Assessment and topographic characterization of locoregional recurrences in head and neck tumours

Purpose: To evaluate the differences between three methods of classification of recurrences in patients with head and neck tumours treated with Radiation Therapy (RT). Materials and methods: 367 patients with head and neck tumours were included in the study. Tumour recurrences were delineated in the CT images taken during patient follow-up and deformable registration was used to transfer this volume into the planning CT. The methods used to classify recurrences were: methodCTV quantified the intersection volume between the recurrence and the Clinical Target Volume (CTV); methodTV quantified the intersection between the Treated Volume and the recurrence (for method CTV and TV, recurrences were classified in-field if more than 95% of their volume were inside the volume of interest, marginal if the intersection was between 20-95% and outfield otherwise); and methodCOM was based on the position of the Centre Of Mass of the recurrence. A dose assessment in the recurrence volume was also made. Results: The 2-year Kaplan-Meier locoregional recurrence incidence was 10%. Tumour recurrences occurred in 22 patients in a mean time of 16.5 ± 9.4 months resulting in 28 recurrence volumes. The percentage of in-field recurrences for methods CTV, TV and COM was 7%, 43% and 50%, respectively. Agreement between the three methods in characterizing individually in-field and marginal recurrences was found only in six cases. Methods CTV and COM agreed in 14. The percentage of outfield recurrences was 29% using all methods. For local recurrences (in-field or marginal to gross disease) the average difference between the prescribed dose and D 98% in the recurrence volume was -5.2 ± 3.5% (range: -10.1%-0.9%). Conclusions: The classification of in-field and marginal recurrences is very dependent on the method used to characterize recurrences. Using methods TV and COM the largest percentage of tumour recurrences occurred in-field in tissues irradiated with high doses. Keywords: Head and neck tumours, Radiation therapy, Characterization of tumour recurrences, Geometric methods, Dosimetric assessmen

ITV versus mid-ventilation for treatment planning in lung SBRT: a comparison of target coverage and PTV adequacy by using in-treatment 4D cone beam CT

International audienceBackground The internal target volume (ITV) approach and the mid-ventilation (MidV) concept are the two main respiratory motion-management strategies under free breathing. The purpose of this work was to compare the actual in-treatment target coverage during volumetric modulated arctherapy (VMAT) delivered through both ITV-based and MidV-based planning target volume (PTV) and to provide knowledge in choosing the optimal PTV for stereotactic body radiotherapy (SBRT) for lung lesions.Methods and materials Thirty-two lung cancer patients treated by a VMAT technique were included in the study. For each fraction, the mean time-weighted position of the target was localized by using a 4-dimensional cone-beam CT (4D-CBCT)-based image guidance procedure. The respiratory-correlated location of the gross tumor volume (GTV) during treatment delivery was determined for each fraction by using in-treatment 4D-CBCT images acquired concurrently with VMAT delivery (4D-CBCTin-treat). The GTV was delineated from each of the ten respiratory phase-sorted 4D-CBCTin-treat datasets for each fraction. We defined target coverage as the average percentage of the GTV included within the PTV during the patient's breathing cycle averaged over the treatment course. Target coverage and PTVs were reported for a MidV-based PTV (PTVMidV) using dose-probabilistic margins and three ITV-based PTVs using isotropic margins of 5 mm (PTVITV + 5mm), 4 mm (PTVITV + 4mm) and 3 mm (PTVITV + 3mm). The in-treatment baseline displacements and target motion amplitudes were reported to evaluate the impact of both parameters on target coverage.Results Overall, 100 4D-CBCTin-treat images were analyzed. The mean target coverage was 98.6, 99.6, 98.9 and 97.2% for PTVMidV, PTVITV + 5mm, PTVITV + 4mm and PTVITV + 3mm, respectively. All the PTV margins led to a target coverage per treatment higher than 95% in at least 90% of the evaluated cases. Compared to PTVITV + 5mm, PTVMidV, PTVITV + 4mm and PTVITV + 3mm had mean PTV reductions of 16, 19 and 33%, respectively.Conclusion When implementing VMAT with 4D-CBCT-based image guidance, an ITV-based approach with a tighter margin than the commonly used 5 mm margin remains an alternative to the MidV-based approach for reducing healthy tissue exposure in lung SBRT. Compared to PTVMidV, PTVITV + 3mm significantly reduced the PTV while still maintaining an adequate in-treatment target coverage

Review of clinical applications of radiation-enhancing nanoparticles

International audienceBut: Des preuves cliniques des effets d’amélioration des rayonnements des nanoparticules ont émergé.Matériaux et méthodes: Nous avons effectué des recherches dans la littérature en anglais et Français sur PubMed jusqu’en octobre 2019. Le terme de recherche était « nanoparticule » ET « radiothérapie », donnant 1270 résultats.Résultats: Les deux principaux NP utilisés dans les essais cliniques étaient l’oxyde de hafnium et le gadolinium impliquant un total de 229 patients. L’oxyde de hafnium NP a été utilisé dans trois essais de phase 1/2 sur le sarcome, le carcinome épidermoïde de la tête et du cou ou le cancer du foie et dans un essai de phase 2/3. Six essais cliniques de phase 1/2 sont en cours pour évaluer la combinaison de NP et de RT à base de gadolinium pour le traitement des métastases cérébrales et du cancer du col de l’utérus.Conclusion: Jusqu’à présent, les nanoparticules d’oxyde de hafnium intratumorales étaient sûres et amélioraient leur efficacité dans le sarcome localement avancé

Validation of transit EPID and application for Head and Neck adaptive radiotherapy

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Voxel-based identification of local recurrence sub-regions from pre-treatment PET/CT for locally advanced head and neck cancers

International audienceBackground - Overall, 40% of patients with a locally advanced head and neck cancer (LAHNC) treated by chemoradiotherapy (CRT) present local recurrence within 2 years after the treatment. The aims of this study were to characterize voxel-wise the sub-regions where tumor recurrence appear and to predict their location from pre-treatment F-fluorodeoxyglucose (FDG) positron emission tomography (PET) images. Materials and methods - Twenty-six patients with local failure after treatment were included in this study. Local recurrence volume was identified by co-registering pre-treatment and recurrent PET/CT images using a customized rigid registration algorithm. A large set of voxel-wise features were extracted from pre-treatment PET to train a random forest model allowing to predict local recurrence at the voxel level. Results - Out of 26 expert-assessed registrations, 15 provided enough accuracy to identify recurrence volumes and were included for further analysis. Recurrence volume represented on average 23% of the initial tumor volume. The MTV with a threshold of 50% of SUVmax plus a 3D margin of 10 mm covered on average 89.8% of the recurrence and 96.9% of the initial tumor. SUV and MTV alone were not sufficient to identify the area of recurrence. Using a random forest model, 15 parameters, combining radiomics and spatial location, were identified, allowing to predict the recurrence sub-regions with a median area under the receiver operating curve of 0.71 (range 0.14-0.91). Conclusion - As opposed to regional comparisons which do not bring enough evidence for accurate prediction of recurrence volume, a voxel-wise analysis of FDG-uptake features suggested a potential to predict recurrence with enough accuracy to consider tailoring CRT by dose escalation within likely radioresistant regions

Characterization of recurrence origin using pre-treatment PET/CT for head and neck cancers

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Adaptive radiotherapy in head and neck cancer to correct tumor underdose and parotid gland overdose

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