Forecasting patient-specific dosimetric benefit from daily online adaptive radiotherapy for cervical cancer

Abstract

Objective: Adaptive Radiotherapy (ART) is an emerging technique for treating cancer patients which facilitates higher delivery accuracy and has the potential to reduce toxicity. However, ART is also resource-intensive, requiring extra human and machine time compared to standard treatment methods. In this analysis, we sought to predict the subset of node-negative cervical cancer patients with the greatest benefit from ART, so resources might be properly allocated to the highest-yield patients.

Approach: CT images, initial plan data, and on-treatment Cone-Beam CT (CBCT) images for 20 retrospective cervical cancer patients were used to simulate doses from daily non-adaptive and adaptive techniques. We evaluated the correlation (R2) between dose and volume metrics from initial treatment plans and the dosimetric benefits to the Bowel V40Gy, Bowel V45Gy, Bladder Dmean, and Rectum Dmean from adaptive radiotherapy using reduced 3mm or 5mm CTV-to-PTV margins. The LASSO technique was used to identify the most predictive metrics for Bowel V40Gy. The three highest performing metrics were used to build multivariate models with leave-one-out validation for Bowel V40Gy. 

Main Results: Patients with higher initial bowel doses were correlated with the largest decreases in Bowel V40Gy from daily adaptation (linear best fit R2=0.77 for a 3mm PTV margin and R2=0.8 for a 5mm PTV margin). Other metrics had intermediate or no correlation. Selected covariates for the multivariate model were differences in the initial Bowel V40Gy and Bladder Dmean using standard versus reduced margins and the initial bladder volume. Leave-one-out validation had an R2 of 0.66 between predicted and true adaptive Bowel V40Gy benefits for both margins. 

Significance: The resulting models could be used to prospectively triage cervical cancer patients on or off daily adaptation to optimally manage clinical resources. Additionally, this work presents a critical foundation for predicting benefits from daily adaptation that can be extended to other patient cohorts.

Simulation and pre-planning omitted radiotherapy (SPORT): a feasibility study for prostate cancer

“…The attending physician then reviews the quality of both plans before deciding which to use for treatment. Numerus studies have demonstrated the feasibility of utilization of the Ethos system for ART for different cancer sites with real patient cases or emulation studies following the standard adaptive workflow [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39]. The goal of this study is to test our novel workflow, in which the required individually optimized preplan is replaced by a properly selected plan from a pre-built plan library.…”

Unlocking the adaptive advantage: correlation and machine learning classification to identify optimal online adaptive stereotactic partial breast candidates

“…This process was repeated for each of five treatment fractions. Reproduced fromGhimire et al (2023). © IOP Publishing Ltd. All rights reserved.…”