Comparison of three methods for determining CT dose profile: presenting the tritium method.

Area of Science:

• Medical Physics
• Radiological Imaging
• Radiation Dosimetry

Background:

• Accurate determination of computed tomography (CT) dose profiles is crucial for radiation safety.
• Existing methods for CT dose profile measurement have limitations in accuracy and complexity.
• The full width at half maximum (FWHM) of the dose profile is a key parameter for characterizing CT beam collimation.

Purpose of the Study:

• To introduce and validate a novel method for CT dose profile determination using imaging plates from computed radiography systems.
• To compare the accuracy of this imaging plate method (tritium method) against established techniques.
• To evaluate the performance of the tritium method across various CT beam collimations.

Main Methods:

• The study employed three methods: the proposed imaging plate method (tritium method), point-dose measurements with a solid-state detector (CT Dose Profiler), and the air kerma-length product (P(KL)) method.
• All methods were used to measure the FWHM of the CT dose profile at different nominal beam collimations.
• Measurements were conducted on a multi-slice CT scanner.

Main Results:

• The tritium method demonstrated high accuracy, with deviations less than 0.1 mm compared to the CT Dose Profiler across all beam collimations.
• The maximum relative error for the tritium method was found to be 2%.
• The P(KL) method exhibited larger deviations (0.2–0.4 mm) and higher relative errors (>10%) for smaller beam collimations.

Conclusions:

• The proposed imaging plate (tritium) method is a highly accurate and reliable technique for determining CT dose profiles.
• The tritium method shows excellent agreement with advanced solid-state detector measurements.
• This imaging plate method offers a practical and precise alternative for CT dose profile analysis.