End-to-end test for computed tomography-based high-dose-rate brachytherapy.

Area of Science:

• Medical Physics
• Radiation Oncology

Background:

• Modern brachytherapy increasingly uses complex technical procedures.
• 3D-imaging is standard for applicator contouring, positioning, and reconstruction.
• Accurate treatment planning and data transfer to afterloading devices are critical.

Purpose of the Study:

• To describe an end-to-end test for CT-based high-dose-rate (HDR) brachytherapy.
• To validate the entire treatment chain, from imaging to dose delivery.
• To meet German radiation-protection-commission recommendations.

Main Methods:

• Utilized a SOMATOM S64 CT scanner and BrachyVision TPS with Acuros algorithm.
• Employed GammaMedplus HDR afterloader with an Ir-192 source.
• Defined measurement setups in a water phantom with PMMA holders, comparing CT-based TPS calculations with PinPoint 3D chamber measurements.

Main Results:

• End-to-end test deviations between computed and measured doses were ≤5% for implant needles and vaginal cylinders.
• The test procedure demonstrated reproducible results.
• Applicator repositioning without a new CT scan yielded consistent outcomes.

Conclusions:

• The end-to-end test provides a practical method for verifying the HDR afterloading and CT-imaging treatment chain.
• The phantom is suitable for periodic system checks.
• The test accurately verifies newly introduced brachytherapy techniques.