doctoralThesis
Uma abordagem multiobjetivo para o problema da realização da radioterapia de intensidade modulada
Fecha
2021-08-10Registro en:
MEDEIROS, Hudson Geovane de. Uma abordagem multiobjetivo para o problema da realização da radioterapia de intensidade modulada. 2021. 94f. Tese (Doutorado em Ciência da Computação) - Centro de Ciências Exatas e da Terra, Universidade Federal do Rio Grande do Norte, Natal, 2021.
Autor
Medeiros, Hudson Geovane de
Resumen
Algorithms are an essential part of the radiation therapy planning, and under a
optimization point of view, can be divided in three subproblems. Defining the angles
by which radiation will be shot and prescribe a fluence map for each angle are two of
them. This work investigates the third problem, called realization problem. It consists
on defining a sequence of configurations for a device (called multileaf collimator) which
correctly delivers the prescribe doses to the patient. A common model for this problem is
the decomposition of a matrix in a weighted sum of (0-1)-matrices, called segments, whose
rows only have consecutive ones. Each segment represents a setup of the collimator. Other
constraints can be also considered. The realization problem has three objectives. The first
one is to minimize the sum of the weights associated to the segments. The second is to
minimize the number of segments. The third minimizes the movement of the leaves. This
work investigates and present algorithms for two variants of the problem: unconstrained
and constrained. A new greedy and randomized algorithm – GRA – was developed firstly
for the unconstrained variant and then extended for the constrained variant. Its results was
compared to other algorithms from the literature, under mono and multiobjective points
of view. On the unconstrained problem, experiments show that GRA outperforms the
other algorithms by all measured indicators. On the constrained problem, GRA presented
competitive results, specially on the second objective, in which it presented the best results.