Development of a current measurement system for 4πγ ionization chamber

Area of Science:

• Medical Physics
• Instrumentation and Measurement

Background:

• Accurate measurement of ionization current is crucial for dosimetry in radiation therapy and nuclear physics.
• Existing systems may face limitations in speed, accuracy, or dynamic range for 4πγ ionization chambers.

Purpose of the Study:

• To develop and validate a novel current measurement system, the ICMS-TIA, for enhanced performance in measuring 4πγ ionization chamber currents.
• To improve the speed and accuracy of ionization current measurements using an advanced I-V conversion technique.

Main Methods:

• Development of the Ionization Current Measurement System based on Transimpedance Amplifier (ICMS-TIA) utilizing an improved high-value resistance I-V conversion method.
• Incorporation of a range switching function to cover a broad measurement spectrum.
• Systematic testing of the ICMS-TIA for accuracy, response time, and linearity.

Main Results:

• The ICMS-TIA effectively measures ionization currents in the range of 50 fA to 50 μA.
• The system exhibits a rapid response time of less than 2.8 seconds.
• Current measurement deviation above 1 pA is below 0.41%, with a maximum linearity deviation of 1.15%.

Conclusions:

• The developed ICMS-TIA system demonstrates high accuracy and rapid response for ionization current measurements.
• The system's performance characteristics make it suitable for applications involving 4πγ ionization chambers.
• The improved I-V conversion method and range switching enhance the utility of the ICMS-TIA.