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An Enhanced Daily Quality Assurance Process for a Six Degrees of Freedom Robotic Table

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E Kremmel

E Kremmel*, L Doyle , Y Yu , A Harrison , Thomas Jefferson University Hospital, Philadelphia, PA


SU-F-T-466 (Sunday, July 31, 2016) 3:00 PM - 6:00 PM Room: Exhibit Hall

Purpose:A Varian PerfectPitch six degrees of freedom robotic table necessitates daily quality assurance (QA). Therapists were credentialed for this QA procedure which was easily incorporated into the existing daily warmup process. This procedure adds depth to TG-142 requirements without additional morning time costs.

Methods:This PerfectPitch table QA introduces a consistent rotation of the QUASAR™ Penta-Guide phantom and requires automatic table corrections through image fusions. Rotational offsets are generated by inserting a platform tool under a specified corner of the phantom; then a conebeamCT is performed. This conebeamCT image is fused with a planned reference CT image set and the table is auto-adjusted to correct for induced translational and rotational offsets. After executing table shifts, a second conebeamCT verifies the table movement and the phantom’s return to isocenter.

Results: Pre-shift and post-shift table corrections were recorded daily. It was discovered that due to slight variations in the setup, it took three performances of the QA for each therapist to have consistent induced rotations. Four therapists performed this QA and after the initial training period, the inter-user variability was minimal. Consistency of the induced rotation was evaluated by the variation of the pre-shift table corrections. Excluding the first three attempts of each therapist, the pre-shift table correction standard deviations were ≤ 0.67mm for the translational axes and ≤ 0.49° for the rotational axes. Accuracy of the automatic table movement was confirmed by the post-shift table corrections. The average post-shift table corrections for the translational axes were ≤ 0.15mm and for the rotational axes were ≤ 0.42°. Using our clinic’s existing table corrections tolerance of <1mm and <0.5°, these results were deemed acceptable.

Conclusion:Therapists successfully and rapidly adopted daily QA procedures using the PerfectPitch table; automated rotational robotic table motions were confirmed through image fusions. This procedure enhances existing TG-142 recommendations.

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