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Dose uncertainty due to needle-tip localization error in prostate seed implantation
Zhengzheng Xu1,2, Theodore H Arsenault1, Bryan Traughber3
1Department of Radiation Oncology, Seidman Cancer Center, University Hospitals Cleveland Medical Center, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA.
Journal of Contemporary Brachytherapy
|February 23, 2023
Summary
Bevel-tip orientation in brachytherapy needles causes significant errors in ultrasound imaging, impacting prostate seed implant accuracy and leading to dosimetric uncertainty. This affects prostate coverage but not urethral or rectal parameters.
Area of Science:
- Medical Physics
- Radiation Oncology
- Medical Imaging
Background:
- Brachytherapy is a crucial treatment for prostate cancer.
- Accurate seed placement is vital for effective treatment and minimizing side effects.
- Ultrasound imaging is commonly used for guidance during prostate brachytherapy.
Purpose of the Study:
- To quantify dosimetric uncertainty in prostate seed implantation.
- To investigate the impact of needle-tip detection errors caused by bevel-tip orientation.
- To assess the effect of these errors on prostate, urethra, and rectum dosimetry.
Main Methods:
- Utilized a trans-rectal ultrasound (TRUS) system with a physical template grid and 18-gauge needles.
- Performed measurements in a water phantom at varying TRUS gains (50% and 100%).
- Retrospectively applied needle-tip localization errors to 45 prostate seed implant plans.
Main Results:
- Maximal needle-tip detection errors were 3.7 mm (50% gain) and 5.2 mm (100% gain).
- Significant decrease in prostate coverage observed (D90 by 12.8%, V100 by 3.9% for smaller prostates).
- No statistically significant dosimetric differences were found for urethral and rectal parameters.
Conclusions:
- Beveled needle-tip orientation significantly affects needle tip detection accuracy in ultrasound.
- These detection errors can lead to substantial dosimetric uncertainty in prostate seed implantation.
- The findings highlight the need for precise needle orientation control during brachytherapy planning and delivery.
