PURPOSE:To retrospectively assess the differences between planned and delivered dose during ultra-hypofractionated (UHF) prostate cancer treatments, by evaluating the dosimetric impact of daily anatomical variations alone, and in combination with prostate intrafraction motion. METHODS:Prostate intrafraction motion was recorded with a transperineal ultrasound probe in 15 patients treated by UHF radiotherapy (36.25 Gy/5 fractions). The dosimetric objective was to cover 99 % of the clinical target volume with the 100 % prescription isodose line. After treatment, planning CT (pCT) images were deformably registered onto daily Cone Beam CT to generate pseudo-CT for dose accumulation (accumulated CT, aCT). The interplay effect was accounted by synchronizing prostatic shifts and beam geometry. Finally, the shifted dose maps were accumulated (moved-accumulated CT, maCT). RESULTS:No significant change in daily CTV volumes was observed. Conversely, CTV V100% was 98.2 ± 0.8 % and 94.7 ± 2.6 % on aCT and maCT, respectively, compared with 99.5 ± 0.2 % on pCT (p < 0.0001). Bladder volume was smaller than planned in 76 % of fractions and D5cc was 33.8 ± 3.2 Gy and 34.4 ± 3.4 Gy on aCT (p = 0.02) and maCT (p = 0.01) compared with the pCT (36.0 ± 1.1 Gy). The rectum was smaller than planned in 50.3 % of fractions, but the dosimetric differences were not statistically significant, except for D1cc, found smaller on the maCT (33.2 ± 3.2 Gy, p = 0.02) compared with the pCT (35.3 ± 0.7 Gy). CONCLUSIONS:Anatomical variations and prostate movements had more important dosimetric impact than anatomical variations alone, although, in some cases, the two phenomena compensated. Therefore, an efficient IGRT protocol is required for treatment implementation to reduce setup errors and control intrafraction motion.

We propose an unsupervised deep learning method to reconstruct a 3D tomographic image from biplanar X-rays, to reduce the number of required projections, the patient dose, and the acquisition time. To address this ill-posed problem, we introduce prior knowledge of anatomic structures by training a generative model on 3D CTs of head and neck. We optimize the latent vectors of the generative model to recover a volume that both integrates this prior knowledge and ensures consistency between the reconstructed image and input projections. Our method outperforms recent methods in terms of reconstruction error while being faster and less radiating than current clinical workflow. We evaluate our method in a clinical configuration for radiotherapy.

Purpose: To investigate the impact on dose distribution of intrafraction motion during moderate hypofractionated prostate cancer treatments and to estimate minimum non-isotropic and asymmetric (NI-AS) treatment margins taking motion into account.& nbsp;Methods: Prostate intrafraction 3D displacements were recorded with a transperineal ultrasound probe and were evaluated in 46 prostate cancer patients (876 fractions) treated by moderate hypofractionated radiation therapy (60 Gy in 20 fractions). For 18 patients (346 fractions), treatment plans were recomputed increasing CTV-to-PTV margins from 0 to 6 mm with an auto-planning optimization algorithm. Dose distribution was estimated using the voxel shifting method by displacing CTV structure according to the retrieved movements. Time-dependent margins were finally calculated using both van Herk's formula and the voxel shifting method.& nbsp;Results: Mean intrafraction prostate displacements observed were-0.02 +/- 0.52 mm, 0.27 +/- 0.78 mm and-0.43 +/- 1.06 mm in left-right, supero-inferior and antero-posterior directions, respectively. The CTV dosimetric coverage increased with increased CTV-to-PTV margins but it decreased with time. Hence using van Herk's formula, after 7 min of treatment, a margin of 0.4 and 0.5 mm was needed in left and right, 1.5 and 0.7 mm in inferior and superior and 1.1 and 3.2 mm in anterior and posterior directions, respectively. Conversely, using the voxel shifting method, a margin of 0 mm was needed in left-right, 2 mm in superior, 3 mm in inferior and anterior and 5 mm in posterior directions, respectively. With this latter NI-AS margin strategy, the dosimetric target coverage was equivalent to the one obtained with a 5 mm homogeneous margin.& nbsp;Conclusions: NI-AS margins would be required to optimally take into account intrafraction motion.

