Magnetic Resonance Imaging-guided Adaptive Radiotherapy for Large Brain Metastases

Displacement and Deformation Analysis of Adaptive Radiotherapy Based on MR-Linac for Large Brain Metastases

This study is an ambispective cohort study to evaluate the displacement and deformation of large brain metastases (BM) treated with magnetic resonance imaging-guided adaptive radiotherapy (MRIgART)

All patients had a pathologically confirmed malignant cancer and were diagnosed with brain metastases (BM) by enhanced magnetic resonance imaging (MRI) with BM volume of 2cm and above. All patients received Unity MR-linac adaptive radiotherapy. Gross tumor volume (GTV) and organs at risk (OARs) were re-delineated for every image set and analyzed for displacement and deformation.

Inclusion Criteria:

1. Age ≥ 18 years; KPS score ≥ 60.
2. pathologically confirmed lung cancer.
3. diagnosed with brain metastases by enhanced MRI.
4. BM volume ≥ 2cm.
5. Anticipated time to survival>3 months.
6. Treated with Unity MR-linac.
7. Good compliance; Able to stay still in supine position for 45 minutes and above.

Exclusion Criteria:

1. Fail to complete radiotherapy as planned; Anticipated time to survival less than 3 months.
2. Suffer from severe back pain in supine position, unable to receive Unity MR-linac.
3. Suffer from severe claustrophobia.
4. Incomplete pre-Unity image data.