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Objective:To customize the individualized 3D printed head film for patients with head tumors undergoing radiotherapy, and to evaluate the physical properties of the material and the precision of this technology compared with the thermoplastic head film.Methods:The 3D printed head film and thermoplastic head film were placed on the solid water surface, and the depth and surface dose were measured at 5 cm by ionization chamber and film, respectively. Thirty patients with head tumors receiving radiotherapy were randomly divided into the control and experimental groups. The patients were fixed with thermoplastic head film and 3D printed head film. The translational and rotational errors in the x, y and z direction were obtained by CBCT.Results:The radiation attenuation rate of two materials at the depth of 5 cm was less than 1%. The dose of thermoplastic head film in the surface position was increased by 27%, and increased by 18% in the 3D printed head film. In two groups, 116 sets of setup errors were collected. The average translational setup errors in the control and experimental groups were 1.29 mm and 1.16 mm, 1.42 mm and 1.24 mm, 1.38 mm and 1.16 mm, respectively, and the average rotational setup errors were 1.29°and 1.08°, 1.02°and 0.96°, 1.01°and 1.00°, respectively. The translational setup errors in the y and z direction and rotational setup errors in the x direction significantly differed between the control and experimental groups (all P<0.05), but no statistical significance was found in the other direction (all P>0.05). Conclusion:The 3D printed head film fixation meets the precise setup requirements of modern radiotherapy, which deserves further application in clinical trials.
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Objective To compare the difference of dose distribution between inverse planning simulated annealing (IPSA) and hybrid inverse treatment planning and optimization (HIPO) in 3D brachytherapy plan of cervical cancer,and to provide evidence for selection of reverse planning optimization method for cervical cancer brachytherapy.Methods From Dec 2016 to May 2017,totally 43 cases of patients with cervical cancer radical surgery were selected.Original IPSA brachytherapy treatment plan optimization was applied to all cases.Based on the information of original image,IPSA and HIPO plans were established according to the same initial conditions.Parameters of Dg0,D100,V100％,Homogeneity Index (HI),and conformal index (CI) of the bladder,rectum and sigmoid D2 cm3 data for High-Risk Clinical Target Volume (HR-CTV) were assessed.Results There was no statistically significant difference in D90,D100 and CI for HR-CTV between the two groups.But the V100％ of HR-CTV in HIPO group was significantly higher than that in IPSA group [(87.72 ±0.49)％ vs.(85.01 ± 0.55)％,t =2.54,P ＜0.05].Furthermore,HI in HIPO group was (0.51 ±0.08),which was higher than that in IPSA group (0.42 ± 0.06),and the difference was statistically significant (t =3.02,P ＜ 0.05).Compared with IPSA,bladder D2 cm3 and rectum D2 cm3 [(3.04 ± 0.37) Gy] for HIPO plan were lower [(3.42 ± 0.17) Gy vs.(3.57 ± 0.28) Gy,(3.04 ± 0.37) Gy vs.(3.57 ± 0.28) Gy],which had reached statistical significance (t =0.27,0.19,P ＜ 0.05).There was no statistical significance in the D2 cm3 dose of sigmoid.Conclusions In the treatment of cervical cancer,better target area HI and less irradiated dose of bladder and rectum can be obtained by HIPO optimization than IPSA optimization.