title: Comparison of the thermal tissue effects produced by aged sapphire and silica hemispherical tips.
abstract: This study evaluated the performance of sapphire and fused silica hemispherical tips under the same exposure conditions. Lesions produced in the chicken breast and a blood field were sectioned for light and transmission polarizing microscopy. Lesion size and thermal damage area were recorded as a function of the tips accumulated exposure. The tips transmission was measured after every 1,000 J of exposure. Fused silica tips lasted for approximately 5,000 J and experienced significant surface and transmission deterioration. The sapphire hemispherical tips lasted for > 12,000 J with no surface and transmission deterioration. Lesions produced with the fused silica tips generally increased in depth with use, and depths of 6 mm were common. Lesions produced by the sapphire tips were subsurface spherical areas of coagulation with the tissue surface relatively intact. This difference in resulting lesions may be attributed to the higher thermal conductivity of sapphire.
authors.affiliation: Food and Drug Administration, Center for Devices and Radiological Health, Rockville, MD 20857.
authors.forename: D D
authors.initials: DD
authors.lastname: Royston
authors.forename: J H
authors.initials: JH
authors.lastname: Torres
authors.forename: S
authors.initials: S
authors.lastname: Thomsen
authors.forename: P S
authors.initials: PS
authors.lastname: Sriram
authors.forename: A J
authors.initials: AJ
authors.lastname: Welch
mesh_terms: D000537:Aluminum Oxide; D000818:Animals; D001769:Blood / Q000528:radiation effects*; D002645:Chickens; D005336:Fiber Optic Technology / Q000295:instrumentation*; D066298:In Vitro Techniques; D053685:Laser Therapy / Q000295:instrumentation; D007834:Lasers; D008859:Microscopy, Polarization; D009132:Muscles / Q000528:radiation effects*; D012822:Silicon Dioxide; D013814:Thermal Conductivity
chemical_list: D012822:Silicon Dioxide; D000537:Aluminum Oxide