In-Room Radiographic Imaging
for Target Localization
Fang-Fang Yin, PhD, Devon Godfrey, PhD, Hui Yan, PhD, Sua Yoo, PhD,
Zhiheng Wang, PhD, Jackie Wu, PhD
Department of Radiation Oncology
Durham,
e-mail: fangfang.yin@duke.edu
Three-dimensional
conformal radiation therapy in the forms of multiple conformal beams, dynamic
conformal arcs, and intensity-modulated radiation therapy (IMRT) has been used
to precisely deliver radiation doses to the treatment target. In external beam
therapy, the task of pre-treatment target localization is to ensure that at the
time of treatment, with the patient in treatment position, the target is
accurately localized with respect to the incident radiation from the treatment
machine. The advances in target definition, treatment planning, and radiation
delivery would be worthless if the target cannot be correctly localized for
treatment. Therefore, techniques used to accurately deliver precise radiation
beams are equally important for successful radiation therapy. Accurate target
localization is aimed to reduce the margin required when expanding from a clinical
target volume (CTV) to a planned target volume (PTV). Technically, this margin
is mainly associated with setup uncertainties and organ motion.
Radiographic image
guidance is a powerful tool for improving treatment accuracy in the treatment
room. Various techniques are either being applied or developed for in-room
imaging to improve the accuracy of patient setup, target localization and
treatment verification. Several imaging formats are available such as
two-dimentional radiographic imaging, two-dimensional fluoroscopic imaging,
three-dimensional tomographic imaging, and four-dimensional organ motion and
functional imaging. Some could be used as real-time or on-line tools while
others are used for off-line verification and analysis. Generally, on-line
intervention requires completion of imaging for immediate evaluation prior to
radiation delivery, while off-line analysis has less demand for imaging and
evaluation time because it is done after radiation delivery.
In this
presentation, we will describe (1) several commercially available in-room radiographic
imaging systems; (2) imaging techniques with clinical applications, and (3) methods
of clinical implementation of different systems. Specific applications using
in-room localization techniques for stereotactic body radiation therapy will be
presented. Its clincial feasibility and efficacy will be discussed.
Acknowledgements:
IGRT Group at
Research support from Varian
Medical Systems
Partial travel support from NACMPA