ĐÁNH GIÁ SAI SỐ TRONG THIẾT LẬP BỆNH NHÂN XẠ TRỊ  ĐIỀU BIẾN LIỀU (IMRT) VÙNG ĐẦU CỔ BẰNG HỆ THỐNG  iViewGT TẠI KHOA XẠ TRỊ - BỆNH VIỆN QUÂN Y 175

Ngọc Nguyễn Thế; Hà Nguyễn Văn; Luân Phạm Thành; Minh Phạm Văn; Hưng Đỗ Thị

doi:10.59354/ydth175.2024.294

Keywords:

Radiation therapy, uncertainty in radiation therapy, systematic errors, random errors

Abstract

Aim: The study is for assessment of errors in three dimensions of patient setup before irradiation delivery and calculating setup margins for head and neck cases with intensity modulated radiation therapy technique.

Methode: 937 orthogonal and corresponding portal iViewGT images of 51 patients with IMRT head and neck treatment were compared with digitally reconstructed radiographs (DRR) from computed tomography simulation scans. The displacements for vertical (A.P), lateral (L.R), longitudinal (S.I) directions were collected. The systematic errors () and random errors () of radiation unit were calculated. Setup margins (A) for 3 dimentional directions were caculated for target volume in head and neck region.

Result: The displacements in vertical (A.P), lateral (L.R) and longitudinal (S.I) directions were 2.2 ± 2.4 mm, -0.03 ± 1.7 mm, 1.95 ± 2.1 mm respectively. The systematic error for each directions were: = 1.15 mm, = 0.74 mm, = 1.17 mm, the random errors for each directions were: = 2.1 mm, = 1.5 mm , = 1.7 mm. Setup margins for treatment volume in head and neck region in each directions were: = 4.3 mm, = 2.9 mm, = 4.1 mm.

Conclusion: Setup errors of patients with head and neck IMRT treatments in Radiation therapy department is in the tolerance for IMRT treatment, well compares with published studies. The setup margin was less than 5 mm in all dimentions and was less than 3 mm if patients have more than 2 times a week iViewGT checks before having treatment. Portal images iViewGT checking is a solution for safe and presice patient setup before delivering IMRT plan.

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