Deep-learning (DL)-based auto-contouring solutions have recently been proposed as a convincing alternative to decrease workload of target volumes and organs-at-risk (OAR) delineation in radiotherapy planning and improve inter-observer consistency. However, there is minimal literature of clinical implementations of such algorithms in a clinical routine. In this paper we first present an update of the state-of-the-art of DL-based solutions. We then summarize recent recommendations proposed by the European society for radiotherapy and oncology (ESTRO) to be followed before any clinical implementation of artificial intelligence-based solutions in clinic. The last section describes the methodology carried out by three French radiation oncology departments to deploy CE-marked commercial solutions. Based on the information collected, a majority of OAR are retained by the centers among those proposed by the manufacturers, validating the usefulness of DL-based models to decrease clinicians’ workload. Target volumes, with the exception of lymph node areas in breast, head and neck and pelvic regions, whole breast, breast wall, prostate and seminal vesicles, are not available in the three commercial solutions at this time. No implemented workflows are currently available to continuously improve the models, but these can be adapted/retrained in some solutions during the commissioning phase to best fit local practices. In reported experiences, automatic workflows were implemented to limit human interactions and make the workflow more fluid. Recommendations published by the ESTRO group will be of importance for guiding physicists in the clinical implementation of patient specific and regular quality assurances.

Contouring Organs at Risk (OAR) is time-consuming and highly inhomogeneous among physicians; it affects the accuracy of high precision image-guided radiotherapy. Artificial intelligence (AI) can accelerate OAR delineation and homogenize volume definition. This study aims at blindly evaluating two versions of an AI-based automatic delineation software for OAR.

Le but de ce travail était de comparer en concomitance les performances de deux systèmes de suivi des mouvements pendant les séances de radiothérapie externe des adénocarcinomes prostatiques. Entre février 2017 et septembre 2018, 13 patients atteints d'un adénocarcinome prostatique (non opéré) ont été inclus dans une étude prospective, évaluant en concomitance l'échographie transpérinéale (Clarity®, Elekta) et un transpondeur électromagnétique (RayPilot®, Micropos Medical). Le transpondeur électromagnétique a été mis en place par voie transpérinéale, sous contrôle par échographie endorectale une semaine avant la scanographie dosimétrique. Lors de cette procédure, deux repères fiduciels étaient positionnés dans le lobe contrôleatéral. La radiothérapie externe était réalisée avec une technique d'arcthérapie volumétrique modulé, selon un schéma hypofractionné (20 séances), avec tomographie conique quotidienne. Le traitement était interrompu en cas de déplacement de plus de 3 mm pendant plus de 30 secondes, avec si nécessaire un repositionnement du patient. Trois patients ont été exclus : pour une prostatite aiguë chez le premier, ayant nécessité l'ablation du transpondeur électromagnétique (la radiothérapie externe a été réalisée par la suite sans difficultés) ; pour une ablation accidentelle du transpondeur électromagnétique chez deux patients, remis en place chez l'un d'entre eux ; en raison de la qualité insuffisante de l'échographie transpérinéale chez un patient. Les données de dix patients (soit 171 séances) étaient évaluables. Les écarts moyens entre l'échographie transpérinéale et le transpondeur électromagnétique étaient inférieure à 0,55 mm chez neuf patients (1,77 mm pour un patient). Les différences maximales ont été observées pour l'axe supéro-inférieur (supérieures à 2 mm plus de 6,5 % du temps de traitement pour trois patients), possiblement en raison de la présence de gaz et de la localisation du transpondeur électromagnétique. Pour la radiothérapie prostatique, une excellente corrélation a été observée entre ces deux systèmes qui représentent des alternatives fiables pour le suivi des mouvements prostatiques pendant les séances.

