Intrafractional rectum anatomy shape prediction based on 3D point cloud representation in online adaptive radiation therapy.

Online Adaptive Radiotherapy for Muscle-Invasive Bladder Cancer: Results of a Pilot Study

Dosimetric Benefits and Practical Pitfalls of Daily Online Adaptive MRI-Guided Stereotactic Radiation Therapy for Pancreatic Cancer

Pan-Canadian assessment of image guided adaptive radiation therapy and the role of the radiation therapist.

Combined Online and Offline Adaptive Radiation Therapy

Assessment of online adaptive MR-guided stereotactic body radiotherapy of liver cancers.

A framework for upskilling Canadian Radiation Therapists for online adaptive radiation therapy.

Combined online and offline adaptive radiation therapy: A dosimetric feasibility study

MR-Guided Online Adaptive Stereotactic Body Radiotherapy (SBRT) of Primary and Metastatic Lung Tumors

Adaptive radiotherapy (ART) involves the continuous adaptation of the radiation plan according to patient- and tumorspecific feedback. In online ART, the plan is optimized in real time during the treatment; in offline ART, the plan is recalculated between treatment sessions. Hybrid linear accelerators with integrated CT, MRI, or PET are required to perform online ART. This review is based on clinically relevant studies on online ART (January 2019 - May 2024) that were retrieved by a selective search in PubMed. Online ART is a new technique for which no phase 3 trials have been published; in contrast, multiple randomized trials are already available for offline ART. The initial findings of a random - ized phase 2 trial of online ART for head and neck cancer showed lower rates of G2 or higher radiation-induced dermatitis (8% vs. 31%, p = 0.05) and a lower dose to the parotid gland (mean dose: 11.5 Gy vs. 16.0 Gy, p = 0.02) with online ART compared to standard radiochemotherapy. Moreover, observational studies show that online ART is feasible and spares organs at risk in patients with esophageal, pancreatic, rectal, and prostatic cancer. Additionally, online ART can enable simulation-free treatment planning and faster initiation of radiotherapy. It is, however, more demanding of time and resources and more costly than standard radiotherapy, and no studies with long-term clinical endpoints are available to date. Initial studies confirm the feasibility of online ART and arouse the hope that it will enable more precise radiotherapy with less damage to surrounding structures. Phase 3 trials are needed so that the patient groups who stand to benefit most from online ART can be identified.

Online adaptive radiotherapy (ART) with frequent imaging has the potential to improve dosimetric accuracy by accounting for anatomical and functional changes during the course of radiotherapy. Presented are three interesting cases that provide an assessment of online adaptive magnetic resonance-guided radiotherapy (MRgRT) for lung stereotactic body radiotherapy (SBRT).The study includes three lung SBRT cases, treated on an MRgRT system where MR images were acquired for planning and prior to each treatment fraction. Prescription dose ranged from 48 to 50 Gy in four to five fractions, normalized to where 95% of the planning target volume (PTV) was covered by 100% of the prescription dose. The process begins with the gross tumor volume (GTV), PTV, spinal cord, lungs, heart, and esophagus being delineated on the planning MRI. The treatment plan was then generated using a step-and-shoot intensity modulated radiotherapy (IMRT) technique, which utilized a Monte Carlo dose calculation. Next, the target and organs at risk (OAR) contours from the planning MRI were deformably propagated to the daily setup MRIs. These deformed contours were reviewed and modified by the physician. To determine the efficacy of ART, two different strategies were explored: 1) Calculating the plan created for the planning MR on each fraction setup MR dataset (Non-Adapt) and 2) creating a new optimized IMRT plan on the fraction setup MR dataset (FxAdapt). The treatment plans from both strategies were compared using the clinical dose-volume constraints.PTV coverage constraints were not met for 33% Non-Adapt fractions; all FxAdapt fractions met this constraint. Eighty-eight percent of all OAR constraints studied were better on FxAdapt plans, while 12% of OAR constraints were superior on Non-Adapt fractions. The OAR that garnered the largest benefit would be the uninvolved lung, with superior sparing in 92% of the FxAdapt studied. Similar, but less pronounced, benefits from adaptive planning were experienced for the spinal cord, chest wall, and esophagus.Online adaptive MR-guided lung SBRT can provide better target conformality and homogeneity and OAR sparing compared with non-adaptive SBRT in selected cases. Conversely, if the PTV isn’t adjacent to multiple OARs, then the benefit from ART may be limited. Further studies, which incorporate a larger cohort of patients with uniform prescriptions, are needed to thoroughly evaluate the benefits of daily online ART during MRgRT.

Reducing Number of Treatment Fractions for Patients With Abdominal Lymph Node Oligometastases: The Need for Online Adaptive Radiation Therapy to Provide Personalized Adaptive Fractionation.

Creation and Implementation of an Interdisciplinary Workflow for CBCT-Based Online Adaptive Radiotherapy

Dosimetric Benefits of Online Adaptive Radiotherapy in Nasopharyngeal Carcinoma

Assessment of Online Adaptive MR-Guided SBRT of Liver Cancers

Optimizing Workflow for Cone Beam Computed Tomography-Based Online Adaptive Radiation Therapy Toward Reduced Physician Involvement