Generalized dual-phase-lag modeling of rectal wall thermal protection in prostate laser therapy using hyaluronic acid, collagen, and balloon spacers

Prostate laser therapy is a widely accepted minimally invasive procedure due to its precision and effective treatment outcomes. However, increasing laser energy to improve therapeutic efficacy can result in excessive thermal exposure to adjacent healthy tissues, particularly the rectum. This raises concerns about rectal toxicity, primarily due to the anatomical proximity of the prostate to the anterior rectal wall. This study numerically investigated the influence of prostate-rectum separation distance and different interstitial spacers, namely Hyaluronic Acid (HA), Collagen, and Balloon Spacers on reducing rectal wall thermal exposure during prostate laser therapy. The simulations were performed using the Generalized Dual-Phase-Lag (GDPL) bioheat transfer model to predict transient temperature distributions in biological tissues. Spacer-induced separation distances of 4.0, 5.1, 7.1, and 8.8 mm were analyzed. The results demonstrated that all spacer materials significantly reduced the peak rectal wall temperature compared to the no spacer condition. Temperature reductions of 53.56 %, 54.81 % and 55.34 % were observed for Collagen, Balloon Spacers and Hyaluronic Acid, respectively. Furthermore, increasing the spacer thickness resulted in additional temperature reductions, with Hyaluronic Acid providing the greatest thermal protection across all distances. These findings suggest that the use of interstitial spacers can effectively mitigate unintended thermal damage to the rectal wall during prostate laser therapy. Among the materials evaluated, Hyaluronic Acid showed superior thermal insulation performance. These results provide valuable insights for improving thermal safety in prostate cancer laser treatments and support future clinical validation.