Optimization of the sources in local hyperthermia using a combined finite element-genetic algorithm method

• Published in: International journal of hyperthermia Vol. 20; no. 8; pp. 815 - 833
• Main Authors: Siauve, N., Nicolas, L., Vollaire, C., Marchal, C.
• Format: Journal Article
• Language: English
• Published: London Informa UK Ltd 01.12.2004; Taylor & Francis
• Subjects: Absorption; Algorithms; Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy; Biological and medical sciences; Blood coagulation; Body Temperature - radiation effects; Computer Simulation; Electric Conductivity; Electromagnetic Fields; Electromagnetic heating; Finite Element Analysis; finite element method; genetic algorithm; Hematology; Humans; hyperthermia treatment planning; Hyperthermia, Induced - methods; Intensive care medicine; Investigative techniques, diagnostic techniques (general aspects); Medical sciences; Neoplasms - therapy; optimization; Pathology. Cytology. Biochemistry. Spectrometry. Miscellaneous investigative techniques; Phantoms, Imaging; Radio Waves - therapeutic use; Reproducibility of Results; specific absorption rate; Tomography, X-Ray Computed; Intensive care; Treatment; Algorithm; Hyperthermia; Optimization; Resuscitation
• ISSN: 0265-6736; 1464-5157
• DOI: 10.1080/02656730410001711664

This article describes an optimization process specially designed for local and regional hyperthermia in order to achieve the desired specific absorption rate in the patient. It is based on a genetic algorithm coupled to a finite element formulation. The optimization method is applied to real human organs meshes assembled from computerized tomography scans. A 3D finite element formulation is used to calculate the electromagnetic field in the patient, achieved by radiofrequency or microwave sources. Space discretization is performed using incomplete first order edge elements. The sparse complex symmetric matrix equation is solved using a conjugate gradient solver with potential projection pre-conditionning. The formulation is validated by comparison of calculated specific absorption rate distributions in a phantom to temperature measurements. A genetic algorithm is used to optimize the specific absorption rate distribution to predict the phases and amplitudes of the sources leading to the best focalization. The objective function is defined as the specific absorption rate ratio in the tumour and healthy tissues. Several constraints, regarding the specific absorption rate in tumour and the total power in the patient, may be prescribed. Results obtained with two types of applicators (waveguides and annular phased array) are presented and show the faculties of the developed optimization process.