Feasibility of integrated IMRT technique for craniospinal irradiation in a supine position / 中华放射肿瘤学杂志

ABSTRACT

Objective To explore the feasibility and safety of integrated intensity-modulated radiation therapy (IMRT) technology applied in craniospinal irradiation in a supine position. Methods The patients were fixed in a supine position using thermoplastic mask and vacuum mat. Three isocenters with a fixed interval of 20-25 cm were adopted according to the height of patients. A total of 13 beams with a length of 2-3 cm in the overlapping region were included in the treatment plan. Fixed jaw technique was employed and overall calculation was performed by the inverse optimization method. The γ-passing rate and absolute point dose verification were performed for three isocenters and two overlapping regions. Cone-beam CT (CBCT) images were scanned for three isocenters before treatment. The setup error of each isocenter in the x,y and z directions of the same coordinate system was recorded and overall analysis was conducted. Results Among 28 patients,the γ-passing rate (%) of three isocenters and two overlapping regions was 99. 36%, 99. 60%,99. 75%,94. 77% and 95. 09%,whereas the absolute point dose verification error was 1. 56%,-1. 56%,0. 52%,-0. 76% and -1. 68%,respectively. Twenty-eight patients received 162 groups of IGRT with 486 setup errors from the CBCT images. The average deviation in the x, y and z direction for three isocenters (neck,chest and abdomen) was 0. 17 mm,0. 10 mm,0. 02 mm,0. 06 mm,0. 04 mm,0. 46 mm, 0. 19 mm, 0. 26 mm and 0. 41 mm, respectively. Conclusions The integrated IMRT techniques for craniospinal irradiation in a supine position is feasible and safe,which is worthy of clinical application.