systems were 1–5 mm were scored for each direction.Results: Experiments on phantom confirmed no interference between the systems and showed deviations of less than 0.5 mm when translations were applied progressively. In presence of rotations (5–15°), both systems displayed systematic shifts up to 6.9 and 3.8 mm for the TP-US and the EM-T, respectively. Absolute mean differences between displacements observed on patients with EM-T and TP-US were ≤0.55 mm in all directions except for one patient (≤1.77 mm). With an exception for this patient, a strong correlation was found in left–right direction: differences >2 mm were monitored less than 0.22% of the time (mean acquisition time:164 minutes) and never exceeded 5 s. Maximum differences were observed in supero-inferior direction with differences >2 mm monitored more than 6.5% of the time for 3 patients. Large prostate rotations, the presence of gas and EM-T location in the prostate may explain important differences.Conclusion: Apart from the systematic shifts induced by the rotations, the two systems were correlated and represent feasible solutions for monitoring prostate cancer treatment.

Introduction et but de l’etude Le but de ce travail etait de comparer en concomitance les performances de deux systemes de suivi des mouvements pendant les seances de radiotherapie externe des adenocarcinomes prostatiques. Materiel et methodes Entre fevrier 2017 et septembre 2018, 13 patients atteints d’un adenocarcinome prostatique (non opere) ont ete inclus dans une etude prospective, evaluant en concomitance l’echographie transperineale (Clarity®, Elekta) et un transpondeur electromagnetique (RayPilot®, Micropos Medical). Le transpondeur electromagnetique a ete mis en place par voie transperineale, sous controle par echographie endorectale une semaine avant la scanographie dosimetrique. Lors de cette procedure, deux reperes fiduciels etaient positionnes dans le lobe controleateral. La radiotherapie externe etait realisee avec une technique d’arctherapie volumetrique module, selon un schema hypofractionne (20 seances), avec tomographie conique quotidienne. Le traitement etait interrompu en cas de deplacement de plus de 3 mm pendant plus de 30 secondes, avec si necessaire un repositionnement du patient. Resultats et analyse statistique Trois patients ont ete exclus : pour une prostatite aigue chez le premier, ayant necessite l’ablation du transpondeur electromagnetique (la radiotherapie externe a ete realisee par la suite sans difficultes) ; pour une ablation accidentelle du transpondeur electromagnetique chez deux patients, remis en place chez l’un d’entre eux ; en raison de la qualite insuffisante de l’echographie transperineale chez un patient. Les donnees de dix patients (soit 171 seances) etaient evaluables. Les ecarts moyens entre l’echographie transperineale et le transpondeur electromagnetique etaient inferieure a 0,55 mm chez neuf patients (1,77 mm pour un patient). Les differences maximales ont ete observees pour l’axe supero-inferieur (superieures a 2 mm plus de 6,5 % du temps de traitement pour trois patients), possiblement en raison de la presence de gaz et de la localisation du transpondeur electromagnetique. Conclusion Pour la radiotherapie prostatique, une excellente correlation a ete observee entre ces deux systemes qui representent des alternatives fiables pour le suivi des mouvements prostatiques pendant les seances.

Introduction et but de l’etude Le traitement des cancers craniospinaux avec une technique d’irradiation par modulation d’intensite, realise avec une Tomotherapy® (Accuray, Etats-Unis) est devenue un standard. Du fait de la precision de la technique, elle necessite un repositionnement precis. Avec les systemes de contention utilises en routine, il est courant d’observer des problemes d’alignement et de rotation entre la colonne cervico-dorsolombaire et sacree et au niveau des bras. Le but de cette etude etait d’evaluer un nouveau type de contention afin d’ameliorer la reproductibilite du traitement et de limiter les reinstallations afin d’envisager une reduction des marges de traitement pour pouvoir diminuer les doses dans les organes a risque. Materiel et methodes Cette etude comparative a porte sur 15 patients positionnes avec notre ancienne contention: masque cinq points (Civco®), moldcare (Civco®) et kneefix et 13 patients avec notre nouvelle: masque cinq points (Civco®), moldcare (Civco®), matelas billes personnalise integrant l’empreinte des bras et de l’ensemble kneewedge/footblock (QFIX®) indexe a la table. Resultats et analyse statistique La nouvelle contention a permis de limiter le nombre de reinstallations quotidiennes (2,2 % contre 13,9 % avec l’ancienne) en remediant aux problemes de courbure lombaire et de rotations superieures aux marges de traitement utilisees en routine (5 mm autour de l’encephale; 1 cm autour de la moelle). La moyenne des rotations est passee de 0,74 a 0,25). Nous avons egalement montre qu’avec cette contention, la marge entre le volume cible anatomoclinique et le volume cible previsionnel autour de la moelle pourrait etre de 7 mm pour 79,6 % des seances et de 5 mm pour 44,06 % des seances. Conclusion Grâce a cette nouvelle contention, nous avons limite les reinstallations, ce qui a permis un gain de temps de mobilisation de la machine et montre que les marges de traitement pourraient etre reduites pour la majorite des patients et ainsi entrainer une diminution de la dose dans les organes a risque.

