PURPOSE: To quantify the anatomic changes caused by external beam radiotherapy in head-and-neck cancer patients in full three dimensions and to relate the local anatomic changes to the planned mean dose. METHODS AND MATERIALS: A nonrigid registration method was adapted for RT image registration. The method was applied in 10 head-and-neck cancer patients, who each underwent a planning and a repeat computed tomography scan. Contoured structures (parotid, submandibular glands, and tumor) were registered in a nonrigid manner. The accuracy of the transformation was determined. The transformation results were used to summarize the anatomic changes on a local scale for the irradiated and spared glands. The volume reduction of the glands was related to the planned mean dose. RESULTS: Transformation was accurate with a mean error of 0.6 +/- 0.5 mm. The volume of all glands and the primary tumor decreased. The lateral regions of the irradiated parotid glands moved inward (average, 3 mm), and the medial regions tended to remain in the same position. The irradiated submandibular glands shrank and moved upward. The spared glands showed only a small deformation ( approximately 1 mm in most regions). Overall, the primary tumors shrank. The volume loss of the parotid glands correlated significantly with the planned mean dose (p <0.001). CONCLUSION: General shrinkage and deformation of irradiated glands was seen. The spared glands showed few changes. These changes were assessed by a nonrigid registration method, which effectively described the local changes occurring in the head-and-neck region after external beam radiotherapy.
PURPOSE: To quantify the anatomic changes caused by external beam radiotherapy in head-and-neck cancerpatients in full three dimensions and to relate the local anatomic changes to the planned mean dose. METHODS AND MATERIALS: A nonrigid registration method was adapted for RT image registration. The method was applied in 10 head-and-neck cancerpatients, who each underwent a planning and a repeat computed tomography scan. Contoured structures (parotid, submandibular glands, and tumor) were registered in a nonrigid manner. The accuracy of the transformation was determined. The transformation results were used to summarize the anatomic changes on a local scale for the irradiated and spared glands. The volume reduction of the glands was related to the planned mean dose. RESULTS: Transformation was accurate with a mean error of 0.6 +/- 0.5 mm. The volume of all glands and the primary tumor decreased. The lateral regions of the irradiated parotid glands moved inward (average, 3 mm), and the medial regions tended to remain in the same position. The irradiated submandibular glands shrank and moved upward. The spared glands showed only a small deformation ( approximately 1 mm in most regions). Overall, the primary tumors shrank. The volume loss of the parotid glands correlated significantly with the planned mean dose (p <0.001). CONCLUSION: General shrinkage and deformation of irradiated glands was seen. The spared glands showed few changes. These changes were assessed by a nonrigid registration method, which effectively described the local changes occurring in the head-and-neck region after external beam radiotherapy.
Authors: Xiaofeng Yang; Ning Wu; Guanghui Cheng; Zhengyang Zhou; David S Yu; Jonathan J Beitler; Walter J Curran; Tian Liu Journal: Int J Radiat Oncol Biol Phys Date: 2014-10-13 Impact factor: 7.038
Authors: A Fiorentino; M Cozzolino; R Caivano; P Pedicini; C Chiumento; C Oliviero; S Clemente; V Fusco Journal: Clin Transl Oncol Date: 2012-10-13 Impact factor: 3.405
Authors: Adam D Yock; Arvind Rao; Lei Dong; Beth M Beadle; Adam S Garden; Rajat J Kudchadker; Laurence E Court Journal: Med Phys Date: 2014-08 Impact factor: 4.071