Development and clinical implementation of simple needle attachment post placement interstitial template (SNAPP-IT) enabling a shorter, more direct needle path while preserving tumor visualization

Abstract

Purpose: Historical gynecologic interstitial brachytherapy templates block direct tumor visualization during needle placement, presenting an opportunity for clinical innovation to develop a novel interstitial template allowing direct tumor visualization during needle insertion. Methods: We designed and implemented a novel interstitial template, Simple Needle Attachment Post Placement Interstitial Template (SNAPP-IT), that allowed direct visualization of the target vaginal tumor during interstitial needle placement while maintaining the ability to individually secure needles to the template, allow a vaginal cylinder, suture holes for securing to the perineum, MRI compatibility and sterilizable for repeat use. Procedure outcomes including procedure time, needle path lengths, and plan dosimetry were prospectively captured in a patient database. Results: Forty gynecologic interstitial brachytherapy cases were recorded (20 SNAPP-IT, 20 traditional templates). Needle insertion depth was reduced using the SNAPP-IT in comparison with traditional interstitial templates (11.8cm vs 3.6cm, p<0.0001). The average CTV volume was 25.6 cc for SNAPP-IT and 20.7 cc for traditional; both methods averaged a similar number of needles (15.8, 15.6). Dosimetric constraints were similarly met in both treatment groups. Procedures performed using the SNAPP-IT were shorter compared with those performed with traditional interstitial devices (83.4 minutes vs 100.7 minutes) and there were no post-operative infections in the SNAPP-IT group. Conclusion: Implementation of a novel gynecologic interstitial brachytherapy template (SNAPP-IT) reduced procedure times, allowed direct tumor visualization, and decreased needle insertion depth. SNAPP-IT provides a useful alternative approach for vaginal interstitial brachytherapy, may increase brachytherapist efficiency with complex procedures and potentially expands access to interstitial brachytherapy.