Scatter radiation effects of titanium osteosynthesis plates in mandibular reconstruction: An experimental 3D-printed phantom and cell culture study

Overview

This experimental investigation evaluated the effects of titanium osteosynthesis plates on scatter radiation distribution and cellular responses in the context of mandibular reconstruction with fibula free flaps. The study addressed a gap in systematic evidence regarding dose perturbations from metallic fixation hardware in patients undergoing adjuvant radiotherapy following reconstructive surgery. The research combined dosimetric analysis using three-dimensional printed phantoms with in vitro cell culture studies to establish correlations between physical dose modifications and biological outcomes.

Methods and approach

A three-dimensional printed mandibular phantom derived from patient CT imaging was combined with a water phantom to simulate clinical irradiation geometry. Irradiation was delivered using an Ethos linear accelerator. Dose distributions in the vicinity of plates with varying diameters and geometric designs were quantified. Human mesenchymal stromal cells and human umbilical vein endothelial cells were exposed to identical irradiation conditions, with cell proliferation assessed via MTS assays to determine biological responses correlating with dosimetric alterations.

Key Findings

Dosimetric analysis revealed distinct dose increases anterior to the plates with corresponding dose reductions in the shadowing region, with magnitude dependent on plate diameter and geometric configuration. Significantly different proliferation responses were observed between hMSC and HUVEC populations exposed to the different radiation dose distributions created by the plate geometries. Physical dose perturbations directly correlated with measurable differences in cellular proliferation outcomes, establishing a relationship between hardware-induced dosimetric modifications and biological cellular responses.

Implications

The findings demonstrate that osteosynthesis plate design functions as a dosimetric modifier during radiotherapy in reconstructed mandibles, with implications for treatment planning in patients requiring adjuvant radiation following surgery. Plate geometry and metal volume represent modifiable design parameters that influence local radiation perturbations. Consideration of these factors during reconstructive planning may reduce radiation-induced complications in tissues surrounding metallic fixation hardware.