A quality assurance test tool for high dose-rate remote afterloading brachytherapy units

Area of Science:

• Medical Physics
• Radiotherapy Technology
• Quality Assurance

Background:

• High-dose-rate (HDR) brachytherapy requires precise quality assurance (QA) for accurate treatment delivery.
• Existing QA methods for HDR units can be time-consuming and complex.
• Accurate source positioning is critical for effective HDR brachytherapy.

Purpose of the Study:

• To develop and validate a novel QA test tool for quantitative measurement of HDR source positioning error.
• To assess the tool's capability in performing HDR timer linearity tests and daily output constancy checks.
• To provide a simple, robust, and reliable tool for routine clinical QA in HDR brachytherapy.

Main Methods:

• The QA test tool utilizes two concentric disks with a detector in the upper disk and a cutout for the HDR catheter in the lower disk.
• Ionization readings are taken at two rotational positions to calculate source positioning error using triangulation.
• The tool is designed for integration with common detectors like diodes or miniature ionization chambers.

Main Results:

• Experimental measurements demonstrate the QA test tool's sensitivity to source positioning errors as small as 0.2 mm.
• The tool effectively facilitates HDR timer linearity tests and daily output constancy checks.
• The QA test tool is also suitable for source travel step size testing.

Conclusions:

• The developed QA test tool offers a quantitative and efficient method for assessing HDR source positioning accuracy.
• Its versatile design supports multiple essential HDR QA procedures, enhancing clinical workflow.
• The tool's robustness and simplicity ensure high confidence in the reliable operation of HDR brachytherapy units.