Comparative Study Of Fixed Field Dynamic Intensity-modulated Radiation Therapy And Fixed Field Static Intensity-modulated Radiation Therapy For Cervical Cancer

Cervical cancer is one of common female cancer in China,nearly 80 percent of cervical cancer patients in need of radiotherapy.Radiation therapy for cervical cancer is divided into external irradiation and brachytherapy,three-dimensional conformal and fixed field intensity-modulated radiotherapy(IMRT)techniques are used in the treatment of cervical cancer in China.Fixed field IMRT technology is mainly divided into fixed field static and fixed field dynamics.Fixed field static IMRT mainly adopts step and shoot(SS)IMRT technology,fixed field dynamic IMRT main has Varian’s sliding window(SW)IMRT technology and Elekta’s dynamic multi-leave collimators(DMLC)IMRT technology.Elekta’s DMLC technology appeared later and has less application experience in cancer radiotherapy,it is necessary to carry out related research,provide clinical support DMLC technology in cervical cancer radiotherapy.This paper collected 20 cases of cervical cancer were diagnosed by pathology during the period from June 2015 to December 2015 in Hunan provincial cancer hospital.After CT simulator scanned,transferred image to Monaco treatment planning system.20 cases of cervical cancer were using DMLC and SS techniques design,and then were compared dosimetric and dosimetric verification of the two radiation treatment planning.Dosimetric mainly compares the dose volume histograms,the target dose distribution,the dose distribution of organs at risk,the machine’s MU and the actual treatment time;dosimetric verification mainly compares the absolute and relative dose verification.Research shows that DMLC technology and SS technology on PTV target prescription dose coverage is basically the same,but there is significant difference between the maximum dose and homogeneity index.DMLC technology’s target dose is more uniform,and the maximum dose is lower.For the amount of organs at risk,there are statistically significant differences in the irradiated volume dose of 4500 cGy with the bladder and rectum,and the volume of DMLC technology is less.The average dose of bladder,rectum,small intestine,femoral head and sigmoid colon,and 3000 cGy,4000cGy dose of small intestine by the volume,and the maximum dose of the femoral head,although there is no significant difference,but DMLC technology is lower than SS technology.The single machine’s MU of DMLC technology is higher than the SS technology,but the single treatment time of DMLC technology is less.Dosimetric verification,the relative dose passing rate of DMLC technology and SS technology are basically the same,but the absolute dose verification of DMLC technology is better than that of SS technology.In short,both the DMLC technology and the SS technology in cervical cancer can meet clinical requirements,but the delivery dose of DMLC technology is more accurately,the target dose uniformity is better,for the protection of organs is better,and greatly shorten the treatment time.