Fabrication and Dosimetric Characteristics of Silicon Elastomer-Based Bolus Using External Beam Radiotherapy

Area of Science:

• Medical Physics
• Radiation Oncology
• Materials Science

Background:

• Boluses are crucial in radiotherapy for dose uniformity on uneven surfaces.
• Tissue-equivalent materials are needed to mimic human tissue response to radiation.
• Silicone elastomer-based materials offer potential for adjustable and non-toxic bolus fabrication.

Purpose of the Study:

• To evaluate the dosimetric characteristics of a novel silicone elastomer-based bolus.
• To determine the suitability of this bolus material for clinical use in external beam radiation therapy.
• To assess the performance of the bolus with megavoltage photons.

Main Methods:

• Fabrication of silicone elastomer boluses using PDMS substrate and curing agent (10:1 ratio) in 0.5cm and 1cm thicknesses.
• Evaluation of key dosimetric properties including transmission factor, mass attenuation coefficient, durability, homogeneity, and density.
• Testing conducted using a Varian Linear accelerator with 6MV photon beams over one month.

Main Results:

• The fabricated silicone elastomer bolus demonstrated satisfactory dosimetric characteristics for radiotherapy applications.
• Transmission factor and mass attenuation coefficient were within acceptable ranges for tissue equivalence.
• Durability and homogeneity tests confirmed the material's stability and uniformity under irradiation.

Conclusions:

• The silicone elastomer bolus effectively increases surface dose and protects organs at risk (OAR).
• The developed bolus is adjustable, transparent, easily fabricated, cost-effective, and non-toxic.
• This material presents a viable option for advanced radiotherapy applications requiring precise dose delivery.