Abstract
PurposeThis work reports the clinical implementation of a real-time motion tracking and correction system using dynamic multileaf collimator and jaws during helical tomotherapy delivery (Synchrony on Radixact; Accuray, Inc). Methods and MaterialsThe first clinical Synchrony on Radixact system was recently installed and tested at our institution. Various clinical workflows, including fiducial implantation, computed tomography simulation, treatment planning, delivery quality assurance, treatment simulation, and delivery, for both fiducial-free and fiducial-based motion tracking methods were developed. Treatment planning and delivery data from initial patients, including dosimetric benefits, real-time target detection, model building, motion tracking accuracy, delivery smoothness, and extra dose from real-time radiographic imaging, were analyzed. ResultsThe Synchrony on Radixact system was tested to be within its performance specifications and has been used to treat 10 lung (fiducial-free) and 5 prostate (fiducial-based) patients with cancer so far in our clinic. The success of these treatments, especially for fiducial-free tracking, depends on multiple factors, including careful selection of the patient, appropriate setting of system parameters, appropriate positioning of the patient and skin markers, and use of treatment simulation. For the lung tumor cases, difficulties in model building, due primarily to the changes of target detectability or respiration patterns, were observed, which led to important system upgrades, including the addition of a treatment delivery simulation capability. Motion tracking metrics for all treated patients were within specifications, for example, (1) delivery quality assurance passing rates >95%; (2) extra dose from radiograph <0.5% of the prescription dose; and (3) average Potential Diff, measured Δ, and Rigid Body were within 6.5, 2.9, and 3.9 mm, respectively. ConclusionsPractical workflows for the use of the first clinical motion tracking and correction system in helical tomotherapy delivery have been developed, and the system has now been successfully implemented in our clinic for treating patients with lung and prostate cancer.
Highlights
Intrafraction organ motion can be significant during radiation therapy (RT) for tumors in thorax, abdomen, and pelvis, and is a major issue affecting RT delivery accuracy.[1,2,3,4] Tumor motion management, including clinical approaches as simple as planning target volume (PTV) expansion, motion compression, or breath hold to more sophisticated techniques such as gating and tracking, has been investigated for decades.[5,6,7,8] In 2019, a real time motion tracking and compensation technique using dynamic multileaf collimator (MLC) and jaws (Synchrony on Radixact; Accuray, Inc) was introduced for tomotherapy delivery.[9]
We report our clinical implementation of this technology focusing on our learning curve, practical workflows, and patient selection criteria
Based on our clinical implementation and the initial clinical experience, we observed that the success of Synchrony treatments relied on (1) careful selection of suitable patients, (2) optimal patient and light-emitting diodes (LEDs) positioning, (3) appropriate setting of tracking parameters, and (4) use of treatment simulation
Summary
Intrafraction organ motion can be significant during radiation therapy (RT) for tumors in thorax, abdomen, and pelvis, and is a major issue affecting RT delivery accuracy.[1,2,3,4] Tumor motion management, including clinical approaches as simple as planning target volume (PTV) expansion, motion compression, or breath hold to more sophisticated techniques such as gating and tracking, has been investigated for decades.[5,6,7,8] In 2019, a real time motion tracking and compensation technique using dynamic multileaf collimator (MLC) and jaws (Synchrony on Radixact; Accuray, Inc) was introduced for tomotherapy delivery.[9]. The fiducial-free tracking is attractive in lung tumor treatment, for example, stereotactic body RT, for possible PTV margin reduction.[11] It avoids the costs and risks associated with surgically inserted fiducial markers. Neither fiducial-free nor fiducial-based tracking, which have been previously used in RT, have been demonstrated with helical delivery.[12] We have previously reported our comprehensive commissioning tests for this helical-based system.[10] In this work, we report our clinical implementation of this technology focusing on our learning curve, practical workflows, and patient selection criteria. Our initial experience gained in using the system for treating patients with lung and prostate cancer is included
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
