title: Laser surface modification of medical grade alloys for reduced heating in a magnetic resonance imaging environment.
abstract: Nanoscale surface modification of medical grade metallic alloys was conducted using a neodymium-doped yttrium aluminum garnet laser-based dopant diffusion technique. The objective of this approach was to minimize the induction heating by reducing the absorbed radio frequency field. Such an approach is advantageous in that the dopant is diffused into the alloy and is not susceptible to detachment or spallation as would an externally applied coating, and is expected to not deteriorate the mechanical and electrical properties of the base alloy or device. Experiments were conducted using a controlled environment laser system with the ability to control laser properties (i.e., laser power, spot size, and irradiation time) and dopant characteristics (i.e., temperature, concentration, and pressure). The reflective and transmissive properties of both the doped and untreated samples were measured in a radio frequency (63.86 MHz) magnetic field using a system comprising a high power signal generator, a localized magnetic field source and sensor, and a signal analyzer. The results indicate an increase in the reflectivity of the laser-treated samples compared to untreated samples. The effect of reflectivity on the heating of the alloys is investigated through a mathematical model incorporating Maxwell's equations and heat conduction.
authors.affiliation: Advanced Materials Processing and Analysis Center (AMPAC), Materials Science and Engineering, Mechanical and Aerospace Engineering, University of Central Florida, Orlando, Florida 32816, USA.
authors.forename: O
authors.initials: O
authors.lastname: Benafan
authors.affiliation: Laser-Advanced Materials Processing Laboratory, Center for Research and Education in Optics and Lasers (CREOL), College of Optics and Photonics, University of Central Florida, Orlando, Florida 32816, USA.
authors.forename: S-Y
authors.initials: SY
authors.lastname: Chen
authors.affiliation: Laser-Advanced Materials Processing Laboratory, Center for Research and Education in Optics and Lasers (CREOL), College of Optics and Photonics, University of Central Florida, Orlando, Florida 32816, USA.
authors.forename: A
authors.initials: A
authors.lastname: Kar
authors.affiliation: Advanced Materials Processing and Analysis Center (AMPAC), Materials Science and Engineering, Mechanical and Aerospace Engineering, University of Central Florida, Orlando, Florida 32816, USA.
authors.forename: R
authors.initials: R
authors.lastname: Vaidyanathan
mesh_terms: D000497:Alloys / Q000737:chemistry* / Q000528:radiation effects; D001672:Biocompatible Materials / Q000737:chemistry* / Q000528:radiation effects; D003198:Computer Simulation; D004307:Dose-Response Relationship, Radiation; D006358:Hot Temperature; D007834:Lasers; D060526:Magnetic Fields; D008279:Magnetic Resonance Imaging; D008422:Materials Testing; D008956:Models, Chemical; D011829:Radiation Dosage; D013499:Surface Properties / Q000528:radiation effects
chemical_list: D000497:Alloys; D001672:Biocompatible Materials