Pseudo Central-Catheter Method for Asymmetrical Vaginal Prescription with Multi-Channel Cylindrical Applicators in Image-Guided High Dose-Rate Brachytherapy

Multi-channel cylindrical applicators for high dose-rate (HDR) brachytherapy are utilized mainly for special gynecology cases often involving image-guidance high dose-rate (IG-HDR or IGBT) brachytherapy. In these cases, doses are prescribed to partial vaginal wall/depth where the disease is indicated by an MRI study scanned on the same day. These novel IG-HDR procedures are logistical challenges comparing to typical HDR out-patient treatments due to the complexity of planning for asymmetrical prescriptions as well as the extension of the whole procedure. Indeed the main advantages of HDR over LDR brachytherapy would be significantly weaken unless the IG-HDR procedures become more efficient in time, thus timely treatment planning becomes crucial. Based on our clinical experience, we propose the pseudo central-catheter method to reduce errors, to minimize uncertainty and to ensure efficiency. In this method, the central hollow path of the multi-channel cylindrical applicator is digitized into a pseudo catheter similar to other active catheters, and the asymmetrical prescription points could be generated corresponding to the pseudo dwelling points in the pseudo central-catheter. The pseudo dwelling points are later deleted after generating the prescription point arrays. This method is robust with minimal chance of errors or uncertainties, and demonstrates high efficiency with much less chance of uncertainty, which is significant for IG-HDR brachytherapy procedures utilizing multi-channel applicators.