2023 North America Conference on Lung Cancer (NACLC) - Posters and Abstracts-PP01.22 (Poster) Single Institution Experience of MRI Guided Radiotherapy for Thoracic Tumors and Clinical Characteristics Impacting Treatment Duty Cycle

PP01.22 (Poster) Single Institution Experience of MRI Guided Radiotherapy for Thoracic Tumors and Clinical Characteristics Impacting Treatment Duty Cycle

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This study reports on the experience of using 0.35T MRI-guided radiotherapy (MRgRT) for thoracic malignancies at a single institution. The researchers aimed to evaluate changes in treatment duty cycle (DC) between the first and final fraction of MRgRT. The study included all patients with intrathoracic tumors treated with MRgRT, and a retrospective chart review was conducted with Institutional Review Board approval.<br /><br />The primary reason for MRgRT (adjacent organ at risk [OAR] vs. motion management [MM] vs. other) was recorded, and the tumor location was classified using the Expanded Hilus grouping. The researchers extracted data on GTV motion, PTV expansions, dose/fractionation, treatment plan time (TPT), and total delivery time (TDT) from the treatment planning system. DC was calculated as TPT/TDT, and the DCs between the first and final fractions were compared using a two-sample t-test.<br /><br />The study included 27 patients with thoracic tumors, including 16 non-small cell lung cancer and 11 thoracic metastases. The median dose/fractionation was 50 Gy/5 fractions, and a total of 169 fractions were delivered, with 30% of them adapted. The DC improved from the first fraction to the final fraction, which was likely attributed to patient familiarity with the treatment. The DC was significantly higher in the final fraction compared to the first fraction.<br /><br />Patients treated for OAR had a higher DC compared to those treated for MM. Patients treated for MM had a higher mean GTV motion compared to those treated for adjacent OAR. Overall, the study suggests that MRgRT can be effective for managing thoracic tumors, and patient familiarity with the treatment can improve treatment duty cycle. The findings have implications for optimizing treatment planning and delivery for thoracic malignancies using MRgRT.

Asset Subtitle

Joseph Miccio

Keywords

0.35T MRI-guided radiotherapy

thoracic malignancies

treatment duty cycle

MRgRT

intrathoracic tumors

chart review

adjacent organ at risk

motion management

Expanded Hilus grouping

GTV motion