Objective To compare the difference in radiotherapy dose caused by different ways of adding bolus.Methods A total of 20 patients who needed to receive postmastectomy chest wall irradiation from October to December on 2014 were selected.Each patient underwent two CT scans;CT-1 was to perform CT scan directly without bolus, and CT-2 was to perform CT scan after adding bolus to the body surface.An equivalent bolus was added for CT-1 in the radiotherapy planning system, and Plan-1, which met the clinical requirements, was performed.Then Plan-1 was put on CT-2 through image fusion and plan verification to develop Plan-2, which was to develop plans with equivalent boluses at other times and perform radiotherapy with a bolus added to the surface of the body.At last, CT-2 was used to perform radiotherapy Plan-3, which met the clinical requirements.The paired t-test was used for comparison of clinical data between any two plans with SPSS 19.0.Results The V20 of the whole lung, V20 of the diseased lung, V30 of the heart, and Dmax of the healthy breast showed no significant differences across the three plans (P=0.074-0.871).The V50 , V55 , conformity index, and homogeneity index of the planning target showed significant differences across the three plans, and the total number of monitor units showed a significant difference between Plan-1 and Plan-2(P=0.002-0.049).The dose distribution in the target volume and the number of monitor units in each radiation field also showed significant differences.Conclusions When the equivalent bolus is added to the body surface before CT scan, such a plan can accurately reflect the dose distribution of the planning target and the dose to organs at risk.

Objective To investigate the clinical value of vacuum pad and body film fixation in radiotherapy for thoracic and abdominal tumors. Methods A total of 240 patients with thoracic and abdominal tumors who were treated with radiotherapy were randomly selected and divided into group A (simple vacuum pad fixation,60 patients),group B(simple body film fixation with unimproved solid plate, 60 patients),and group C(vacuum pad and body film fixation with improved solid plate,120 patients).The difference between groups were analyzed with single variance analysis method. Results The setup error was small in group C and large in groups A and B. There were significant differences in the setup error between the three fixation methods(P=0.000). Conclusions A combination of vacuum pad and body film fixation is better than vacuum pad or body film fixation in radiotherapy for thoracic and abdominal tumors. The combination method has many benefits, including simple and convenient operation, comfortable and repeatable body fixation,reduced artificial errors,and improved positioning precision.