Repeated deep-inspiration breath-hold CT scans at planning underestimate the actual motion between breath-holds at treatment for lung cancer and lymphoma patients

Repeated deep-inspiration breath-hold CT scans at planning underestimate the actual motion between breath-holds at treatment for lung cancer and lymphoma patients

•DIBH variations are smaller at CT-scanning than between pre- and post-treatment CBCTs.•Lung tumours show larger intra-fractional DIBH variations than lymph nodes.•Rescanning and repeated training reduce intra-fractional baseline shifts.•Intra-fractional baseline shifts vary greatly between patients...

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Bibliographic Details
Published in:Radiotherapy and oncology Vol. 188; p. 109887
Main Authors: Hoffmann, Lone, Ehmsen, ML, Hansen, J., Hansen, R., Knap, MM, Mortensen, HR, Poulsen, PR, Ravkilde, T., Rose, HK, Schmidt, HH, Worm, ES, Møller, DS
Format: Journal Article
Language:English
Published: Elsevier B.V 01-11-2023
Subjects:
DIBH
Intra-fraction
Lung cancer
Lymphoma
DIBH
Intra-fraction
Lymphoma
Lung cancer
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Summary:•DIBH variations are smaller at CT-scanning than between pre- and post-treatment CBCTs.•Lung tumours show larger intra-fractional DIBH variations than lymph nodes.•Rescanning and repeated training reduce intra-fractional baseline shifts.•Intra-fractional baseline shifts vary greatly between patients. Deep-inspiration breath-hold (DIBH) during radiotherapy may reduce dose to the lungs and heart compared to treatment in free breathing. However, intra-fractional target shifts between several breath-holds may decrease target coverage. We compared target shifts between four DIBHs at the planning-CT session with those measured on CBCT-scans obtained pre- and post-DIBH treatments. Twenty-nine lung cancer and nine lymphoma patients were treated in DIBH. An external gating block was used as surrogate for the DIBH-level with a window of 2 mm. Four DIBH CT-scans were acquired: one for planning (CTDIBH3) and three additional (CTDIBH1,2,4) to assess the intra-DIBH target shifts at scanning by registration to CTDIBH3. During treatment, pre-treatment (CBCTpre) and post-treatment (CBCTpost) scans were acquired. For each pair of CBCTpre/post, the target intra-DIBH shift was determined. For lung cancer, tumour (GTV-Tlung) and lymph nodes (GTV-Nlung) were analysed separately. Group mean (GM), systematic and random errors, and GM for the absolute maximum shifts (GMmax) were calculated for the shifts between CTDIBH1,2,3,4 and between CBCTpre/post. For GTV-Tlung, GMmax was larger at CBCT than CT in all directions. GMmax in cranio-caudal direction was 3.3 mm (CT)and 6.1 mm (CBCT). The standard deviations of the shifts in the left–right and cranio-caudal directions were larger at CBCT than CT. For GTV-Nlung and CTVlymphoma, no difference was found in GMmax or SD. Intra-DIBH shifts at planning-CT session are generally smaller than intra-DIBH shifts observed at CBCTpre/post and therefore underestimate the intra-fractional DIBH uncertainty during treatment. Lung tumours show larger intra-fractional variations than lymph nodes and lymphoma targets.
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ISSN:0167-8140
1879-0887
DOI:10.1016/j.radonc.2023.109887