Clinical 3D/4D cumulative proton dose assessment methods for thoracic tumours with large motion. (May 2023)

• Record Type: Journal Article
• Authors: Visser, Sabine; Korevaar, Erik W.; Muijs, Christina T.; Wijsman, Robin; Langendijk, Johannes A.; Pisciotta, Pietro; Gutteres Marmitt, Gabriel; O. Ribeiro, Cássia; Both, Stefan
• Is Part Of: Radiotherapy and oncology. Volume 182(2023)
• Publication Date: 2023-05
• Subjects: Lung cancer -- Oesophageal cancer -- Large motion -- Intensity-modulated proton therapy -- 4D dose assessment -- Dose accumulation; Oncology -- Periodicals; Radiotherapy -- Periodicals; Tumors -- Periodicals; Medical Oncology -- Periodicals; Neoplasms -- radiotherapy -- Periodicals; Radiotherapy -- Periodicals; Radiothérapie -- Périodiques; Cancérologie -- Périodiques; Tumeurs -- Périodiques; Electronic journals; 616.9940642
• DOI: 10.1016/j.radonc.2023.109575
• Languages: English
• ISSNs: 0167-8140

Abstract

Highlights: This study describes the first clinical experiences with the IMPT treatment of large moving target volumes in terms of robustness. Comprehensive 3D and 4D robustness evaluation methods were explored to assess target coverage and OAR dose in the clinical IMPT treatment of large movers. Adequate course-wise target dose coverage was assured for IMPT for intra-thoracic tumours with large motion (10–17 mm). The influence of anatomical changes, setup and range errors was larger than the effect of respiratory motion on target and OAR dose robustness in fractionated IMPT treatments. Offline adaptation based on weekly imaging seems sufficient to ensure adequate course-wise target coverage. Abstract: Purpose: Despite the anticipated clinical benefits of intensity-modulated proton therapy (IMPT), plan robustness may be compromised due to its sensitivity to patient treatment uncertainties, especially for tumours with large motion. In this study, we investigated treatment course-wise plan robustness for intra-thoracic tumours with large motion comparing a 4D pre-clinical evaluation method (4DREM) to our clinical 3D/4D dose reconstruction and accumulation methods. Materials and methods: Twenty patients with large target motion (>10 mm) were treated with five times layered rescanned IMPT. The 3D-robust optimised plans were generated on the averaged planning 4DCT. Using multiple 4DCTs, treatment plan robustness was assessed on a weekly and treatment course-wise basis through the 3D robustness evaluation method (3DREM, based on averaged 4DCTs), the 4D robustness evaluation method (4DREM, including the time structure of treatment delivery and 4DCT phases) and 4D dose reconstruction and accumulation (4DREAL, based on fraction-wise information). Results: Baseline target motion for all patients ranged from 11–17 mm. For the offline adapted course-wise dose assessment, adequate target dose coverage was found for all patients. The target volume receiving 95% of the prescription dose was consistent between methods with 16/20 patients showing differences < 1%. 4DREAL showed the highest target coverage (99.8 ± 0.6%, p < 0.001), while no differences were observed between 3DREM and 4DREM (99.3 ± 1.3% and 99.4 ± 1.1%, respectively). Conclusion: Our results show that intra-thoracic tumours can be adequately treated with IMPT in free breathing for target motion amplitudes up to 17 mm employing any of the accumulation methods. Anatomical changes, setup and range errors demonstrated a more severe impact on target coverage than motion in these patients treated with fractionated proton radiotherapy.