| Objective To dicuss IGRT(Image guided radiotherapy)positioning errors in IGRT in intensity modulated radiotherapy for advanced cervical cancer and analyze the effect of positioning error on target area and organ.At the same time,we compared the short-term curative effects,the acute radiation toxic and side effects of two groups,the IGRT group and Intensity Modulated Radiation Therapy(IMRT)group.Methods IGRT combined linear accelerators with imaging equipment.Cone Beam Computer Tomography(CBCT)was used to obtain the pre-treatment imaging image,and compared it to the original image.Axial translation errors of X(left and right),Y(head and foot)and Z(ventromedial and dorsal)were measured after the first positioning,after the positioning error was corrected and after treatment.The simulation plan was formed by using the initial positioning error.The position error was analyzed.The PTV dose and the irradiated volume of organs at risk of original plan and simulated plan were compared.We observed the short-term efficacy and acute radioactive side effects of patients in the IGRT group and IMRT group.Results(1)After initial positioning in the X,Y and Z directions,the errors were(2.27± 0.09)mm,(4.24±0.11)mm and(2.58 ±0.09)mm.After correction,the positioning errors in the X,Y and Z directions were(0.22 ±0.04)mm,(0.76± 0.05)mm and(0.34 ±0.05)mm,respectively.There were significant differences statistically in all directions(P<0.05).(2)After correction,the positioning errors in the X,Y and Z directions were(0.22± 0.04)mm,(0.76 ±0.05)mm and(0.34± 0.05)mm,respectively.After treatment the positioning errors in the X,Y and Z directions were(0.27 ±0.04)mm,(0.73 ±0.05)mm and(0.43± 0.04)mm,respectively.There was no significant difference in all directions(P>0.05).(3)Short-term effective rate: There were 18 CRcases and 2 PR cases in IGRT group,,the total effective rate(CR+PR)was 90.91%(20/22).There were 15 CR and 3 PR cases in IMRT group cases,,the total effective rate(CR+PR)was 90%(18/20).There was no significant difference(P>0.05).(4)Acute toxic and side effects of radiation: In IGRT group,level 0 + level Ⅰ of acute urinary tract reaction rate and acute gastrointestinal reaction rate was respectively 95.45% and90.90%;Ⅱ + Ⅲ level of acute urinary tract reaction rate and acute gastrointestinal reaction rate was respectively 4.55% and 9.10%.In IMRT group,level 0 + level Ⅰ of acute urinary tract reaction rate and acute gastrointestinal reaction rate was respectively 95% and55%;Levels Ⅱ + Ⅲ acute reaction rate of urinary system and acute gastrointestinal reaction rate was respectively 5% and 45%.There were statistically significant differences in the Ⅱ + Ⅲlevel of acute gastrointestinal reaction rate between the two groups(P< 0.05).However,there was no significant difference in other toxic reaction rates(P> 0.05).The incidence of bone marrow suppression of Ⅰ degree,Ⅱ degree and Ⅲ degree for patients in IGRT group was respectively 63.63%,27.27% and 9.09%,while in IMRT group it was respectively 60%,30% and 10%.There was no significant difference between the two groups(P> 0.05).In IGRT group,the acute radioactive skin reaction rate of level 0,level Ⅰand level Ⅱ was 59.09%,31.82% and 9.09% respectively,while in IMRT group it was 50%,40% and 10% respectively.There was no significant difference between the two groups(P>0.05).Conclusion Compared to IMRT,IGRT could improve the precision of locally advanced cervical cancer radiotherapy,and significantly reduce the acute gastrointestinal reaction rate of Ⅱ + Ⅲlevel. |
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