title: Treatment planning for lung cancer: traditional homogeneous point-dose prescription compared with heterogeneity-corrected dose-volume prescription.
abstract: OBJECTIVE
  To quantify the differences in doses to target volumes and critical thoracic structures calculated by traditional homogeneous point-dose prescription and heterogeneity-corrected volume-dose prescription.
  
  
  METHODS
  Between 1998 and 2001, 30 patients with inoperable Stage I/II non-small-cell lung cancer underwent radiation treatment planning at our institution. A commercially available convolution/superposition- based algorithm was used. Three treatment plans were calculated for each patient using identical beam geometries: one plan was generated by traditional homogeneous point-dose prescription, a second by the traditional method with heterogeneity correction, and a third by heterogeneity-corrected volume-dose prescription that would cover 95% of the planned target volume (PTV). Target volume coverage, isocenter dose, and dose uniformity in the second and third plans were compared.
  
  
  RESULTS
  The PTV, clinical target volume (CTV), and isocenter calculated by the heterogeneity-corrected volume-dose method were equivalent to those calculated by the traditional homogeneous point-dose method with heterogeneity correction. The fraction of the PTV covered by heterogeneity-corrected volume-dose prescription was significantly greater than the fraction covered by traditional homogeneous point-dose prescription with heterogeneity correction (p = 0.05). The dose prescribed using the traditional method would have been delivered to less than 90% of the PTV in 14 of 30 patients. There was no significant difference in the maximum and minimum doses to the PTV, the CTV, or the isocenter calculated by the traditional homogeneous method with heterogeneity correction and the heterogeneity-corrected volume-dose method. There was also no significant difference in the planned volume of lung receiving greater than 20 Gy as calculated by these two methods.
  
  
  CONCLUSIONS
  When compared with traditional homogeneous radiation treatment planning, heterogeneity-corrected methods produce equivalent PTV, CTV, and isocenter doses while providing superior PTV coverage.
authors.affiliation: Department of Radiation Oncology, The University of Texas M. D. Anderson Cancer Center, Houston, TX 77030, USA. sjfrank@mdanderson.org
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Frank
authors.forename: Kenneth M
authors.initials: KM
authors.lastname: Forster
authors.forename: Craig W
authors.initials: CW
authors.lastname: Stevens
authors.forename: James D
authors.initials: JD
authors.lastname: Cox
authors.forename: Ritsuko
authors.initials: R
authors.lastname: Komaki
authors.forename: Zhongxing
authors.initials: Z
authors.lastname: Liao
authors.forename: Susan
authors.initials: S
authors.lastname: Tucker
authors.forename: Xuemei
authors.initials: X
authors.lastname: Wang
authors.forename: Roy E
authors.initials: RE
authors.lastname: Steadham
authors.forename: Chris
authors.initials: C
authors.lastname: Brooks
authors.forename: George
authors.initials: G
authors.lastname: Starkschall
mesh_terms: D002289:Carcinoma, Non-Small-Cell Lung / Q000532:radiotherapy*; D006801:Humans; D008175:Lung Neoplasms / Q000532:radiotherapy*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted