title: A study to establish reasonable action limits for patient-specific quality assurance in intensity-modulated radiation therapy.
abstract: An effective patient quality assurance (QA) program for intensity-modulated radiation therapy (IMRT) requires accurate and realistic plan acceptance criteria--that is, action limits. Based on dose measurements performed with a commercially available two-dimensional (2D) diode array, we analyzed 747 fluence maps resulting from a routine patient QA program for IMRT plans. The fluence maps were calculated by three different commercially available (ADAC, CMS, Eclipse) treatment planning systems (TPSs) and were delivered using 6-MV X-ray beams produced by linear accelerators. To establish reasonably achievable and clinically acceptable limits for the dose deviations, the agreement between the measured and calculated fluence maps was evaluated in terms of percent dose error (PDE) for a few points and percent of passing points (PPP) for the isodose distribution. The analysis was conducted for each TPS used in the study (365 ADAC, 162 CMS,220 Eclipse), for multiple treatment sites (prostate, pelvis, head and neck, spine, rectum, anus, lung, brain), at the normalization point for 3% percentage difference (%Diff) and 3-mm distance to agreement (DTA) criteria. We investigated the treatment-site dependency of PPP and PDE. The results show that, at 3% and 3-mm criteria, a 95% PPP and 3% PDE can be achieved for prostate treatments and a 90% PPP and 5% PDE are attainable for any treatment site.
authors.affiliation: Department of Radiation Oncology, Medical Physics Division, University of Pennsylvania, Philadelphia, Pennsylvania, USA. bothstf@hotmail.com
authors.forename: Stefan
authors.initials: S
authors.lastname: Both
authors.forename: Ionut M
authors.initials: IM
authors.lastname: Alecu
authors.forename: Andrada R
authors.initials: AR
authors.lastname: Stan
authors.forename: Marius
authors.initials: M
authors.lastname: Alecu
authors.forename: Andrei
authors.initials: A
authors.lastname: Ciura
authors.forename: Jeremy M
authors.initials: JM
authors.lastname: Hansen
authors.forename: Rodica
authors.initials: R
authors.lastname: Alecu
mesh_terms: D011785:Quality Assurance, Health Care / Q000379:methods* / Q000592:standards*; D011874:Radiometry / Q000592:standards*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000592:standards*; D020266:Radiotherapy, Conformal / Q000592:standards*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014481:United States