2010 AAPM Annual Meeting
Dr. Lu Wang, PhD, Fox Chase Cancer Center, Philadelphia, PA, 19111
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Purpose: To provide a practical overview on physics and dosimetry issues involved in
stereotactic body radiotherapy (SBRT) and to introduce current approaches for SBRT.
Introduction: SBRT is a new and evolving treatment technique that was mainly
designed for delivery of a highly focused and quick falloff dose distribution using large
dose fractionation. Due to this feature, accuracy for the treatment delivery is required to
be more stringent compared to conventional radiotherapy. Moreover, SBRT was
developed to mimic intracranial stereotactic radiosurgery (SRS)for extracranial
application. However, unlike the situation involving intracranial application in which
sharp fixation of a patient’s skull warrants tumor localization, extracranial targets are
generally subject to respiratory and cardiovascular motions. This creates great challenges
in treatment planning and treatment delivery for tumors in the extracranial regions,
especially in the thorax and abdominal regions. In this presentation, we will discuss
some of the unique physics and dosimetry issues and tasks involved in the SBRT
approach. These issues/tasks include commissioning aspects of the treatment machines
and accessories, the treatment planning aspect and quality assurance of the delivery. The
treatment planning aspect concerns patient immobilization, imaging modalities for
simulation, target motion accountability and management, block margin consideration,
and planning strategies. The treatment delivery generally utilizes volumetric imaging
guidance to improve dose delivery accuracy. Thus, advanced imaging guidance
techniques will be reviewed and the benefits and disadvantages will be discussed during
this presentation. We anticipate that, after the presentation, the audience will become
familiar with the physics and dosimetry issues involved in establishing a SBRT program.
1. Understand the differences between the SBRT approach and conventional RT.
2. Become familiar with the physics and dosimetric issues pertaining to the SBRT.
3. Become familiar with the general practical approaches used in SBRT.