Program Information
Evaluation of a Method to Define Motion Target Edge by Golden Fiducial Marker Embedded Dynamic Phantom
K Li1*, (1) Associates In Medical Physics, Lanham, MD
Presentations
SU-I-GPD-J-93 (Sunday, July 30, 2017) 3:00 PM - 6:00 PM Room: Exhibit Hall
Purpose: A physical magnification algorithm to define motion target edge was investigated by embedding a golden fiducial marker into the dynamic phantom
Methods: A CIRS Dynamic Phantom was inserted a lung equivalent rod with a 2cm diameter ball as target, which was made with approximately water equivalent material. A golden marker provided by Carbon Medical Technologies was attached to the hole used for taking out the 2cm ball. The golden marker was shielded and stabilized with wax and inserted to the hole. Then a helical scan with static target and a 4DCT scan with motion along inferior and superior (IS) direction at 15mm amplitude with 5 second cycle, and the surrogate amplitude was at 5mm. The scans were done by GE LightSpeed RT CT. And both Helical and Cine scan energy parameters were set at 120KV and 250mA. Then the Hounsfield Unit (HU) were attained in different image modes and phase image sets. The variation of HU due to motion were used to detect the sensitivity between golden fiducial markers and the inserted target.
Results: For this motion setting, the average HU for the golden marker and the target were 2438 and 27, with standard deviations at 670 and 24. And range of HU for golden marker and target were 1668 and 64, corresponding to a ratio of 26.
Conclusion: A magnification method of detecting edge of motion target was developed to by employing a golden fiducial maker. Clinically, it may be appropriate to implant a gold marker for motion target definition. Further study should include different motion parameters such as direction, and speed and imaging modalities to generate a standard threshold sets for auto segmentation application
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