Estimation of delivered dose to lung tumours considering setup uncertainties and breathing motion in a cohort of patients treated with stereotactic body radiation therapy

Kristin Karlsson; Ingmar Lax; Elias Lindbäck; Vitali Grozman; Karin Lindberg; Peter Wersäll; Gavin Poludniowski

doi:10.1016/j.ejmp.2021.06.015

Estimation of delivered dose to lung tumours considering setup uncertainties and breathing motion in a cohort of patients treated with stereotactic body radiation therapy

Phys Med. 2021 Aug:88:53-64. doi: 10.1016/j.ejmp.2021.06.015. Epub 2021 Jun 25.

Authors

Kristin Karlsson¹, Ingmar Lax², Elias Lindbäck³, Vitali Grozman⁴, Karin Lindberg⁵, Peter Wersäll⁶, Gavin Poludniowski⁷

Affiliations

¹ Section of Radiotherapy Physics and Engineering, Department of Medical Radiation Physics and Nuclear Medicine, Karolinska University Hospital, Stockholm, Sweden; Department of Oncology and Pathology, Karolinska Institutet, Stockholm, Sweden. Electronic address: [email protected].
² Section of Radiotherapy Physics and Engineering, Department of Medical Radiation Physics and Nuclear Medicine, Karolinska University Hospital, Stockholm, Sweden; Department of Oncology and Pathology, Karolinska Institutet, Stockholm, Sweden. Electronic address: [email protected].
³ Section of Radiotherapy Physics and Engineering, Department of Medical Radiation Physics and Nuclear Medicine, Karolinska University Hospital, Stockholm, Sweden; Department of Oncology and Pathology, Karolinska Institutet, Stockholm, Sweden. Electronic address: [email protected].
⁴ Section of Thoracic Radiology, Department of Radiology, Karolinska University Hospital, Stockholm, Sweden; Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden. Electronic address: [email protected].
⁵ Department of Oncology and Pathology, Karolinska Institutet, Stockholm, Sweden; Section of Head, Neck, Lung and Skin Tumours, Department of Cancer, Karolinska University Hospital, Stockholm, Sweden. Electronic address: [email protected].
⁶ Department of Oncology and Pathology, Karolinska Institutet, Stockholm, Sweden; Section of Radiotherapy, Department of Cancer, Karolinska University Hospital, Stockholm, Sweden. Electronic address: [email protected].
⁷ Department of Oncology and Pathology, Karolinska Institutet, Stockholm, Sweden; Department of Medical Radiation Physics and Nuclear Medicine, Karolinska University Hospital, Stockholm, Sweden. Electronic address: [email protected].

PMID: 34175747
DOI: 10.1016/j.ejmp.2021.06.015

Abstract

Introduction: Dose-response relationships for local control of lung tumours treated with stereotactic body radiotherapy (SBRT) have proved ambiguous, however, these have been based on the prescribed or planned dose. Delivered dose to the target may be a better predictor for local control. In this study, the probability of the delivered minimum dose to the clinical target volume (CTV) in relation to the prescribed dose was estimated for a cohort of patients, considering geometrical uncertainties.

Materials and methods: Delivered doses were retrospectively simulated for 50 patients treated with SBRT for lung tumours, comparing two image-guidance techniques: pre-treatment verification computed tomography (IG1) and online cone-beam computed tomography (IG2). The prescribed dose was typically to the 67% isodose line of the treatment plan. Simulations used in-house software that shifted the static planned dose according to a breathing motion and sampled setup/matching errors. Each treatment was repeatedly simulated, generating a multiplicity of dose-volume histograms (DVH). From these, tumour-specific and population-averaged statistics were derived.

Results: For IG1, the probability that the minimum CTV dose (D_98%) exceeded 100% of the prescribed dose was 90%. With IG2, this probability increased to 99%.

Conclusions: Doses below the prescribed dose were delivered to a considerably larger part of the population prior to the introduction of online soft-tissue image-guidance. However, there is no clear evidence that this impacts local control, when compared to previous published data.

Keywords: Delivered CTV dose; Dose-shift; Geometrical uncertainties; Stereotactic body radiation therapy.

MeSH terms

Humans
Lung Neoplasms* / radiotherapy
Lung Neoplasms* / surgery
Radiosurgery*
Radiotherapy Dosage
Radiotherapy Planning, Computer-Assisted
Retrospective Studies