Intrafraction target shift comparison using two breath-hold systems in lung stereotactic body radiotherapy

•Surface-guided-based and spirometry-based deep-inspiration breath hold were accuracy-equivalent for intrafraction control.•Intrafraction shift was reduced when using spirometry-based than surface-guided-based deep-inspiration breath hold.•Higher superior-inferior shifts were found for patients with inferior lobe tumors.•Systematic and random intrafraction errors were higher for surface-guidance than for spirometry. In lung Stereotactic Body Radiotherapy (SBRT) respiratory management is used to reduce target motion due to respiration. This study aimed (1) to estimate intrafraction shifts through a Cone Beam Computed Tomography (CBCT) acquired during the first treatment arc when deep inspiration breath-hold (DIBH) was performed using spirometry-based (SB) or surface-guidance (SG) systems and (2) to analyze the obtained results depending on lesion localization. A sample of 157 patients with 243 lesions was analyzed. A total of 860 and 410 fractions were treated using SB and SG. Averaged intrafraction shifts were estimated by the offsets obtained when registering a CBCT acquired during the first treatment arc with the planning CT. Offsets were recorded in superior-inferior (SI), left–right (LR) and anterior-posterior (AP). Significance tests were applied to account for differences in average offsets and variances between DIBH systems. Systematic and random errors were computed. Average offset moduli were 2.4 ± 2.2 mm and 3.5 ± 2.6 mm for SB and SG treatments (p 0.3). However, variances were statistically smaller for SB than for SG (p