Variability of Gross Tumor Volume Delineation for Stereotactic Body Radiotherapy of the Lung With Tri-60Co Magnetic Resonance Image-Guided Radiotherapy System (ViewRay): A Comparative Study With Magnetic Resonance- and Computed Tomography-Based Target Delineation. (16th July 2018)

• Record Type: Journal Article
• Authors: Wee, Chan Woo; An, Hyun Joon; Kang, Hyun-Cheol; Kim, Hak Jae; Wu, Hong-Gyun
• Is Part Of: Technology in cancer research & treatment. Volume 17(2018)
• Publication Date: 2018-07-16
• Subjects: ViewRay -- magnetic resonance imaging -- lung -- stereotactic body radiotherapy -- stereotactic ablative body radiotherapy -- gross tumor volume -- image-guided radiotherapy; Oncology -- Periodicals; Cancer -- Diagnosis -- Periodicals; Cancer -- Treatment -- Technological innovations -- Periodicals; 616.994
• DOI: 10.1177/1533033818787383
• Languages: English
• ISSNs: 1533-0346

Abstract

Introduction: To evaluate the intra-/interobserver variability of gross target volumes between delineation based on magnetic resonance imaging and computed tomography in patients simulated for stereotactic body radiotherapy for primary lung cancer and lung metastasis. Materials and Methods: Twenty-five patients (27 lesions) who underwent computed tomography and magnetic resonance simulation with the MR- 60 Co system (ViewRay) were included in the study. Gross target volumes were delineated on the magnetic resonance imaging (GTVMR ) and computed tomography (GTVCT ) images by 2 radiation oncologists (RO1 and RO2). Volumes of all contours were measured. Levels of intraobserver (GTVMR _RO vs GTVCT _RO) and interobserver (GTVMR _RO1 vs GTVMR _RO2; GTVCT _RO1 vs GTVCT _RO2) agreement were evaluated using the generalized κ statistics and the paired t test. Results: No significant volumetric difference was observed between all 4 comparisons (GTVMR _RO1 vs GTVCT _RO1, GTVMR _RO2 vs GTVCT _RO2, GTVMR _RO1 vs GTVMR _RO2, and GTVCT _RO1 vs GTVCT _RO2; P > .05), with mean volumes of GTVs ranging 5 to 6 cm 3 . The levels of agreement between those 4 comparisons were all substantial with mean κ values of 0.64, 0.66, 0.74, and 0.63, respectively. However, the interobserver agreement level was significantly higher for GTVCT compared to GTVMR ( P <.001). The mean κ values significantly increased in all 4 comparisons for tumors >5 cm 3 compared to tumors ≤5 cm 3 (all P < .05). Conclusion: No significant differences in volumes between magnetic resonance- and computed tomograpghy-based Gross target volumes were found among 2 ROs. Magnetic resonance-based GTV delineation for lung stereotactic body radiotherapy also demonstrated acceptable interobserver agreement. Tumors >5 cm 3 show higher intra-/interobserver agreement compared to tumors <5 cm 3 . More experience should be accumulated to reduce variability in magnetic resonance-based Gross target volumes delineation in lung stereotactic body radiotherapy.