Visually guided respiratory motion management for Ethos adaptive radiotherapy

Kim, Sang Woo; Ji, Zhen; Lewis, Benjamin; Laugeman, Eric; Price, Alex; Hao, Yaowu; Hugo, Geoffrey D.; Knutson, Nels C.; Cai, Bin; Kim, Hyun; Henke, Lauren E.

doi:10.1002/acm2.13441

Cited by 12 publications

(4 citation statements)

References 13 publications

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“…CT‐STAR was demonstrated to account for inter‐fractional anatomic changes 2,5,20,21 . However, intra‐fractional respiratory motion management on the Ethos system has been a practical challenge due to the closed‐bore ring gantry LINAC and offset kV panel of the Ethos system 22 . To the authors’ knowledge, there is limited literature available on the topic of intra‐fractional respiratory motion management with a surface imaging solution for Ethos stereotactic body adaptive radiotherapy 23,24 .…”

Section: Introductionmentioning

confidence: 99%

“… 2 , 5 , 20 , 21 However, intra‐fractional respiratory motion management on the Ethos system has been a practical challenge due to the closed‐bore ring gantry LINAC and offset kV panel of the Ethos system. 22 To the authors’ knowledge, there is limited literature available on the topic of intra‐fractional respiratory motion management with a surface imaging solution for Ethos stereotactic body adaptive radiotherapy. 23 , 24 Recently, our institution incorporated the SGRT system, IDENTIFY (Varian Medical Systems, CA), with the Ethos system.…”

Section: Introductionmentioning

confidence: 99%

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Feasibility of surface‐guidance combined with CBCT for intra‐fractional breath‐hold motion management during Ethos RT

Kim,

Laugeman,

Kiser

et al. 2024

J Applied Clin Med Phys

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PurposeHigh‐quality CBCT and AI‐enhanced adaptive planning techniques allow CBCT‐guided stereotactic adaptive radiotherapy (CT‐STAR) to account for inter‐fractional anatomic changes. Studies of intra‐fractional respiratory motion management with a surface imaging solution for CT‐STAR have not been fully conducted. We investigated intra‐fractional motion management in breath‐hold Ethos‐based CT‐STAR and CT‐SBRT (stereotactic body non‐adaptive radiotherapy) using optical surface imaging combined with onboard CBCTs.MethodsTen cancer patients with mobile lower lung or upper abdominal malignancies participated in an IRB‐approved clinical trial (Phase I) of optical surface image‐guided Ethos CT‐STAR/SBRT. In the clinical trial, a pre‐configured gating window (± 2 mm in AP direction) on optical surface imaging was used for manually triggering intra‐fractional CBCT acquisition and treatment beam irradiation during breath‐hold (seven patients for the end of exhalation and three patients for the end of inhalation). Two inter‐fractional CBCTs at the ends of exhalation and inhalation in each fraction were acquired to verify the primary direction and range of the tumor/imaging‐surrogate (donut‐shaped fiducial) motion. Intra‐fractional CBCTs were used to quantify the residual motion of the tumor/imaging‐surrogate within the pre‐configured breath‐hold window in the AP direction. Fifty fractions of Ethos RT were delivered under surface image‐guidance: Thirty‐two fractions with CT‐STAR (adaptive RT) and 18 fractions with CT‐SBRT (non‐adaptive RT). The residual motion of the tumor was quantified by determining variations in the tumor centroid position. The dosimetric impact on target coverage was calculated based on the residual motion.ResultsWe used 46 fractions for the analysis of intra‐fractional residual motion and 43 fractions for the inter‐fractional motion analysis due to study constraints. Using the image registration method, 43 pairs of inter‐fractional CBCTs and 100 intra‐fractional CBCTs attached to dose maps were analyzed. In the motion range study (image registration) from the inter‐fractional CBCTs, the primary motion (mean ± std) was 16.6 ± 9.2 mm in the SI direction (magnitude: 26.4 ± 11.3 mm) for the tumors and 15.5 ± 7.3 mm in the AP direction (magnitude: 20.4 ± 7.0 mm) for the imaging‐surrogate, respectively. The residual motion of the tumor (image registration) from intra‐fractional breath‐hold CBCTs was 2.2 ± 2.0 mm for SI, 1.4 ± 1.4 mm for RL, and 1.3 ± 1.3 mm for AP directions (magnitude: 3.5 ± 2.1 mm). The ratio of the actual dose coverage to 99%, 90%, and 50% of the target volume decreased by 0.95 ± 0.11, 0.96 ± 0.10, 0.99 ± 0.05, respectively. The mean percentage of the target volume covered by the prescribed dose decreased by 2.8 ± 4.4%.ConclusionWe demonstrated the intra‐fractional motion‐managed treatment strategy in breath‐hold Ethos CT‐STAR/SBRT using optical surface imaging and CBCT. While the controlled residual tumor motion measured at 3.5 mm exceeded the predetermined setup value of 2 mm, it is important to note that this motion still fell within the clinically acceptable range defined by the PTV margin of 5 mm. Nonetheless, additional caution is needed with intra‐fractional motion management in breath‐hold Ethos CT‐STAR/SBRT using optical surface imaging and CBCT.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Feasibility of surface‐guidance combined with CBCT for intra‐fractional breath‐hold motion management during Ethos RT

