Stability of gel wax based optical scattering phantoms.

Phantoms with tuneable optical scattering properties are essential in the development and refinement of optical based imaging techniques. Mineral oil based 'gel wax' phantoms are the subject of increasing interest due to their ease and speed of manufacture, non-toxic nature, ability to cast into anatomically realistic shapes, as well as their cost-effective nature of production. The addition of scatterers such as titanium dioxide powder and monodisperse silica microspheres to the gel wax allows for the creation of phantoms with a controllable optical scattering coefficient. To enable repeated use of such phantoms, the stability of the scattering properties must be determined-a property which has yet to be investigated. We present an analysis of the stability of the reduced scattering coefficient ( ) of such phantoms over time. We conclude that due to the measurable reduction in scattering coefficient over time, gel wax phantoms embedded with silica spheres may not be suitable for repeated use over time, however gel wax-TiO phantoms are much more temporally stable.