Introduction Hypofractionated radiotherapy protocols in prostate cancer treatment require a better accuracy in dose delivery because of an increased risk of toxicity to the surrounding tissues. To achieve this goal a robust pre-treatment imaging device combined with a real-time prostate monitoring system for correcting inter and intrafraction motions is required. Two monitoring modalities are available in our department: intra-prostatic electromagnetic transmitter (RP) (RayPilot®, Micropos Medical, Sweden) and ultrasound imaging using transperineal probe (TP-US) (Clarity®, Elekta, Sweden). The first goal of this study was to assess the monitoring algorithm of the TP-US on prostate patients by comparing it to the RP system. Finally a retrospective study of intra-fraction motion observed during treatment with the TP-US has been done. Methods Four prostate patients were monitored using both monitoring devices simultaneously (80 treatment sessions). Intra-fraction motions collected with the TP-US were retrospectively analyzed for 23 prostate patients (730 sessions lasting 420s). Finally a simulation of the number of beam stops that would be required per session was done for different intervention thresholds (time/distance). Results A strong correlation was found between the 2 monitoring devices. Mean differences between the displacements observed were 0.03 ± 0.28 mm, 0.06 ± 0.39 mm, −0.11 ± 0.36 mm in the left-right (LR), anterior-posterior (AP) and superior-inferior (SI) direction, respectively. The differences were less than 1 mm in 91 % of the time considering all the 3 directions. Larger differences were found in AP and SI directions (9% and 7.7% of points were above 1 mm, respectively). The retrospective analysis showed that mean motions observed were less than 2 mm in all directions ( Table 1 ). A larger variability was found in SI and AP directions. Note that this was patient-dependent since some patients exhibited large movements whereas others did not move. By fixing action levels of 2 mm and 3 mm for at least 15s, the mean number of interruptions per session was 0.94 and 0.47, respectively, over all the patients. For patients exhibiting large movements the numbers of interventions reached 2.13 and 1.43, for action levels of 2 mm and 3 mm, respectively. Conclusions TP-US is a reliable technique for monitoring prostate during radiotherapy treatment. This device has the advantage to be non-invasive and non-ionizing. The magnitude of the motions observed over all patients is not important. However significant shifts are random and patient-dependent which requires prostate monitoring.

Purpose The aim of this study was to evaluate a new system based on transperineal ultrasound (TP-US) acquisitions for prostate and post-prostatectomy pre-treatment positioning by comparing this device to cone-beam computed tomography (CBCT). Methods The differences between CBCT/CT and TP-US/TP-US registrations were analyzed on 427 and 453 sessions for 13 prostate and 14 post-prostatectomy patients, respectively. The inter-operator variability (IOV) of the registration process, and the impact and variability of the probe pressure were also evaluated. Results CBCT and TP-US shift agreements at ± 5 mm were 76.6%, 95.1%, 96.3% and 90.3%, 85.0%, 97.6% in anterior-posterior, superior-inferior and left-right directions, for prostate and post-prostatectomy patients, respectively. IOV values were similar between the 2 modalities. Displacements above 5 mm due to strong pressures were observed on both localizations, but such pressures were rarely reproduced during treatment courses. Conclusions High concordance between CBCT/CT and TP-US/TP-US localization of prostates or prostatic beds was found in this study. TP-US based prepositioning is a feasible method to ensure accurate treatment delivery, and represents an attractive alternative to invasive and/or irradiating imaging modalities.

