2791 - The Study of a Novel Free-Assembled Interstitial Template Used in Cervical Cancer Brachytherapy
Presenter(s)
R. Liang1, B. Bi1, Y. Dong1, and X. Wang2; 1Sichuan Cancer Hospital& Institution, Chengdu, China, 2Sichuan Cancer Hospital and Research Institute, University of Electronic Science and Technology of China, Chengdu, China
Purpose/Objective(s): Optimally placing interstitial needles in brachytherapy for locally advanced cervical cancer is highly dependent on physician's expertise and skills, especially when addressing dosimetric challenges in covering the distal parametrial and large volume tumors. The free-assembled interstitial template (FAIT) integrating intracavitary tube with radially optimized non-coplanar interstitial needles. FAIT guides needles to dosimetrically advantageous position, simplifying procedures while improving needles distribution and dose optimization.
Materials/Methods: The novel FAIT based on the initial non-angled interstitial template (NAIT) with peripheral channels supporting radial and oblique insertion of interstitial needles, while the central channel allows flexible fixation of either an intracavitary tube or interstitial needles. We reviewed 18 cervical cancer patients who received FAIT-guided brachytherapy at our institution between December 2024 and February 2025, including 6 patients who also underwent an additional NAIT treatment. We extracted treatment planning parameters from the Oncentra system, including: HRCTV-90%, HRCTV-D90, dose parameters for the organ at risk (OARs: bladder, small intestine, rectum, and sigmoid). Data are mean ± standard deviation. We first evaluated target coverage and organ sparing in 18 FAIT patients, then used one-way analysis of variance (ANOVA) to compare HRCTV, OARs doses, and dose distribution in 6 patients treated with FAIT followed by NAIT.
Results: All 18 FAIT treatments were successfully delivered. The mean HRCTV-90% and HRCTV-D90 were 57.66±12.90 ccm and 617.96±18.18 cGy (prescription dose: 600 cGy), respectively. The mean bladder dose was 428.23±25.35 cGy, while doses to the small bowel, rectum, and sigmoid colon were all below 400 cGy, demonstrating satisfactory dose distribution. Further analysis the six patients receiving both FAIT and NAIT treatments revealed no significant difference in HRCTV-90% between the two modalities (FAIT: 57.83 ± 13.68 ccm vs. NAIT: 61.94 ± 17.76 ccm), demonstrating their comparability and suitability for dose distribution analysis. Compared to the NAIT, FAIT achieved significantly lower doses to the OARs due to its enhanced flexibility. Meanwhile, FAIT maintained excellent target coverage with a mean HRCTV-D90 of 618.64 ± 16.72 cGy, comparable to NAIT’s 619.65 ± 17.20 cGy, further emphasizing its clinical advantages.
Conclusion: Compared with initial NAIT, the FAIT is convenient for physicians to adjust the angle and fix the position of the interstitial needles, which reduces the complexity of operation. On the other hand, the lower dose distribution of the OARs facilitates the increase of the dose in the appropriate target area and improves the therapeutic efficacy.