European, Canadian and US brachytherapy organizations have come together to create consensus guidelines for brachytherapy for vaginal tumor recurrences from cervical or endometrial cancers, and Table 1 includes most of what you need to know. First of all, a T2-weight MRI both prior to and at the end of any preceding external beam irradiation is ideal. The first structure is simply the gross residual tumor (GTV) which is typically well-visualized on MRI. The second structure is the high-risk clinical target volume (CTV-HR), which is determined primarily by physical exam and includes the GTV plus any abnormally thickened or fibrotic vaginal mucosa within the initial tumor extent. The third structure is the intermediate-risk CTV (CTV-IR) which includes a 0.5 cm-margin on CTV-HR plus the original tumor extent. Of note, in the case of a complete response to external beam radiation, there is no GTV or CTV-HR and only a CTV-IR is created which would encompass the original tumor extent. Finally, the normal appearing vagina (cropped from CTV-HR) is contoured and used as the organ at risk during planning. Unfortunately dose recommendations are not included here. | Kamrava, Int J Radiat Oncol Biol Phys 2023
