Preliminary results of the exposed dose of head, body and tail of the hippocampus in nasopharyngeal carcinoma patients treated with intensity modulated radiotherapy

Objective To analyze the radiation doses to the head, body, and tail of the hippocampus in intensity-modulated radiotherapy (IMRT) for nasopharyngeal carcinoma (NPC). Methods Ten NPC patients treated with IMRT were selected, and the head, body, and tail of both hippocampi were delineated on T1-weighted images. The doses to the hippocampus were then analyzed. WAIS-CR speech test results were tested by paired sample t-test. Results The mean doses to left and right hippocampi were 1147±976 cGy and 1011±602 cGy, respectively. The mean doses to the head, body, and tail of the left hippocampus were 1739±1317 cGy, 890±982 cGy, and 547±688 cGy, respectively (P=0.042); the mean doses to the head, body, and tail of the right hippocampus were 1691±942 cGy, 744±483 cGy, and 531±603 cGy, respectively (P=0.002). The dose to the hippocampus decreased from the head to the tail, and the irradiated volume also decreased as the dose varied. Conclusions The dose to hippocampus decreases from the head to the tail in NPC patients treated with IMRT, which is worthy of attention. Key words: Nasopharyngeal neoplasms/intensity modulated radiotherapy; Radiotherapy dosage; Hippocampus