Equivalent uniform dose and normal tissue complication probability of acute esophagitis in head-and-neck radiotherapy: Sensitivity to dose calculation accuracy

Background: to quantify the influence of photon dose-calculation algorithm selection on the cervical esophagus (ce) dose indices and the derived equivalent uniform dose (eud) and normal-tissue complication probability (ntcp) for acute esophagitis in patients with head-and-neck cancer (hnc). materials and methods: the fast photon effective path (fpep) and collapsed-cone convolution superposition (cccs) algorithms on the prowess panther treatment planning system were compared for 30 patients (six tumor sites). the lyman-kutcher-burmann (lkb) model was used to calculate the euds and ntcps. results: on average, the more simplistic fpep algorithm overestimated the mean dose to ce planning organ-at-risk volumes (prvs) by 2.0% (p = 0.003). the average absolute difference in mean dose was 2.7% and the maximum difference was 9.3%. the v5gy, v10gy, v15gy, v20gy, v25gy and v30gy values were significantly higher with fpep, while the point-dose and d2cc hot spots were similar. in turn, the dose differences led to an underestimation of the lkb-model prediction of the eud by 1.4% (p = 0.297). the mean absolute difference in eud was 4.5% and the maximum difference was 15.3%. in the 14-50 gy mean dose range, the resulting ntcps with fpep were lower on average by 2.6% than cccs (p = 0.041). conclusions: in the group of hnc patients considered in this study, the eud and ntcp for acute esophagitis showed to be moderately sensitive to the choice of dose-calculation algorithm. despite an overestimated mean dose by the simpler algorithm, the ntcp underestimation, which can be large in some patients, is of clinical concern.