title: Are IMRT treatments in the head and neck region increasing the risk of secondary cancers?
abstract: BACKGROUND
  Intensity-modulated radiation therapy (IMRT) has been increasingly employed for treating head and neck (H&N) tumours due to its ability to produce isodoses suitable for the complex anatomy of the region. The aim of this study was to assess possible differences between IMRT and conformal radiation therapy (CRT) with regard to risk of radiation-induced secondary malignancies for H&N tumours.
  
  
  METHODS
  IMRT and CRT plans were made for 10 H&N adult patients and the resulting treatment planning data were used to calculate the risk of radiation-induced malignancies in four different tissues. Three risk models with biologically relevant parameters were used for calculations. The influence of scatter radiation and repeated imaging sessions has also been investigated.
  
  
  RESULTS
  The results showed that the total lifetime risks of developing radiation-induced secondary malignancies from the two treatment techniques, CRT and IMRT, were comparable and in the interval 0.9-2.5%. The risk contributions from the primary beam and scatter radiation were comparable, whereas the contribution from repeated diagnostic imaging was considerably smaller.
  
  
  CONCLUSIONS
  The results indicated that the redistribution of the dose characteristic to IMRT leads to a redistribution of the risks in individual tissues. However, the total levels of risk were similar between the two irradiation techniques considered.
authors.affiliation: Medical Radiation Physics, Department of Physics, Stockholm University , Stockholm , Sweden.
authors.forename: Oscar
authors.initials: O
authors.lastname: Ardenfors
authors.forename: Dan
authors.initials: D
authors.lastname: Josefsson
authors.forename: Alexandru
authors.initials: A
authors.lastname: Dasu
mesh_terms: D000328:Adult; D000465:Algorithms; D003952:Diagnostic Imaging / Q000009:adverse effects; D004947:Esophagus / Q000528:radiation effects; D005260:Female; D006258:Head and Neck Neoplasms / Q000532:radiotherapy*; D006801:Humans; D007012:Hypopharyngeal Neoplasms / Q000532:radiotherapy; D008168:Lung / Q000528:radiation effects; D008297:Male; D009381:Neoplasms, Radiation-Induced / Q000209:etiology*; D016609:Neoplasms, Second Primary / Q000209:etiology*; D058958:Organs at Risk / Q000528:radiation effects; D010306:Parotid Gland / Q000528:radiation effects; D019047:Phantoms, Imaging; D017785:Photons / Q000627:therapeutic use; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods; D020266:Radiotherapy, Conformal / Q000009:adverse effects* / Q000379:methods; D061089:Radiotherapy, Image-Guided / Q000009:adverse effects / Q000379:methods; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects* / Q000379:methods; D012306:Risk; D012542:Scattering, Radiation; D012737:Sex Factors; D014062:Tongue Neoplasms / Q000532:radiotherapy; D014067:Tonsillar Neoplasms / Q000532:radiotherapy