Physical measurements with a high-energy proton beam using liquid and solid tissue substitutes

Area of Science:

• Medical physics
• Radiation oncology
• Biophysical research

Background:

• Accurate characterization of high-energy proton beams is crucial for effective radiation therapy.
• Tissue equivalence of materials used in phantoms is essential for reliable dose distribution measurements.
• Understanding the impact of various human tissues on proton beam interactions is vital for treatment planning.

Purpose of the Study:

• To describe the measurement of physical parameters for a high-energy proton beam.
• To present the system, detectors, and experimental verification of tissue-equivalent materials.
• To investigate the effects of different tissues on dose distributions and establish necessary corrections.

Main Methods:

• Utilized a range of liquid and solid tissue substitutes for proton beam measurements.
• Employed specific detectors for measuring beam parameters.
• Compared measurements from scattered, uncollimated beams with scattered, collimated beams in tissue-equivalent liquids and water.
• Investigated the influence of lung, fat, and bone on dose distributions using composite phantoms.

Main Results:

• Experimental verification confirmed the tissue equivalence of new substitutes.
• Measurements in muscle- and brain-equivalent liquids showed variations between collimated and uncollimated beams.
• Corrections for the effects of lung, fat, and bone on dose distributions were established.
• Simulated patient treatment demonstrated precise Bragg peak positioning within +/- 0.5 mm.

Conclusions:

• The developed system and tissue substitutes enable accurate measurement of proton beam physical parameters.
• The study provides a method for accounting for tissue heterogeneity in dose calculations.
• High precision in Bragg peak positioning is achievable, improving the safety and efficacy of proton therapy.