A liquid-filled ionization chamber for high precision relative dosimetry.

Area of Science:

• Medical Physics
• Radiation Oncology
• Dosimetry

Background:

• Radiosurgery and intensity-modulated radiation therapy (IMRT) utilize narrow, irregularly shaped megavoltage photon beams.
• These beams present challenges in quality assurance (QA) due to lack of charged particle equilibrium and steep dose gradients.
• Accurate QA requires dosimeters with high spatial resolution and a good signal-to-noise ratio.

Purpose of the Study:

• To present a novel liquid-filled ionization chamber for precise dosimetry in advanced radiation therapy techniques.
• To evaluate the performance of this liquid ionization chamber for quality assurance measurements.
• To assess the stability and accuracy of the liquid ionization chamber compared to existing detectors.

Main Methods:

• Development and characterization of a liquid-filled ionization chamber using non-polar organic liquids as the active medium.
• Comparative measurements of beam profiles and penumbrae using the liquid ionization chamber and an unshielded diode.
• Medium-term stability tests were conducted on the liquid ionization chamber.

Main Results:

• The liquid-filled ionization chamber demonstrated high accuracy in performing profile measurements and determining penumbrae.
• Comparative analysis showed the liquid ionization chamber's suitability for QA in IMRT and radiosurgery.
• The detector exhibited proper signal stability over the studied medium-term period.

Conclusions:

• The presented liquid-filled ionization chamber is a viable and accurate tool for quality assurance in radiosurgery and IMRT.
• Its design and performance address the need for high spatial resolution dosimeters in advanced radiation therapy.
• The chamber offers a reliable solution for precise beam characteristic measurements, enhancing treatment safety.