Ionization chamber dosimetry for photon and electron beams. Theoretical considerations

Area of Science:

• Medical Physics
• Radiation Dosimetry
• Radiological Physics

Background:

• Ionization chambers are crucial for accurate radiation dosimetry.
• Existing Clambda-values, such as those in ICRU Report No. 14, may require updates for specific materials.
• The composition of the inner wall of ionization chambers significantly impacts dosimetry calculations.

Purpose of the Study:

• To propose new Clambda-values for ionization chambers with air-equivalent inner walls (plastic or graphite).
• To introduce updated Clambda-values for chambers with water-equivalent inner walls.
• To present new CE-values for both air-equivalent and water-equivalent chambers.

Main Methods:

• Calculation and comparison of new Clambda-values against established values (ICRU Report No. 14).
• Evaluation of the impact of air-equivalent and water-equivalent inner wall materials on Clambda-values.
• Derivation of new CE-values based on updated dosimetry considerations.

Main Results:

• Proposed Clambda-values are up to 3% lower for air-equivalent inner walls.
• New Clambda-values for water-equivalent inner walls are up to 3% higher than previously published values.
• Two sets of CE-values (Cair,E and Cwater,E) are proposed, with Cwater,E being approximately 3% higher.

Conclusions:

• The proposed Clambda-values provide improved accuracy for ionization chambers, especially those with water-equivalent walls.
• Updated CE-values are essential for precise radiation dosimetry in clinical and research settings.
• These advancements contribute to more reliable radiation measurements in medical physics and related fields.