Dosimetry of organs at risk between involved field radiation and extended field radiation in patients with thoracic esophageal cancer / 中国辐射卫生

Objective To study the irradiation dose of organs at risk (OAR) in involved field radiation and extended field radiation in patients with thoracic esophageal cancer who received intensity modulated radiotherapy (IMRT). Methods A total of 40 patients with thoracic esophageal cancer were treated with IMRT. The involved field, extended field, and OAR were outlined to generate IMRT plans. The conformity index (CI) and homogeneity index (HI) of planning target volume (PTV) and the irradiation parameters of OAR were evaluated for the two plans. Paired t-test was used for comparison of irradiation parameters. Results The PTV of both plans received the prescribed dose. There were no significant differences in CI and HI of PTV between the two groups (P = 0.317, 0.130). There were significant differences in average lung dose, lung V5, lung V20, lung V30, spinal cord Dmean, heart Dmean, heart Dmax, heart V30, heart V40, and heart V60 between the two groups (P < 0.01). Conclusion Compared with the extended field, the involved field can reduce the irradiation dose of ORA in patients with thoracic esophageal cancer, thus reducing the risk of radiation.

Dosimetric study of adaptive radiotherapy for nasopharyngeal carcinoma / 安徽医科大学学报

Seven patients with nasopharyngeal carcinoma treated with ART were recruited . All patients were treated with SIB-IMRT regimen( named IMRT) . All patients had a second computed tomography scan after 10 fractions and a new plan based on this was initiated from fraction 11 ( ART1 ) . And a third CT scan after 21 fractions and a new plan based on this was initiated from fraction 22(ART2). When the treatment was finished,a fourth CT scan was made. Results revealed that the volumes of primary tumors and parotid glands regressed significantly after the teat-ment. The position of the parotid glands shifted medially an average of 4.5(1.6~9.2)mm during the plans. ART1 reduced mean dose to left parotid by 0. 42 Gy(1. 68%)(P=0.019) and right parotid by 0. 79 Gy (3.04%) (P=0. 013) over the IMRT alone. ART2 further reduced the mean left parotid dose by 0. 86 Gy or 3.5% ( P =0.001 ) and right parotid by 1 . 04 Gy or 4 . 13% ( P=0.035 ) .