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Finite Element Modeling of Bare-Tip and Cylindrical Diffusing Optical Fibers for Prostate Cancer Focal Laser Ablation

Authors :

Sajjad Saadati Rad¹ Alireza Mehridehnavi² Seyed Mojtaba Karbalaee³

1- دانشگاه علوم پزشکی اصفهان 2- دانشگاه علوم پزشکی اصفهان 3- دانشکده علوم پزشکی شوشتر

Keywords :

Focal Laser Ablation،Laser Therapies،Prostate Cancer،Minimally Invasive Surgery،Finite Element Method

Abstract :

Prostate cancer is the second most frequently diagnosed malignancy among men worldwide and remains a major contributor to cancer-related mortality. Standard whole-gland treatments, such as prostatectomy and radiotherapy, achieve effective cancer control but are often accompanied by significant long-term morbidity. Focal laser ablation (FLA) has emerged as a minimally invasive alternative, offering selective tumor destruction with reduced functional side effects. Optical fiber design plays a decisive role in shaping ablation outcomes: bare-tip fibers provide highly concentrated heating suitable for small lesions, whereas cylindrical diffusing fibers distribute energy more evenly, enabling broader and more uniform coverage. This study employs finite element modeling (FEM) to directly compare these two fiber types under controlled conditions in prostate tissue. A spherical prostate model with bioheat transfer and Arrhenius damage formulations was used to simulate two representative scenarios: a bare-tip fiber at 0.4 W and a cylindrical diffuser at 1 W with 1 cm emission length. Results demonstrated that the bare-tip fiber generated a sharply localized, teardrop-shaped lesion of ~467 mm³, while the diffuser produced a more symmetric, ellipsoidal lesion with a threefold larger damage volume (~1709 mm³) without excessive local overheating. These findings reveal a fundamental trade-off between precision and coverage. Bare-tip fibers may be optimal for small, well-confined tumors, whereas diffusers provide safer margins for larger or irregular lesions. The FEM framework establishes a foundation for MRI-based, patient-specific planning of FLA.