Program Information
3D Printing and 3D Dosimetry for LDR I-125 Eye Plaque Brachytherapy Quality Assurance
A Rodrigues1*, S Yoon1,2 , N Morales-Medina1,2, M Oldham1,2 , J Adamovics3 , S Meltsner1,2, O Craciunescu1,2 , (1) Duke University Medical Center, Durham, NC, (2) Duke Univeristy Medical Physics Graduate Program, Durham, NC, (3) John Adamovics, Skillman, NJ
Presentations
SU-E-205-2 (Sunday, July 30, 2017) 1:00 PM - 1:55 PM Room: 205
Purpose: The purpose of this study is to develop an improved QA procedure for eye plaque brachytherapy utilizing high resolution 3D dosimetry and 3D printing capabilities. 3D dosimetry for I-125 loaded eye plaques is not routinely performed as part of commissioning or patient-specific QA for eye plaque brachytherapy. This is due to limitations in reproducibility and accuracy in experimental set-up and dosimetry. Typically, seed assay from the same batch as the loaded eye plaque serves as an indirect QA.
Methods: A novel eye plaque specific jig was 3D printed using a .stl file provided by the vendor with modifications based on our experimental set-up with the goal of allowing precise positioning of a 3D dosimeter (PRESAGE®) and attachment with the eye plaque. A treatment plan using an EP2029N eye plaque (Eye Physics) loaded with I-125 (IsoAid Advantage) seeds was planned to deliver 30 Gy at a depth of 5mm. Post treatment the 3D dose was measured at 0.1mm³ resolution by an optimized optical CT scan. Measurements were compared to calculations from Plaque Simulator (v6.4.3, Eye Physics) and BrachyVision (v13.6, Varian).
Results: The 3D printed eye plaque specific jig held the eye plaque and dosimeter in a stable position during the experiment. 3D data was successfully acquired. At depths of 4-8mm, all three methods matched well. At depths of 0-4mm, the measured dose distribution displayed a similar trend as Plaque Simulator, as the TG-43 modified algorithm takes into account the non-homogeneous environment (gold eye plaque material and collimated slots) when compared to BrachyVision.
Conclusion: Accurate 3D eye plaque dosimetry presents special challenges based on the experimental set-up reproducibility and accuracy. The presented eye plaque specific 3D printed jig and 3D dosimeter could overcome these challenges and improve commissioning and patient-specific QA for eye plaque brachytherapy.
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