Presidential Greeting - American Society for Laser Medicine and ...

patient basis for increased efficacy and safety of cutaneous laser
treatments.
#32
A LED BASED IMAGING SYSTEM FOR
OPTIMIZATION OF PHOTODYNAMIC THERAPY
OF BASAL CELL CARCINOMA
Rolf B. Saager, David J. Cuccia, Steven Saggesse,
Kristen M. Kelly, Anthony J. Durkin
Beckman Laser Institute and Medical Clinic, University of
California, Irvine, CA; Modulated Imaging, Inc., Irvine, CA
Background: PDT offers the potential for enhanced treatment of
BCC skin cancer without the detriments associated with current
treatment methods: healthy tissue loss, scarring. Yet, PDT has
still not achieved the consistent performance required to gain
widespread clinical acceptance for treatment of skin cancer. One
particular limitation is a lack of quantitative tools to perform in
vivo dosimetry that monitors the light dose during therapy. Even
when dosimetry is used, lesion variability leads to treatment plans
that are not optimum. To this end, we have developed a new
quantitative imaging device that may enable optimized therapy.
Study: Clinical imaging of BCC lesions was performed using
Spatial Frequency Domain Imaging (SFDI). SFDI can quantify
spatially resolved absorption and reduced scattering coefficients.
With knowledge of these properties, it is possible to address
critical aspects of PDT dosimetry including: (1) therapeutic light
dose within the affected tissue, (2) oxygen supply necessary to
generate destructive radicals within the lesion and (3)
photosensitizer distribution and uptake within the tissue. We
present a device designed to address these aspects by: (1)
determining the optical properties at the therapeutic wavelength,
(2) deducing spatially resolved absorption values to determine
blood oxygenation in the tissue microvasculature, and (3)
quantifying fluorescence from the photosensitizer by
compensating for native tissue properties.
Results: Preliminary clinical study of nine lesions demonstrate
that optical properties vary greatly both spatially (101%, 48%) for
absorption and reduced scattering, respectively, and from patient
to patient (102%, 57%). Oxygenation maps may be generated at
50-mm resolution. Fluorescence signals from the photosensitizer
can be accurately converted to drug concentrations to within
0.2 mg/L.
Conclusion: These preliminary results indicate that this
technique provides quantitative, non-invasive assessments
which characterize lesions based on physiologic parameters
that are inaccessible to clinicians. This technology may lead to
the development of subject and lesion specific treatment
strategies.
#33
American Society for Laser Medicine and Surgery Abstracts 11
REFLECTION MODALITY CONTINUOUS-WAVE
TERAHERTZ IMAGER FOR CANCER
DEMARCATION
Cecil Joseph, Anna Yaroslavsky, Thomas Goyette,
Robert Giles
University of Massachusetts, Lowell, MA
Background: Continuous-wave terahertz imaging has the
potential to offer a non-invasive and comparatively inexpensive
technique for demarcating skin cancers. The implementation of a
coherent room temperature detection scheme, which offers
increased SNR, is critical to the eventual goal of implementing a
continuous-wave terahertz imaging system that can delineate
cancer margins.
Study: The goal of this study was to construct a heterodyne
receiver based imager at 1.39 THz, determine its resolution and
available signal-to-noise ratio, and demonstrate imaging of skin
cancer specimens. CO 2 laser pumped far-infrared gas lasers were
used as the terahertz sources for the experiments. A room
temperature heterodyne detection scheme was designed and
implemented. The system was tested using resolution targets and
skin cancer specimens. Its resolution and signal-to-noise ratio
(SNR), in reflection modality, were determined. The samples were
scanned across the focal plane using a two axis motion controlled
stage, and the on-axis reflection image was generated.
Results: The system resolution was determined to be 0.5 mm. The
SNR was determined to lie between 110 and 130 dB. Preliminary
imaging data of cancer specimens show good correlation between
the terahertz images and Hematoxylin & Eosin (H&E)
histopathology.
Conclusion: A coherent hetrodyne detection scheme significantly
improves the SNR of continuous-wave terahertz imaging for
cancer demarcation.
#34
TEST METHODOLOGIES FOR ESTABLISHING
SAFETY OF HOME-USE LASER BASED DEVICES
David Sliney, Michail Smirnov, Stewart Wilson,
Oldrich Laznicka, Oksana Bradley, Felicia Whitney,
Gregory Altshuler, Ilya Yaroslavsky
Fallston, MD; Palomar Medical Technologies, Burlington, MA
Background: A number of home-use, laser-based devices for
treatment of various skin conditions either have been recently
introduced to the marketplace or are in different stages of
development. A common feature of these devices is the presence of
a safety suite designed to enable safe operation of the device by the
average person with no prior experience or training. This state of
affairs highlights the need for formulating realistic, universally
accepted product safety requirements, reflected in an industrywide
standard, such as IEC 60825. A Class 1C (conditional Class
1) has been proposed and is currently under discussion by the
respective technical groups. One important aspect of codifying the
safety requirements for such devices is to define the most suitable
testing techniques to ensure both compliance and practical safety
of the device.
Study: Two principal approaches to the test are considered: (1)
clinical test (possibly with a mock-up device) attempting to
reproduce real-life scenarios of the device use; and (2) an ex vivo
and/or phantom test with a pre-formulated set of quantitative
criteria. Both types of tests have been conducted on a home-use,
fractional non-ablative laser device (PaloVia, Palomar Medical
Technologies, Inc.).
Results: Ocular safety of the tested device has been demonstrated
with both types of tests. Similarities and differences in the
outcomes of the two types of testing, as well as their relative
advantages and disadvantages for the purpose of laser safety
standards, have been evaluated.
Conclusion: Phantom test methodologies can be considered the
preferred method to ensure compliance of the tested device with
the requirements of the future performance standard.