A Prospective Cohort Study of Gated Stereotactic Liver Radiation Therapy Using Continuous Internal Electromagnetic Motion Monitoring

Worm, E.; Høyer, Morten; Hansen, Rune; Larsen, Lars; Weber, Britta; Grau, Cai; Poulsen, Per Rugaard

doi:10.1016/j.ijrobp.2018.02.010

Cited by 48 publications

(71 citation statements)

References 51 publications

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“…The Calypso electromagnetic transponders have been successfully used for RT image guidance in soft tissues throughout the body. [1][2][3] The most robust clinical experience is reported in prostate cancer, where real-time tracking of the tumor has enabled the use of smaller radiation fields that resulted in reduced treatment-related morbidity. 4 For lung applications, the Calypso Beacon transponder has been modified by the addition of a nitinol anchor feature to allow for positional stability when implanted bronchoscopically into small airways within the lung.…”

Section: Introductionmentioning

confidence: 99%

Anchored Transponder Guided Lung Radiation Therapy

Dobelbower

Popple

Minnich

et al. 2020

Practical Radiation Oncology

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Section: Introductionmentioning

confidence: 99%

Anchored Transponder Guided Lung Radiation Therapy

Dobelbower

Popple

Minnich

et al. 2020

Practical Radiation Oncology

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“…The purpose of this study was to bring DoseTracker closer to the clinic by expanding it to patient anatomy. As a proof of principle, we applied DoseTracker to liver SBRT patients previously treated using Calypso‐guided gating in our clinic …”

Section: Introductionmentioning

confidence: 99%

Simulated real‐time dose reconstruction for moving tumors in stereotactic liver radiotherapy

Skouboe¹,

Poulsen²,

Muurholm³

et al. 2019

Medical Physics

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Purpose: In radiotherapy, tumor motion may deteriorate the planned dose distribution. However, the dosimetric consequences of the motion are normally unknown for individual treatments. We here present a method for real-time motion-including tumor dose reconstruction and demonstrate its use for simulated stereotactic body radiotherapy (SBRT) of patients with liver cancer previously treated with Calypso-guided gating. Methods: Real-time motion-including dose reconstruction was performed using in-house developed software, DoseTracker, on offline replays of previous clinical treatments. The patient cohort consisted of fifteen patients previously treated in our clinic with three-fraction SBRT to the liver using conformal or IMRT plans. The tumor motion at treatment was monitored with implanted electromagnetic transponders. The dose reconstruction was performed for both the actual gated treatments and simulated nongated treatments using a 21 Hz data stream containing accelerator parameters and the recorded motion. The dose was reconstructed in the same calculation points within the planning target volume (PTV) as used by the treatment planning system (TPS). The reconstructed doses were compared with calculations performed in the TPS, in which the motion was modeled as a series of isocenter shifts. The comparison included point doses as a function of treatment time and the dose volume histogram (DVH) for the clinical target volume (CTV). The motion-induced reduction in the dose to 95% of the CTV, DD 95% , and in the mean CTV dose, DD Mean , was compared between DoseTracker and the TPS for each simulated fraction. DoseTracker currently assumes water density within the patient contour, so for comparison, the TPS calculations were performed with both CT density and water density. The calculation times were additionally analyzed. Results: Dose reconstruction was carried out for ninety SBRT sessions with calculation volumes ranging from 9.9 to 366.4 cm 3 and median calculation times of 55-155 ms (equivalent to 18.2-6.5 Hz). Time-resolved trends of doses to a single calculation point in the patient were well replicated and dose differences between actual and planned calculations matched well. DD Mean had a range of À0.1%-30.7%-points and was estimated by DoseTracker with a root-mean-square deviation (RMSD) to the TPS calculations of 0.43%-points (water density) and 0.79%-points (CT density). Similarly, DD 95% had a range of 0.0%-35.2%-points and was estimated by Dose-Tracker with an RMSD of 0.80%-points (water density) and 1.33%-points (CT density). Dose-Tracker predicted losses in tumor dose coverage above 5%-points with high sensitivity (91.7%) and specificity (97.6%). Conclusions: Real-time dose reconstruction to moving tumors was demonstrated on offline replays of previous clinical treatments. DVHs of actually delivered dose are made available immediately after the end of treatment fractions. It shows promising results for liver SBRT with accurate estimation of

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“…The EMT tracking system used in this study has proved to be an accurate tool to monitor in real-time the prostate gland during RT [17,18] and its accuracy has been thoroughly investigated [19][20][21]. Various studies have investigated its potential for motion monitoring and EMT-based gating of liver or pancreas tumors [22][23][24][25][26]. The first use of this EMT tracking system in human lungs was described by Shah et al in an observational study evaluating the implantation, migration and feasibility of tumor tracking using smooth EMTs (i.e.…”

Section: Discussionmentioning

confidence: 99%

Clinical experience with lung-specific electromagnetic transponders for real-time tumor tracking in lung stereotactic body radiotherapy

Jaccard

Champion

Dubouloz

et al. 2019

Physics and Imaging in Radiation Oncology

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Background and purposes: Motion management is crucial for optimal stereotactic body radiotherapy (SBRT) of moving targets. We aimed to describe our clinical experience with real-time tracking of lung-specific electromagnetic transponders (EMTs) for SBRT of early stage non-small cell lung cancer in free-breathing (FB) or deep inspiration breath-hold (DIBH). Material and methods: Seven patients were implanted with EMTs. Simulation for SBRT was performed in FB and in DIBH. We prescribed 60 Gy in 3, 5 or 8 fractions to the tumor and delivered SBRT with volumetric modulated arcs and a 6 MV flattening filter free photon beam. Patients' setup at the linac was performed using EMT positions and cone-beam CT (CBCT) verification. Four patients were treated in DIBH because of a dosimetric benefit. We analysed patient alignment and treatment delivery parameters using DIBH or FB and EMT real-time tracking. Results: There were no complications from the EMT implantation. Visual inspection of CBCT before and/or after SBRT revealed good alignment of structures and EMTs. The median setup time was 9.8 min (range: 4.6-34.1 min) and the median session time was 14.7 min (range: 7.3-36.5 min). EMT positions in lungs remained stable during overall treatment and allowed real-time tracking both in FB and in DIBH SBRT. The treatment beam was gated when EMT centroid position exceeded tolerance thresholds ensuring correct delivery of radiation to the tumor. Conclusion: Using EMTs for real-time tracking of tumor motion during lung SBRT proved to be safe, accurate and easy to integrate clinically for treatments in FB or DIBH.

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A Prospective Cohort Study of Gated Stereotactic Liver Radiation Therapy Using Continuous Internal Electromagnetic Motion Monitoring

Cited by 48 publications

References 51 publications

Anchored Transponder Guided Lung Radiation Therapy

Anchored Transponder Guided Lung Radiation Therapy

Simulated real‐time dose reconstruction for moving tumors in stereotactic liver radiotherapy

Clinical experience with lung-specific electromagnetic transponders for real-time tumor tracking in lung stereotactic body radiotherapy

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