title: Decay time characteristics of La2O2S:Eu and La2O2S:Tb for use within an optical sensor for human skin temperature measurement.
abstract: We focus on the development of a remote temperature sensing technology, i.e., an optical laser-based sensor, using thermographic phosphors for medical applications, particularly within an electromagnetically hostile magnetic resonance imaging (MRI) environment. A MRI scanner uses a strong magnetic field and radio waves to generate images of the inside of the body. The quality of the image improves with increasing magnetic resonance; however, the drawback of applying a greater magnetic strength is the inducement of heat into the body tissue. Therefore, monitoring the patient's temperature inside MRI is vital, but until now, a practical solution for temperature measurement did not exist. We show europium doped lanthanum oxysulphide (La(2)O(2)S:Eu) and terbium doped lanthanum oxysulphide (La(2)O(2)S:Tb) are both temperature sensitive to a low temperature range of 10-50 degrees C when under ultraviolet (UV) excitation. The emission spectra and decay time characteristics of these phosphors were demonstrated. The results indicate that La(2)O(2)S:Eu has a quenching rate of 13.7 m degrees C(-1) and 4 m degrees C(-1) at 512 nm and 538 nm, respectively. In addition, La(2)O(2)S:Tb has a lower quenching rate of 4.19 m degrees C(-1) at 548 nm due to its faster decay time.
authors.affiliation: School of Science and Technology, Nottingham Trent University, Clifton Lane, Nottingham, NG11 8NS, UK. sook.yap@ntu.ac.uk
authors.forename: Sook Voon
authors.initials: SV
authors.lastname: Yap
authors.forename: Robert M
authors.initials: RM
authors.lastname: Ranson
authors.forename: Wayne M
authors.initials: WM
authors.lastname: Cranton
authors.forename: Demosthenes
authors.initials: D
authors.lastname: Koutsogeorgis
mesh_terms: D004867:Equipment Design; D019544:Equipment Failure Analysis; D006358:Hot Temperature; D006801:Humans; D007811:Lanthanum / Q000737:chemistry* / Q000528:radiation effects; D007834:Lasers; D008422:Materials Testing; D055095:Optics and Photonics / Q000295:instrumentation*; D010087:Oxides / Q000737:chemistry* / Q000528:radiation effects; D012881:Skin Temperature / Q000502:physiology*; D013817:Thermography / Q000295:instrumentation* / Q000379:methods; D014159:Transducers
chemical_list: D010087:Oxides; C103829:lanthanum oxide; D007811:Lanthanum