The Effect of PTV Size on PTV Dose Homogeneity

  • Steven M. Morrill
  • J. E. Bayouth
  • Robin L. Kendall
Conference paper

Abstract

The Nomos COR VUS1 System is a clinically-accepted method for IMRT treatment planning. Its dose calculation algorithm uses finite-area pencil beams with typical areas2 of either 1 cm2 (1 X 1), 2 cm2 (1 X 2), or 0.5 cm2 (0.5 X 1). In our particular system, a Siemen’s PRIMART3 linear accelerator using step and shoot static fields, we have selected a pencil beam area of 1 cm2. For our optimization parameters, a pencil beam area of 1 cm2 typically leads to 20–80 treatment segments. A smaller pencil beam area leads to better conformation with the given Planning Target Volume (PTV) and better PTV dose homogeneity, but also results in a larger number of beam segments generated by the inverse treatment plan optimization. The purpose of this investigation is to characterize the limitations of a 1 cm2 pencil beam area by investigating the PTV dose homogeneity as a function of the size (diameter) of a given PTV.

References

  1. [1]
    CORVUS v3.0, Nomos Corporation, Sewickley, PA, USA.Google Scholar
  2. [2]
    Larsen, S., Nomos Corporation, personal communication.Google Scholar
  3. [3]
    Siemens Medical Systems, Inc., Concord, CA, USA.Google Scholar
  4. [4]
    Larsen, S., Nomos Corporation, personal communication.Google Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2000

Authors and Affiliations

  • Steven M. Morrill
    • 1
  • J. E. Bayouth
    • 1
  • Robin L. Kendall
    • 1
  1. 1.Dept. of Radiation OncologyUniversity of Texas Medical BranchGalvestonUSA

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