Impact of four-dimensional cone-beam computed tomography on target localization for gastric mucosa-associated lymphoid tissue lymphoma radiotherapy: reducing planning target volume

Abstract Background Radiotherapy of gastric mucosa-associated lymphoid tissue (MALT) lymphoma should be delivered to the entire stomach with planning target volume (PTV) that accounts for variations in volume, respiratory movement, and patient set-up error. In this study, we evaluated whether use four-dimensional cone-beam computed tomography (4D-CBCT) reduces PTV. Methods Eight patients underwent radiotherapy 15 fractions MALT using 4D-CBCT. PTV structures 5–30 mm margins (5 intervals) from clinical (CTV) delineated based on 4D-CT images (CTV-4D) were generated. For localization, performed matching skin marking (skin matching), bone anatomy (bone (4D soft-tissue matching) registration between CT 4D-CBCT 10 phases. each patient, calculated covering ratio (CR) variable structures, images, a total 150 phases [CR (%) = (number phases/150 phases) × 100], three localization methods. We compared CR values different methods defined an average ≥ 95% all patients. Results The increased 17.9 100%, 19.6 99.8%, 33.8 skin, bone, 4D matchings, respectively, as 5 30 mm. obtained by was superior ( P 0.013) 0.008) structure margin. required additional margin 20 (average CR: 95.2%), 25 99.1%), 98.0%) CTV-4D respectively. Conclusions This study demonstrates when applying matching, matchings. Additionally, does not reduce traditional matching.