WE-EF-303-01: FEATURED PRESENTATION: Hydrogel Fiducial Markers for In-Vivo Proton Therapy and Range Verifications Using PET
- UT MD Anderson Cancer Center, Houston, TX (United States)
- Augmenix, Inc., Waltham, MA (United States)
- Rice University, Houston, TX - Texas (United States)
- MD Anderson Cancer Ctr., Houston, TX (United States)
- M.D. Anderson Cancer Center, Houston, TX (United States)
- MD Anderson Cancer Center, Houston, TX (United States)
- UT MD Anderson Cancer Center, Houston, TX (TX) (United States)
Purpose: Currently there are no clinically used techniques for in-vivo proton treatment/range verification. Our aim was to develop patient implantable markers that can be visualized in CT/x-ray for treatment-planning/beam-positioning, and also in PET for proton treatment/range verification. Methods: Biocompatible/biodegradable hydrogel polymers were immersed in O18-enriched water and O16 water, respectively to create O18-water hydrogels (0.5 cm3) and O16-water hydrogels (1 cm3) (both >99% water and <1% polymer). Also, 5–8 µm Zn powder was suspended in O16 water and O18-enriched water and cross-linked with hydrogel polymers to create Zn/16O-water hydrogels (30%/70% mass ratio, <1% polymer) and Zn/18O-water hydrogels (10%/90%). A block of extra-firm “wet” tofu (12.3×8.8×4.9 cm, ρ{sup =}1) immersed in water was injected with Zn/O16-water hydrogels (0.9 cm3 each) at four different depths using an 18 gauge needle. Similarly, Zn/18O-water hydrogels (0.9 cm3) were injected in a different tofu phantom. As a reference, both 16O-water and O18-water hydrogels in petri-dishes were irradiated in a “dry” environment. The hydrogels in the “wet” tofu phantoms and “dry” petri-dishes were CT-scanned and treatment-planned. Then, they were positioned at the proton distal dose fall-off region and irradiated (2 Gy) followed by PET/CT imaging. Results: Significantly high PET signals were observed only at O18-water hydrogels in the “dry” environment. Zn/O16-water hydrogels injected in the tofu phantom showed outstanding CT visibility but provided no noticeable PET signals. Zn/O18-water hydrogels in the “wet” tofu showed excellent CT visibility and moderate PET visibility, however, weaker PET signals than the “dry” environment possibly due to O18-water leaching out. Conclusion: The developed hydrogel markers can be used as universal fiducial markers due to their CT/PET/MRI/US visibility. Their PET visibility (possibly contributed more by activated O18-water than Zn) after proton irradiation can be utilized for proton therapy/range verification. More investigation is needed to slow down the leaching of O18-water.
- OSTI ID:
- 22572212
- Journal Information:
- Medical Physics, Vol. 42, Issue 6; Other Information: (c) 2015 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA); ISSN 0094-2405
- Country of Publication:
- United States
- Language:
- English
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