EC Engineering Consultants LLC
EC Engineering Consultants (ECEC) was formed by Jorge Llacer, Ph.D. in 1993 for the purpose of studying, developing and exploiting some ideas on radiation therapy optimization for cancer treatment. Those ideas were based on the Maximum Likelihood Estimator (MLE) method of parameter estimation that had initially been published by Larry Schepp at the Bell Laboratories and worked on by J. Llacer at the Lawrence National Berkeley Laboratory and by many others over a period of several years for the purpose of reconstructing images in emission tomography. The experiences gained by sitting in long sessions on the biology and mathematics of radiation treatment at Laboratory, as part of the team headed by Dr. Cornelius Tobias, were also important influences in the work carried out at ECEC during the first years. The work carried out until 2001 had the benefit of a Small Business Innovation Grant from the National Cancer Institute. A US patent on the resulting Dynamically Penalized Likelihood (DPL) method of therapy optimization for IMRT/IMRS was obtained in 1997. That patent has been non-exclusively licensed by BrainLAB A.G. of Heimstetten, Germany and that firm has included the DPL software in their BrainSCAN therapy optimization software package, which is being sold world-wide.
An initial paper on the DPL was published in Medical Physics. It was followed by some presentations at meetings of the AAPM and in other venues. An up-to-date form of the DPL was published by Physics in 2001 by Medicine and Biology, in which a comparison with other well recognized algorithms showed that the DPL yields optimization parameters that are at least as good as those of other algorithms, but at much faster computation speeds. The absence of local minima effects in intensity modulated optimization with dose-volume constraints was studied in substantial detail in 2002 and the conclusion was reached that, when minimizing quadratic cost functions, or maximizing likelihood with the DPL method, those effects do not interfere with obtaining results that are useful in the clinic. A paper was published in 2004 in which issues relating to degeneracy, frequency response and filtering in IMRT optimization are studied in detail. One of the principal conclusion is that degeneracy of optimizations is not important in the clinic, provided that enough iterations are carried out in the inversion algorithm.
In the years following 2004, a study on optimizing the selection of beam directions in brain IMRT was carried out. The final paper on the subject was published in PMB, 54 (2009) 1337-1368.
The following are links to some relevant information:
Curriculum Vitae and list of Publications
Later papers on Intensity Modulated Radiation Treatment Planning:
(To return to this page after reading one of the papers, use to top left arrow in the browser)
"Degeneracy, frequency response and filtering in IMRT optimization", PMB 49, 2004
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