Medical Physics -- May 2000 -- Volume 27, Issue 5, pp. 1034-1046

Generation of uniformly distributed dose points for anatomy-based three-dimensional dose optimization methods in brachytherapy

Michael Lahanas, D. Baltas, S. Giannouli, N. Milickovic, N. Zamboglou

(Received 9 August 1999; accepted 8 February 2000)

We have studied the accuracy of statistical parameters of dose distributions in brachytherapy using actual clinical implants. These include the mean, minimum and maximum dose values and the variance of the dose distribution inside the PTV (planning target volume), and on the surface of the PTV. These properties have been studied as a function of the number of uniformly distributed sampling points. These parameters, or the variants of these parameters, are used directly or indirectly in optimization procedures or for a description of the dose distribution. The accurate determination of these parameters depends on the sampling point distribution from which they have been obtained. Some optimization methods ignore catheters and critical structures surrounded by the PTV or alternatively consider as surface dose points only those on the contour lines of the PTV. Dmin and Dmax are extreme dose values which are either on the PTV surface or within the PTV. They must be avoided for specification and optimization purposes in brachytherapy. Using Dmean and the variance of D which we have shown to be stable parameters, achieves a more reliable description of the dose distribution on the PTV surface and within the PTV volume than does Dmin and Dmax. Generation of dose points on the real surface of the PTV is obligatory and the consideration of catheter volumes results in a realistic description of anatomical dose distributions.


(pdf 704 KB)

MeSH Terms:
  • Algorithms
  • Biophysics
  • Brachytherapy/methods*
  • Brachytherapy/statistics & numerical data
  • Catheterization
  • Comparative Study
  • Female
  • Human
  • Male
  • Neoplasms/pathology
  • Neoplasms/radiotherapy
  • Radiotherapy Planning, Computer-Assisted/methods*
  • Radiotherapy Planning, Computer-Assisted/statistics & numerical data
  • Support, Non-U.S. Gov't