Correlations between intraplan and postplan parameters in I-125 permanent prostate brachytherapy using loose seeds or...

Area of Science:

• Oncology
• Medical Physics
• Radiotherapy

Background:

• Permanent prostate brachytherapy using Iodine-125 (I-125) is a common treatment for localized prostate cancer.
• Seed arrangement is crucial for effective dose delivery and minimizing toxicity.
• Comparing linked versus loose seed techniques is essential for treatment optimization.

Purpose of the Study:

• To determine the optimal seed arrangement in I-125 permanent prostate brachytherapy.
• To compare treatment outcomes and normal organ toxicity between linked and loose seed methods.
• To identify dosimetric parameters that correlate between the two seed arrangement techniques.

Main Methods:

• A comparative study involving 61 patients with localized prostate cancer treated with I-125 brachytherapy.
• Modified peripheral loading technique for seed placement.
• Evaluation of prostate (D90, V100, V150), urethral (D90, D10, D5), and rectal (V100, D2) dosimetric parameters.
• Regression analysis to assess correlations (r and r²).

Main Results:

• Significant correlations were observed for Prostate V150, urethral D90, D10, D5, and rectal D2 (RD2) across both linked and loose seed methods.
• Specific parameters showed significant correlations within each group (linked or loose seeds) and in combined analyses.
• Prostate D90 and V100 did not show significant correlations between the methods.
• Normal organ damage parameters correlated well between intraplan and postplan assessments.

Conclusions:

• Both linked and loose seed arrangements in I-125 prostate brachytherapy demonstrate significant dosimetric correlations for key parameters.
• The evaluated parameters, especially those related to normal organ damage, can help guide treatment decisions.
• These findings support the use of specific dosimetric evaluations for optimizing seed arrangement and patient outcomes in prostate brachytherapy.