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

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.

Linear Accelerator-Based Radiotherapy Simulation Using On-Board Kilovoltage Cone-Beam Computed Tomography for 3-Dimensional Volumetric Planning and Rapid Treatment in the Palliative Setting.

BACKGROUND: Palliation of advanced disease using radiotherapy can create difficult clinical situations where standard computed tomography simulation and immobilization techniques are not feasible. We developed a linear accelerator-based radiotherapy simulation technique using nonstandard patient positioning for head and neck palliation using on-board kilovoltage cone-beam computed tomography for 3-D volumetric planning and rapid treatment. Material and Methods: We proved cone-beam computed tomography simulation feasibility for semi-upright patient positioning using an anthropomorphic phantom on a clinical Elekta-Synergy linear accelerator. Cone-beam computed tomography imaging parameters were optimized for high-resolution image reconstruction and to ensure mechanical clearance. The patient was simulated using a cone-beam computed tomography-based approach and the cone-beam computed tomography digital imaging and communications in medicine file was imported to the treatment planning software to generate radiotherapy target volumes. Rapid planning was achieved by using a 3-level bulk density correction for air, soft tissue, and bone set at 0, 1.0, and 1.4 g/cm3, respectively. RESULTS: Patient volumetric imaging was obtained through cone-beam computed tomography simulation and treatment was delivered as planned without incident. Bulk density corrections were verified against conventionally simulated patients where differences were less than 1%. Conclusion: We successfully developed and employed a semi-upright kilovoltage cone-beam computed tomography-based head and neck simulation and treatment planning method for 3-D conformal radiotherapy delivery. This approach provides 3-D documentation of the radiotherapy plan and allows tabulation of quantitative spatial dose information which is valuable if additional palliative treatments are needed in the future. This is a potentially valuable technique that has broad clinical applicability for benign and palliative treatments across multiple disease sites-particularly where standard supine simulation and immobilization techniques are not possible.