Introduction To achieve a better accuracy in dose delivering in prostate cancer treatment a real-time prostate monitoring system for correcting interand intrafraction motion, such as the intramodality transperineal ultrasound device (TP-US) (Clarity®, Elekta, Sweden) is required. Previous studies had shown a good correlation between Cone beam CT (CBCT) without fiducial markers (FM) and TP-US [1] . However important differences remained in the antero-posterior direction (shift agreement at 5 mm: 82.6%) probably because of the low soft-tissue contrast of CBCT acquisitions. The first goal of this study was to compare pre-treatment registration results obtained with CBCT imaging with FM (CBCT + FM) to TP-US for prostate cancer treatment. Finally treatment margins were calculated for 4 treatment protocols: CT/CBCT + FM (1), CT/CBCT + FM followed by intra-fraction monitoring (IFM) (2), TP-US/TP-US + IFM (3) and TP-US/TP-US registration corrected by CT/CBCT + FM for the first 5 sessions + IFM (4). Methods 16 prostate patients were involved in this study. Pre-treatment positioning was first performed with TP-US/TP-US registration then corrected by CT/CBCT + FM registration as it was considered as the “gold standard”. The shifts detected during CBCT imaging and treatment were collected. After 5 sessions the mean of the differences between CBCT + FM and TP-US was calculated and applied to subsequent TP-US registrations to correct for the systematic differences observed between the 2 modalities. The differences between TP-US/TP-US and CBCT/CT registrations were analyzed on 255 sessions. Finally treatment margins considering inter-fraction motion, IFM and inter-operator variability as sources of uncertainties were calculated using van Herk formula [2] . Results CBCT + FM and TP-US shift agreements at ±5 mm were 91.8%, 92.2%, 95.3% in the left-right (LR), anterior-posterior (AP) and superior-inferior (SI) direction, respectively. Treatment margins were smaller using CT/CBCT + FM as a reference modality for pretreatment registration ( Table 1 ). The main differences between CBCT and TP-US protocols came from the uncertainties of interfraction motion, which were not considered in CBCT protocols, as it was the “gold standard”. The use of the IFM (2) as well as correction of systematic shifts for TP-US registrations (4) enabled to considerably reduce margins compared to (1) and (3), respectively. Conclusions A strong correlation was found between TP-US and CBCT + FM registrations. The use of IFM enabled to considerably reduce treatment margins. Furthers investigations are in progress to assess the robustness of CBCT + FM registrations notably in case of prostate rotations.

International audience; PurposeTo evaluate the accuracy of an intra-modality trans-abdominal ultrasound (TA-US) device against soft-tissue based Cone-Beam Computed tomography (CBCT) registration for prostate and post-prostatectomy pre-treatment positioning.MethodsThe differences between CBCT and US shifts were calculated on 25 prostate cancer patients (cohort A) and 11 post-prostatectomy patients (cohort B), resulting in 284 and 106 paired shifts for cohorts A and B, respectively. As a second step, a corrective method was applied to the US registration results to decrease the systematic shifts observed between TA-US and CBCT results. This method consisted of subtracting the mean difference obtained between US and CBCT registration results during the first 3 sessions from the US registration results of the subsequent sessions. Inter-operator registration variability (IOV) was also investigated for both modalities.ResultsAfter initial review, about 20% of the US images were excluded because of insufficient quality. The average differences between US and CBCT were: 2.8 ± 4.1 mm, −0.9 ± 4.2 mm, 0.4 ± 3.4 mm for cohort A and 1.3 ± 5.0 mm, −2.3 ± 4.6 mm, 0.5 ± 2.9 mm for cohort B, in the anterior-posterior (AP), superior-inferior (SI) and lateral (LR) directions, respectively. After applying the corrective method, only the differences in the AP direction remained significant (p

