Analysis geometrical uncertainties of 220 cases in helical tomotherapy (HT) / 中华放射肿瘤学杂志

ABSTRACT

Objective To analyze geometrical uncertainties of the target and provide the margin enlarging from clinic target volume (CTV) to planning target volume (PTV) with HT.Methods Analysis set-up data of 220 cases include 97 cases of head and neck,45 cases of chest and 78 cases of abdomen and pelvic,calculating the systematic error (Σ) and the random error (σ) in the three-dimension and check whether the set-up data accord with the normal distribution or not,then acquire the values expand in the three directions based on formula 2.0Σ + 0.7σandμ ± 2.58σ.Results The systematic error (Σ) and random error (σ) of head and neck,the chest and abdomen and pelvic were (0.7-1.9 mm,1.1-1.4 mm),(0.8-4.2 mm,1.5-3.2 mm),(1.1-4.1 mm,1.8-4.1 mm),respectively,and the margin that expand in the direction of x,y,z were (5.2,6.5,7.7 mum),(7.5,16.2,10.3 mm),(7.6,17.1,15.7 mm),respectively.Conclusions The curative effect of this task need prove with a large sample during HT,but other should establish data of margin by yourself.