MLC tracking for lung SABR is feasible, efficient and delivers high-precision target dose and lower normal tissue dose

Jeremy Booth; Vincent Caillet; Adam Briggs; Nicholas Hardcastle; Georgios Angelis; Dasantha Jayamanne; Meegan Shepherd; Alexander Podreka; Kathryn Szymura; Doan Trang Nguyen; Per Poulsen; Ricky O'Brien; Benjamin Harris; Carol Haddad; Thomas Eade; Paul Keall

doi:10.1016/j.radonc.2020.10.036

MLC tracking for lung SABR is feasible, efficient and delivers high-precision target dose and lower normal tissue dose

Radiother Oncol. 2021 Feb:155:131-137. doi: 10.1016/j.radonc.2020.10.036. Epub 2020 Nov 3.

Authors

Jeremy Booth¹, Vincent Caillet², Adam Briggs³, Nicholas Hardcastle⁴, Georgios Angelis⁵, Dasantha Jayamanne⁶, Meegan Shepherd³, Alexander Podreka³, Kathryn Szymura³, Doan Trang Nguyen⁷, Per Poulsen⁸, Ricky O'Brien⁹, Benjamin Harris¹⁰, Carol Haddad³, Thomas Eade⁶, Paul Keall⁹

Affiliations

¹ Northern Sydney Cancer Centre, Royal North Shore Hospital, Sydney, Australia; Institute of Medical Physics, School of Physics, University of Sydney, Australia. Electronic address: Jeremy.Booth@health.nsw.gov.au.
² Northern Sydney Cancer Centre, Royal North Shore Hospital, Sydney, Australia; ACRF Image X Institute, Central Clinical School, University of Sydney, Australia.
³ Northern Sydney Cancer Centre, Royal North Shore Hospital, Sydney, Australia.
⁴ Department of Physical Sciences, Peter MacCallum Cancer Centre, Melbourne, Australia; Centre for Medical Radiation Physics, University of Wollongong, Australia.
⁵ Northern Sydney Cancer Centre, Royal North Shore Hospital, Sydney, Australia; Institute of Medical Physics, School of Physics, University of Sydney, Australia.
⁶ Northern Sydney Cancer Centre, Royal North Shore Hospital, Sydney, Australia; Northern Clinical School, University of Sydney, Australia.
⁷ ACRF Image X Institute, Central Clinical School, University of Sydney, Australia; School of Biomedical Engineering, University of Technology Sydney, Australia.
⁸ Department of Oncology and Danish Center for Particle Therapy, Aarhus University Hospital, Aarhus, Denmark.
⁹ ACRF Image X Institute, Central Clinical School, University of Sydney, Australia.
¹⁰ Department of Respiratory and Sleep Medicine, Royal North Shore Hospital, Sydney, Australia.

PMID: 33152399
DOI: 10.1016/j.radonc.2020.10.036

Abstract

Background and purpose: The purpose of this work is to present the clinical experience from the first-in-human trial of real-time tumor targeting via MLC tracking for stereotactic ablative body radiotherapy (SABR) of lung lesions.

Methods and materials: Seventeen patients with stage 1 non-small cell lung cancer (NSCLC) or lung metastases were included in a study of electromagnetic transponder-guided MLC tracking for SABR (NCT02514512). Patients had electromagnetic transponders inserted near the tumor. An MLC tracking SABR plan was generated with planning target volume (PTV) expanded 5 mm from the end-exhale gross tumor volume (GTV). A clinically approved comparator plan was generated with PTV expanded 5 mm from a 4DCT-derived internal target volume (ITV). Treatment was delivered using a standard linear accelerator to continuously adapt the MLC based on transponder motion. Treated volumes and reconstructed delivered dose were compared between MLC tracking and comparator ITV-based treatment.

Results: All seventeen patients were successfully treated with MLC tracking (70 successful fractions). MLC tracking treatment delivery time averaged 8 minutes. The time from the start of CBCT to the end of treatment averaged 22 minutes. The MLC tracking PTV for 16/17 patients was smaller than the ITV-based PTV (range -1.6% to 44% reduction, or -0.6 to 18 cc). Reductions in mean lung dose (27 cGy) and V20Gy (50 cc) were statistically significant (p < 0.02). Reconstruction of treatment doses confirmed a statistically significant improvement in delivered GTV D98% (p < 0.05) from planned dose compared with the ITV-based plans.

Conclusion: The first treatments with lung MLC tracking have been successfully performed in seventeen SABR patients. MLC tracking for lung SABR is feasible, efficient and delivers high-precision target dose and lower normal tissue dose.

Keywords: Adaptive radiotherapy; Lung SABR; MLC tracking.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Carcinoma, Non-Small-Cell Lung* / diagnostic imaging
Carcinoma, Non-Small-Cell Lung* / radiotherapy
Carcinoma, Non-Small-Cell Lung* / surgery
Humans
Lung
Lung Neoplasms* / radiotherapy
Lung Neoplasms* / surgery
Radiosurgery*
Radiotherapy Dosage
Radiotherapy Planning, Computer-Assisted
Radiotherapy, Intensity-Modulated*

Associated data

ClinicalTrials.gov/NCT02514512