Resume La technique d'irradiation extracrânienne en conditions stereotaxiques est mise en œuvre au centre Leon-Berard. Cette technique est fondee sur l'utilisation d'un cadre stereotaxique non invasif qui sert de referentiel pour localiser avec precision la tumeur. Elle est associee a un systeme d'asservissement respiratoire [compression diaphragmatique ou Active Breathing Control (ABC)] permettant l'utilisation de marges reduites autour du volume tumoral. La planimetrie est realisee a partir de trois examens scanographiques differents en conditions de traitement. Le repositionnement tridimensionnel du patient s'effectue grâce a une acquisition scanographique volumique (de basse energie) ainsi que des images orthogonales (de basse energie [kV] et de haute energie [MV]). L'irradiation extracrânienne en conditions stereotaxiques impose un systeme de limitation des mouvements internes. Bien que plus contraignant pour le patient, l'ABC permettrait de diminuer les marges par rapport a la compression diaphragmatique. Toutefois, l'ABC n'est pas compatible avec les acquisitions volumiques qui ameliorent le repositionnement du patient. En conclusion, la qualite du repositionnement et le haut niveau de conformation permettent de delivrer en mode hypofractionne de forts equivalents de dose (> 100 Gy) sans augmenter la toxicite. L'irradiation extracrânienne en conditions stereotaxiques s'integre parfaitement dans les dernieres innovations technologiques de la radiotherapie (collimateur micromultilame, repositionnement tridimensionnel, asservissement respiratoire…) et se presente comme une technique d'avenir.

Purpose To evaluate the impact of transabdominal probe pressure on prostate positioning with an intramodality ultrasound (US) image-guided-radiotherapy system and to quantify pressure variability over the treatment course. Material and methods 8 prostate cancer patients (group A) and 17 healthy volunteers underwent 3 consecutive US images with increasing probe pressure levels, and 1 CT acquisition for the group A only. Prostate positions were compared after manual registration of the first US image contour projected on 2 others. Group A’s pressure levels were quantified by measuring skin-to-skin distances between corresponding CT–US images. The same methodology was used on paired CT/CBCT–US images acquired during treatments of 18 prostate cancer patients to determine whether the different pressure levels applied to the group A were close to the clinical practices and to quantify pressure variability along the treatment course. Results 84% of 3D prostate displacements were above 2 mm for at least one pressure level. Probe pressures deliberately applied were similar to the ones observed clinically. The latter drastically varied between sessions. Conclusion Even with an intramodality system, probe pressure can impact prostate localization because of the pressure variability along the treatment course. Therefore, margins should be expanded from 0.5 to 1.2 mm to ensure treatment accuracy.

Objectif de l’etude Evaluer la performance de l’echographie transperineale quadridimensionnelle (Clarity, Elekta) pour la radiotherapie guidee par l’image (IGRT) des cancers prostatiques en tant que dispositif de repositionnement entre les seances, et analyser les mouvements pendant les seances observes. Materiel et methode Vingt-sept patients traites par irradiation externe pour un adenocarcinome prostatique localise (13 avec prostate en place [groupe A], 14 apres prostatectomie [groupe B]) ont ete inclus dans cette etude prospective. Une echographie transperineale quadridimensionnelle a ete realisee lors de la scanographie a visee dosimetrique et lors de chaque seance d’irradiation. Une tomographie conique a ete realisee a chaque seance. Les differences de positionnement du patient obtenues entre les recalages manuels entre les echographies transperineales quadridimensionnelle et celle de reference et les recalages entre les tomographies conique et la scanographie a visee dosimetrique ont ete analyses pour respectivement 427 et 453 seances pour les groupes A et B. La variabilite entre les observateurs pour l’analyse des echographies transperineales quadridimensionnelles a ete etudiee pour 13 observateurs evaluant 208 recalages chez 16 patients. Resultats La coherence entre les recalages entre les tomographies conique et la scanographie a visee dosimetrique et les echographies transperineales quadridimensionnelle et celle de reference a + –5 mm etait de 76,6 %, 95,1 %, 96,3 % et 90,3 %, 85,0 %, 97,6 % dans les directions anteroposterieure, supero-inferieure et droit-gauche, pour les patients groupe A et B, respectivement. Les 880 recalages des deux groupes ont donne les ecarts entre observateurs suivant : Conclusion La radiotherapie guidee par echographie transperineale quadridimensionnelle est une alternative interessante aux modalites irradiantes (tomographie conique, e-view) et/ou invasives (reperes fiduciels, transpondeurs) de guidage par l’image, particulierement en cas d’hypofractionnement.

