Quantification and Minimization of Uncertainties of Internal Target Volume for Stereotactic Body Radiation Therapy of Lung Cancer

Journal Article · Fri Feb 01 04:00:00 EST 2013 · International Journal of Radiation Oncology, Biology and Physics

DOI:https://doi.org/10.1016/J.IJROBP.2012.04.032· OSTI ID:22149771

Hong, Ge ^[1]; Jing, Cai; Kelsey, Chris R. ^[1]

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1. Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina (United States)

Purpose: To quantify uncertainties in delineating an internal target volume (ITV) and to understand how these uncertainties may be individually minimized for stereotactic body radiation therapy (SBRT) of early stage non-small cell lung cancer (NSCLC). Methods and Materials: Twenty patients with NSCLC who were undergoing SBRT were imaged with free-breathing 3-dimensional computed tomography (3DCT) and 10-phase 4-dimensional CT (4DCT) for delineating gross tumor volume (GTV){sub 3D} and ITV{sub 10Phase} (ITV3). The maximum intensity projection (MIP) CT was also calculated from 10-phase 4DCT for contouring ITV{sub MIP} (ITV1). Then, ITV{sub COMB} (ITV2), ITV{sub 10Phase+GTV3D} (ITV4), and ITV{sub 10Phase+ITVCOMB} (ITV5) were generated by combining ITV{sub MIP} and GTV{sub 3D}, ITV{sub 10phase} and GTV{sub 3D}, and ITV{sub 10phase} and ITV{sub COMB}, respectively. All 6 volumes (GTV{sub 3D} and ITV1 to ITV5) were delineated in the same lung window by the same radiation oncologist. The percentage of volume difference (PVD) between any 2 different volumes was determined and was correlated to effective tumor diameter (ETD), tumor motion ranges, R{sub 3D}, and the amplitude variability of the recorded breathing signal (v) to assess their volume variations. Results: The mean (range) tumor motion (R{sub SI}, R{sub AP}, R{sub ML}, and R{sub 3D}) and breathing variability (v) were 7.6 mm (2-18 mm), 4.0 mm (2-8 mm), 3.3 mm (0-7.5 mm), 9.9 mm (4.1-18.7 mm), and 0.17 (0.07-0.37), respectively. The trend of volume variation was GTV{sub 3D} =}0.503, P{<=}.047). The PVDs for pairs of ITV2 vs ITV5 and ITV5 vs ITV4 negatively correlated with ETD (r=0.502, -0.626; P=.047, .010). No other correlation was found. Conclusion: Uncertainties in individualized ITVs for SBRT of early stage NSCLC could effectively be minimized by combining information from 3DCT, 4DCT, and MIP. If these images cannot be efficiently contoured, a combination of ITV{sub MIP} and GTV{sub 3D} could be an effective alternative.

• OSTI ID: 22149771
• Journal Information: International Journal of Radiation Oncology, Biology and Physics, Journal Name: International Journal of Radiation Oncology, Biology and Physics Journal Issue: 2 Vol. 85; ISSN IOBPD3; ISSN 0360-3016
• Country of Publication: United States
• Language: English

Related Subjects

62 RADIOLOGY AND NUCLEAR MEDICINE
COMPUTERIZED TOMOGRAPHY
IMAGES
LUNGS
MEDICAL PERSONNEL
MINIMIZATION
NEOPLASMS
PATIENTS
RADIOTHERAPY
RESPIRATION