Dosimetrics Study Of Two Different Techniques In Postoperative Irradiation Of Cardiac Carcinoma

ObjectTo explore the difference of dose distribution in target volume and organs at riskbetween two treatment plans for postoperation patients of cardiac carcinoma in order toprovide a reference for the choice of clinical treatment.MethodsTen patients with Clinical stage T3,4or any T,N+cardiac carcinoma in the firstaffiliated hospital radiotherapy of An Hui Medical University were enrolled. UsingTopslane Venus planning system, proceed CT scanning for the10patients with cardiaccarcinoma, then transmited the CT scanning image to the treatment planning system(TPS). Gross Clinical target volume (CTV)and organs at risk(OAR)(spinal cord, lungand kidney) were contoured layer by layer. Two radiotherapy plans, plan A and B weremade for each patient. Plan A included a single target containing3-5cm esophageal, thepostoperative cardia tumor bed and the regional lymph nodes. Plan B included twotarget, one containing3-5cm esophageal and the postoperative cardia tumor bed and theother containing regional lymph nodes. Dosimetry studies were carried out by the twodifferent plans as above mentioned for each patient with a prescribed dose of45Gy to atlease95%of PTV. In this study the V45, V42.75of target volume, conformity index(CI), evenness index (HI), external volume index(EI) and the mean dose of lung tissue,liver tissue, kidney tissue and spinal cord were compared by dose volume histogram(DVH).Results1. The dose parameters of V45， V42.75， HI and EI in plan B were （96.059±0.3929）%、（99.518±0.1665）%、0.9987±0.2240and0.2104±0.0641，which were no difference between two treatment plans（P>0.05）.2. The plan B has a better CI compared with plan A（P<0.001）.3. In plan B, the mean dose of left lung, right lung, liver, the highest dose ofspinal cord, V15and V23to the left kidney were （511.204±151.879）Gy、（517.996±90.4701）Gy、（2030.034±292.746）Gy、（86.586±6.8068）%、（60.790±10.1584）%, which were significantly better than that in plan A(p<0.05), the dose in plan A were（638.467±140.9345）Gy、（618.550±110.7761）Gy、（2251.763±284.493）Gy、（96.785±1.6586）%、（67.316±8.3406）%, respectively.4. There was no significant difference in the V15(P=0.712) and V23(P=0.427) to the right kidney.ConclusionBoth of the two treatment plan for postoperation of cardiac carcinoma can ensurethe dosimetric distribution of target volume. But the plan B has a advantages of in theprotection of organs at risk including lung, liver, kidney and spinal cord.