DVH comparison of threeª²dimensional conformal and conventional radiotherapies in normal tissues of patients with nasopharyngeal carcinoma

    YUAN Jin, CHENG Huiª²Hua, FU Zhiª²Chao£¬LIN Guiª²Shan, ZHU Jinª²Feng

    Department of Radiotherapy, Fuzhou General Hospital, Nanjing Military Area Command, Fuzhou 350025, China

    ¡¾Abstract¡¿ AIM: To investigate the effect of threeª²dimensional conformal radiotherapies (3Dª²CRT) and conventional radiotherapies on normal tissues in patients with nasopharyngeal carcinoma by comparing the dose distribution in normal tissues so as to pick out the better method. METHODS: Forty cases of nasopharyngeal carcinoma (18 cases at stage T1 and 22 at stage T2, according to 92 Fuzhou staging) underwent conventional radiotherapy and 3Dª²CRT respectively. Treatment planning system (TPS) was used to mark the dose distribution and quantity in normal tissues (bilateral lens, optic nerves, brain stem, spinal cord, parotid glands and temporomandibular joints) and the data obtained were analyzed with doseª²volume histogram (DVH). The major fields in conventional radiotherapy were bilateral neckª²conjoined horizontal field and preª²auricular field, the preª²nasal. The topª²head fields were respectively added in the first and second phases in 3Dª²CRT and 3 to 5 conplane or nonª²conplane fields were designed in the third phase. The prescribed dose of the two groups was 70Gy respectively. RESULTS: 3Dª²CRT had satisfactory dose coverage of target volume of nasopharyngeal carcinoma compared with conventional radiotherapy. 3Dª²CRT plans spared more parotid glands and twoª²side lens than conventional treatment (P<0.05), the conventional treatment spared a little more brain stem and bilateral optic nerves than 3Dª²CRT(P<0.05) and the received dose in other organs was similar in the two plans(P>0.05). CONCLUSION: 3Dª²CRT not only satisfies the dose coverage of target volume, especially in subclinical lesion region, but also spares more normal tissues compared with conventional radiotherapy. ......