Toward 3D-TRUS image-guided interstitial brachytherapy for cervical cancer

Area of Science:

• Medical Imaging
• Oncology
• Radiotherapy

Background:

• Cervical cancer brachytherapy requires precise needle placement for effective treatment.
• Accurate visualization of brachytherapy needles is crucial for both intracavitary and interstitial applications.
• Magnetic resonance imaging (MRI) is the current gold standard for needle visibility assessment.

Purpose of the Study:

• To qualitatively and quantitatively compare needle visibility in cervical cancer brachytherapy using 3D transrectal ultrasound (TRUS) against MRI.
• To assess the detectability of different needle types (straight, oblique, free-hand) on TRUS.

Main Methods:

• Image acquisition using a customized TRUS stepper unit and subsequent MRI with the applicator in place.
• Qualitative assessment using a visibility scoring system (0-3).
• Quantitative assessment by measuring needle-to-tandem distance and comparing TRUS and MRI measurements.

Main Results:

• Overall needle visibility on TRUS was 79% (87% straight, 51% oblique, 76% free-hand).
• Mean visibility score was 1.4 ± 0.5.
• Mean distance difference between MRI and TRUS was -0.3 mm ± 2.6 mm, with 11% differing by more than 3 mm.

Conclusions:

• Straight needles demonstrate significantly better detectability on TRUS compared to oblique needles.
• Factors like probe rotation, image quality, and anatomy impact needle detection.
• Further investigation into standardized imaging protocols and tracking for TRUS is recommended for real-time image guidance and online treatment planning.