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

Patrick Naumann; Vania Batista; Benjamin Farnia; Jann Fischer; Jakob Liermann; Eric Tonndorf-Martini; Bernhard Rhein; Jürgen Debus

doi:10.3389/fonc.2020.573279

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

Front Oncol. 2020 Sep 25:10:573279. doi: 10.3389/fonc.2020.573279. eCollection 2020.

Authors

Patrick Naumann^{1

2

3}, Vania Batista^{1

2

3}, Benjamin Farnia⁴, Jann Fischer^{1

2

3}, Jakob Liermann^{1

2

3}, Eric Tonndorf-Martini^{1

2

3}, Bernhard Rhein^{1

2

3

5}, Jürgen Debus^{1

2

3

5

6

7}

Affiliations

¹ Department of Radiation Oncology, Heidelberg University Hospital, Heidelberg, Germany.
² Heidelberg Institute of Radiation Oncology (HIRO), Heidelberg, Germany.
³ National Center for Tumor diseases (NCT), Heidelberg, Germany.
⁴ Department of Radiation Oncology, University of Miami, Miami, FL, United States.
⁵ Heidelberg Ion-Beam Therapy Center (HIT), Department of Radiation Oncology, Heidelberg University Hospital, Heidelberg, Germany.
⁶ German Cancer Consortium (DKTK), Heidelberg, Germany.
⁷ Clinical Cooperation Unit Radiation Oncology, German Cancer Research Center (DKFZ), Heidelberg, Germany.

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 set-up, 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 distance between the fixed and moveable landmarks confirmed higher interfractional variability (interquartile range (IQR) 6.8 mm) than intrafractional variability (IQR 2.8 mm). In contrast, lung target variability was low, indicating a better correlation of patients' surface to lung targets (intrafractional IQR 2.5 mm and interfractional IQR 1.7 mm).

Conclusion: SBRT in DIBH utilizing SGRT and IGRT is feasible and results in significantly lower irradiated volumes. Nevertheless, IGRT is of paramount importance given that interfractional variability was high, particularly for liver tumors.

Keywords: Deep-inspiration breath-hold; Image-guided radiation therapy; liver metastasis; lung tumor; precision radiation oncology; stereotactic body radiation; surface-guided radiation therapy.