BACKGROUND: Adaptive radiotherapy (ART) could be a tool to reduce toxicity and to facilitate dose escalation in stage III NSCLC. Our aim was to identify the most appropriate time and potential benefit of ART. MATERIAL AND METHODS: We analyzed volume reduction and dosimetric consequences of 41 patients who were treated with concurrent (cCRT) (n = 21) or sequential (sCRT) chemoradiotherapy to a median dose of 70 Gy, 2 Gy/F. At every treatment fraction a cone-beam CT (CBCT) was performed. The gross tumor volume (GTV-T) was adapted (exclusion of lymph nodes) to create the GTV-T-F1. Every fifth fraction (F5-F30), the GTV-T-F1 was adapted on the CBCT to create a GTV-T-Fx. Dose volume histograms were recalculated for every GTV-T-Fx, enabling to create lookup tables to predict the theoretical dosimetric advantage on common lung dose constraints. RESULTS: The average GTV reduction was 42.1% (range 4.0-69.3%); 50.1% and 33.7% for the cCRT and sCRT patients, respectively. A linear relationship between GTV-T-F1 volume and absolute volume decrease was found for both groups. The mean V5, V20, V30 and mean lung dose increased by 0.8, 3.1, 5.2 and 3.4%, respectively. A larger increase (p < 0.05) was observed for peripheral tumors and cCRT. Lookup tables were generated. CONCLUSION: ART offers the most beneficial dosimetric effects when performed around fraction 15, especially for patients with a large initial GTV-T treated by cCRT.
BACKGROUND: Adaptive radiotherapy (ART) could be a tool to reduce toxicity and to facilitate dose escalation in stage III NSCLC. Our aim was to identify the most appropriate time and potential benefit of ART. MATERIAL AND METHODS: We analyzed volume reduction and dosimetric consequences of 41 patients who were treated with concurrent (cCRT) (n = 21) or sequential (sCRT) chemoradiotherapy to a median dose of 70 Gy, 2 Gy/F. At every treatment fraction a cone-beam CT (CBCT) was performed. The gross tumor volume (GTV-T) was adapted (exclusion of lymph nodes) to create the GTV-T-F1. Every fifth fraction (F5-F30), the GTV-T-F1 was adapted on the CBCT to create a GTV-T-Fx. Dose volume histograms were recalculated for every GTV-T-Fx, enabling to create lookup tables to predict the theoretical dosimetric advantage on common lung dose constraints. RESULTS: The average GTV reduction was 42.1% (range 4.0-69.3%); 50.1% and 33.7% for the cCRT and sCRTpatients, respectively. A linear relationship between GTV-T-F1 volume and absolute volume decrease was found for both groups. The mean V5, V20, V30 and mean lung dose increased by 0.8, 3.1, 5.2 and 3.4%, respectively. A larger increase (p < 0.05) was observed for peripheral tumors and cCRT. Lookup tables were generated. CONCLUSION:ART offers the most beneficial dosimetric effects when performed around fraction 15, especially for patients with a large initial GTV-T treated by cCRT.
Authors: Philipp Hoegen; Clemens Lang; Sati Akbaba; Peter Häring; Mona Splinter; Annette Miltner; Marion Bachmann; Christiane Stahl-Arnsberger; Thomas Brechter; Rami A El Shafie; Fabian Weykamp; Laila König; Jürgen Debus; Juliane Hörner-Rieber Journal: Front Oncol Date: 2020-12-09 Impact factor: 6.244
Authors: Matthias Mäurer; Lukas Käsmann; Daniel F Fleischmann; Michael Oertel; Danny Jazmati; Daniel Medenwald Journal: Radiat Oncol Date: 2022-02-09 Impact factor: 3.481