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Program Information

Proton Therapy Fiducial Comparison

E Ramirez

E Ramirez*, Y Zheng, S Rana, ProCure Treatment Centers, Oklahoma City, OK

SU-E-J-33 Sunday 3:00PM - 6:00PM Room: Exhibit Hall


Fiducial markers are commonly used in Image Guided Radiotherapy as landmarks to ensure patient setup accuracy and reproducibility. Good fiducials need to be radiopaque, yet not so much to create significant CT artifacts and disturb the tumor dose downstream. The latter is even more important in Proton radiotherapy to fully achieve its preciseness. The purpose of the study is to investigate several potential fiducial markers on their suitability for prostate proton therapy.


In total, eight commercially available fiducial markers were compared in this study. These fiducials include: 3 types of VisiCoil (VC1-0.5x5 mm, VC2-0.35x5 mm, VC3-0.35x10 mm), BiomarC, FusionCoil, PolyMark, PointCoil, and FlexiCoil. We compared them in 4 ways. First, we scanned them using a GE RT16 scanner with a clinically used scanning protocol, and evaluated the degree of CT artifacts in two different water tank geometries; second, we evaluated visibility on kV images used for patient positioning, third, we compared their visibility on MRI. In addition, we looked at the perturbance of isodose lines distal to the fiducials in our treatment planning system.


Our preliminary study shows that PolyMark, BiomarC, VC2, and VC3 have the least CT artifacts of the group; FusionCoil, Flexicoil, PointCoil, and VC1 are most visible and PolyMark almost invisible on kV images; Evaluation of MRI visibility and dosimetric effects for these fiducials are in progress.

The VC1 and BiomarC seem to have the best performance in balance of CT artifacts and x-ray visibility. Further study on MRI visibility and dosimetric effect will be conducted to determine the overall performance of each fiducial and its suitability for clinical use in proton therapy.

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