ABSTRACT
Objective To compare the dosimetric difference on organ at risk (OAR) in intensitymodulated radiotherapy (IMRT) with three-dimensional conformal radiotherapy (3D-CRT) in treatment with cervical carcinoma. Methods 36 cases of cervical cancer patients accepted radiotherapy both on IMRT and 3D-CRT in the same time,clinical target volume (CTV) focused on primary tumor and its lymphatic drainage area.Lymphatic drainage area was determined as follows:1.0 cm extension were added to the margin of pelvic vessels,the obturator lymph nodes region was extended by 1.8 cm from the pelvis inner margin.CTV does not include pelvic tissue. Data of dose distribution and irradiation volume of OAR on the basis of distributing on 45 Gy and 50 Gy were analyzed individually. The margins of planning target volume (PTV) was obtained based on CTV margins by which added 1.0 cm extension in inferior and superior directions,0.7 cm were added in all other directions. Results With the comparison of variety on irradiation volume of organs at risk (OAR) by DVH in both groups,underlying the treatment dose 45 Gy,the individual volume of D30,D40 and D45 were all lesser in IMRT plan than that of 3D-CRT plan. Even on the dose 50 Gy at pelvic wall lymph nodes regions,the volume of OAR was lesser than that in 3D-CRT plan.Conclusion In the radiotherapy of cervical cancer,IMRT should have improved protections for tumor surrounding OAR which has domestic superiority in clinical application.