Phase impact factor: A novel parameter for determining optimal CT phase in 4D radiation therapy treatment planning for mobile lung cancer Conference Paper


Authors: Song, Y.; Huang, X.; Mueller, B.; Mychalczak, B.
Title: Phase impact factor: A novel parameter for determining optimal CT phase in 4D radiation therapy treatment planning for mobile lung cancer
Conference Title: Medical Imaging 2008: Visualization, Image-Guided Procedures, and Modeling
Abstract: Due to respiratory motion, lung tumor can move up to several centimeters. If respiratory motion is not carefully considered during the radiation treatment planning, the highly conformal dose distribution with steep gradients could miss the target. To address this issue, the common strategy is to add a population-derived safety margin to the gross tumor volume (GTV). However, during a free breathing CT simulation, the images could be acquired at any phase of a breathing cycle. With such a generalized uniform margin, the planning target volume (PTV) may either include more normal lung tissue than required or miss the GTV at certain phases of a breathing cycle. Recently, respiration correlated CT (4DCT) has been developed and implemented. With 4DCT, it is now possible to trace the tumor 3D trajectories during a breathing cycle and to define the tumor volume as the union of these 3D trajectories. The tumor volume defined in this way is called the internal target volume (ITV). In this study, we introduced a novel parameter, the phase impact factor (PIF), to determine the optimal CT phase for intensity modulated radiation therapy (IMRT) treatment planning for lung cancer. A minimum PIF yields a minimum probability for the GTV to move out of the ITV during the course of an IMRT treatment, providing a minimum probability of a geometric miss. Once the CT images with the optimal phase were determined, an IMRT plan with three to five co-planner beams was computed and optimized using the inverse treatment planning technique.
Keywords: three dimensional; treatment planning; radiation; radiotherapy; lung cancer; patient monitoring; image enhancement; imrt; computerized tomography; medical imaging; physical therapy; targets; tumors; probability; tumor volumes; cobalt; visualization; biological organs; tissue; radiation treatment planning; respiratory motions; respiratory mechanics; planning; dose distributions; common strategy; imaging techniques; radiation therapy treatment planning; trajectories; lung cancers; lung tumors; biomechanics; respiratory therapy; 4drt; bellows system; fdam; itv; mip; pif; cable stayed bridges; clutches; cobalt compounds; cosine transforms; discrete cosine transforms; electric instrument transformers; probability distributions; (001) parameter; 3-d trajectories; breathing cycle; computer tomography (ct) images; ct simulation; free breathing (fb); gross tumor volume (gtv); image-guided procedures; impact factor (if); imrt treatment; intensity-modulated radiation therapy (imrt) treatment; internal target volume (itv); lung tissues; planning target volume (ptv); respiration correlated ct; safety margin (sm); steep gradients
Journal Title Proceedings of SPIE
Volume: 6918
Conference Dates: 2008 Feb 17
Conference Location: San Diego, CA
ISBN: 0277-786X
Publisher: SPIE  
Date Published: 2008-01-01
Start Page: 6918 1D
Language: English
DOI: 10.1117/12.770968
PROVIDER: scopus
DOI/URL:
Notes: --- - Progress in Biomedical Optics and Imaging - Proceedings of SPIE - Progr. Biomed. Opt. Imaging Proc. SPIE - "Conference code: 72207" - "Export Date: 17 November 2011" - "Sponsors: The International Society for Optical Engineering (SPIE)" - 17 February 2008 through 19 February 2008 - "Source: Scopus"
Altmetric Score
MSK Authors
  1. Boris A Mueller
    41 Mueller
  2. Yulin Song
    87 Song