SU-E-J-81: Beveled Needle Tip Detection Error in Ultrasound-Guided Prostate Brachytherapy

Area of Science:

• Medical Imaging
• Surgical Navigation
• Biomedical Engineering

Background:

• Accurate needle placement is critical for effective prostate brachytherapy.
• Ultrasound imaging is commonly used for guidance during seed implantation.
• Bevel-tip needles are standard for brachytherapy but can introduce imaging artifacts.

Purpose of the Study:

• To quantify needle tip detection errors in ultrasound images.
• To assess the impact of needle bevel orientation on detection accuracy.
• To evaluate how these errors vary with needle placement on a template grid.

Main Methods:

• Utilized a transrectal ultrasound (TRUS) system and an 18-gauge beveled brachytherapy needle.
• Performed measurements in a water phantom at varying TRUS gains (50% and 100%).
• Assessed needle tip detection errors with bevel-tip oriented up (0-degree) and down (180-degree) at different template grid locations.

Main Results:

• Bevel-tip orientation caused significant needle tip detection errors, ranging from 0.57mm to 5.24mm.
• Errors increased with distance from the TRUS probe, showing a linear trend across grid locations.
• Ultrasound gain did not consistently affect errors, with no observed effect directly above the probe.

Conclusions:

• Beveled needle tip orientation is a critical factor affecting needle tip detection accuracy in ultrasound imaging.
• These detection errors can lead to substantial dosimetric deviations in prostate brachytherapy.
• Optimizing needle orientation and accounting for these errors is essential for precise seed implantation.