UCLA Journal of Radiation Oncology Issue 4 - Flipbook - Page 24
UCLA RADIATION ONCOLOGY JOURNAL
5DCT: Clinical Experiences
and Future Directions
O
Our group has led the effort to entirely replace 4DCT as standard of care
in radiation oncology with an alternative approach which we term modelbased 5DCT
ne of the most inaccurate and unpredictable processes in radiation therapy is the
measurement and modeling of breathing motion for treatment planning and its
associated tumor delineation. These errors are mostly due to the commercial imaging
process known as 4DCT, which was developed by vendors in the early 2000s to provide
respiratory amplitude- or phase-gated images for radiation oncology. They developed 4DCT
as a modification of cardiac-gated imaging, which on the surface would provide the desired
temporally resolved images, but in effect often provided artifact-ridden images and only
qualitative motion assessments. Our group has led the effort to entirely replace 4DCT as standard
of care in radiation oncology with an alternative approach which we term model-based 5DCT
that fundamentally changes the CT acquisition method (using multiple fast-helical free-breathing
CT, FHFBCT, scans) and replaces the assumption of temporal regularity with an assumption of
proportionality between breathing motion and real-time acquired breathing surrogates.
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