A clinical study of CBCT reduction before IMRT in nasopharyngeal carcinoma / 重庆医学

ABSTRACT

Objective To explore the feasibility of reduction by using cone beam computed tomography (CBCT) before intensity modulated radiation therapy(IMRT) in the patients with nasopharyngeal carcinoma.Methods Twenty-three patients with nasopharyngeal carcinoma (NPC) undergoing IMRT were included in this study.The reverse IMRT plan with CBCT verification was prepared with location center coordinates origin as the planned central point.Before therapy,the CBCT reduction was adopted,the CBCT scanning was performed before the second and third radiotherapies.The registering data in 3 times were analyzed and summarized.Results In CBCT reduction,the absolute value at any direction≤3 mm accounted for 89.9％ (62/69),＜5 mm accounted for 98.6 ％ (68/69),and the deviation value at every direction was (0.6 ± 2.1)mm;in the second and third CBCT,the absolute value at any direction ≤3 mm accounted for 92.8％ (128 q38),＜5 mm accounted for 99.3％ (137/138),and the deviation value at every direction was (0.4 ± 2.0) mmthe difference between the two sets of data had no statistically significant difference (P＞ 0.05).Conclusion In formulating the nasopharyngeal carcinoma IMRT plan withthe location center coordinates origin as the planned central point,adopting the CBCT reduction is intuitional,convenient,practicable and feasible.