Banca de DEFESA: HUDSON GEOVANE DE MEDEIROS

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : HUDSON GEOVANE DE MEDEIROS
DATE: 27/07/2021
TIME: 14:00
LOCAL: https://meet.google.com/wej-iueu-nfx
TITLE:

A multiobjective approach to the leaf sequencing problem on intensity modulated radiation therapy

KEY WORDS:

Radiation therapy, Multileaf collimator, Leaf sequencing

PAGES: 94
BIG AREA: Ciências Exatas e da Terra
AREA: Ciência da Computação
SUBÁREA: Sistemas de Computação
SPECIALTY: Arquitetura de Sistemas de Computação
SUMMARY:

Algorithms are an essential part of the radiation therapy planning, and under aoptimization point of view, can be divided in three subproblems. Defining the anglesby which radiation will be shot and prescribe a fluence map for each angle are two ofthem. This work investigates the third problem, called realization problem. It consistson defining a sequence of configurations for a device (called multileaf collimator) whichcorrectly delivers the prescribe doses to the patient. A common model for this problem isthe decomposition of a matrix in a weighted sum of (0-1)-matrices, called segments, whoserows only have consecutive ones. Each segment represents a setup of the collimator. Otherconstraints can be also considered. The realization problem has three objectives. The firstone is to minimize the sum of the weights associated to the segments. The second is tominimize the number of segments. The third minimizes the movement of the leaves. Thiswork investigates and present algorithms for two variants of the problem: unconstrainedand constrained. A new greedy and randomized algorithm – GRA – was developed firstlyfor the unconstrained variant and then extended for the constrained variant. Its results wascompared to other algorithms from the literature, under mono and multiobjective pointsof view. On the unconstrained problem, experiments show that GRA outperforms theother algorithms by all measured indicators. On the constrained problem, GRA presentedcompetitive results, specially on the second objective, in which it presented the best results.

BANKING MEMBERS:
Presidente - 1201268 - ELIZABETH FERREIRA GOUVEA GOLDBARG
Interno - 1149561 - MARCO CESAR GOLDBARG
Externa ao Programa - 1885001 - ANNA GISELLE CAMARA DANTAS RIBEIRO RODRIGUES
Externo à Instituição - MATHEUS DA SILVA MENEZES - UFERSA
Externa à Instituição - THALITA MONTEIRO OBAL - UTFPR