Target coverage of daily cone-beam computed tomography in breath-hold image-guided radiotherapy for gastric lymphoma

Abstract

Objectives: We evaluated retrospectively the daily target coverage using cone-beam computed tomography (CBCT) in breath-hold image-guided radiotherapy (BH-IGRT) for gastric lymphoma. Methods: BH-IGRT was performed using a prescribed dose of 30.6 Gy in 17 fractions for the whole stomach. We assessed the target coverage of the whole stomach on daily CBCT images (daily CTV), which was delineated individually by two observers. We evaluated V95% (percentage of volume receiving ≥95% of the prescribed dose) of daily CTV. Results: In total, 102 fractions from six patients were assessed. The mean V95% of daily CTV was 97.2%, which was over 95%. In 2 of 6 patients, the V95% of daily CTV was over 95% for either observer in all fractions. One patient had significant interobserver variation (p = 0.013). In 95 fractions (93%), the V95% of daily CTV was over 95% for either observer. Conclusions: Daily target coverage for CTV in BH-IGRT for gastric lymphoma seems to be favorable, even when using CBCT. Advances in knowledge: A previous study ascertained good daily target coverage in BH-IGRT for gastric lymphoma using in-room CT. Even when using CBCT in our study, daily target coverage for CTV in BH-IGRT for gastric lymphoma seems to be favorable.