Dosimetry Comparison Of IMRT And3D-CRT In Postoperative Radiotherapy Of Cervical Cancer And Adverse Reactions Observation

Objective: To compare target-conformal, irradiation dose volume of organ ofrisk(OAR) and early response of radiotherapy in postoperative radiotherapy ofcervical cancer between the two radiotherapy(IMRT and3D-CRT).Method：Selected87patients with stage IB~IIA in postoperative radiotherapyof cervical cancer treated with extensive hysterectomy, bilateral ovariectomy andpelvic lymph node dissection (KPS score was80points or above).46patients weretreated with IMRT and41patients treated with3D-CRT. Patients oraled diatrizoateglue in order to display intestinal twelve hours and three hours before CT location.Then patients got the CT scan after bladder filling. Doctors sketched target and organsat risk. Clinical target volume included pelvic lymph node drainage area (left andright common iliac, internal iliac, external iliac, obturator lymph nodes and presacrallymph nodes), parametrial tissue, cervical stump to the middle of the vagina. Organsat risk included rectum, bladder, small intestine, pelvic bone and femoral head.Planning target volume(PTV) was based on CTV,and PTV was extended0.8cm in alldirections. The comparison dose was45Gy/1.8Gy/25f or46.8Gy/1.8Gy/26f. The3D-CRT use4-field box irradiation. IMRT use7-wild intensity modulated irradiation.Compared and analyzed target-conformal, irradiation dose volume of organ atrisk(OAR) and early response of radiotherapy in postoperative radiotherapy ofcervical cancer between the two radiotherapy.Results: In the same radiation dose, target-conformal index of IMRT (0.748±0.037) was significantly higher than that of3D-CRT (0.386±0.013). There was nosignificant difference between the volume of bladder and rectum with the dose of 20Gy in IMRT group and3D-CRT group (P>0.05). The radiation volume of bladderwith the dose of30Gy and40Gy in IMRT were67.53±3.78and43.72±5.45respectively, significantly lower than the3D-CRT group were94.27±10.74and82.22±11.28respectively. There were significantly differences between the twogroups.(P=0.00). The radiation volume of rectum with the dose of30Gy and40Gy inIMRT were80.44±10.64and50.17±12.36, significantly lower than the3D-CRTgroup were98.26±5.73and89.23±8.53. It had statistical significance. IMRT groupwas better than3D-CRT group in the early response to radiotherapy. The incidence ofI and II degrees intestinal teaction in IMRT were30.43%and10.90%respectively,significantly lower than the3D-CRT group were63.41%and26.83%. The incidenceof I and II degrees bladder reaction in IMRT were13.04%and4.35%respectively,lower than3D-CRT group were31.71%and17.07%. No III degree or above adversebladder and intestinal reactions were observed. In the adverse reactions of the bonemarrow hematopoietic system, there was mainly I degree adverse reaction in IMRT.The ratio was37.48%. No IV degree adverse reaction were observed. The incidenceof II and III degrees adverse reaction were23.91%and15.22%respectively, lowerthan the3D-CRT group were31.71%and26.83%respectively.Conclusions: In the premise of the same radiation dose, IMRT has moresignificant advantages on improving target conformal degree, reducing radiation doseand volume of organs at risk such as bladder, rectum etc and reducingcomplication.,compared with3D-CRT.