27 pages; International audience; PURPOSE: To investigate the performances of two commercial treatment planning systems (TPS) for Volumetric Modulated Arc Therapy (VMAT) optimization regarding prostate cancer. The TPS were compared in terms of dose distributions, treatment delivery parameters and quality control results. MATERIALS AND METHODS: For ten patients, two VMAT plans were generated: one with Monaco TPS (Elekta) and one with Pinnacle TPS (Philips Medical Systems). The total prescribed dose was 78 Gy delivered in one 360° arc with a Synergy(®) linear accelerator equipped with a MLCi2(®). RESULTS: VMAT with Monaco provided better homogeneity and conformity indexes but lower mean dose to PTVs than Pinnacle. For the bladder wall (p = 0.019), the femoral heads (p = 0.017), and healthy tissues (p = 0.005), significantly lower mean doses were found using Monaco. For the rectal wall, VMAT with Pinnacle provided a significantly (p = 0.047) lower mean dose, and lower dose into 50% of the volume (p = 0.047) compared to Monaco. Despite a greater number of monitor units (factor 1.5) for Monaco TPS, the total treatment time was equivalent to that of Pinnacle. The treatment delivery parameter analysis showed larger mean MLC area for Pinnacle and lower mean dose rate compared to Monaco. The quality control results gave a high passing rate (>97.4%) for the gamma index for both TPS but Monaco provided slightly better results. CONCLUSION: For prostate cancer patients, VMAT treatment plans obtained with Monaco and Pinnacle offered clinically acceptable dose distributions. Further investigations are in progress to confirm the performances of the two TPS for irradiating more complex volumes.

Although radiosensitive, spinal locations of Ewing's sarcomas are challenging for the radiation oncologist due to poor radiation tolerance of the spinal cord. However, some favorable anatomical compartments - that may represent more than 20% - were associated with a better outcome and could benefit from a radiation dose escalation using the most recent radiation therapy techniques.We performed a dose escalation study on one patient, declined in two scenarios: (1) a tumour located within a single vertebral body and (2) a locally advanced disease involving the vertebral foramen and paraspinal soft tissues. Five dose-levels are proposed: 44.8Gy, 54.4Gy, 59.2Gy, 65.6Gy and 70.4Gy (1.6Gy per session, 8Gy per week). The 3D-conformational technique is compared with static intensity modulated radiation therapy (IMRT), helical tomotherapy, volumetric modulated arc therapy (VMAT), stereotactic body robotic radiation therapy (SBRT) and protontherapy (passive scattering). Two constraints had to be respected in order to skip to the next level: the planned target volume (PTV) coverage must exceed 95% and the D(2%) on the spinal cord shall not exceed a given constraint set at 50Gy in case 1 and 44Gy in case 2 due to initial neurological sufferance.Only protontherapy, SBRT, helical tomotherapy and VMAT appear able to reach the last dose level while respecting the constraints in case 1. On the other hand, only helical tomotherapy seems capable of reaching 59.2Gy on the PTV in case 2.With the most recent radiation therapy techniques, it becomes possible to deliver up to 70.4Gy in a favorable compartment in this sham patient. Unfavorable compartments can receive up to 59.2Gy. Definitive radiation therapy may be an interesting local treatment option to be validated in an early phase trial.

The main objective of this work was to propose recommendations concerning the delineation of the target volume of the nasopharyngeal cancers, the planification of the treatment, and describe the expected results about the efficacity and the toxicities. Theses recommendations are based upon anatomy, natural history of theses tumors, and upon published experiences from different teams working with IMRT.

Objectifs Evaluer le benefice apporte par la mise en place d’un ballon biodegradable (BioProtect™) dans l’espace rectoprostatique sur la couverture du volume cible et sur l’epargne du rectum en fonction de differentes marges de volume cible previsionnel et de differents fractionnements lors d’une irradiation prostatique. Materiel et methodes Une etude dosimetrique a ete menee sur deux scanographies realisees chez un patient atteint d’un adenocarcinome prostatique de risque eleve selon la classification d’Amico traite par irradiation conformationnelle avec modulation d’intensite (Tomotherapy®) : l’une realisee avant implantation du ballon, l’autre le lendemain. Trois volumes cibles previsionnels differents ont ete crees par expansion automatique avec des marges isotropiques de 3, 5 et 7 mm et pour chacun des trois plans de traitement et trois fractionnements ont ete realises (80 Gy en 40 fractions de 2 Gy, 60 Gy en 30 fractions de 3 Gy, 36,25 Gy en 5 fractions de 7,25 Gy). La priorite etait le respect strict des contraintes de dose aux organes a risque. Resultats Concernant le volume cible previsionnel, la D98 % (dose recue dans 98 % du volume) etait meilleure apres implantation du ballon quel que soit le plan de traitement considere. Le gain etait plus important pour les plans de traitement en cinq fractions et ce d’autant plus que la marge definissant le volume cible previsionnel etait large. L’implantation du ballon a egalement permis de reduire les doses recues par la paroi rectale pour l’ensemble des dix-huit plans de traitement realises. La difference etait plus importante pour un volume cible previsionnel reduit et pour les fortes doses recues par un faible volume. Conclusion La mise en place d’un ballon dans l’espace rectoprostatique permet un gain en termes de couverture du volume cible d’autant plus marque que le protocole est hypofractionne et la marge utilisee pour definir le volume cible previsionnel large. Le ballon permet egalement une meilleure preservation du rectum.

