Polymethylmethacrylate blocking trays. The effects of repeated usage.

Area of Science:

• Materials Science
• Medical Physics
• Polymer Engineering

Background:

• Polymethylmethacrylate (PMMA) sheets, often referred to as Lucite, are widely utilized in radiation therapy to immobilize low-melting-point alloy blocks.
• Recycling of these PMMA sheets is common practice, leading to the presence of numerous holes in the material.
• The potential impact of these perforations on the structural integrity of PMMA sheets used in critical medical applications requires investigation.

Purpose of the Study:

• To evaluate the mechanical strength and deflection characteristics of recycled polymethylmethacrylate sheets.
• To determine if the presence of multiple holes significantly compromises the structural integrity of PMMA sheets used in radiation therapy.

Main Methods:

• Experimental testing was conducted to measure the deflection of polymethylmethacrylate plates under applied load.
• Sheets with a substantial number of holes, representative of recycled materials, were subjected to mechanical stress analysis.

Main Results:

• Experimental data demonstrated that polymethylmethacrylate sheets exhibit minimal reduction in strength, even when containing a significant number of holes.
• The deflection measurements indicated that the structural integrity is largely preserved despite the perforations.

Conclusions:

• Recycled polymethylmethacrylate sheets retain substantial mechanical strength, making them suitable for continued use in radiation therapy applications.
• The presence of holes from recycling does not significantly diminish the load-bearing capacity or structural performance of these PMMA sheets.