title: A quality assurance method for analyzing and verifying intensity modulated fields.
abstract: A quality assurance method is developed for measuring, verifying and analyzing intensity modulated radiation fields. It is applicable for rotational and fixed-beam intensity modulated radiation therapy (IMRT) treatments. A gantry-mount device was constructed to measure the transmission dose of an IMRT field using radiographic films. A double-exposure technique with optimal kernel estimate method was developed to minimize the errors from measurements. A chi2 confidence level test method was developed to detect the discrepancies between measured and prescribed IMRT fluence distributions. Our method was tested for rotational and fixed-beam IMRT treatment verifications. The method was found insensitive to the hardware-related parameters for rotational and fixed-beam IMRT deliveries. The chi2 confidence level test was found to be more sensitive than linear correlation method in detecting relative small errors for cases with a few segments or narrow regions of interest. In conclusion, we demonstrated a quantitative method for verifying and analyzing IMRT treatment deliveries.
authors.affiliation: Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA. lma001@umaryland.edu
authors.forename: Lijun
authors.initials: L
authors.lastname: Ma
authors.forename: N
authors.initials: N
authors.lastname: Phaisangittisakul
authors.forename: C X
authors.initials: CX
authors.lastname: Yu
authors.forename: M
authors.initials: M
authors.lastname: Sarfaraz
mesh_terms: D015233:Models, Statistical; D011786:Quality Control; D011874:Radiometry; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D020266:Radiotherapy, Conformal / Q000295:instrumentation* / Q000379:methods*; D012680:Sensitivity and Specificity