We fully describe an innovative radiotherapy technique called Stereotactic Body Radiation Therapy (SBRT), and explain how this technique is commonly used for clinical purpose at the anticancer center Léon-Bérard (Lyon, France). In this technique, a non-invasive stereotactic body frame is used to locate the tumor site with a great precision. This frame is combined with a system, which enables to track the respiratory motions (Active Breathing Control (ABC) or diaphragmatic compression (DC)) in order to reduce the treatment margins for organ motion due to breathing. Thus, the volume of normal tissues that will be irradiated is considerably reduced. The dosimetry is realized with 3 CT exams performed in treatment conditions. The 3D patient "repositioning" is done with a volume CT acquisition (kV) combined with orthogonal images (kV and MV). The SBRT requires a system to limit the organ motions. Although the ABC seems to be more fastidious for patient, it would enable to use smaller margins than with DC technique. Nevertheless, the ABC is not compatible with volume CT acquisitions, which considerably improve the patient repositioning. In conclusion, the quality of repositioning and the high level of conformation enable to deliver high equivalent doses (100 Gy) in hypofractionated mode, without increasing the treatment toxicity. The SBRT employs the last technologic innovations in radiotherapy and is therefore considered as a new efficient tool for solid tumors treatment.

Purpose: The aim of the present work is to propose and evaluate registration algorithms of three-dimensional (3D) transabdominal (TA) ultrasound (US) images to setup postprostatectomy patients during radiation therapy. Methods: Three registration methods have been developed and evaluated to register a reference 3D-TA-US image acquired during the planning CT session and a 3D-TA-US image acquired before each treatment session. The first method (method A) uses only gray value information, whereas the second one (method B) uses only gradient information. The third one (method C) combines both sets of information. All methods restrict the comparison to a region of interest computed from the dilated reference positioning volume drawn on the reference image and use mutual information as a similarity measure. The considered geometric transformations are translations and have been optimized by using the adaptive stochastic gradient descent algorithm. Validation has been carried out using manual registration by three operators of the same set of image pairs as the algorithms. Sixty-two treatment US images of seven patients irradiated after a prostatectomy have been registered to their corresponding reference US image. The reference registration has been defined as the average of the manual registration values. Registration error has been calculated by subtracting themore » reference registration from the algorithm result. For each session, the method has been considered a failure if the registration error was above both the interoperator variability of the session and a global threshold of 3.0 mm. Results: All proposed registration algorithms have no systematic bias. Method B leads to the best results with mean errors of −0.6, 0.7, and −0.2 mm in left–right (LR), superior–inferior (SI), and anterior–posterior (AP) directions, respectively. With this method, the standard deviations of the mean error are of 1.7, 2.4, and 2.6 mm in LR, SI, and AP directions, respectively. The latter are inferior to the interoperator registration variabilities which are of 2.5, 2.5, and 3.5 mm in LR, SI, and AP directions, respectively. Failures occur in 5%, 18%, and 10% of cases in LR, SI, and AP directions, respectively. 69% of the sessions have no failure. Conclusions: Results of the best proposed registration algorithm of 3D-TA-US images for postprostatectomy treatment have no bias and are in the same variability range as manual registration. As the algorithm requires a short computation time, it could be used in clinical practice provided that a visual review is performed.« less

