Lack of Correlation Between External Fiducial Positions and Internal Tumor Positions During Breath-Hold CT

Journal Article · Thu Apr 15 04:00:00 EDT 2010 · International Journal of Radiation Oncology, Biology and Physics

DOI:https://doi.org/10.1016/j.ijrobp.2009.08.008· OSTI ID:21372230

Hunjan, Sandeep ^[1]; Starkschall, George; Prado, Karl; Lei, Dong; Balter, Peter ^[1]

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1. Department of Radiation Physics, University of Texas M. D. Anderson Cancer Center, Houston, TX (United States)

Purpose: For thoracic tumors, if four-dimensional computed tomography (4DCT) is unavailable, the internal margin can be estimated by use of breath-hold (BH) CT scans acquired at end inspiration (EI) and end expiration (EE). By use of external surrogates for tumor position, BH accuracy is estimated by minimizing the difference between respiratory extrema BH and mean equivalent-phase free breathing (FB) positions. We tested the assumption that an external surrogate for BH accuracy correlates with internal tumor positional accuracy during BH CT. Methods and Materials: In 16 lung cancer patients, 4DCT images, as well as BH CT images at EI and EE, were acquired. Absolute differences between BH and mean equivalent-phase (FB) positions were calculated for both external fiducials and gross tumor volume (GTV) centroids as metrics of external and internal BH accuracy, respectively, and the results were correlated. Results: At EI, the absolute difference between mean FB and BH fiducial displacement correlated poorly with the absolute difference between FB and BH GTV centroid positions on CT images (R{sup 2} = 0.11). Similarly, at EE, the absolute difference between mean FB and BH fiducial displacements correlated poorly with the absolute difference between FB and BH GTV centroid positions on CT images (R{sup 2} = 0.18). Conclusions: External surrogates for tumor position are not an accurate metric of BH accuracy for lung cancer patients. This implies that care should be taken when using such an approach because an incorrect internal margin could be generated.

• OSTI ID: 21372230
• Journal Information: International Journal of Radiation Oncology, Biology and Physics, Journal Name: International Journal of Radiation Oncology, Biology and Physics Journal Issue: 5 Vol. 76; ISSN IOBPD3; ISSN 0360-3016
• Country of Publication: United States
• Language: English

Related Subjects

62 RADIOLOGY AND NUCLEAR MEDICINE
ACCURACY
BODY
BREATH
CAT SCANNING
COMPUTERIZED TOMOGRAPHY
CORRELATIONS
DIAGNOSTIC TECHNIQUES
DISEASES
LUNGS
NEOPLASMS
ORGANS
POSITIONING
RESPIRATION
RESPIRATORY SYSTEM
TOMOGRAPHY