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The Characterization of a 3D Real-Time Surface System with a Single High-Definition (HD) Camera

J Peng

J Peng*, D Jacqmin, D McDonald, N Koch, M Ashenafi, K Vanek, Medical University of South Carolina, Charleston, SC

SU-E-J-54 Sunday 3:00PM - 6:00PM Room: Exhibit Hall

Purpose: To investigate a single high-definition (HD) camera of 3D real-time surface system (AlignRT_1HD, VisionRT, Inc.) as the potential alternative to the standard configuration of the system with three charge-coupled device (CCD) cameras (AlignRT_3C) and to evaluate the localization accuracy of AlignRT_1HD compared to AlignRT_3C.

Methods: Both AlignRT_3C and AlignRT_1HD were installed in the same treatment room with Varian LINAC. A commercial daily QA phantom (DailyQA3TM, Sun Nuclear) and 5 IMRT patients with intracranial and head and neck tumors receiving non-coplanar treatment were used to evaluate system characteristics and position-tracking accuracies of AlignRT_1HD through comparison with the AlignRT_3C and kV-CBCTs. Surface-image data sets were acquired simultaneously by both systems for the evaluation of inter- and intra-fractional motion at daily treatment of each patient.

Results:The system origin displacements agreed to within 0.5 mm/0.5°. Compared to the CBCTs without couch rotations, the mean registration errors obtained using AlignRT_1HD were approximately 0.4 mm/0.8° (for phantom displacements up to ± 3cm in 3 axes), 1.1 mm/0.8° (for inter_frational motion in patients), and 0.3 mm/0.4° (for intra_frational motionin patients) less than those obtained using the AlignRT_3C. For non-coplanar treatments, without the surface images acquired by two side camera pods using AlignRT_1HD in this study, the accuracy of patient setup was only guaranteed up to ±10° couch angles. The average setup time using AlignRT_1HD was reduced by approximately 1 min per session.

Conclusion:As judged by CBCTs, AlignRT_1HD is capable of increasing in positioning accuracy and setup efficiency for high precision treatment, with the enhancements in image resolution, frame rate and field of view using HD cameras. The standard configuration with 3-camera-pods of AlignRT_3HD was essential for non-coplanar treatment and the localization accuracy with couch angle up to 90° needs to be further quantified .

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