A Novel Brachytherapy Endoscopic Tandem and Inflatable Ovoids Applicator for Cervical and Uterine Neoplasms

Abstract

Brachytherapy using the Fletcher-Suit-Delclos (FSD) applicator is an effective treatment modality for cervical and uterine cancers. The traditional FSD applicator typically consists of 8-pieces that are assembled in the patient under anesthesia. The procedure can be lengthy due to difficulty visualizing the cervical os, poor applicator design and assembly difficulty. The purpose of this study is to build prototypes of a user-friendly applicator, which improve patient comfort and care while minimizing intravaginal manipulation and optimizing inter fractions reproducible geometry with superior dosimetric properties. 3D CAD software was used to create a model of an applicator and simulate its intended functionalities. A CT and MRI friendly prototype made of balloons and plastics manufactured based on the CAD model. The prototype device is comprised of two main pieces; an endoscopic tandem using a miniaturized Complementary Metal Oxide Semiconductor (CMOS) camera connected to a computer and two inflatable ovoids. The ovoids consist of a two inflatable balloon assembly that can be inserted simultaneously and attached to the already placed tandem, and be inflated with different volumes of water. Further, balloon retractors were designed to separate the bladder and the rectum from the implant plane. The prototype was assembled with CT and MRI scans acquired. Isodose lines for a 7Gy dose to point A were generated. Our preliminary tests found an easier and faster assembly of the endoscopic tandem and inflatable ovoids. All the minor adjustments to an ideal geometry can be done outside the patient similar to a laparoscopy procedure minimizing intravaginal manipulations. The endoscopic tandem easily visualizes the cervical os while prevents the perforations or injury to the uterus. The bladder and rectal balloons replacing the painful gauze packing and inflate to get a bladder and rectum displacement of >2cm from the plane of the implant sparing the organs at risk significantly. Our initial estimates indicate that our device will decrease the implant times significantly, reducing the time under anesthesia, while promoting patient safety, complication reduction, and lowering overall treatment cost. The applicator CT and MRI images confirmed applicator’s compatibilities with these imaging modalities. The endoscopic tandem improves cervical os visibility and overall tandem placement. Further, with up to 15% of the tandems causing uterine perforation, using the camera aids in preventing the injury and potential morbidities associated with it. We achieve significant improvement in sparing the bladder and the rectum while delivering the same dose as the conventional FSD device. A comparative implant and dosimetric studies in a phantom with the applicators currently in clinical use are warranted in future studies.