ESTRO 2025 - Abstract Book

S281

Brachytherapy - Gynaecology

ESTRO 2025

Results: A strong correlation was observed between TRAK/Vol and D90%, with TRAK/Vol in the range of 0.01 to 0.015 values associated with increased score, indicating a distinct optimal range for achieving clinically desirable outcomes. Plans in this optimal range averaged 4.8 ranging from 4 to 5. Plans achieving lower scores (Rating less than 4) were all outside the optimal range, suggesting a threshold effect. Correlation between TRAK/Vol and D90% for plans rating 3 or higher fit is seen in the range 0.006 to 0.019.

Conclusion: TRAK/Vol provides valuable insight into dose coverage and plan quality in interstitial brachytherapy for cervical and uterine cancers. We suggest that a TRAK/Vol range of 0.006 to 0.019 be used to quantitatively measure dose coverage for acceptable treatment plans and an optimal range targeted between 0.01 and 0.015. TRAK/Vol may serve as potential benchmarks for evaluating and optimizing interstitial gynecological brachytherapy treatment plans.

Keywords: TRAK, Interstitial, HDR

References: 1. Yaparpalvi R, Mehta KJ. Correlation of total reference air-kerma (TRAK) to prescription isodose surface volume in vaginal cylinder high-dose-rate brachytherapy. J Contemp Brachytherapy. 2021 Aug;13(4):447-450. doi: 10.5114/jcb.2021.108599. Epub 2021 Aug 24. PMID: 34484360; PMCID: PMC8407256.