Equivalency of beam scan data collection using a 1D tank and automated couch movements to traditional 3D tank measurements

• Published in: Journal of applied clinical medical physics Vol. 19; no. 6; pp. 60 - 67
• Main Authors: Knutson, Nels C., Schmidt, Matthew C., Belley, Matthew D., Nguyen, Ngoc, Price, Michael, Mutic, Sasa, Sajo, Erno, Li, H. Harold
• Format: Journal Article
• Language: English
• Published: Hoboken John Wiley and Sons Inc 06.09.2018
• Subjects: Radiation Oncology Physics
• ISSN: 1526-9914
• DOI: 10.1002/acm2.12444

This work shows the feasibility of collecting linear accelerator beam data using just a 1‐D water tank and automated couch movements with the goal to maximize the cost effectiveness in resource‐limited clinical settings. Two commissioning datasets were acquired: (a) using a standard of practice 3D water tank scanning system (3 DS ) and (b) using a novel technique to translate a commercial TG ‐51 complaint 1D water tank via automated couch movements (1 DS ). The Extensible Markup Language ( XML ) was used to dynamically move the linear accelerator couch position (and thus the 1D tank) during radiation delivery for the acquisition of inline, crossline, and diagonal profiles. Both the 1 DS and 3 DS datasets were used to generate beam models ( BM 1 DS and BM 3 DS ) in a commercial treatment planning system ( TPS ). 98.7% of 1 DS measured points had a gamma value (2%/2 mm) < 1 when compared with the 3 DS . Static jaw defined field and dynamic MLC field dose distribution comparisons for the TPS beam models BM 1 DS and BM 3 DS had 3D gamma values (2%/2 mm) < 1 for all 24,900,000 data points tested and >99.5% pass rate with gamma value (1%/1 mm) < 1. In conclusion, automated couch motions and a 1D scanning tank were used to collect commissioning beam data with accuracy comparable to traditionally acquired data using a 3D scanning system. TPS beam models generated directly from 1 DS measured data were clinically equivalent to a model derived from 3 DS data.