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The effect of irregular breathing patterns on internal target volumes in four-dimensional CT and cone-beam CT images in the context of stereotactic lung radiotherapy

2013; Wiley; Volume: 40; Issue: 2 Linguagem: Inglês

10.1118/1.4773310

2473-4209

Natalie Clements, Tomas Kron, Rick Franich, Leon Dunn, Paul Roxby, Yolanda Aarons, Brent Chesson, Shankar Siva, Danny Duplan, David Ball,

Lung Cancer Diagnosis and Treatment

Purpose: Stereotactic lung radiotherapy is complicated by tumour motion from patient respiration.Four-dimensional CT (4DCT) imaging is a motion compensation method used in treatment planning to generate a maximum intensity projection (MIP) internal target volume (ITV).Image guided radiotherapy during treatment may involve acquiring a volumetric cone-beam CT (CBCT) image and visually aligning the tumour to the planning 4DCT MIP ITV contour.Moving targets imaged with CBCT can appear blurred and currently there are no studies reporting on the effect that irregular breathing patterns have on CBCT volumes and their alignment to 4DCT MIP ITV contours.The objective of this work was therefore to image a phantom moving with irregular breathing patterns to determine whether any configurations resulted in errors in volume contouring or alignment.Methods: A Perspex thorax phantom was used to simulate a patient.Three wooden 'lung' inserts with embedded Perspex 'lesions' were moved up to 4 cm with computer-generated motion patterns, and up to 1 cm with patient-specific breathing patterns.The phantom was imaged on 4DCT and CBCT with the same acquisition settings used for stereotactic lung patients in the clinic and the volumes on all