Kim,

Laugeman,

Kiser

et al. 2024

J Applied Clin Med Phys

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“…This imaging unit is coupled with a dedicated, on-board treatment planning system (TPS) capable of online ART. 22 , 23 , 24 Its utility for adaptive SBRT for the ultracentral thorax has yet to be investigated. In that context, we conducted a prospective in silico imaging clinical trial to evaluate the feasibility and potential dosimetric advantages of CBCT-guided stereotactic adaptive radiation therapy (CT-STAR) for the ablation of ultracentral thoracic disease.…”

Section: Introductionmentioning

confidence: 99%

Prospective In Silico Evaluation of Cone-Beam Computed Tomography-Guided StereoTactic Adaptive Radiation Therapy (CT-STAR) for the Ablative Treatment of Ultracentral Thoracic Disease

Schiff¹,

Laugeman²,

Stowe³

et al. 2023

Advances in Radiation Oncology

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“…In recent years, MR imaging for IGRT has gained importance due to the higher soft tissue contrast compared to CT images and allows dedicated online-ART work ows [5][6][7]. Recently treatment units which support streamlined online-ART work ows based on x-ray images became commercially available [8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Evaluation of a novel CBCT conversion method implemented in a treatment planning system

Lechner

Kanalas

Haupt

et al. 2023

Preprint

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Background: To evaluate a novel CBCT conversion algorithm for dose calculation implemented in a research version of a treatment planning system (TPS). Methods: The algorithm was implemented in a research version of RayStation (v. 11B-DTK, RaySearch, Stockholm, Sweden). CBCTs acquired for each ten head and neck (HN), gynecology (GYN) and lung cancer (LNG) patients were collected and converted using the new algorithm (CBCTc). A bulk density overriding technique implemented in the same version of the TPS was used for comparison (CBCTb). A deformed CT (dCT) was created by using deformable image registration of the planning CT (pCT) to the CBCT to reduce anatomical changes. All treatment plans were recalculated on the pCT, dCT, CBCTc and the CBCTb. The resulting dose distributions were analyzed using the MICE toolkit (NONPIMedical AB Sweden, Umeå) with local gamma analysis, with 1% dose difference and 1 mm distance to agreement criteria. A Wilcoxon paired rank sum test was applied to test the differences in gamma pass rates (GPRs). A p-value smaller than 0.05 considered statistically significant. Results: The GPRs for the CBCTb method were systematically lower compared to the CBCTc method. Using the 10% dose threshold and the dCT as reference the median GPRs were for the CBCTc method were 100% and 99.8% for the HN and GYN cases, respectively. Compared to that the GPRs of the CBCTb method were lower with values of 99.8% and 98.0%, for the HN and GYN cases, respectively. The GPRs of the LNG cases were 99.9% and 97.5% for the CBCTc and CBCTb method, respectively. These differences were statistically significant. The main differences between the dose calculated on the CBCTs and the pCTs were found in regions near air/tissue interfaces, which are also subject to anatomical variations. Conclusion: The dose distribution calculated using the new CBCTc method showed excellent agreement with the dose calculated using dCT and pCT and was superior to the CBCTb method. The main reasons for deviations of the calculated dose distribution were caused by anatomical variations between the pCT and the corrected CBCT.

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Visually guided respiratory motion management for Ethos adaptive radiotherapy

Cited by 12 publications

References 13 publications

Feasibility of surface‐guidance combined with CBCT for intra‐fractional breath‐hold motion management during Ethos RT

Feasibility of surface‐guidance combined with CBCT for intra‐fractional breath‐hold motion management during Ethos RT

Prospective In Silico Evaluation of Cone-Beam Computed Tomography-Guided StereoTactic Adaptive Radiation Therapy (CT-STAR) for the Ablative Treatment of Ultracentral Thoracic Disease

Evaluation of a novel CBCT conversion method implemented in a treatment planning system

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