Vaginal vault brachytherapy in endometrial cancer: verifying target coverage with image-guided applicator placement

Objective: This quality assurance study assesses whether CT image-guided verification has led to improvements in the technique when compared with previous studies. Methods: The CT images were studied from a cohort of 105 consecutive patients with endometrial cancer having adjuvant brachytherapy to the vaginal vault in 2010. Images were taken at first insertion, checked for air gaps and treatment delivered. Images were later transferred to the planning system and air gaps between vaginal mucosa and vaginal cylinder were measured. Comparisons were made with the 2008 results from this centre and the literature series. Results: Images from two patients were not assessable owing to artefacts from hip replacements. Air gaps >2mm were seen in 11/103 patients. Repositioning or use of a larger cylinder reduced air gaps to 7/103 patients. In total, 96/103 patients (over 93%) were able to achieve good vaginal contact throughout the treatment volume. This shows a significant improvement in applicator positioning in our centre since 2008 and also a significant improvement over the total data published in 2010 (Pearson chi(2) test = 46.19; p<0.0001). Conclusion: The vaginal cylinder technique with CT imaging was proven to be effective for 96/103 patients. It is necessary to consider whether there is a better technique for the few patients with air gaps >2mm. Advances in knowledge: For the vast majority of patients, this technique is well tolerated, without the need for analgesia, and will continue to be the first choice technique in this centre.