title: Volume and dosimetric changes and initial clinical experience of a two-step adaptive intensity modulated radiation therapy (IMRT) scheme for head and neck cancer.
abstract: OBJECTIVE
  The aim of this study was to show the benefit of a two-step intensity modulated radiotherapy (IMRT) method by examining geometric and dosimetric changes.
  
  
  METHODS
  Twenty patients with pharyngeal cancers treated with two-step IMRT combined with chemotherapy were included. Treatment-planning CT was done twice before IMRT (CT-1) and at the third or fourth week of IMRT for boost IMRT (CT-2). Transferred plans recalculated initial plan on CT-2 were compared with the initial plans on CT-1. Dose parameters were calculated for a total dose of 70 Gy for each plan.
  
  
  RESULTS
  The volumes of primary tumors and parotid glands on CT-2 regressed significantly. Parotid glands shifted medially an average of 4.2mm on CT-2. The mean doses of the parotid glands in the initial and transferred plans were 25.2 Gy and 30.5 Gy, respectively. D(2) (dose to 2% of the volume) doses of the spinal cord were 37.1 Gy and 39.2 Gy per 70 Gy, respectively. Of 15 patients in whom xerostomia scores could be evaluated 1-2 years after IMRT, no patient complained of grade 2 or more xerostomia.
  
  
  CONCLUSIONS
  This two-step IMRT method as an adaptive RT scheme could adapt to changes in body contour, target volumes and risk organs during IMRT.
authors: Department of Radiation Oncology, Kinki University Faculty of Medicine, Osaka-Sayama, Japan. tamakinishi_1213@kxa.biglobe.ne.jp
authors: Tamaki
authors: T
authors: Nishi
authors: Yasumasa
authors: Y
authors: Nishimura
authors: Toru
authors: T
authors: Shibata
authors: Masaya
authors: M
authors: Tamura
authors: Naohiro
authors: N
authors: Nishigaito
authors: Masahiko
authors: M
authors: Okumura
mesh_terms: D006258:Head and Neck Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D006801:Humans; D010306:Parotid Gland / Q000528:radiation effects; D011879:Radiotherapy Dosage; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D047368:Tumor Burden