ABSTRACT
Objective The literature study the setup errors of head and neck, thoracic, abdominal and pelvic tumors by megavoltage fan-beam CT based image guidance in TOMO-HD to provide the margin enlarging from clinic target volume (CTV) to planning target volume (PTV) in treatment planning system of TOMO-HD. Methods 103 patients with head and neck (30 patients), thoracic (42 patients), abdominal and pelvic (31 patients) carcinoma were enrolled. Megavoltage fan-beam CT based image guidance in tomotherapy-HD was used to acquire CT scan before every treatment. The left-right (X), superior-inferior (Y), anterior-posterior (Z) and rotation (Fy) setup errors of patients can be obtained from the tomography image automatically restructured by the system. Calculating the systematic error and the random error in the three dimensions and check whether the setup data accord with the normal distribution or not, then acquire the data expand in the three directions. Results According to 2593 fan-beam CT scans, the shift errors (µ ± s) in X, Y, Z and Fy (rotation) of three study group were [(−0.31 ± 2.16) mm、(1.09 ± 3.56) mm、(2.36 ± 2.27) mm, (0.29 ± 0.96)°] (head and neck tumor), [(−0.98 ± 2.95) mm、(0.45 ± 6.86) mm、(3.79 ± 2.47) mm, (0.18 ± 0.60)°] (thoracic cancer) and [(−0.86 ± 2.85) mm、(−1.59 ± 6.91) mm、(5.77 ± 2.40) mm, (0.20 ± 0.68)°](abdominal and pelvic carcinoma). The systematic errors (∑) and random errors (σ) in X, Y, Z dimensions of patients with head and neck, thoracic, abdominal and pelvic tumors were (1.06 mm and 1.84 mm), (1.93 mm and 3.43 mm), (2.41 mm and 2.71 mm), (1.10 mm and 2.56 mm), (3.79 mm and 5.46 mm), (1.38 mm and 1.99 mm) and (1.39 mm and 0.87 mm), (4.98 mm and 5.69 mm), (1.19 mm and 2.05 mm), respectively. Conclusion It is recommended as a reference for image guidance in TOMO-HD according to the frequency distribution of setup errors, for patients with head and neck, chest and abdominal and pelvic tumors, the maximum range of motion in three dimensions are (5.00, 5.00, 5.00) mm, (6.63, 17.25, 16.00) mm and (6.49, 16.24, 13.60) mm.
ABSTRACT
Objective To compare the dosimetry between three -dimensional conformal radiotherapy (3DCRT)and intensity -modulated radiotherapy(IMRT)in the treatment of upper thoracic esophageal carcino-ma,and to provide references to choose radiotherapy program for clinical physician .Methods twenty-five cases with upper esophageal carcinoma (clinical stageⅠ~Ⅲstage)were treated by 3DCRT and IMRT at the concentra three-dimensional radiation treatment planning system .The different exposure doses between target area and effected organs were compared by dose volume histogram ( DVH) with the planed target volume ( PTV) ,which must reach 95% of the prescriptive doses.Results Two different radiotherapy plans of IMRT and 3DCRT:V95, (99.91 ±0.14)%,(95.73 ±4.14)% respectively,P0.05;targeting minimum dose(Dmin)were(5 458.88 ±184.06) cGy,(4541.60 ±599.0)cGy,P0.05;Lung V10 (35.39 ±11.41)%,(29.0 ±8.80)%,P<0.05,Lung V5(44.95 ±15.55)%,(37.27 ±11.93)%,P<0.05. Conclusion Intensity-modulated radiotherapy is better than 3DCRT technology in showing PTV volume ,target conformal degrees and the mean index ,spinal cord protection ,However ,The risk of lung injury could be increased with the enlarged area of low -dose irradiation in lung .