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MO‐D‐AUD C‐01: Targeting Using Surrogates
Author(s) -
Yin F,
Roach M,
Shirato H,
Balter J
Publication year - 2008
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.2962351
Subject(s) - fiducial marker , image guided radiation therapy , medical imaging , medical physics , medical physicist , computer science , medicine , radiation therapy , radiology
While technology for image guided radiotherapy (IGRT) has advanced dramatically over the past few years, the basic fact remains that the actual treated target remains poorly or not at all visible using most in‐room imaging technologies. As a result, target localization and tracking is typically performed via the use of surrogates of the tumor. These surrogates may be endogenous to the patient (e.g. skeletal anatomy, diaphragm, external surface indicators), or exogenous and introduced into the patient to aid in localization / tracking (e.g. implanted radiopaque or electromagnetic fiducial markers). The selection of a surrogate should take into account the dynamic relationship between reference information and tumor position / configuration, and immobilization techniques (especially for breathing) may further aid in the fidelity of a given anatomic surrogate. Implanted markers carry a number of special considerations, including selection of marker, implant location and technique, clinical implications and marker stability over the time course of treatment, reference identification method, and guidance technique. As the vast majority of implanted marker methods have been developed on an ad hoc basis, a systematic discussion of these methods and related considerations can significantly help to guide medical physicists. Educational Objectives: 1. To discuss the various types of tumor surrogates, both anatomical and implanted, used for radiation therapy targeting. 2. To discuss techniques for identifying or implanting surrogates. 3. To discuss in‐room localization or imaging techniques for different surrogates, including the relationship between immobilization and surrogate fidelity. 4. To discuss the application of different surrogates, clinical feasibility and efficacy, and limitations. 5. To discuss quality assurance procedures and programs. 6. To discuss current challenges and future directions.