(Monday, 4/9/2018) 4:30 PM - 5:30 PM
Room: Marquis Ballroom 5-8
In this session, we explore the technological advances in two exciting fields, total body irradiation (TBI) and magnetic resonance image-based brachytherapy treatment planning.
Conventional TBI techniques adopt large treatment fields with or without lung blocks to irradiate the patient’s entire body, standing or in the decubitus position, at an extended source-to-skin distance, e.g. 5 meters. The technique is exhausting for immunocompromised patients and the overall treatment time is often extended because of compliance issues.
Significant technological advances have been introduced by delivering radiation using multiple segmented or modulated beamlets, intensity-modulated radiation therapy (IMRT) which allows for greater sculpting of radiation doses to fit treatment targeted regions while sparing adjacent critical organs. Total marrow irradiation (TMI) becomes feasible with IMRT technique advancement. In this part of presentation, we will review conventional TBI techniques and the recent development of dedicated TBI irradiators, followed by descriptions of new TBI techniques using IMRT, including floor-based inverse-planned modulated-arc TBI (MATABI), volumetric arc therapy-based TBI (VMAT-TBI), and TMI with helical Tomotherapy. Clinical experience with advanced modulation radiotherapy will be shared. Future technical and clinical development of TBI/TMI will be discussed.
As computed tomography (CT) and magnetic resonance imaging (MRI) have become more widely available in clinics and hospitals, brachytherapy imaging has undergone a transition from the use of planar to volumetric imaging. Over the last two decades, there has been increasing interest in MRI either in conjunction with CT or independently for image guidance. Compared with CT, MR images have superior soft tissue resolution that has demonstrated a clear advantage for HDR brachytherapy.
Although GEC-ESTRO has published a series of recommendations to assist in the standardization of image-based brachytherapy treatment planning, their scope is limited to the experience of a few key European institutions using magnetic field strengths that did not exceed 1.5T. The recently published ICRU 89 report provides a good description of current volumetric imaging for the cervix with the addition of 4D adaptive target concepts and updated radiobiology and DVH parameter reporting for target and organs-at-risk. With the approval of Task Group 303 on MRI Guidance in HDR Brachytherapy - Considerations from Simulation to Treatment, the AAPM has recognized the need for developing guidance on MRI guided brachytherapy from a U.S. perspective. This segment of the presentation will provide an overview of task group 303 and their initial recommendations for MR-guided HDR brachytherapy for gynecologic and prostate cancers.
Learning Objectives:
1. Understand the principles and applications of TBI/TMI for bone marrow transplantation.
2. Learn about recent technological advances of TBI/TMI using modulated radiotherapy.
3. Learn clinical experience of new TBI/TMI treatment techniques and discuss future technique development and clinical implementation.
4. Understand the rationale for transitioning to MR guided brachytherapy for gynecologic and prostate cancers.
5. Understand the process of commissioning, QA, and clinical implementation of MR guided brachytherapy.
6. Discuss workflow options for implementing MR guided brachytherapy for gynecologic and prostate cancers.
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