| Cervical cancer is one of the most common malignancies in gynecology.Nearly 80% of patients with cervical cancer require radiotherapy at different clinical stages.In recent years,with the development of radiotherapy technology,most patients with cervical cancer are mainly treated with three-dimensional conformal radiotherapy(3DCRT)and intensity-modulated radiotherapy(IMRT).Four – field conformation is usually applied in 3DCRT,however,five – field or seven – field conformation is generally applied in IMRT).As cervical cancer patients in many local hospitals have financial difficulties,by using)IMRT with fewer fields to ease patients’ financial stresses,but still achieve a better dose distribution is our main purpose in this study).In addition,it also provides dosimetry evidence for the application of three-field IMRT in the clinic.In this study,30 cervical cancer patients treated with radiotherapy at the First People’s Hospital of Chen Zhou from May 2016 to May 2019 were selected.The images scanned by the large-aperture CT were transmitted to the Varian Eclipse treatment planning system for three-field,five-field,or seven-field IMRT and four-filed 3DCRT planning design.After planning,a three-dimensional treatment planning system were used to compare the four types of plans and evaluate their dosimetry distribution characteristics.Based on the dose-volume histogram(DVH),the irradiation dose between the target area and normal tissues such as the small intestine,bladder,rectum,etc.,and the homogeneity index,conformal index of the dose distribution in the target area were analyzed.Studies show that in terms of dosimetry,three-field,five-field or seven-field IMRT and four-filed 3DCRT plan have 95% coverage of the prescribed dose,and their conformal index are(0.72±0.06),(0.82±0.05),(0.83±0.04),(0.55±0.07),respectively.IMRT performs better than3 DCRT,and their homogeneity index are(1.07±0.05),(1.06±0.03),(1.05±0.03)and(1.09±0.04).There is no significant difference between the four types of plans.In these plans,the volume of the bladder under4500 c Gy dose are(36.56±12.13)%,(33.36±10.15)%,(30.85±7.62)%,(72.36±11.25)%,for rectum,the volume with 4500 c Gy are(28.36±10.15)%,(22.23±9.26)%,(20.41±8.25)%,(75.35±13.18)%,for small intestine the volume with(12.61±5.86)%,(8.75±4.22)%,(8.38±3.83)%,(32.18±9.95)%and with 4000 c Gy are(18.77±8.06)%,(15.43±6.08)%,(15.29±5.05)%,(38.38±9.98)%.In conclusion,IMRT can reduce the radiation dose of normal organs such as the bladder,rectum,and small intestine compared to four-filed 3DCRT.The results indicate that IMRT compared to 3DCRT can reduce the radiation dose of normal organs when meeting the tumor radiotherapy dose,and also reduce the occurrence of complications.Therefore,IMRT should be more widely used in clinical,for those patients limited with economic conditions.Three-filed IMRT is more beneficial than four-filed 3DCRT. |
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