Purpose Improvement of prostate cancer treatment in radiotherapy requires reliable, non-invasive and if possible non-irradiating modalities to correct target position before each irradiation session. The goal of this study is to evaluate an ultrasound-based (US) verification system for prostate alignment (CLARITY-ELEKTA). Contrary to other systems based on a cross-modality registration (between reference CT and treatment US images), this system proposes an intra-modality registration that could potentially improve the inter-sessions repositioning quality [1]. Methods and materials 14 patients with primary prostate cancer (P) and 9 patients with prostatectomy (post-P) were included in the first study. For each patient, a US image (US-ref) was acquired during the CT (CT-ref) stage. During the treatment session, a US image (US-T) was acquired just before performing a cone-beam computed tomography (CBCT). The shifts obtained with a US-ref/US-T registration were compared to those obtained with a CT-ref/CBCT registration. In the second study, 14 volunteers underwent three successive US acquisitions with increasing pressure in order to evaluate the impact of probe pressure on prostate localization with the Clarity system. Results For the first study, the average registration differences between US-ref/US-T and CT-ref/CBCT were 2.8 ± 4.1 mm, 1.9 ± 5.8 mm and 3.5 ± 3.8 mm for the P group, and of 0.3 ± 4.4 mm, 2.9 ± 7.5 mm and 1.6 ± 6.7 mm for the post-P group in lateral, superior–inferior and anterior-posterior directions, respectively. The second study showed that probe pressure can imply a prostate displacement up to 4 mm. Conclusion The first study pointed out significant standard deviations discrepancies between these two registration methods. However, both techniques have uncertainties. Soft tissue registration with CBCT imaging modality is not a ground truth, which needs to be considered in the analysis of the results[2,3]. Moreover, as highlighted with the second study, probe pressure can affect prostate localization and therefore can be one of uncertainty sources of US modality. Further studies are in progress to evaluate uncertainties of these two modalities in order to use this US system in clinical routine.

Purpose In order to evaluate the quality of treatment plan in VMAT, we have developed software to view and compare the expected and delivered parameters. The purpose is to evaluate the differences in the ‘‘fluence” delivered in three situations: impact of a new MLC calibration, the complexity of the treatment plan and performance comparison between linac. Materials and method The linac parameters (Synergy with MLCi2, RTD 7.01, Elekta) have been recorded in real time (4 Hz) and saved in a text file. Using this file and the RT PLAN data (Pinnacle version 9.0, Philips), Matlab software enables to visualize the variations of linac parameters (leaves positions, UM, dose rate, gantry angle, etc.) during treatment delivery. The product area.UM is defined to estimate the difference in fluence generated by the linac. The difference at each control point is normalized to the average value of these parameters. The irradiation sequences with several degrees of complexity have been defined: a cylindrical target, a concave target (AAPM TG119) and clinical cases (prostate, head and neck). The study was repeated for three linac Synergy/Elekta. Results With the concave geometry, increasing the dose gradient of 4.27 cGy/mm, 4.90 cGy/mm and 6.10 cGy/mm causes deviations of 0.03% (SD = 4.77%), –0.50% (SD = 5.59%) and –0.74% (SD = 5.56%), respectively. The analysis before and after MLC calibration shows deviations of –0.12% (SD = 4.01%) before calibration and –0.10% (SD = 4.02%) after calibration. Concerning comparative performance study of different linac, it shows that average deviation for the cylindrical geometry varies from –0.10% to –0.41% and standard deviation ranged from 4.02% to 6.62% for three linac. Conclusion These results show the potential of the software to evaluate the control parameters of the linac during treatment delivery. The differences observed indicate that the complexity of the plan is related to differences in the fluence, due to increased constraints on the linac parameters. This quality assurance tool allows physicists to check the stability and the accuracy of the linac according to the constraints for the implementation of the plan VMAT.

International audience; Motivation: to propose a simulation framework to validate ultrasound registration algorithms.Methodsthe proposed framework is composed of 4 steps: (1) an ultrasound image is simulated from a real one, (2) the scatterers are displaced with a known transformation and (3) a new ultrasound image is generated from this transformed scatterer map. Finally (4), registration is performed between the images simulated at steps 1 and 3. Registration results are compared to the applied transform (step 2).Resultsthe experts admitted the simulated images were highly realistic. The mean registration errors were -0.8±1.3 mm, -1.2±2.6 mm in anterior-posterior and superior-inferior directions, respectively.