PURPOSE: Radiologic lung density changes are observed in more than 50% of patients after stereotactic body radiotherapy (SBRT) for lung cancer. We studied the relationship between SBRT dose and posttreatment computed tomography (CT) density changes, a surrogate for lung injury. METHODS AND MATERIALS: The SBRT fractionation schemes used to treat Stage I lung cancer with RapidArc were three fractions of 18 Gy, five fractions of 11 Gy, or eight fractions of 7.5 Gy, prescribed at the 80% isodose. Follow-up CT scans performed at less than 6 months (n = 50) and between 6 and 9 months (n = 30) after SBRT were reviewed. Posttreatment scans were coregistered with baseline scans using a B-spline deformable registration algorithm. Voxel-Hounsfield unit histograms were created for doses between 0.5 and 50 Gy. Linear mixed effects models were used to assess the effects of SBRT dose on CT density, and the influence of possible confounders was tested. RESULTS: Increased CT density was associated with higher dose, increasing planning target volume size, and increasing time after SBRT (all p < 0.0001). Density increases were apparent in areas receiving >6 Gy, were most prominent in areas receiving >20 Gy, and seemed to plateau above 40 Gy. In regions receiving >36 Gy, the reduction in air-filled fraction of lung after treatment was up to 18%. No increase in CT density was observed in the contralateral lung receiving ≥3 Gy. CONCLUSIONS: A dose-response relationship exists for quantitative CT density changes after SBRT. A threshold of effect is seen at low doses, and a plateau at highest doses.
PURPOSE: Radiologic lung density changes are observed in more than 50% of patients after stereotactic body radiotherapy (SBRT) for lung cancer. We studied the relationship between SBRT dose and posttreatment computed tomography (CT) density changes, a surrogate for lung injury. METHODS AND MATERIALS: The SBRT fractionation schemes used to treat Stage I lung cancer with RapidArc were three fractions of 18 Gy, five fractions of 11 Gy, or eight fractions of 7.5 Gy, prescribed at the 80% isodose. Follow-up CT scans performed at less than 6 months (n = 50) and between 6 and 9 months (n = 30) after SBRT were reviewed. Posttreatment scans were coregistered with baseline scans using a B-spline deformable registration algorithm. Voxel-Hounsfield unit histograms were created for doses between 0.5 and 50 Gy. Linear mixed effects models were used to assess the effects of SBRT dose on CT density, and the influence of possible confounders was tested. RESULTS: Increased CT density was associated with higher dose, increasing planning target volume size, and increasing time after SBRT (all p < 0.0001). Density increases were apparent in areas receiving >6 Gy, were most prominent in areas receiving >20 Gy, and seemed to plateau above 40 Gy. In regions receiving >36 Gy, the reduction in air-filled fraction of lung after treatment was up to 18%. No increase in CT density was observed in the contralateral lung receiving ≥3 Gy. CONCLUSIONS: A dose-response relationship exists for quantitative CT density changes after SBRT. A threshold of effect is seen at low doses, and a plateau at highest doses.
Authors: Judit Boda-Heggemann; Ulrike Attenberger; Johannes Budjan; Anika Jahnke; Lennart Jahnke; Lena Vogel; Anna O Simeonova-Chergou; Carsten Herskind; Frederik Wenz; Frank Lohr Journal: Strahlenther Onkol Date: 2016-07-08 Impact factor: 3.621
Authors: Alexandra R Cunliffe; Samuel G Armato; Christopher Straus; Renuka Malik; Hania A Al-Hallaq Journal: Phys Med Biol Date: 2014-08-26 Impact factor: 3.609
Authors: S Arcangeli; L Agolli; L Portalone; M R Migliorino; M G Lopergolo; A Monaco; J Dognini; M C Pressello; S Bracci; V Donato Journal: Br J Radiol Date: 2015-02-03 Impact factor: 3.039
Authors: Ke Nie; Hania Al-Hallaq; X Allen Li; Stanley H Benedict; Jason W Sohn; Jean M Moran; Yong Fan; Mi Huang; Michael V Knopp; Jeff M Michalski; James Monroe; Ceferino Obcemea; Christina I Tsien; Timothy Solberg; Jackie Wu; Ping Xia; Ying Xiao; Issam El Naqa Journal: Int J Radiat Oncol Biol Phys Date: 2019-01-31 Impact factor: 7.038