AIM: To investigate whether the target-isocenter deviations reported by a conventional Winston-Lutz (WL) test actually reflect the shifts of the measured prescription isodose line with respect to the target. BACKGROUND: A conventional WL test uses a metallic ball as a target that aims at several fields. But this test does not report information on the accuracy of the delivery in terms of dose. MATERIALS AND METHODS: A conventional WL test using a metallic pointer as a target (Pointer-WL test) has been recreated in the Eclipse treatment planning system over an acrylic phantom containing a radiochromic film (Dose-WL test). After Dose-WL test delivery, the shift of the 80% prescription isodose line with respect to the target center (d80%-center) was measured using film dosimetry. The Pointer-WL and Dose-WL tests were performed in 10 different sessions. The isocenter deviation reported by the Pointer-WL test was compared to the d80%-center vector, according to the three patient's directions (Left-Right or LR; Anterior-Posterior or AP; and Superior-Inferior or SI). RESULTS: The deviations (mean ± SD) found for the Dose-WL tests (LR: 0.5 ± 0.4 mm; AP: 0.5 ± 0.4 mm; SI: 0.6 ± 0.2 mm) were in most cases less than 1 mm, and they were significantly smaller (all p < 0.05) than the maximum deviations reported by the Pointer-WL tests (LR: 1.3 ± 0.3 mm; AP: 1.2 ± 0.4 mm; SI: 1.1 ± 0.3 mm). CONCLUSIONS: The Dose-WL test described in this study allows estimating the spatial accuracy of the prescription isodose line.
AIM: To investigate whether the target-isocenter deviations reported by a conventional Winston-Lutz (WL) test actually reflect the shifts of the measured prescription isodose line with respect to the target. BACKGROUND: A conventional WL test uses a metallic ball as a target that aims at several fields. But this test does not report information on the accuracy of the delivery in terms of dose. MATERIALS AND METHODS: A conventional WL test using a metallic pointer as a target (Pointer-WL test) has been recreated in the Eclipse treatment planning system over an acrylic phantom containing a radiochromic film (Dose-WL test). After Dose-WL test delivery, the shift of the 80% prescription isodose line with respect to the target center (d80%-center) was measured using film dosimetry. The Pointer-WL and Dose-WL tests were performed in 10 different sessions. The isocenter deviation reported by the Pointer-WL test was compared to the d80%-center vector, according to the three patient's directions (Left-Right or LR; Anterior-Posterior or AP; and Superior-Inferior or SI). RESULTS: The deviations (mean ± SD) found for the Dose-WL tests (LR: 0.5 ± 0.4 mm; AP: 0.5 ± 0.4 mm; SI: 0.6 ± 0.2 mm) were in most cases less than 1 mm, and they were significantly smaller (all p < 0.05) than the maximum deviations reported by the Pointer-WL tests (LR: 1.3 ± 0.3 mm; AP: 1.2 ± 0.4 mm; SI: 1.1 ± 0.3 mm). CONCLUSIONS: The Dose-WL test described in this study allows estimating the spatial accuracy of the prescription isodose line.
Authors: Dirk Verellen; Guy Soete; Nadine Linthout; Swana Van Acker; Patsy De Roover; Vincent Vinh-Hung; Jan Van de Steene; Guy Storme Journal: Radiother Oncol Date: 2003-04 Impact factor: 6.280
Authors: Juan Francisco Calvo Ortega; Wouter Wunderink; David Delgado; Sandra Moragues; Miquel Pozo; Joan Casals Journal: Med Dosim Date: 2016-03-16 Impact factor: 1.482
Authors: Juan Francisco Calvo; Sol San José; Lluís Garrido; Enrique Puertas; Sandra Moragues; Miquel Pozo; Joan Casals Journal: Med Dosim Date: 2013-03-26 Impact factor: 1.482
Authors: Juan-Francisco Calvo-Ortega; Peter B Greer; Sandra Moragues-Femenía; Miguel Pozo-Massó; Joan Casals-Farran Journal: Rep Pract Oncol Radiother Date: 2022-07-29