A solid water phantom material for radiotherapy x-ray and gamma-ray beam calibrations

Area of Science:

• Medical Physics
• Materials Science
• Radiation Dosimetry

Background:

• Accurate radiotherapy requires precise dose calibration.
• Water is the standard phantom material, but its use can be cumbersome.
• Developing a water substitute with similar radiation properties is beneficial.

Purpose of the Study:

• To formulate, manufacture, and test an epoxy resin-based solid substitute for water.
• To evaluate its radiation characteristics and utility as a dosimetry phantom.
• To assess its potential for simplifying radiotherapy beam calibrations.

Main Methods:

• Formulation of an epoxy resin-based solid material.
• Manufacturing and testing of the solid water substitute.
• Relative transmission measurements using X- and gamma-ray beams.

Main Results:

• The solid water exhibits radiation characteristics volumetrically close to those of water.
• Transmission through 10 cm of solid water is within 0.2% of water for X- and gamma rays.
• Eliminates the need for phantom-to-water and density corrections in dosimetry.

Conclusions:

• The developed solid water is a viable substitute for water in radiotherapy dosimetry.
• Its use simplifies calibration procedures and can enhance accuracy.
• Facilitates achieving radiotherapy beam calibration goals within +/- 1.0% of the true dose rate.