Quality control strategies for head and neck brachytherapy (interventional radiotherapy)

Purpose: This study aimed to investigate quality control (QC) strategies to enhance treatment delivery in interventional radiotherapy (IRT) for head and neck (H&N) cancers, focusing on ensuring the accuracy of therapy while addressing specific challenges, such as catheter displacement and tube misconnection. Material and methods: A retrospective analysis was conducted among 30 patients treated with IRT for nasal vestibule or eyelid cancers at our institutional center from January 2022 to December 2023. All treatments involved 14 frac-tions over nine days. QC measures were implemented to monitor catheter placement and prevent misconnection, with daily visual checks and mid-course CT evaluations. Distance measurements between catheter markers were compared across scans, and variations exceeding 2 mm prompted re-planning. Statistical analyses included one-way t tests to assess marker displacement significance. Results: A total of 420 fractions were delivered, and 360 marker distance measurements were analyzed. No sig-nificant differences were observed between initial and mid-course CT scans (mean distances, 35.2 +/- 10.5 mm and 35.9 +/- 10.5 mm, respectively). However, in 16.6% of cases, re-planning was required due to catheter displacement or marker variation exceeding 2 mm. Notably, patients with nasal vestibule cancers demonstrated higher number of catheters and increased risk of displacement. Dosimetric evaluation confirmed significant dose distribution changes in a sub-set of cases, highlighting the clinical importance of QC. Conclusions: Quality control strategies are essential to ensure precise treatment delivery in H&N IRT, especially in complex anatomical sites and risk of catheter displacement. Implementation of systematic checks and re-planning criteria enhances patient safety and treatment efficacy. Further research is warranted to refine QC measures and eval-uate their impact on clinical outcomes.