Introduction. Inverse planning requires delineating a large number of Organs at Risk (OAR) which is a time-consuming process in radiotherapy. In Centre Léon Bérard (CLB), our team uses MonacoSim for more than 10 years and has a real expertise with the available tools. MiM Maestro (MiMSoftware) and Syngo.via (Siemens) were recently purchased and the associated new features (auto-contouring atlases, advanced contouring tools) were evaluated. The objective of this study is to evaluate the saving of time allowed by these new tools for OAR contouring in thoracic and in pelvic regions.

Background and purpose: To compare two in-beam monitoring devices for prostate radiotherapy: intraprostatic 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 (515 ), 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. (C) 2019 Elsevier B. V. All rights reserved. Radiotherapy and Oncology

and could result in sub-optimal treatment.For a patient with small differences between DIBH scans, no concerning differences in dose due to intra-fraction uncertainty could be identified.

Hypofractionated radiotherapy protocols in prostate cancer treatment require a better accuracy in dose delivery because of an increased risk of toxicity in 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 motion is required. Two monitoring modalities are available in our department: intra-prostatic electromagnetic transmitters (EM-T) (RayPilot, Micropos Medical, Sweden) and ultrasound imaging using transperineal probe (TP-US) (Clarity, Elekta, Sweden). The objective is to report the monitoring results obtained with the two devices used concomitantly. The accuracy of the two systems was first investigated in a phantom study. Then intra-fraction motions measured with the two devices used simultaneously were analyzed for 3 intermediate risk prostate adenocarcinoma patients (60 sessions). Patients were implanted with the EM-T and two fiducial markers 8 days before the simulation CT. Pre-treatment positioning was first performed with the TP-US. The shifts obtained were then controlled by a Cone Beam CT (CBCT) imaging (+ fiducial markers)/CT registration. During CBCT imaging the 2 devices monitoring mode were started. Irradiation was stopped and patient positioning adjusted for shifts above a threshold of 3 mm for at least 15 seconds for both devices. Each time threshold was exceeded a CBCT was performed to confirm the obtained shifts. On phantom, differences between TP-US and EM-T were below 1.5 mm in all directions if only translational shifts were applied on the target volume. When large rotations were applied (pitch 4°, yaw 9°), the correlation between EM-T vs CBCT was superior than between TP-US vs CBCT (i.e. 1.6 mm difference vs 5.3 mm in supero-inferior direction for EM-T vs TP-US, respectively). Mean differences between displacements observed on patients with EM-T and TP-US were less than 0.5 mm in all directions (Table 1). A larger variability was found in the antero-posterior direction where more important shifts were observed. However, the maximum differences over all the sessions were found less than 1.5 mm. EM-T is a reliable technique for monitoring prostate during radiotherapy treatment. It can be implemented rapidly and in situ dosimetry will be soon operational. TP-US is a promising option because it is non-invasive and enables visualization of the target and organs at risk. However the accuracy of the TP-US system needs further investigations in case of prostate rotations.Abstract 1119; Table 1Mean differences between displacements observed with EM-T and TP-US during all the treatment sessionsLeft-Right (mm)Supero-inferior (mm)Antero-Posterior (mm)Patient 10 ± 0,28-0,13 ± 0,210,12 ± 0,29Patient 20,1 ± 0,26-0,4 ± 0,370,22 ± 0,30Patient 30,02 ± 0,16-0,10 ± 0,14-0,11 ± 0,45 Open table in a new tab

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] Fargier-Voiron et al. Phys Med. 2016; PubMed Google Scholar ]. 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] van Herk Semin Radiat Oncol. 2004; PubMed Google Scholar ]. 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.

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.

