Electron depth absorbed doses for small phantom depths. Comparison between different accelerators

Area of Science:

• Medical Physics
• Radiation Dosimetry

Background:

• Accurate absorbed dose measurement is crucial for effective radiation therapy.
• Understanding depth dose distributions, especially at small phantom depths, is essential for precise treatment planning.

Purpose of the Study:

• To measure depth dose distributions in polystyrene at small phantom depths using a liquid ionization chamber.
• To evaluate the impact of electron energy and field size on surface absorbed dose.
• To compare central beam measurements with off-axis data.

Main Methods:

• Measurements were conducted using a liquid ionization chamber across six different accelerators.
• Depth dose distributions were analyzed at small phantom depths (e.g., 0.5 mm).
• Variations in absorbed dose were assessed relative to the absorbed dose maximum for 10 MeV electrons.

Main Results:

• The absorbed dose at 0.5 mm depth relative to the maximum varied from 0.77 to 0.92 for 10 MeV electrons.
• Surface absorbed dose generally increased with higher electron energy and smaller field sizes.
• Off-axis measurements showed minor deviations compared to central beam data.

Conclusions:

• Depth dose distributions in polystyrene exhibit significant variation at small phantom depths.
• Electron beam energy and field size are critical factors influencing surface dose.
• These findings are important for optimizing radiation dosimetry and treatment planning in clinical settings.