Clinical implementation, logistics and workflow guide for MRI image based interstitial HDR brachytherapy for gynecological cancers

Abstract

Interstitial brachytherapy (IBT) is often utilized to treat women with bulky endometrial or cervical cancers not amendable to intracavitary treatments. A modern trend in IBT is the utilization of magnetic resonance imaging (MRI) with a high dose rate (HDR) afterloader for conformal 3D image‐based treatments. The challenging part of this procedure is to properly complete many sequenced and co‐related physics preparations. We presented the physics preparations and clinical workflow required for implementing MRI‐based HDR IBT (MRI‐HDR‐IBT) of gynecologic cancer patients in a high‐volume brachytherapy center. The present document is designed to focus on the clinical steps required from a physicist’s standpoint. Those steps include: (a) testing IBT equipment with MRI scanner, (b) preparation of templates and catheters, (c) preparation of MRI line markers, (d) acquisition, importation and registration of MRI images, (e) development of treatment plans and (f) treatment evaluation and documentation. The checklists of imaging acquisition, registration and plan development are also presented. Based on the TG‐100 recommendations, a workflow chart, a fault tree analysis and an error‐solution table listing the speculated errors and solutions of each step are provided. Our workflow and practice indicated the MRI‐HDR‐IBT is achievable in most radiation oncology clinics if the following equipment is available: MRI scanner, CT (computed tomography) scanner, MRI/CT compatible templates and applicators, MRI line markers, HDR afterloader and a brachytherapy treatment planning system capable of utilizing MRI images. The OR/procedure room availability and anesthesiology support are also important. The techniques and approaches adopted from the GEC‐ESTRO (Groupe Européen de Curiethérapie ‐ European Society for Therapeutic Radiology and Oncology) recommendations and other publications are proven to be feasible. The MRI‐HDR‐IBT program can be developed over time and progressively validated through clinical experience, this document is expected to serve as a reference workflow guideline for implementing and performing the procedure.

Verification of Guiding Needle Placement by Registered Ultrasound Image During Combined Intracavitary/Interstitial Gynecologic Brachytherapy

“…Some research preferred to use plastic needles with metal obturators to assist insertion smoothly. 22 Because the obturator occupied the micro electromagnetic sensor’s position, 3D-printed improved the needle tips with threads at the bottom by 3D-printing technology to assist needle insertion in clinical research. Third, additional studies are needed to construct the needle shaft in preoperative CT image space by threading it along the shaft after needle placement.…”

Development of a gynecologic brachytherapy curriculum and simulation modules to improve radiation oncology trainees’ skills and confidence

“…The trainees discussed treatment recommendations, review of a prebrachytherapy checklist (see appendix), and applicator selection. On entering the OR environment, each resident independently performed all aspects of applicator insertion on the cadaver model evaluated by a brachytherapy checklist (see appendix) developed from our institutional MRI-based high-dose-rate brachytherapy procedure workflow (22). The second hour consisted of contouring, dosimetric planning, and treatment evaluation with the same patient information and imaging provided at the start of each session.…”

Verification of needle guidance accuracy in pelvic phantom using registered ultrasound and MRI images for intracavitary/interstitial gynecologic brachytherapy

“…16. Prospective workflow for clinical research sertion [23]. Since the obturator was inserted into the needle shaft during needle insertion and occupied the position of micro electromagnetic sensor, we plan to use 3D-printed needle tapers with threads at the bottom, which can connect to the plastic shafts to assist needle insertion in a clinical research.…”

“…Howev-er, filling the needles with agar mixture is not possible for patient procedures. Zhang et al produced MRI line markers using plastic tubes filled with medical saline, which were validated to provide the best visualization of needles in intraoperative T2-weighted MRI images [23]. This kind of MRI line marker also avoids artifacts in images and has the same effects as agar mixture.…”