Image Guided and Breathing Adapted Radiotherapy of Early Stage Lung Cancer
Lung tumours move with respiration. This must be considered when designing margins for
radiotherapy. This movement can be quantified by fluoroscopy or 4DCT. It is possible to
identify a tumour middle position for planning. This middle position will vary from day to
day and the extent of this variation is not fully known. The aim of this study is to
quantify the variation in tumour middle position during a course of stereotactic body
radiotherapy (SBRT), and thereby be able to design margins for patients that take into
account the full motion span throughout an entire course of SBRT Patients: 15 consecutive
patients with inoperable low stage lung cancer or solitary metastases to the lung (1-2)
referred for SBRT - 45 Gy/3 fractions.
Methods: A gold coil will be implanted into the lung tumour one week before the planning. At
planning and all treatment days supplementary 4DCT of thorax and two orthogonal fluoroscopy
sessions will be performed. Tumour motion in the superior-inferior, medio-lateral and
cranio-caudal direction will be measured and variation in amplitude and baseline for the
tumour motion will be reported.
Perspective: By examining the variation in tumour movement it will be possible design
margins for SBRT, accounting for the full tumour motion span and minimizing the risk of
geographical miss and thereby optimizing the chance for local tumour control.
Endpoint Classification: Safety Study, Intervention Model: Single Group Assignment, Masking: Open Label, Primary Purpose: Basic Science
motion of lung tumours
Gitte F Persson, MD
Denmark: The Regional Committee on Biomedical Research Ethics