Dosimetric And Clinical Toxicity Comparison Of Critical Organs Preservation Among 3DCRT,IMRT And RapidArc For The Treatment Of Locally Advanced Pancreatic Cancer

Purpose: To perform dosimetric and clinical toxicity comparision among 3-dimensional conformal radiotherapy(3DCRT), intensity-modulated radiotherapy(IMRT) and RapidArc(RA) for locally advanced pancreatic cancer(LAPC). We hypothesized that technique with better organ at risk(OAR) sparing and target dose distributions may lead to decreased clinical toxicity.Methods: Two hundred and eighty patients of LAPC who had undergone radiotherapy were analyzed in the study. Dosimetric comparision study was perfomed using 20 LAPC patients. Dose-volume histograms(DVHs) for the target volume and the OARs were compared. Clinical toxicity comparison study was perfomed using the 280 LAPC patients who received radiation with 3DCRT, IMRT or RA.Results:(1)Dose distribution of target volume: Both RA and IMRT achieved better CI, HI, V95% and V110% than 3DCRT;(2)Protection of organs at risk: RA reduced V10,V20 and mean duodenum dose, as well as V20 of right kidney, liver mean dose compared with 3DCRT or IMRT. RA decreased V35,V45 of duodenum, small bowel mean dose and V15 of right kidney compared with 3DCRT;(3)Comparative acute toxicity:RA reduced the incidence of Grade 3–4 diarrhea(p=0.037) and anorexia(p=0.042) compared with 3DCRT. RA decreased the incidence of Grade 3–4 diarrhea(p=0.027) compared with IMRT.Conclusion:(1)RA and IMRT were more effective in maintaining target coverage than 3DCRT;(2)RA showed better OARs sparing than 3DCRT or IMRT, especially for duodenum, small bowel and right kidney;(3)RA reduced acute Grade 3-4 GI toxicity compared with 3DCRT or IMRT;(4)Technique with better organ at risk(OAR) sparing and target dose distributions may lead to decreased clinical toxicity for the treatment of LAPC.