The dose distribution within the target was more homogenous, and the doses for healthy tissue were less in the FIF plan compared to the tangential wedge plans.

Objective: To evaluate the incidence, size and predisposing factors for air pockets around the vaginal cylinder and their dosimetric effect on the vaginal mucosa. Methods: We investigated 174 patients with endometrial carcinoma treated with external radiotherapy (RT) and brachytherapy (BRT) (101 patients, 58%) or BRT alone (73 patients, 42%). The quantity, volume and dosimetric impact of the air pockets surrounding the vaginal cylinder were quantified. The proportions of patients with or without air pockets during application were stratified according to menopausal status, treatment modality and interval between surgery and RT. Results: Air pockets around the vaginal cylinder were seen in 75 patients (43%), while 99 patients (57%) had no air pockets. Only 11 patients (6.3%) received less than the prescribed dose (average 93.9% of prescribed dose; range, 79.0-99.2%). Air pockets were significantly fewer in pre-menopausal patients or in patients treated with the combination of external RT and BRT than in postmenopausal patients or patients treated with BRT alone. A significant correlation existed between the mucosal displacement of the air gap and the ratio of the measured dose at the surface of the air gap and prescribed dose (Pearson r 5 20.775; p , 0.001). Conclusion: Air pockets were still a frequent problem during vaginal vault BRT, especially in post-menopausal patients or in patients treated with BRT alone, which may potentially cause dose reductions at the vaginal mucosa. Advances in knowledge: Air pockets around the vaginal cylinder remain a significant problem, which may potentially cause dose reduction in the target volume.The primary treatment of choice in localized endometrial cancer is surgery. Adjuvant radiotherapy (RT) is recommended in intermediate-and high-risk patients in order to diminish disease recurrence. RT can be in the form of external RT (ERT) with vaginal vault brachytherapy (BRT) or BRT only, depending on the risk factors and stage of disease.The purpose of vaginal vault BRT is to eradicate a microscopic tumour at the lymphatics located in the vaginal vault. It was demonstrated that .90% of lymphatics lie within 2-3 mm from the surface of stretched mucosa.1 For this reason, in order to deliver adequate doses to the submucosal lymphatics, the vaginal cylinder must be in direct contact with the vaginal surface, as recommended by the American Brachytherapy Society (ABS).2 The Group Europeén de Curiethérapie and the European Society for Radiotherapy & Oncology (GEC-ESTRO) guidance 3 is to prescribe vaginal BRT to 5 mm from the applicator surface with a 2-mm tolerance. The most commonly used applicator for vaginal vault high-dose-rate BRT is a segmented cylinder. 4 However, during application, air gaps may be observed, which may potentially cause underdosage of the vaginal mucosa.Cameron et al 5 found that 18 of 25 patients (72%) had air gaps .2 mm in the cranial part of the vagina, with the median number of air pockets per patient being 1 (range, 0-5). Richardson et al 6 reported that 20 o...

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Our study demonstrated that CBCT-FM was not superior to CBCT-P for image-guided radiotherapy in prostate cancer patients.

The delineation course improved interobserver variability for gastric cancer. However, impact of target volume changes on toxicity and local control should be evaluated for further studies. Advances in knowledge: This study demonstrated that a delineation course based on current recommendations helped physicians delineate smaller and more homogeneous target volumes. Better target volume delineation allows proper target volume irradiation and preventing unnecessary normal tissue irradiation.