A new normal portion of the esophagus (NPE) sparing technique for upper and middle esophagus cancer by SIB-IMRT automatic planning

During upper and middle esophageal cancer patients' radiation therapy, dose hot spots located in the normal portion of the esophagus (NPE) may increase radiation esophagitis, so NPE may also needs sparing. Automatic planning may have an advantage on sparing NPE over conventional trial-and-error type planning. We compared radiation esophagitis predicted by two esophageal NTCP models between different optimization strategies.

20 upper and middle esophagus cancer patients were reviewed and re-optimized by three strategies: autoplan in which NPE was not spared called A1 plan; trial-and-error type plan in which NPE was spared called T plan; autoplan in which NPE was spared called A2 plan.Dose volume parameters of four different esophagus structures were compared between three types of plans. Predicted radiation esophagitis between different optimization strategies were compared.

Target dose coverage of three types of plans all met clinical desires. Dose hot spots of ESOwhole-PGTV and ESOinfield-PGTV from A2 plans are lowest in 3 types of plans. While Dose hot spots of ESOwhole and ESOin field from T plans are highest.V60 and Dmax of four types of esophagus structures in A2 plans are lower than T plans. AET =2 probabilities predicted by Kwint modle for A2 plans are slightly lower than T plans, respectively 70.1±2.5%,76.9±3.2%,54.8±1.7% and 72.7±2.8%.AET=3 probabilities were also lowest for A2 plans. Standard deviation of dose volume parameters and AETs of four types of esophagus structures in automatic plans are significant less than T plans.

Upper and middle esophagus cancer patients who received SIB-IMRT could benefited by a new NPE sparing technique by automatic planning. It may decrease patients’ radiation esophagitis.