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Poster — Thur Eve — 50: Planning and delivery accuracy of stereotactic radiosurgery with Tomotherapy as compared to linear‐accelerator and robotic based radiosurgery
Author(s) -
Thakur V,
Soisson E,
Ruo R,
Doucet R,
Parker W,
Seuntjens J
Publication year - 2012
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.4740158
Subject(s) - tomotherapy , radiosurgery , linear particle accelerator , imaging phantom , collimator , nuclear medicine , radiation treatment planning , ionization chamber , dosimetry , cyberknife , image guided radiation therapy , medical physics , isocenter , physics , medical imaging , computer science , radiation therapy , medicine , optics , beam (structure) , radiology , artificial intelligence , ion , quantum mechanics , ionization
This study includes planning and delivery comparison of three stereotactic radiosurgery techniques : Helical Tomotherapy (HT), circular collimator‐based Linear‐accelerator and robotic‐radiosurgery. Plans were generated for two spherical targets of diameter 6 mm and 10 mm contoured at the center of a Lucite phantom, using similar planning constrains. Planning comparison showed that average conformality (0–1best) for Linear‐accelerator, robotic‐radiosurgery and HT was 1.43, 1.24, and 1.77 and gradient index (less is better) was 2.72, 4.50 and 13.56 respectively. For delivery comparison, plans were delivered to radiochromic film and measured dose was compared with the planned dose. For Linear‐accelerator and robotic‐radiosurgery more than 99% pixels‐passing a gamma criteria of 3% dose difference and 1 mm distance to agreement where as for HT this value was as low as 40% for off‐axis targets. Further investigation of the delivery accuracy as a function of the location of the target with in the bore was initiated using small volume A1SL (0.057 cm 3 ) and MicroLion liquid ion chamber (0.0017 cm 3 ). Point dose measurements for targets located at the center and 10 cm away from the center of the bore showed that delivered dose varied by more than 15% for targets placed away from the center of the bore as opposed to at the center. In conclusion, Linear‐accelerator and the robotic‐radiosurgery techniques showed preferable gradient and conformality. For HT, point dose measurements were significantly lower than predicted by the TPS when the target was positioned away from the isocenter, while they were found to be higher at isocenter.