Thumbnail
Access Restriction
Open

Author Jermoumi, M. ♦ Cao, D. ♦ Mehta, V. ♦ Shepard, D.
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword APPLIED LIFE SCIENCES ♦ RADIATION PROTECTION AND DOSIMETRY ♦ BIOMEDICAL RADIOGRAPHY ♦ COMPUTERIZED TOMOGRAPHY ♦ ERRORS ♦ IMAGES ♦ LUNGS ♦ PATIENTS ♦ RADIOTHERAPY
Abstract Purpose: Surface guided radiation therapy (SGRT) uses stereoscopic video images in combination with patterns projected onto the patient’s surface to dynamically capture and reconstruct a 3D surface map. In this work, we used a C-RAD Catalyst HD system (C-RAD) to evaluate intrafraction motion in the delivery of lung SBRT. Methods: The surface acquired from the 4DCT images from our preliminary cohort of eight lung cancer patients treated with SBRT were matched to the surface images acquired prior to each treatment. Additionally, a CBCT image set was acquired. A linear regression model was established between the external and internal motion of tumor during pretreatment and used to predict the CBCT deviation during treatment. The shifts determined from CBCT and the shifts from surface map imaging were compared and assessed using Bland-Altman method. For intrafraction motion, we assessed the percentage of mean errors that fell outside of the threshold of 2 mm, 3 mm, and 5 mm along the translational directions. The required PTV margin was quantified over the course of treatment. The correlation between intrafraction treatment time and mean error of 3D displacement was evaluated using the Pearson coefficient, r Results: A total of 7971 data points were analyzed. Deviations of 2mm, 3mm, and 5mm were observed less than 7%, 2 %, and 0 % of the time along the translational direction. CBCT and Catalyst showed close agreement during patient positioning. Furthermore, the calculated PTV margins were less than our clinical tolerance of 5 mm. Using the Pearson coefficient r,the mean error of 3D displacement showed significant correlation with treatment time (r=0.69, p= 0.000002). Conclusion: SGRT can be used to ensure accurate patient positioning during treatment without an additional delivery of dose to the patient. This study shows that importance of treatment time as a consideration during the treatment planning process.
ISSN 00942405
Educational Use Research
Learning Resource Type Article
Publisher Date 2016-06-15
Publisher Place United States
Journal Medical Physics
Volume Number 43
Issue Number 6


Open content in new tab

   Open content in new tab