(Monday, 4/9/2018) 10:30 AM - 12:30 PM
Room: Marquis Ballroom 5-8
Which Planning CT Should Be Used for Lung SBRT, Free-breathing CT, MIP-CT, or AIP-CT?
Ping Xia, PhD - The Cleveland Clinic Foundation
Using stereotactic body radiotherapy (SBRT) for early staged, medically inoperable, lung cancer has been dramatically increased recently. To account for the tumor motion, four-dimensional (4D) - CT is often acquired to assess the magnitude of tumor motion. The internal target volume (ITV) can be directly delineated on the 4D-CT or CT in the cine mode. Alternatively, the ITV can be delineated on the maximum intensity projection (MIP)-CT. Because of 4D-CT involving multiple phases, directly using 4D-CT for treatment planning is clinically challenging. Free-breathing (FB) CT, MIP CT, averaged intensity project (AIP- derived from 4D-CT) CT, or a single phase CT (mid-inspiration CT) are used for treatment planning. There is no consensus on which CT should be used for planning CT. Furthermore, when daily cone-beam CT is applied for tumor localization, selection of a planning CT, which is the reference CT during IGRT, becomes more important. The objectives of this education session are to discuss advantages and disadvantages of choosing above mentioned planning CTs and provide cautions to clinical physicists about the potential pitfalls when choosing one of these CTs for treatment planning.
Mitigation of the Effects of Irregular Respiration in 4D-CT
Tinsu Pan, PhD - M.D. Anderson Cancer Center
Artifacts caused by irregular respiration are a major source of error in 4D-CT imaging. New techniques for cine and helical 4D-CT to combat the irregular respiration in 4D-CT have been developed. For cine 4D-CT, an approach to mitigate the impact of irregular respiration without new hardware, software or off-line data-processing on the GE CT scanner has been developed and can be applied in the clinic today. For helical 4D-CT, statistical analysis of the breathing signal for projection binning and incorporation of an artifact measure through phase and local amplitude based reconstructions have been proposed. It is the purpose of this symposium to provide an overview of the 4D-CT and to demonstrate the new and practical techniques for removing the irregular respiration and mitigating the impact of irregular respiration in 4D-CT.
Learning Objectives:
1. Understand differences between 4D-CT, MIP, and AIP
2. Understand challenges of using 4D-CT for treatment planning
3. Understand potential pitfalls of using FB-CT, MIP-CT, and AIP-CT as the treatment planning CTs
4. Understand how to align CBCT to the reference CT during daily IGRT.
5. Learn the basics of 4D-CT
6. Identify the sources of artifacts in 4D-CT
7. Lean new techniques to combat the artifacts in 4D-CT
Funding Support, Disclosures, and Conflict of Interest: Ping Xia, PhD: Research grant from Phillips Medical Systems Tinsu Pan, PhD: Nothing to declare
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