Interstitial cervical needle-guide ring-cap prototype for patient-specific ring-and-tandem brachytherapy

Area of Science:

• Medical Physics
• Oncology
• Biomedical Engineering

Background:

• Hybrid intracavitary-interstitial brachytherapy (IC/ISBT) is a crucial treatment for cervical cancer.
• Existing applicators have limitations in achieving patient-specific interstitial needle placement.
• Optimizing radiation dose distribution is key to improving treatment efficacy and reducing toxicity.

Purpose of the Study:

• To develop and evaluate a novel 3D-printed guide cap for MRI-compatible ring-and-tandem (R&T) applicators.
• To enable patient-specific interstitial needle guidance in hybrid IC/ISBT.
• To assess the impact of the guide cap on radiation dosimetry for the target volume and organs at risk.

Main Methods:

• A unique guide cap with six interstitial needle channels was designed using SolidWorks and 3D-printed.
• The guide cap was tested for compatibility with a commercial R&T applicator and interstitial needles.
• Dosimetric analysis was performed by replanning patient cases using virtual needle paths in EclipseBV software.

Main Results:

• 3D-printed guide caps demonstrated physical compatibility with the R&T applicator.
• Interstitial needles could be accommodated with a bending precision of ±1°.
• Significant improvements in target volume coverage (HR-CTV D90%) and reductions in organ-at-risk doses (bladder, rectum, sigmoid, small bowel D2cc) were observed.

Conclusions:

• A novel 3D-printed guide cap prototype enhances existing R&T applicators for IC/ISBT.
• The guide cap facilitates patient-specific interstitial needle placement with customizable angles and positions.
• This innovation improves radiation dosimetry, offering potential for more effective and safer cervical cancer treatment.