Thumbnail
Access Restriction
Open

Author Nishibuchi, Ikuno ♦ Kimura, Tomoki ♦ Nakashima, Takeo ♦ Ochi, Yusuke ♦ Takahashi, Ippei ♦ Doi, Yoshiko ♦ Kenjo, Masahiro ♦ Kaneyasu, Yuko ♦ Ozawa, Syuichi ♦ Murakami, Yuji ♦ Wadasaki, Koichi ♦ Nagata, Yasushi
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword RADIOLOGY AND NUCLEAR MEDICINE ♦ BIOMEDICAL RADIOGRAPHY ♦ CAT SCANNING ♦ LUNGS ♦ NEOPLASMS ♦ PATIENTS ♦ PLANNING ♦ RADIOTHERAPY ♦ RESPIRATION
Abstract Purpose: To consider nonuniform tumor motion within the internal target volume (ITV) by defining time-adjusted ITV (TTV), a volume designed to include heterogeneity of tumor existence on the basis of 4-dimensional computed tomography (4D-CT). Methods and Materials: We evaluated 30 lung cancer patients. Breath-hold CT (BH-CT) and free-breathing 4D-CT scans were acquired for each patient. The tumors were manually delineated using a lung CT window setting (window, 1600 HU; level, −300 HU). Tumor in BH-CT images was defined as gross tumor volume (GTV), and the sum of tumors in 4D-CT images was defined as ITV-4D. The TTV images were generated from the 4D-CT datasets, and the tumor existence probability within ITV-4D was calculated. We calculated the TTV{sub 80} value, which is the percentage of the volume with a tumor existence probability that exceeded 80% on ITV-4D. Several factors that affected the TTV{sub 80} value, such as the ITV-4D/GTV ratio or tumor centroid deviation, were evaluated. Results: Time-adjusted ITV images were acquired for all patients, and tumor respiratory motion heterogeneity was visualized. The median (range) ITV-4D/GTV ratio and median tumor centroid deviation were 1.6 (1.0-4.1) and 6.3 mm (0.1-30.3 mm), respectively. The median TTV{sub 80} value was 43.3% (2.9-98.7%). Strong correlations were observed between the TTV{sub 80} value and the ITV-4D/GTV ratio (R=−0.71) and tumor centroid deviation (R=−0.72). The TTV images revealed the tumor motion pattern features within ITV. Conclusions: The TTV images reflected nonuniform tumor motion, and they revealed the tumor motion pattern features, suggesting that the TTV concept may facilitate various aspects of radiation therapy planning of lung cancer while incorporating respiratory motion in the future.
ISSN 03603016
Educational Use Research
Learning Resource Type Article
Publisher Date 2014-08-01
Publisher Place United States
Journal International Journal of Radiation Oncology, Biology and Physics
Volume Number 89
Issue Number 5


Open content in new tab

   Open content in new tab