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SU‐GG‐T‐215: Respiratory Gated IMRT Quality Assurance with Motion in Two Dimensions for Varying Field Sizes
Author(s) -
Daniels M,
Massie T
Publication year - 2010
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 - 10.1118/1.3468605
Subject(s) - quality assurance , nuclear medicine , medicine , motion (physics) , medical physics , computer science , artificial intelligence , pathology , external quality assessment
Purpose : Currently, there is little baseline information available on how varying amounts of tumor motion in multiple dimensions affect our ability to deliver acceptable respiratory‐gated IMRT. We present a study that considers how varying amounts tumor motion in two dimensions as well as varying field sizes effect respiratory gated IMRT quality assurance (QA) results. By developing this baseline information, we can develop guidelines for acceptable limits on tumor motion and field size for respiratory‐gated IMRT. Method and Materials: Respiratory‐gated IMRT QA was performed with Sun Nuclear's Mapcheck and MotionSim products. Respiratory‐gated IMRT patient plans were utilized in this study for four different field sizes. Simulated tumor motion ranged from no motion (the baseline case) to 1 cm in both the superior‐inferior and left‐right directions. A QA plan was generated for all four patient plans and delivered with varying amounts of tumor motion. The treated and planned dose planes were then compared. An acceptance criteria of 3%/ 3mm was utilized to determine if an IMRT plan passed or failed. In addition, a new IMRT QA product (Sun Nuclear's 3DVH) was utilized to evaluate how tumor motion affected the dose delivered to the tumor and critical organs. Results : Smaller field sizes allowed for more tumor motion then large field sizes when meeting our acceptance criteria. In addition, it was found that motion in the left‐right direction plays a significant role in the acceptability of respiratory‐gated IMRT. Conclusions : Our results demonstrate that there are several factors in determining the acceptability of respiratory‐gated IMRT. Field size as well as motion in two dimensions must be evaluated in order to ensure adequate tumor coverage during treatment. We found that the 3DVH product demonstrated a unique ability to determine how errors in respiratory ‐ated IMRT delivery affect tumor coverage and critical organ sparing.