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Title: The impact of breathing motion versus heterogeneity effects in lung cancer treatment planning

Abstract

The purpose of this study is to investigate the effects of tissue heterogeneity and breathing-induced motion/deformation on conformal treatment planning for pulmonary tumors and to compare the magnitude and the clinical importance of changes induced by these effects. Treatment planning scans were acquired at normal exhale/inhale breathing states for fifteen patients. The internal target volume (ITV) was defined as the union of exhale and inhale gross tumor volumes uniformly expanded by 5 mm. Anterior/posterior opposed beams (AP/PA) and three-dimensional (3D)-conformal plans were designed using the unit-density exhale (''static'') dataset. These plans were further used to calculate (a) density-corrected (''heterogeneous'') static dose and (b) heterogeneous cumulative dose, including breathing deformations. The DPM Monte Carlo code was used for dose computations. For larger than coin-sized tumors, relative to unit-density plans, tumor and lung doses increased in the heterogeneity-corrected plans. In comparing cumulative and static plans, larger normal tissue complication probability changes were observed for tumors with larger motion amplitudes and uncompensated breathing-induced hot/cold spots in lung. Accounting for tissue heterogeneity resulted in average increases of 9% and 7% in mean lung dose (MLD) for the 6 MV and 15 MV photon beams, respectively. Breathing-induced effects resulted in approximately 1% and 2% averagemore » decreases in MLD from the static value, for the 6 and 15 MV photon beams, respectively. The magnitude of these effects was not found to correlate with the treatment plan technique, i.e., AP/PA versus 3D-CRT. Given a properly designed ITV, tissue heterogeneity effects are likely to have a larger clinical significance on tumor and normal lung treatment evaluation metrics than four-dimensional respiratory-induced changes.« less

Authors:
; ; ;  [1];  [2];  [2]
  1. Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan 48109-0010 (United States)
  2. (United States)
Publication Date:
OSTI Identifier:
20951163
Resource Type:
Journal Article
Resource Relation:
Journal Name: Medical Physics; Journal Volume: 34; Journal Issue: 4; Other Information: DOI: 10.1118/1.2713427; (c) 2007 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
62 RADIOLOGY AND NUCLEAR MEDICINE; CARCINOMAS; DOSIMETRY; LUNGS; METRICS; MONTE CARLO METHOD; PHOTON BEAMS; PLANNING; RADIATION DOSES; RESPIRATION

Citation Formats

Rosu, Mihaela, Chetty, Indrin J., Tatro, Daniel S., Haken, Randall K. ten, Department of Radiation Oncology, University of Nebraska Medical Center, Omaha, Nebraska 68198-7521, and Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan 48109-0010. The impact of breathing motion versus heterogeneity effects in lung cancer treatment planning. United States: N. p., 2007. Web. doi:10.1118/1.2713427.
Rosu, Mihaela, Chetty, Indrin J., Tatro, Daniel S., Haken, Randall K. ten, Department of Radiation Oncology, University of Nebraska Medical Center, Omaha, Nebraska 68198-7521, & Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan 48109-0010. The impact of breathing motion versus heterogeneity effects in lung cancer treatment planning. United States. doi:10.1118/1.2713427.
Rosu, Mihaela, Chetty, Indrin J., Tatro, Daniel S., Haken, Randall K. ten, Department of Radiation Oncology, University of Nebraska Medical Center, Omaha, Nebraska 68198-7521, and Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan 48109-0010. Sun . "The impact of breathing motion versus heterogeneity effects in lung cancer treatment planning". United States. doi:10.1118/1.2713427.
@article{osti_20951163,
title = {The impact of breathing motion versus heterogeneity effects in lung cancer treatment planning},
author = {Rosu, Mihaela and Chetty, Indrin J. and Tatro, Daniel S. and Haken, Randall K. ten and Department of Radiation Oncology, University of Nebraska Medical Center, Omaha, Nebraska 68198-7521 and Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan 48109-0010},
abstractNote = {The purpose of this study is to investigate the effects of tissue heterogeneity and breathing-induced motion/deformation on conformal treatment planning for pulmonary tumors and to compare the magnitude and the clinical importance of changes induced by these effects. Treatment planning scans were acquired at normal exhale/inhale breathing states for fifteen patients. The internal target volume (ITV) was defined as the union of exhale and inhale gross tumor volumes uniformly expanded by 5 mm. Anterior/posterior opposed beams (AP/PA) and three-dimensional (3D)-conformal plans were designed using the unit-density exhale (''static'') dataset. These plans were further used to calculate (a) density-corrected (''heterogeneous'') static dose and (b) heterogeneous cumulative dose, including breathing deformations. The DPM Monte Carlo code was used for dose computations. For larger than coin-sized tumors, relative to unit-density plans, tumor and lung doses increased in the heterogeneity-corrected plans. In comparing cumulative and static plans, larger normal tissue complication probability changes were observed for tumors with larger motion amplitudes and uncompensated breathing-induced hot/cold spots in lung. Accounting for tissue heterogeneity resulted in average increases of 9% and 7% in mean lung dose (MLD) for the 6 MV and 15 MV photon beams, respectively. Breathing-induced effects resulted in approximately 1% and 2% average decreases in MLD from the static value, for the 6 and 15 MV photon beams, respectively. The magnitude of these effects was not found to correlate with the treatment plan technique, i.e., AP/PA versus 3D-CRT. Given a properly designed ITV, tissue heterogeneity effects are likely to have a larger clinical significance on tumor and normal lung treatment evaluation metrics than four-dimensional respiratory-induced changes.},
doi = {10.1118/1.2713427},
journal = {Medical Physics},
number = 4,
volume = 34,
place = {United States},
year = {Sun Apr 15 00:00:00 EDT 2007},
month = {Sun Apr 15 00:00:00 EDT 2007}
}