Integrated optimization of needle paths and dwell time for individualized template-guided interstitial brachytherapy

Area of Science:

• Medical Physics
• Radiation Oncology
• Medical Imaging

Background:

• 3D-printed individualized template (3D-PIT) guided interstitial brachytherapy (ISBT) is a key treatment for cervical cancer.
• Current manual planning is operator-dependent and can cause trauma.

Purpose of the Study:

• To develop and validate an automated method for optimizing needle paths and dwell times in 3D-PIT ISBT for recurrent cervical cancer.
• To reduce operator dependence and improve treatment consistency.

Main Methods:

• A two-layer optimization strategy was used: simulated annealing for needle paths and dwell times.
• 40 patient cases (219 fractions) were analyzed, comparing automated plans to clinical plans.
• Dosimetric results and organ-at-risk (OAR) protection were evaluated.

Main Results:

• Automated plans were generated in 1.5 ± 1.2 minutes, meeting clinical constraints.
• OAR doses (rectum, bladder, colon, small intestine, urethra) were significantly reduced compared to clinical plans.
• HR-CTV coverage (V100%) was maintained, while V150% slightly increased; total dwell time decreased.

Conclusions:

• The automated method offers a fast, standardized pre-planning tool for 3D-PIT ISBT.
• It reduces operator dependence and provides a clinical baseline for consistent dosimetric quality.