Bone-demineralization diagnosis in a bone-tissue-skin matrix using the pulsed-chirped photothermal radar

Sreekumar Kaiplavil; Andreas Mandelis

doi:10.1117/12.908659

9 February 2012 Bone-demineralization diagnosis in a bone-tissue-skin matrix using the pulsed-chirped photothermal radar

Sreekumar Kaiplavil, Andreas Mandelis

Author Affiliations +

Proceedings Volume 8207, Photonic Therapeutics and Diagnostics VIII; 82076L (2012) https://doi.org/10.1117/12.908659
Event: SPIE BiOS, 2012, San Francisco, California, United States

Abstract

A chirped pulsed photothermal radiometric radar is introduced for the diagnosis of biological samples, especially bones with tissue and skin overlayers. The constraints imposed by the laser safety (maximum permissible exposure, MPE) ceiling on pump laser energy and the strong attenuation of thermal-wave signals in tissues significantly limit the photothermally active depth in most biological specimens to a level which is normally insufficient for practical applications (approx. 1 mm below the skin surface). A theoretical approach for improvement of signal-to-noise ratio (SNR), minimizing the static (dc) component of the photothermal signal and making use of the photothermal radiometric nonlinearity has been introduced and verified by comparing the SNR of four distinct excitation wave forms (sine-wave, square-wave, constant- width and constant duty-cycle pulses) for chirping the pump laser, under constant exposure energy. At low frequencies fixed-pulsewidth chirps of large peak power were found to be superior to all other equal-energy modalities, with an SNR improvement up to two orders of magnitude. Distinct thickness-dependent characteristic delay times in a goat bone were obtained, establishing an active depth resolution range of ca. 2.8 mm in a layered skin-fat- bone structure, a favorable result compared to the maximum reported pulsed photothermal radiometric depth resolution < 1 mm in turbid biological media. Compared to radar peak delay and amplitude, the long-delayed radar output amplitude is found to be more sensitive to subsurface conditions. Two-dimensional spatial plots of this parameter depicting the back surface conditions of bones with and without fat-tissue overlayers are presented.

Citation Download Citation

Sreekumar Kaiplavil and Andreas Mandelis "Bone-demineralization diagnosis in a bone-tissue-skin matrix using the pulsed-chirped photothermal radar", Proc. SPIE 8207, Photonic Therapeutics and Diagnostics VIII, 82076L (9 February 2012); https://doi.org/10.1117/12.908659

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

;

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available

Members: $17.00

Non-members: $21.00 ADD TO CART

PROCEEDINGS
13 PAGES

DOWNLOAD PAPER SAVE TO MY LIBRARY

GET CITATION

RIGHTS & PERMISSIONS

Get copyright permission Get copyright permission on Copyright Marketplace

KEYWORDS

Bone

Radar

Signal to noise ratio

Skin

Modulation

Natural surfaces

Tissues

Show All Keywords

Keywords/Phrases

Search In:

Publication Years