An Evaluation of Total Internal Motions of Locally Advanced Pancreatic Cancer during SABR Using Calypso® Extracranial Tracking, and Its Possible Clinical Impact on Motion Management

Abstract

(1) Background: the aims of this study were to determine the total extent of pancreatic cancer’s internal motions, using Calypso® extracranial tracking, and to indicate possible clinical advantages of continuous intrafractional fiducial-based tumor motion tracking during SABR. (2) Methods: thirty-four patients were treated with SABR for LAPC using Calypso® for motion management. Planning MSCTs in FB and DBH, and 4D-CTs were performed. Using data from Calypso® and 4D-CTs, the movements of the lesions in the CC, AP and LR directions, as well as the volumes of the 4D-CT-based ITV and the volumes of the Calypso®-based ITV were compared. (3) Results: significantly larger medians of tumor excursions were found with Calypso® than with 4D-CT: CC: 29 mm (p < 0.001); AP: 14 mm (p < 0.001) and LR: 11 mm (p < 0.039). The median volume of the Calypso®-based ITV was significantly larger than that of the 4D-CT based ITV (p < 0.001). (4) Conclusion: beside known respiratory-induced internal motions, pancreatic cancer seems to have significant additional motions which should be considered during respiratory motion management. Only direct and continuous intrafractional fiducial-based motion tracking seems to provide complete coverage of the target lesion with the prescribed isodose, which could allow for safe tumor dose escalation.

Stereotactic Ablative Radiotherapy Using CALYPSO® Extracranial Tracking for Intrafractional Tumor Motion Management—A New Potential Local Treatment for Unresectable Locally Advanced Pancreatic Cancer? Results from a Retrospective Study

“…According to the manufacturer’s specifications, the lag time of the system is up to 100 milliseconds. Figure 1 shows the implantation needle, electromagnetic array, and Beacon ® transponders (the figure is taken from [ 39 ]).…”

“…We did not present the analysis of the pancreas movements in current paper, as the evaluation of total pancreatic movements using the Calypso ® system was presented in a greater detail in our previously published paper [ 39 ]. We aimed primarily to report on our clinical outcomes of SABR using this motion management technique for LAPC.…”

Dosimetric impact of intrafraction motion under abdominal compression during MR-guided SBRT for (Peri-) pancreatic tumors

“…This is not only because of the large variability and unpredictability of tumor motion in the upper abdomen (Bussels et al 2003, Feng et al 2009, but also because beam-on times are generally prolonged on MRguided systems due to their limited linac dose rate compared to conventional systems. Active motion management methods, like using internal targets for gating (Poulsen et al 2015, Worm et al 2018 or tracking (Vinogradskiy et al 2019, Kaučić et al 2021, or gating on deep inspiration breath holds (Zeng et al 2019), can significantly improve target coverage. The downside of methods using internal targets is the invasive placement of internal markers, and gating generally prolongs treatment (Heerkens et al 2014, Placidi et al 2020b.…”

Advancing the frontiers of MR-guided radiotherapy for pancreatic cancer

“…This is not only because of the large variability and unpredictability of tumor motion in the upper abdomen, 27,28 but also because beam-on times are generally prolonged on MR-guided systems due to their limited linac dose rate compared to conventional systems. Active motion management methods, like using internal targets for gating 86,87 or tracking, 88,89 or gating on deep inspiration breath holds, 90 can significantly improve target coverage. The downside of methods using internal targets is the invasive placement of internal markers, and gating generally prolongs treatment.…”