Program Information
Characterization of Spatial Drift for the AlignRT 3D Surface Imaging System Under Multiple Warm-Up Scenarios
D Jacqmin*, J Huang , A Besemer , K Schaefer , University of Wisconsin, Madison, WI
Presentations
TU-L-GePD-J(B)-1 (Tuesday, August 1, 2017) 1:15 PM - 1:45 PM Room: Joint Imaging-Therapy ePoster Lounge - B
Purpose: Optical surface imaging systems like AlignRT are known to exhibit spatial drift during warm-up of the equipment. This work investigates the spatial drift in two clinically relevant warm-up scenarios.
Methods: The AlignRT system was powered down for one hour to allow the system to cool to room temperature. Then the system was powered on and the software was prepared for measurements. Spatial drift was quantified by taking a reference image of a female torso phantom as soon as the software was prepared for measurement and monitoring the suggested translations and rotations as a function of time. In Scenario 1, the projector bulbs were turned on and remained on during a measurement period of 30 minutes. In Scenario 2, the spatial drift was monitored using periodic snap-shots of the phantom. Between measurements, the AlignRT projector bulbs were turned off. After 30 minutes, the projectors were turned on and remained on for 30 additional minutes of periodic measurements.
Results: In scenario 1, the spatial drift of the system increased from 0 to 0.9 mm during the first 15 minutes, then plateaued. In Scenario 2, the spatial drift of the system increased from 0 to 0.3 mm during the first 15 minutes and then plateaued. Once the projector bulbs were turned on at 30 minutes, the spatial drift increased to 0.8 mm over the course of 15 minutes, then plateaued again. In both scenarios, the drift was predominately in the vertical direction.
Conclusion: The total spatial drift of the AlignRT system is on the order of 0.8-0.9 mm. Scenario 2 shows that the warm-up of the system is dominated by the projector bulb warm-up. This work demonstrates that warming up the system with the projectors on is critical for use of AlignRT when sub-millimeter accuracy is required.
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