Dose analysis of hippocampus in T₃, T₄ nasopharyngeal carcinoma patients treated with intensity modulated radiotherapy

Objective: To analyze the exposed dose of hippocampus (HC) of T₃, T₄ nasopharyngeal carcinoma patients treated with intensity modulated radiotherapy (IMRT). Methods: The bilateral HCs were delineated and were divided into head (HH), body (HB) and tail (HT) for 62 nasopharyngeal carcinoma patients treated with IMRT. The dose parameters of HC were then analyzed. Results: The mean dose of left and right HC was (1127 ± 704) cGy, (1173 ± 762) cGy. The mean dose of left HH, HB and HT was (1732 ± 1029) cGy, (820 ± 632) cGy, (423 ± 366) cGy (P = 0.000); while the mean dose of right HH, HB and HT was (1985 ± 1101) cGy, (837 ± 531) cGy, (432 ± 343) cGy (P = 0.000). The exposed dose and the volume exposed in different dose of HH were obviously higher than those of HB and HT. The dose parameters of HH, HB and HT decreased in turn. The involvement of sphenoid sinus, ethmoid sinus and cavernous sinus correlated with high exposed dose of HC. Conclusions: The exposed dose of HH, HB and HT was different in nasopharyngeal carcinoma patients treated with IMRT. The exposed dose of HH was the highest, which should be emphasized especially. The involvement of sphenoid sinus, ethmoid sinus and cavernous sinus suggest high exposed dose of HC. (authors)