Introduction The aim of this study is to quantitatively evaluate the dosimetric difference between 3D conformal radiation therapy (RT) and Helical Tomotherapy (HT) for mediastinal Hodgkin lymphoma by comparing the doses received by the different organs at risk close to the lesion. Methods Between 2015 and 2016, 15 patients with cervico-medistinal tumors were treated at the Centre Leon Bérard. Four of them were treated by 3D conformal radiation therapy based on antero-posterior fields calculated with the TPS XiO® (superposition) and delivered with an Synergy® accelerator (MLC Agility®: 5 mm leafs). The others were treated by IMRT with Helical Tomotherapy using Accuray® dedicated console. To evaluate the impact of the treatment method, we realize the dosimetric study of the two techniques for each patient. The plans quality of the 3D and Helical Tomotherapy were compared in terms of target coverage, target mean dose, dose sparing of organ at risk. These parameters were defined with physician according to published data (recommendations of the ICRU 83, SFRO, Quantec…). We have especially collected pulmonary and cardiac dose of different volumes. Coverage of the targets volumes was also collected. Results A better target volumes coverage was ensured by the Tomotherapy for the whole patient cohort (98.9% of average cover with HT vs 91% en 3D). Cardiac volume covered by 5 Gy and 15 Gy are lower with 3D conformal RT, we observe a mean difference of 12% for the V5Gy and 8% for the V15Gy. The V20Gy and V30Gy of the lungs are higher with 3D technique (15% vs 26% and 3.6% vs 13.8% respectively). However in the most cases the mean dose of the lungs and the heart are lower in 3D (10.2 Gy vs 10.9 Gy and 13.6 Gy vs 15.9 Gy respectively). Conclusions Tomotherapy has generally better dosimetric results except for low doses. As Hodgkin lymphoma often occur in young population, problem of low doses and thus of second cancer radio-induced can be discuss. Further investigations are possible to determine the most appropriate treatment depending on patient and lymphoma localization.

Évaluer la performance de l’échographie transpérinéale quadridimensionnelle (Clarity, Elekta) pour la radiothérapie guidée par l’image (IGRT) des cancers prostatiques en tant que dispositif de repositionnement entre les séances, et analyser les mouvements pendant les séances observés. Vingt-sept patients traités par irradiation externe pour un adénocarcinome prostatique localisé (13 avec prostate en place [groupe A], 14 après prostatectomie [groupe B]) ont été inclus dans cette étude prospective. Une échographie transpérinéale quadridimensionnelle a été réalisée lors de la scanographie à visée dosimétrique et lors de chaque séance d’irradiation. Une tomographie conique a été réalisée à chaque séance. Les différences de positionnement du patient obtenues entre les recalages manuels entre les échographies transpérinéales quadridimensionnelle et celle de référence et les recalages entre les tomographies conique et la scanographie à visée dosimétrique ont été analysés pour respectivement 427 et 453 séances pour les groupes A et B. La variabilité entre les observateurs pour l’analyse des échographies transpérinéales quadridimensionnelles a été étudiée pour 13 observateurs évaluant 208 recalages chez 16 patients. La cohérence entre les recalages entre les tomographies conique et la scanographie à visée dosimétrique et les échographies transpérinéales quadridimensionnelle et celle de référence à + –5 mm était de 76,6 %, 95,1 %, 96,3 % et 90,3 %, 85,0 %, 97,6 % dans les directions antéropostérieure, supéro-inférieure et droit-gauche, pour les patients groupe A et B, respectivement. Les 880 recalages des deux groupes ont donné les écarts entre observateurs suivant : < 3 mm dans 11,5 % des cas, 5 ; 8 et 4,9 % et < 5 mm dans 2,4 % ; 1,5 et 0,7 % pour les directions antéropostérieure, supéro-inférieure et droit-gauche. Les déplacements pendant les fractions dépendaient du patient et de la durée de l’irradiation : supérieurs à 3 mm pour 5 et 1,9 % du temps lors de la première minute et pour 38 et 10,8 % du temps à la septième minute, respectivement pour les groupes A et B. La radiothérapie guidée par échographie transpérinéale quadridimensionnelle est une alternative intéressante aux modalités irradiantes (tomographie conique, e-view) et/ou invasives (repères fiduciels, transpondeurs) de guidage par l’image, particulièrement en cas d’hypofractionnement.

PurposeThe 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).MethodsThe 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.ResultsCBCT 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.ConclusionsHigh 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.