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

Shigeo Takahashi; Takamasa Nishide; Masato Tsuzuki; Hiroki Katayama; Masahide Anada; Toshifumi Kinoshita; Shohei Kozai; Toru Shibata

doi:10.1259/bjro.20200062

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

BJR Open. 2021 Jul 5;2(1):20200062. doi: 10.1259/bjro.20200062. eCollection 2021.

Authors

Shigeo Takahashi¹, Takamasa Nishide¹, Masato Tsuzuki², Hiroki Katayama², Masahide Anada¹, Toshifumi Kinoshita¹, Shohei Kozai¹, Toru Shibata¹

Affiliations

¹ Department of Radiation Oncology, Kagawa University Hospital, Kagawa, Japan.
² Department of Clinical Radiology, Kagawa University Hospital, Kagawa, Japan.

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 clinical target volume (CTV)], which was delineated individually by two observers. We evaluated V_95% (percentage of volume receiving ≥95% of the prescribed dose) of daily CTV.

Results: In total, 102 fractions from 6 patients were assessed. The mean V_95% of daily CTV was 97.2%, which was over 95%. In two of six patients, the V_95% 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 V_95% of daily CTV was over 95% for either observer.

Conclusion: 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.