(Sunday, 7/12/2020) [Eastern Time (GMT-4)]
Room: AAPM ePoster Library
Purpose:
To commission and assess the performance of the first prototype of AlignRT InBore, a Halcyon™-dedicated Surface Guided Radiation Therapy (SGRT) platform.
Methods:
AlignRT InBore for Halcyon™ combines ceiling-mounted cameras for patient setup and bore-mounted cameras for in-bore tracking. To check the potential impact of in-bore cameras on dose delivery, 16 SRS, H&N, breast and pelvis patients’ QA were performed with/without AlignRT InBore and using ArcCHECK® and SRS MapCHECK®. Impact on image quality was also determined using Catphan® 540 phantom and considering all available MV and CBCT protocols (head, breast, chest and pelvis). The overall performance of AlignRT InBore was assessed while also determining its accuracy when managing the transition from virtual to treatment isocentres using an anthropomorphic phantom.
Results:
Comparison of 2D dose distributions with/without AlignRT InBore showed no impact on treatment delivery for all 16 patient QA checks (p-value > 0.9). No artefacts on 2D and CBCT images were observed with no statistically significant differences on contrast, resolution and noise values measured with Catphan® 540. Anti-collision sensors proved to be unaffected by the bore-mounted cameras. Additionally, the new In-Bore cameras proved to have similar performance compared to the standard ceiling-mounted cameras with sub-0.5mm accuracy and sub-0.4mm stability (over 30 min monitoring), frame rate (3-5 fps for breast) and surface resolution (10 pixels/vertex for breast). In-bore tracking surface coverage was ~60x40x25 cc. Halcyon™ rotations during CBCT and beam delivery resulted in limited camera vibrations with translation uncertainty <0.5 mm in left-right and anterior-posterior directions and <0.1 mm in head-feet direction. Finally, phantom tests proved AlignRT InBore to accurately match patient setup with in-bore tracking while also showing a couch sag with increasing patient weight confirmed on CBCT.
Conclusion:
AlignRT InBore platform proved to have no adverse effect on Halcyon™ with overall performance comparable to standard SGRT solutions.
Funding Support, Disclosures, and Conflict of Interest: J FARAH, P MATHIEU, J HUGHES currently work for Vision RT
Keywords
Surface Matching, Breast, Setup Verification
Taxonomy
TH- RT Interfraction Motion Management: Development (new technology and techniques)
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