Room: ePoster Forums
Purpose: Application of Hybrid source in slotted plaque brachytherapy for the treatment of uveal melanoma and dosimetric comparison of plans with I-125 and Pd-103 sources.
Methods: In these investigations, dosimetric advantage and applicability of HYBRID source has been investigated for slotted plaque brachytherapy. The Hybrid source â€œADVANTAGEâ„¢ HYBRID PdIâ€? used in these investigations consists of 50 % of I-125 and 50% Pd-103. Dosimetric parameters of this source determined by Meigooni et. al. were entered in Plaque simulator software developed by Eye Physics, LLC.Ten previously treated patients for uveal melanoma using I-125 seeds at our institution were re-planned with HYBRID and Pd-103 sources. Results of Hybrid source were compared with plans generated with conventional Pd-103 and I-125(IAI-125A) sources.In this project, prescription dose was kept the same as for Pd-103, Hybrid and I-125 seeds (85Gy to the tumor apex). In addition, seeds loading pattern, plaque type and model were also kept the same as that of the original plans with I-125 sources.
Results: Results of our investigations show that dose to critical structures like, optic nerve, retina, lens, and macula was lower for plans with Pd-103 source as compared to plans with Hybrid and I-125 sources. Prescription point for Eye Plaque, being the apex of the tumor is the farthest point to deliver 85Gy(prescription dose) that results in the highest base of apex dose ratio for Pd-103 for large tumor <5mm as compared plans with other two sources. Although, dose gradient of I-125 is lower than Hybrid source but dose to critical structures was noted lower for the implants with Hybrid sources.
Conclusion: Our results indicate that Pd-103 is suited for small uveal melanoma tumors whereas, I-125 provides low dose gradient for larger tumor. Our results demonstrate that Hybrid source is better for small as well as larger uveal melanoma.
Not Applicable / None Entered.