Determining the optimal block margin on the planning target volume for extracranial stereotactic radiotherapy.

Journal Article (Journal Article)

PURPOSE: To determine the block margin that minimizes normal tissue irradiation outside of the planning target volume (PTV) for body stereotactic radiotherapy (Body-SRT) of lung and liver tumors. METHODS AND MATERIALS: Representative patient cases of lung and liver tumors were chosen for analysis. A PTV was constructed for each case and plans were generated which employed an array of block margins ranging from -2.5 mm to 10 mm at isocenter. Plans were generated for cerrobend blocks and for a multileaf collimator. The prescription isodose coverage was renormalized for each case and dose-volume histograms (DVH) and normal tissue complication probabilities (NTCP) were determined for each plan. RESULTS AND CONCLUSION: For the cases studied, the optimal block margin was in the 0.0 mm range. The ranking of plans was identical for both dose-volume based and biological based criteria. The method of blocking had no significant effect on treatment plans. The use of narrow margins for Body-SRT results in normal tissue sparing and creates significant target dose inhomogeneity which may be beneficial for tumor control.

Full Text

Duke Authors

Cited Authors

  • Cardinale, RM; Wu, Q; Benedict, SH; Kavanagh, BD; Bump, E; Mohan, R

Published Date

  • September 1, 1999

Published In

Volume / Issue

  • 45 / 2

Start / End Page

  • 515 - 520

PubMed ID

  • 10487579

International Standard Serial Number (ISSN)

  • 0360-3016

Digital Object Identifier (DOI)

  • 10.1016/s0360-3016(99)00203-5


  • eng

Conference Location

  • United States