EP-1245: Gated Rapidarc using KV intrafraction verification for liver stereotactic treatment

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Breathing adapted radiotherapy: a 4D gating software for lung cancer

<p>Abstract</p> <p>Purpose</p> <p>Physiological respiratory motion of tumors growing in the lung can be corrected with respiratory gating when treated with radiotherapy (RT). The optimal respiratory phase for beam-on may be assessed with a respiratory phase optimizer (RPO), a 4D image processing software developed with this purpose.</p> <p>Methods and Materials</p> <p>Fourteen patients with lung cancer were included in the study. Every patient underwent a 4D-CT providing ten datasets of ten phases of the respiratory cycle (0-100% of the cycle). We defined two morphological parameters for comparison of 4D-CT images in different respiratory phases: tumor-volume to lung-volume ratio and tumor-to-spinal cord distance. The RPO automatized the calculations (200 per patient) of these parameters for each phase of the respiratory cycle allowing to determine the optimal interval for RT.</p> <p>Results</p> <p>Lower lobe lung tumors not attached to the diaphragm presented with the largest motion with breathing. Maximum inspiration was considered the optimal phase for treatment in 4 patients (28.6%). In 7 patients (50%), however, the RPO showed a most favorable volumetric and spatial configuration in phases other than maximum inspiration. In 2 cases (14.4%) the RPO showed no benefit from gating. This tool was not conclusive in only one case.</p> <p>Conclusions</p> <p>The RPO software presented in this study can help to determine the optimal respiratory phase for gated RT based on a few simple morphological parameters. Easy to apply in daily routine, it may be a useful tool for selecting patients who might benefit from breathing adapted RT.</p

A multi-centric evaluation of self-learning GAN based pseudo-CT generation software for low field pelvic magnetic resonance imaging

Purpose/objectivesAn artificial intelligence-based pseudo-CT from low-field MR images is proposed and clinically evaluated to unlock the full potential of MRI-guided adaptive radiotherapy for pelvic cancer care.Materials and methodIn collaboration with TheraPanacea (TheraPanacea, Paris, France) a pseudo-CT AI-model was generated using end-to-end ensembled self-supervised GANs endowed with cycle consistency using data from 350 pairs of weakly aligned data of pelvis planning CTs and TrueFisp-(0.35T)MRIs. The image accuracy of the generated pCT were evaluated using a retrospective cohort involving 20 test cases coming from eight different institutions (US: 2, EU: 5, AS: 1) and different CT vendors. Reconstruction performance was assessed using the organs at risk used for treatment. Concerning the dosimetric evaluation, twenty-nine prostate cancer patients treated on the low field MR-Linac (ViewRay) at Montpellier Cancer Institute were selected. Planning CTs were non-rigidly registered to the MRIs for each patient. Treatment plans were optimized on the planning CT with a clinical TPS fulfilling all clinical criteria and recalculated on the warped CT (wCT) and the pCT. Three different algorithms were used: AAA, AcurosXB and MonteCarlo. Dose distributions were compared using the global gamma passing rates and dose metrics.ResultsThe observed average scaled (between maximum and minimum HU values of the CT) difference between the pCT and the planning CT was 33.20 with significant discrepancies across organs. Femoral heads were the most reliably reconstructed (4.51 and 4.77) while anal canal and rectum were the less precise ones (63.08 and 53.13). Mean gamma passing rates for 1%1mm, 2%/2mm, and 3%/3mm tolerance criteria and 10% threshold were greater than 96%, 99% and 99%, respectively, regardless the algorithm used. Dose metrics analysis showed a good agreement between the pCT and the wCT. The mean relative difference were within 1% for the target volumes (CTV and PTV) and 2% for the OARs.ConclusionThis study demonstrated the feasibility of generating clinically acceptable an artificial intelligence-based pseudo CT for low field MR in pelvis with consistent image accuracy and dosimetric results

Modalités et intérêt de radiothérapie guidée par l’image pour les cancers du sein en situation adjuvante

International audienceIn adjuvant setting, breast cancer radiotherapy volumes include whole mammary gland or chest wall, and when indicated, nodal area such as axilla, supraclavicular, and internal mammary chain. An accurate patients positioning is required due to some geometric complexity of target volumes closed to organs at risk as heart and lung. Image guided radiation therapy allows such accuracy. Here we propose a review on image guided radiotherapy for breast cancer

L’irradiation des aires ganglionnaires (sus-claviculaire et mammaire interne) augmente-t-elle la toxicité de la radiothérapie adjuvante mammaire ?

International audienceTreatment volume is a major risk factor of radiation-induced toxicity. As nodal irradiation increases treatment volume, radiation toxicity should be greater. Nevertheless, scientific randomised data do not support this fact. However, a radiation-induced toxicity is possible outside tangential fields in the nodal volumes not related to breast-only treatment. Treatment should not be adapted only to the disease but personalized to the individual risk of toxicity for each patient

Le grand débat : cancers du sein pN1mi – pour l’irradiation des aires ganglionnaires

International audienceStandard of care in breast cancer management is well-defined. However, some gray zones still exist, in particular adjuvant radiotherapy indications in case of pN1mi breast cancer. Here we propose to define their prognosis, to underpin the benefit of adjuvant treatments in such patients' management and to define lymphedema risk, which is the most common late side effect of locoregional treatments

Impact de la modulation d’intensité dans l’irradiation des aires ganglionnaires du cancer du sein

International audienceIrradiation of node areas is still a complex challenge in external radiotherapy for breast cancer. Acceptable target coverage is always balanced by protection of organs at risk and patient morphology. Intensity-modulated radiotherapy increases the quality of dose distribution on the planning target volume, but modifies dramatically the irradiation coverage of critical structures in a different way compared to 3D treatment. In this paper we analyze this new technique in breast treatment with node regions, its expected gain and potential risks.L’irradiation des aires ganglionnaires de drainage du sein reste complexe dans le cadre d’une classique radiothérapie conformationnelle tridimensionnelle. La bonne couverture des volumes cibles est souvent compromise par la morphologie de la patiente et la protection des organes à risque. La radiothérapie conformationelle avec modulation d’intensité permet d’améliorer cette couverture mais modifie la distribution de la dose délivrée aux organes à risque par rapport à celle connue avec les techniques passées. Nous rapportons ici l’analyse de cette nouvelle technique, de son gain probable et de ses risques potentiels