Mid-Ventilation PTV Approach for Stereotactic Ablative Body Radiotherapy in Stage I Non-Small-Cell Lung Carcinoma: Implementation of a Single-System Workflow

Abstract

IntroductionThe Mid-Ventilation (MidV) approach is an alternative to the Internal Target Volume (ITV) method for generating a Planning Target Volume (PTV) in lung Stereotactic Ablative Radiotherapy (SABR). The MidV approach aims to reduce PTV volumes, minimizing the volume of the normal lung tissue irradiated and potentially reducing damage to normal surrounding lung tissues whilst providing very high local control rates.AimsThis study aimed to outline the development and validation of a mid-ventilation workflow developed at our institution using the Eclipse (v15.6) treatment planning system (TPS) and Aria (v16.0) oncology information system. This workflow uses a combination of deformable image registration (DIR) of 4DCT images, generation of 4D contour statistics in Eclipse, and an embedded PTV calculation spreadsheet in Aria with the purpose of creating an integrated, efficient, and seamless workflow.MethodsThe workflow was retrospectively tested on 10 patients who had previously participated in the Phase II Study of SABR for Stage I Non-Small-Cell Lung Carcinoma (NSCLC). Treatment plans were retrospectively generated and compared using both ITV and MidV methods.ResultsMidV treatment plans demonstrated PTV reductions compared with the ITV treatment plans with a corresponding reduction in the Mean Lung Dose (MLD) and lung V20Gy. The geometric performance of the Eclipse DIR algorithm yielded a mean distance to agreement of 0.86 mm relative to the manual user contours.ConclusionThe results of this study confirmed the clinical feasibility and application of the MidV workflow using Eclipse and Aria. It is postulated that the ease and integrated nature of this MidV workflow in a single TPS will facilitate the uptake of this method.

Note:
Funding Information: No funding has been received towards the assembly of this paper.

Declaration of Interests: Author Joel Poder has received honoraria from Varian Medical Systems for a virtual presentation on a topic unrelated to the subject of this manuscript. All the remaining authors declare no conflict of interest.

Ethics Approval Statement: This study is a retrospective study and had ethical approval as follows: 2021/ETH11990: Implementation of Mid-Ventilation Stereotactic Ablative Body Radiotherapy for Stage I Non-Small-Cell Lung Carcinoma. This application was reviewed as a low- or negligible-risk review pathway by the South Eastern Sydney Local Health District ethics committee. Patient consent was obtained by all patients within this research.

Keywords: Lung SABR, Mid-Ventilation & Early-State Lung Cancer.