Thermographic Analysis of Block and Cylindrical Bone Phantoms and In Vitro Human Bone Samples after Therapeutic Ultrasound Stimulation

Abstract

Therapeutic ultrasound (TUS) has been used for the management of musculoskeletal disorders, but some questions regarding dosage and bio-effects still arise. Since bone phantoms have been proposed for acoustic propagation studies, this work aimed at comparing the heating distribution from thermographic images in cortical bone phantoms (block and cylinder) and in vitro human femur samples using TUS, after a 1-MHz 5-minute stimulation with different pulsed regimens. Thermographic images were analyzed to estimate temperature values inside a region-of-interest by means of an intensity-based processing algorithm. Five minutes of stimulation led to small differences in mean temperatures and standard deviation, as analyzed with an intensity-based processing technique for thermographic images (continuous mode: block = 32.52 ± 4.41 °C; cylinder = 31.73 ± 3.00 °C; bone = 32.59 ± 3.70 °C. Pulsed 1:10 mode: block = 26.30 ± 0.54 °C; cylinder = 26.54 ± 0.34 °C; bone = 27.73 ± 0.61 °C ). Temperature distributions among the samples were different (p < 0.001), maybe because of the anatomical variations and geometries. Results are promising and may lead to the development of an experimental setup closer to reality.KeywordsUltrasoundBonePhantomThermographyHeating