TRiP98 optimize command



optimize / iterations() graceiterations(1) H2Obased CTbased  events() debug
           bio        singly         eps(1E-3) geps(2E-3) myfac(0.5) 
           phys       matchonly      doseweightfactor()  
           field(*)   nopreopt    
                      optalgorithm(fr)
                      bioalgorithm(ld)
                      dosealgorithm(allpoints)

Purpose

Handles optimization of dose with respect to particle numbers.

Parameters

iter()
Maximum number of iterations. Remembered. Startup default is 5.
graceiter()
Number of initial "grace" iterations for which tests on relative change of chi-square are suspended. Startup default is 1.
bio
Optimize using biological dose. Remembered.
phys
Optimize using physical dose. Remembered.
H2Obased
CTbased
Optimization principle.
H2Obased selects separate optimization of single fields, with fast, but less accurate algorithms, based on a H2O-equivalent grid. This is the default.
CTbased selects optimization based on the CT grid. Mandatory for simultaneous optimization of multiple fields.
singly
Separate optimization of multiple fields.
Not yet implemented.
nopreopt
Skips H2Obased pre-optimization so CTbased is invoked with zero particle number as startup value. Use it with care.
matchonly
Optimize using only a simple peak-to-dose matching algorithm. Otherwise a conjugate gradient method is used to equilibrate peaks and valleys. This applies to H2Obased optimizations only.
dosealgorithm(dalg)
Selects algorithm for dose calculation. Same choices as for dose cube calculation:
bioalgorithm(balg)
Selects algorithm for biological effect calculation. Note, however, that the default choice is valid only for doses up to some 10GyE, but is considerably faster.
optalgorithm(oalg)
Selects algorithm for dose optimization. The selection is affects CTbased optimizations, as of version 1001d H2Obased too. Choices are As it turns out, "Fletcher-Reeves" is usually the fastest converging one.
events(nevt)
Not yet implemented.
eps(eps)
Minimum relative change of chi-square. If the actual change is below, the iteration is aborted.
Startup default is 1E-3.
geps(geps)
Controls relative contribution of raster points to dose voxels. Contributions less than geps are omitted, thereby reducing memory and time consumption. Should not be raised above some 1E-3, otherwise optimized and real dose distributions will differ.
Startup default is 2E-3.
myfac(myfac)
Controls search stepsize for gradient based optimization algorithms for the RBE-weighted (biological) dose. The default value is 0.5, designed for total biological target doses about 3GyE. For lower doses (0.5..1GyE) or high RBE, lower values of myfac might be appropriate. There is some builtin stepsize "autopilot", but if the results aren't satisfactory, one might manually choose lower values, e.g. down to 0.1 to 0.25.
As of version 1001D, this parameter applies for H2Obased optimizations as well.
doseweightfactor(dwf)
The prescribed dose is multiplied with this factor to introduce sort of an "experimental uncertainty", which enters as a weight in the chi-square evaluation. Startup default is 2.5E-2, corresponding to half of the deviation between measured and calculated absorbed dose allowed by authorities.
field(idlist)
List of field id's to be optimized.
debug
Debug switch. Lots of output!

Remarks

later

Examples

  1. opt / field(*) bio
    
    Optimize all defined fields using the biologically effective dose. Fields are optimized separately with "classic" algorithms
  2. opt / field(*) ctbased bio dosealg(ap) optalg(fr) bioalg(ld) geps(2E-3) eps(1e-2) iter(500)
    
    Optimize all defined fields simultaneously (IMRT-style), with "fast" biological calculations and the Fletcher-Reeves algorithm.

Last updated:
$Id: trip98cmdopt.html,v 1.9 2011/07/09 07:42:57 kraemer Exp $
M.Kraemer@gsi.de