The primary objective of the Laser and Optical Radiation Safety (LORS) research program is to provide innovative regulatory science tools and advanced test methodologies for evaluating laser and optical radiation safety and performance of new and emerging medical devices. The program specific goals are focused on development and implementation of: (1) test protocols and standard methods for assessing critical laser and optical radiation safety characteristics of non-ionizing light sources used in emerging devices; (2) noninvasive label-free methods for sensing intrinsic biomarkers and computational models related to dominant light-tissue interaction mechanisms affecting safety and efficacy; (3) advanced methods for standardized performance evaluation of photoacoustic imaging technology and devices; and (4) novel quantitative data for developing guidance documents and standards for laser and optical radiation emitting marketed products associated with safety hazard concerns and adverse events.
1. Laser and optical radiation safety of coherent and noncoherent light sources in emerging medical devices
This key research project of the LORS program aims to develop and implement novel test protocols and standard methods for evaluation of critical laser and optical radiation safety characteristics of coherent (laser) and noncoherent broadband light sources used in emerging optical therapeutic and diagnostic devices based on the use of femtosecond, fractional, scanning and pulsed laser sources; intense pulsed light (IPL) and light emitting diodes (LEDs) incoherent light sources; laser-activated plasmonic nanoparticle based therapeutics; and photobiomodulation therapeutics (Fig. 1) [1-3]. The project addresses unmet regulatory and public health needs to assess device-specific laser and optical radiation safety characteristics unresolved in current standards such as spectral (UV, VIS and IR), temporal (CW and pulsed, millisecond-to-femtosecond), and spatial properties of lasers and broadband light sources.
Fig. 1. Evaluation of new laser radiation safety concerns associated with: femtosecond laser therapeutics (a); fractional laser therapeutics (b); and multiwavelength powerful laser pointers (c).
2. Sensing intrinsic biomarkers and computational models related to safety and devise performance
This key LORS research project is focused on employing advanced fingerprint sensing approaches based on infrared, Raman and fluorescence spectroscopy for noninvasive label-free detection and assessment of new intrinsic biomarkers at cellular and tissue levels related to dominant light-tissue interaction mechanisms that affect cellular and tissue safety and device performance (Fig, 2a) [4-6]. The project includes also the development of computational models of photothermal laser-tissue interactions during pulse and scanning laser irradiation of tissue. The analytical models involve two approaches: a melanin granule lattice model (MGLM) for evaluating photothermal effects and laser damage thresholds (Fig. 2b) ; and a 3D transient optical-thermal model to simulate energy deposition, temperature distribution and laser-induced thermal damage in breast tissue (Fig. 2c) . The project provides novel test methodologies and quantitative database for evaluation of laser dosimetric, photothermal and tissue characteristics affecting radiation safety and efficacy of diagnostic and therapeutic devices.
Fig. 2. A fiber-optic Fourier transform infrared (FO-FTIR) spectroscopy platform for label-free sensing of intrinsic biomarkers in optical therapeutic devices (a) [4-6]; a MGLM method for evaluation of photothermal effects and laser damage thresholds (b) ; and a 3D transient optical-thermal model to simulate energy deposition, temperature distribution and laser thermal damage in breast tissue (c) .
3. Standard performance evaluation of photoacoustic imaging technology
This key LORS research project is motivated by the significant interest for developing clinical photoacoustic imaging modalities, the increased number of applications for device clearance and the lack of standard methods to assess performance of photoacoustic tomography (PAT) and photoacoustic microscopy (PAM) imaging. The project is focused on the development and validation of biologically relevant phantoms with tunable optical and acoustic properties for performance evaluation PAT imaging systems (Fig. 3a) . It includes also the development of experimental and analytical test methods for precise evaluation of critical image performance characteristics of optical-resolution PAM (ORPAM) compared to confocal laser scanning microscopy (CLSM) modality (Fig. 3b) . The project provides proof-of-concept test methodologies towards standardized PAT and PAM technologies and devices.
Fig. 3. A PAT test system and a tissue-simulated phantom with tunable optical and acoustic properties for PAT performance evaluation (Fig. 3a) ; and precise performance evaluation and multimodal comparison between ORPAM and CLSM systems (Fig. 3b) .
Current funding sources
Ilko K Ilev, Ph.D.
T Joshua Pfefer, Ph.D.
William Vogt, Ph.D.
William Calhoun, Ph.D.
Quanzeng Wang, Ph.D.
Anant Agrawal, Ph.D.
Daniel Hammer, Ph.D.
Dexiu Shi, Ph.D.
Sharon Miller, Ph.D.
- Uniformed Services University
- Johns Hopkins University
- Duke University
- National Institutes of Health
- George Washington University
- University of Maryland
- Harvard Medical School
- Cornell University
- Tufts University
- Laser Institute of America
- Laser scanning confocal microscopy platforms
- Hyperspectral imaging platform for microscopic and macroscopic images
- Two-photon fluorescence microscopy platform
- Photoacoustic microscopy platform
- RESCAN: Radiant Exposure calculation software using various SCANning patterns
Relevant standards & guidances
- ISO 15004-2
- IEC 60825-1
- ANSI Z136.1
- Guidance for Industry and FDA staff: Evaluation of Optical Radiation Hazard from Optical Devcies with Scanning/Focused Lights
Selected peer review publications
- Calhoun and Ilev, Effect of therapeutic femtosecond laser pulse energy, repetition rate, and numerical aperture on laser-induced second and third harmonic generation in corneal tissue, Lasers in Medical Science, 2015.
- Calhoun et al., Evaluation of broadband spectral transmission characteristics of fresh and gamma-irradiated corneal tissues, Cornea, 2015.
- James et al, Evaluation of the potential optical radiation hazards with LED lamps intended for home use, Health Physics Journal, 2017.
- Kosoglu et al, Developing test methodology to identify intrinsic biomarker in biological model using Fourier transform infrared (FTIR) spectroscopy, IEEE Journal of Selected Topics in Quantum Electronics, 2017.
- Hassan et al, Detecting bacteria contamination on medical device surfaces using an integrated fiber-optic mid-infrared spectroscopy sensing method, Sensors and Actuators B, 2016.
- Hassan et al, Noninvasive and label-free sensing of endotoxin contamination in ophthalmic viscosurgical devices using a fiber-optic Fourier-transform infrared spectroscopy based method, IEEE Journal of Selected Topics in Quantum Electronics, 2017.
- Kim et al, Consideration of dynamic photothermal effect for evaluation of scanning light sources in optical devices using pulsed-source criteria, Journal of Biomedical Optics, 2014.
- Gould et al, Optical-thermal light-tissue interactions during photoacoustic breast imaging, Biomedical Optics Express, 2014.
- Vogt et al, Biologically relevant photoacoustic imaging phantoms with tunable optical and acoustic properties, Journal of Biomedical Optics, 2016.
- U-Thainual et al, Comparison between optical-resolution photoacoustic microscopy and confocal laser scanning microscopy for turbid sample imaging, Journal of Biomedical Optics, 2015.