The perturbation correction factor of ionisation chambers in beta-radiation fields

Area of Science:

• Medical Physics
• Radiation Dosimetry
• Nuclear Science

Background:

• Accurate absorbed dose determination in solid media using ionization chambers requires accounting for radiation field perturbation.
• A specific correction factor for beta radiation has been lacking, hindering precise measurements.

Purpose of the Study:

• To experimentally determine the perturbation correction factor for beta radiation using an extrapolation chamber.
• To investigate the dependence of this factor on chamber geometry and radiation fields.
• To highlight the significance of this factor for depth dose curve measurements.

Main Methods:

• Experimental determination of the perturbation correction factor for beta radiation fields (147Pm, 204Tl, 90Sr + 90Y).
• Utilized an extrapolation chamber for measurements.
• Analyzed the factor as a product of shield and scatter components.

Main Results:

• The perturbation correction factor was successfully determined experimentally for specific beta emitters.
• The factor can be approximated as a product of a shield factor and a scatter factor.
• The magnitudes of these factors are influenced by chamber geometry and the characteristics of the beta radiation field.

Conclusions:

• The developed method provides a means to quantify the perturbation correction factor for beta radiation.
• Understanding this factor is essential for accurate absorbed dose measurements, particularly in phantom materials.
• The findings are critical for improving the accuracy of depth dose measurements in radiotherapy and radiation protection involving beta emitters.