Dosimetric study of simplified intensity modulated radiation therapy for cervical cancer

Abstract

Objective To compare the homogeneity and conformity of dose distribution in the target and the dose to the organs at risk among 3-dimensional conformal radiation therapy (3DCRT), intensity modulated radiation therapy (IMRT) and simplified intensity modulated radiation therapy (sIMRT), and then to evaluate the clinical value of sIMRT for cervical cancer. Methods Ten patients with cervical canc-er receiving radical radiotherapy and brachytherapy were enrolled. Before radiotherapy, CT was performed and target volumes were delineated. The clinical target volume (CTV) included supravaginal portion, cervi-cal stump, paracervical tissue, common iliac lymph nodes, internal and external iliac lymph nodes, obtura-tor lymph nodes, sacral lymph nodes, and the surrounding tissues. If the vagina was involved, the target vol-ume included the whole vagina. Margins between planning target volume (PTV) and CTV were 10 mm in the anterior direction, and 5 mm in other directions. The prescribed dose was 95% PTV receiving 45 Gy in 25 fractions of 1.8 Gy. The dose volume histogram, conformity index, homogeneity index and treatment time per faction were compared. Results Among the three radiotherapy techniques, 3DCRT had the best homo-geneity of dose distribution, while there was no significant difference between IMRT and slMRT. According to the conformity of dose distribution, sIMRT was better than 3DCRT, but worse than IMRT. Comparing the bladder sparing, IMRT was the best followed by sIMRT. The volume of the small intestine receiving high dose was increased significantly with slMRT when compared with IMRT. And the treatment time per faction was4, 10 and 18 minutes for3 DCRT, sIMRT and IMRT, respectively. Conclusions sIMRT could re-duce the work intensity of the staff, shorten the treatment time per fraction, and simplify the authenticate procedure, which is cost-effective and suitable in the treatment of cervical cancer. Key words: Cervical neoplasms/radiotherapy; Radiotherapy, simplified intensity-modulated; Dosimetry