| Objective: To assess the dose distribution by threedimensional conformal treatment planning system (TPS) for theprimary lesion and normal tissues around esophagus carcinoma,discussing the effect of treatment plan and correlative factors toshort term results.Methods: From Jul.2003 to Oct.2004, 44 patients ofuntreated esophageal carcinoma were treated. They wereimmobilized and simulated under simulator in the treatmentposition . The field centers , gantrys and collimators were notedand marked by barium meal while being simulated . And then ,they were scanned by CT simulator with the same position . Theimages were transferred through local network to the treatmentplanning system (CMS Focus 3.0 or ADAC Pinnacle 6.2b) andreconstructed by TPS. The gross tumor volume(GTV),clinicaltarget volume (CTV), planning target volume (PTV) and organsat risk (OAR) were outlined basing on the findings ofesophagogram , esophagoscopy and CT images. Three treatmentplans were designed for each patient: 1. Conventional treatmentplan (CTP) , all data was achieved by conventional simulatingand being imported to the TPS. 2. Three dimensional conformalradiotherapy plan (3DCRT), the most excellent dose distributionfor GTV, CTV, PTV and normal tissues around was achieved bythree dimensional TPS. 3. Virtual conventional treatment plan(VCTP), all conditions were same as the second plan but withrectangle fields . The patients were treated with 3DCRT.Prescription dose: 5800 cGy~7000 cGy, the median prescriptiondose: 6600 cGy. Twenty-four patients received conventionalfraction radiation :200cGy/per fraction, 1 fraction/ per day, 5fractions/per week.The last 20 patients received conventionalfraction radiation for the first 3~4 weeks , from the 4th or 5thweek , received accelerated radiation , 300cGy/per fraction ,1fraction/per day , 5 fractions/per week .Results: ⑴The average length of lesion was 5.42 cmshown on esophageal barium meal and 8.42 cm on CTscan .There was a significant difference between two methods ,P=0.000. The greatest diameter of tumor were 5.48cm (right-left)shown on CT scan , the average volume of GTV was 59.68cm~3(9.00 cm~3~166cm~3). The deviation of field center along X, Y,Z axis was 7.67mm, 13.21mm, 7.68mm. Of that, there was asignificant difference between X axis , P=0.001. ⑵The doses of100% GTV volume were 3406.8 cGy,6379.1 cGy and 6290.0cGy from CTP, VCTP and CRT, respectively . The doses of 95%GTV volume were 4344.1 cGy, 6484.7 cGy and 6453.6 cGy,respectively . The doses of 100%, 95% GTV volume of CRTwere significantly higher than that of CPT, P=0.000, but werelower than that of VCTP, P<0.05. The volumes of GTV coveredby 50%~100% isodose curves for CTP were all less than that ofCRT, P<0.01, of that , the volumes of GTV covered byprescription dose were 40.6%. Over than 98% GTV volumeswere covered by 95% isodose curve and 100% GTV volumeswere covered by 90% isodose curve for VCTP and CRT. Thedoses of 100% CTV volume were 1541.4 cGy, 5387.3 cGy and4892.3 cGy from CTP, VCTP and CRT , respectively . Thedoses of 95% CTV volumes were 3303.0 cGy, 6375.3 cGy and6081.8 cGy, the dose of CTV for CRT were higher than that ofCTP, P=0.000, but lower than that of VCTP, P<0.01. The TCPvalues for CTP, VCTP and CRT were 12.84%, 36.24% and36.15% , respectively .⑶The lungs V20 was 22.5%, 33.6% and22.5%, the lungs V30 was 15.5%, 22.1% and 12.7%, lungsNTCP was 3.1%, 23.4% and 2.3%, there was no significantdifference between CTP and CRT. ⑷The overall 1-yearsurvival rate was 69.15%. The 1-year survival rate was 87.50%and 56.81 for patients of tumors ≤7cm and >7cm(P=0.0465) .For GTV volumes ≤80cm~3 group and >80cm~3group , the 1-year survival rate was 77.13% and 45.00% ,P=0.0019. For the late course accelerated radiation group andconventional radiation group , the 1-year survival rate was87.97% and 60.26% , P=0.2996.Conclusions: 3DCRT can well achieve ideal dosedistribution and coverage to the target volumes and well protectthe normal tissues at the same time , compared with the CTPand VCTP. The large tumor volume or the long lesion indicateda bad prognosis . The late course accelerated conformal...
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