Application Of Image-guided Intensity-modulate Radiotherapy For Breast Cancer After Conservative Surgery

Objective: Image Guided Radiation Therapy with KV-CBCT measurement of breastcancer after conservative surgery intensity-modulated radiotherapy beam position error,Discuss beam position error of the tumor target volume and the surrounding normaltissues illuminated doses of influence.Methods:21patients who underwent breast cancerafter conservative surgery by image-guided intensity-modulated radiotherapy, We obtained105group first beam position error data, Use these data in3D treatment planning systemsimulation of the actual treatment in patients with process, beam position error of thetumor target area and the surrounding normal organs illuminated doses ofinfluence.Results:21cases of breast cancer after conservative surgery for the first timeput a total of CBCT scanning105times, The systematic random error inX,Y,andZdirection was (3.35±0.98)mm,（3.73±1.83）mm,(2.77±0.97)mm,respectively. For thesebeam position errors are corrected in real time, After correcting X, Y, Z three directionsbeam position error of the system error and random error correction are lower than thoseof former level. Beam position error of patients accept95%PTV dose and standardproject phase is increased1.7Gy. PTV minimum dose and dose were down an average of2.1Gy and2.6Gy, Beam position error correction to improve the PTV95%volumeilluminated dose,The difference was statistically significant（t=0.01p<0.05）Doublelung and heart surrounding normal tissues illuminated dose effect. Difference was notstatistically significant. Conclusion:The breast cancer after conservative surgerypatients with postoperative application image-guided intensity-modulated radiotherapy on the beam position error correction is very meaningful patients can reduce the beamposition error and improve the PTV illuminated dose and treatment precision. Beamposition error of double lung, heart illuminated dose not seen obvious change.