Volumetric and dosimetric impact of Post-Surgical MRI guided radiotherapy for Glioblastoma: A pilot study

Objectives: Glioblastoma (GBM) radiotherapy (RT) target delineation requires MRI, ideally concurrent with CT simulation (pre-RT MRI). Due to limited MRI availability, <72 h post-surgery MRI is commonly used instead. Whilst previous investigations assessed volumetric differences between post-surgical and pre-RT delineations, dosimetric impact remains unknown. We quantify volumetric and dosimetric impact of using post-surgical MRI for GBM target delineation. Methods: Gross tumour volumes (GTVs) for five GBM patients receiving chemo-RT with post-surgical and pre-RT MRIs were delineated by three independent observers. Planning target volumes (PTVs) and RT plans were generated for each GTV. Volumetric and dosimetric differences were assessed through: absolute volumes, volume-distance histograms, and dose-volume histogram statistics. Results: Post-surgical MRI delineations had significantly (p < 0.05) larger GTV and PTV volumes (median 16.7 and 64.4 cm3 respectively). Post-surgical RT plans, applied to pre-RT delineations, had significantly decreased (p < 0.01) median PTV doses (ΔD99% = −8.1 Gy and ΔD95% = −2.0 Gy). Median organ at risk (OAR) dose increases (brainstem ΔD5% =+0.8, normal brain mean dose =+2.9 and normal brain ΔD10% = 5.3 Gy) were observed. Conclusion: Post-surgical MRI delineation significantly impacted RT planning, with larger normal-appearing tissue volumes irradiated and increased OAR doses, despite a reduced coverage of the pre-RT defined target. Advances in knowledge: We believe this is the first investigation assessing the dosimetric impact of using post-surgical MRI for GBM target delineation. It highlights the potential of significantly degraded RT plans, showing the clinical-need for dedicated MRI for GBM RT.

Comprehensive and Clinically Accurate Head and Neck Organs at Risk Delineation via Stratified Deep Learning: A Large-scale Multi-Institutional Study

Accurate organ at risk (OAR) segmentation is critical to reduce the radiotherapy post-treatment complications. Consensus guidelines recommend a set of more than 40 OARs in the head and neck (H&N) region, however, due to the predictable prohibitive labor-cost of this task, most institutions choose a substantially simplified protocol by delineating a smaller subset of OARs and neglecting the dose distributions associated with other OARs. In this work we propose a novel, automated and highly effective stratified OAR segmentation (SOARS) system using deep learning to precisely delineate a comprehensive set of 42 H&N OARs. SOARS stratifies 42 OARs into anchor, mid-level, and small & hard subcategories, with specifically derived neural network architectures for each category by neural architecture search (NAS) principles. We built SOARS models using 176 training patients in an internal institution and independently evaluated on 1327 external patients across six different institutions. It consistently outperformed other state-of-the-art methods by at least 3-5% in Dice score for each institutional evaluation (up to 36% relative error reduction in other metrics). More importantly, extensive multi-user studies evidently demonstrated that 98% of the SOARS predictions need only very minor or no revisions for direct clinical acceptance (saving 90% radiation oncologists workload), and their segmentation and dosimetric accuracy are within or smaller than the inter-user variation. These findings confirmed the strong clinical applicability of SOARS for the OAR delineation process in H&N cancer radiotherapy workflows, with improved efficiency, comprehensiveness, and quality.

Radiation therapy for prostate cancer: What’s the best in 2021

Radiotherapy is highly involved in the management of prostate cancer. Its features and potential applications experienced a radical evolution over last decades, as they are associated to the continuous evolution of available technology and current oncological innovations. Some application of radiotherapy like brachytherapy have been recently enriched by innovative features and multidisciplinary dedications. In this report we aim to put some questions regarding the following issues regarding multiple aspects of modern application of radiation oncology: the current application of radiation oncology; the modern role of stereotactic body radiotherapy (SBRT) for both the management of primary lesions and for lymph-nodal recurrence; the management of the oligometastatic presentations; the role of brachytherapy; the aid played by the application of the organ at risk spacer (spacer OAR), fiducial markers, electromagnetic tracking systems and on-line Magnetic Resonance guided radiotherapy (MRgRT), and the role of the new opportunity represented by radiomic analysis.

Analysis Of Dose At 3D-Crt And Imrt Techniques In Left Breast Cancer Case With Hypofractionation Using Deep Inspiration Breath-Hold (Dibh)

In terms of breast cancer radiation treatment, it has radiation using the 3D-Conformal Radiotherapy (3D-CRT) technique and the continuation of the 3D-CRT technique, namely the Intensity Modulated Radiation Therapy (IMRT) technique. This study aims to evaluate the dosage aspects of PTV and OAR between the 3D-CRT and IMRT techniques in cases of left breast cancer with hypofractionation using the Deep Inspiration Breath Hold (DIBH) method using the Conformity Index (CI) and Homogeneity Index (H.I.) and H.I. organ at risk uses tolerance limits. This type of research is comparative quantitative with ten samples with primary data conducted at Siloam T.B. Hospital. Simatupang from November 2019 to April 2020. The research was carried out in the form of radiation planning with 3D-CRT techniques and IMRT techniques, and the results of planning both techniques were evaluated between 3D-CRT techniques and IMRT techniques through PTV evaluations using CI and H.I. values. Furthermore, the organs at risk use tolerance limits on each organ. The results showed the assessment between 3D-CRT and IMRT on PTV and organs at risk received different doses. The PTV shows the CI value, which is almost the same as the difference of 0.034, and there is a slight difference in H.I. with an average value in the IMRT technique of 0.07 and 3D-CRT of 0.11, and it can be seen that the IMRT is slightly superior because the excellent H.I. value is the closest to 0. Then at the dose of organ at risk received by the sample, the 3D-CRT technique is slightly superior by obtaining a lower dose that obtains the difference in the heart by 0.53%, lung by 3.46%, spinal cord by 6.51 Gy, esophagus at 4.5 Gy, and larynx at 5.18 Gy.