title: Curtailing patient-specific IMRT QA procedures from 2D dose error distribution.
abstract: A patient-specific quality assurance (QA) test is conducted to verify the accuracy of dose delivery. It generally consists of three verification processes: the absolute point dose difference, the planar dose differences at each gantry angle, and the planar dose differences by 3D composite irradiation. However, this imposes a substantial workload on medical physicists. The objective of this study was to determine whether our novel method that predicts the 3D delivered dose allows certain patient-specific IMRT QAs to be curtailed. The object was IMRT QA for the pelvic region with regard to point dose and composite planar dose differences. We compared measured doses, doses calculated in the treatment planning system, and doses predicted by in-house software. The 3D predicted dose was reconstructed from the per-field measurement by incorporating the relative dose error distribution into the original dose grid of each beam. All point dose differences between the measured and the calculated dose were within ±3%, whereas 93.3% of them between the predicted and the calculated dose were within ±3%. As for planar dose differences, the gamma passing rates between the calculated and the predicted dose were higher than those between the calculated and the measured dose. Comparison and statistical analysis revealed a correlation between the predicted and the measured dose with regard to both point dose and planar dose differences. We concluded that the prediction-based approach is an accurate substitute for the conventional measurement-based approach in IMRT QA for the pelvic region. Our novel approach will help medical physicists save time on IMRT QA.
authors.affiliation: Department of Radiation Oncology, Osaka University Graduate School of Medicine, Osaka, 565-0871, Japan Department of Radiology, Osaka University Hospital, Osaka, 565-0871, Japan.
authors.forename: Keita
authors.initials: K
authors.lastname: Kurosu
authors.affiliation: Department of Radiation Oncology, Osaka University Graduate School of Medicine, Osaka, 565-0871, Japan sumida@radonc.med.osaka-u.ac.jp.
authors.forename: Iori
authors.initials: I
authors.lastname: Sumida
authors.affiliation: Department of Radiation Oncology, Osaka University Graduate School of Medicine, Osaka, 565-0871, Japan.
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Mizuno
authors.affiliation: Department of Radiation Oncology, Osaka University Graduate School of Medicine, Osaka, 565-0871, Japan.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Otani
authors.affiliation: Department of Radiation Oncology, Osaka University Graduate School of Medicine, Osaka, 565-0871, Japan Department of Radiology, Osaka University Hospital, Osaka, 565-0871, Japan.
authors.forename: Michio
authors.initials: M
authors.lastname: Oda
authors.affiliation: Department of Radiation Oncology, Osaka University Graduate School of Medicine, Osaka, 565-0871, Japan.
authors.forename: Fumiaki
authors.initials: F
authors.lastname: Isohashi
authors.affiliation: Department of Radiation Oncology, Osaka University Graduate School of Medicine, Osaka, 565-0871, Japan.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Seo
authors.affiliation: Department of Radiation Oncology, Osaka University Graduate School of Medicine, Osaka, 565-0871, Japan.
authors.forename: Osamu
authors.initials: O
authors.lastname: Suzuki
authors.affiliation: Department of Radiation Oncology, Osaka University Graduate School of Medicine, Osaka, 565-0871, Japan.
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Ogawa
mesh_terms: D004305:Dose-Response Relationship, Drug; D005720:Gamma Rays; D006801:Humans; D011785:Quality Assurance, Health Care; D011879:Radiotherapy Dosage; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods* / Q000592:standards*
keywords: IMRT; MapCHECK; QA; gamma index; prediction