Feasibility of Optical Surface-Guidance for Position Verification and Monitoring of Stereotactic Body Radiotherapy in Deep-Inspiration Breath-Hold

Abstract

Background: Reductions in tumor movement allow for more precise and accurate radiotherapy with decreased dose delivery to adjacent normal tissue that is crucial in stereotactic body radiotherapy (SBRT). Deep inspiration breath-hold (DIBH) is an established approach to mitigate respiratory motion during radiotherapy. We assessed the feasibility of combining modern optical surface-guided radiotherapy (SGRT) and image-guided radiotherapy (IGRT) to ensure and monitor reproducibility of DIBH and to ensure accurate tumor localization for SBRT as an imaging-guided precision medicine. Methods: We defined a new workflow for delivering SBRT in DIBH for lung and liver tumors incorporating SGRT and IGRT with cone beam computed tomography (CBCT) twice per treatment fraction. Daily position corrections were analyzed and for every patient two points retrospectively characterized: an anatomically stable landmark (predominately Schmorl's nodes or spinal enostosis) and a respiratory-dependent landmark (predominately surgical clips or branching vessel). The spatial distance of these points was compared for each CBCT and used as surrogate for intra-and interfractional variability. Differences between the lung and liver targets were assessed using the Welch t-test. Finally, the planning target volumes were compared to those of free-breathing plans, prepared as a precautionary measure in case of technical or patient-related problems with DIBH. Results: Ten patients were treated with SBRT according this workflow (7 liver, 3 lung). Planning target volumes could be reduced significantly from an average of 148 ml in free breathing to 110 ml utilizing DIBH (p < 0.001, paired t-test). After SGRT-based patient setup , subsequent IGRT in DIBH yielded significantly higher mean corrections for liver targets compared to lung targets (9 mm vs. 5 mm, p = 0.017). Analysis of spatial

Motion Management in a Patient With Tracheostomy During Lung Stereotactic Body Radiation Therapy: Breath Hold Is Worth a Try

“…This is in line with already published data on residual motion during breath-hold in patients receiving lung-SBRT: Koshani et al measured a short-and long-term reproducibility of lung tumor positions during ABC-controlled breath-hold with a standard deviation of 1.5 mm and 3.8 mm in anterior-posterior direction [29]. In another study, the intrafractional interquartile range during DIBH-gated surface-guided lung-SBRT was 2.5 mm [30].…”

“…In another study, the intrafractional interquartile range during DIBH-gated surface-guided lung-SBRT was 2.5 mm. 30 …”

A review of surface guidance in extracranial stereotactic body radiotherapy (SBRT/SABR) for set-up and intra-fraction motion management

“…Liver targets required more corrections compared to lung targets on IGRT after SG set up (9 mm vs. 5 mm, p = 0.017). Lung target variability was low, indicating a better correlation of patients’ surface to lung targets (intra-fractional IQR 2.5 mm and inter-fractional IQR 1.7 mm) [8] .…”

“…Naumann et al had a smaller patient cohort of 10 patients, treated using DIBH [8] . Liver targets required significantly larger corrections, than lung targets on IGRT after SG set up.…”

“…A number of commercial systems are available [1] , [2] , [3] , [4] . The additional benefit is that the system can also be used to monitor the patient throughout treatment for intra-fraction motion [5] , [6] , [7] , [8] .…”