Prediction Model of Parotid Mean Dose in Intensity Modulated Radiation Therapy on Nasopharyngeal Carcinoma

Objective To investigate the prediction model of parotid mean dose and D50% in intensity modulated radiation therapy (IMRT) on nasopharyngeal carcinoma (NPC).

Methods We selected 50 NPC patients who underwent IMRT, scanned the radiotherapy plan CT, analyzed the relationship between the parotid volume and its mean absorbed dose and D50%, and predicted parotid mean dose and D50% before planning IMRT.

Results There were significant correlation between Vparotid/Vparotid and Dmean/Dprescription (confidence coefficient=0.01, r=0.895), Voverlap/Vparotid and D50%/Dprescription (confidence coefficient=0.01, r=0.812). Matlab software was used to fit the correlation formula.

Conclusion For the patients who underwent IMRT, we can predict Dmean and D50% by Voverlap/Vparotid under the prescription according to the relevant mathematical model fitted in this study before making the radiotherapy plan, and reduce the impact of subjective factors in the radiotherapy plan optimization process, as a standard for assessing programs.