We describe the development, design, fabrication, and testing of an optical wire to assist in the surgical removal of small lesions during breast-conserving surgery. We modify a standard localization wire by adding a 200-µm optical fiber alongside it; the resulting optical wire fit through an 18 gauge needle for insertion in the breast. The optical wire is anchored in the lesion by a radiologist under ultrasonic and mammographic guidance. At surgery, the tip is illuminated with an eye-safe, red, HeNe laser, and the resulting glowball of light in the breast tissue surrounds the lesion. The surgeon readily visualizes the glowball in the operating room. This glowball provides sufficient feedback to the surgeon that it is used (1) to find the lesion and (2) as a guide during resection. Light-guided lumpectomy is a simple enhancement to traditional wire localization that could improve the current standard of care for surgical treatment of small, nonpalpable breast lesions.
In both industry and medicine there is no optical technique to measure distance through light scattering media.
Such a technique may be useful for localizing embedded structures, or may be a non-contact method of measuring
turbid media. The limits of a frequency domain based technique were explored in three polyurethane optical
phantoms. We have demonstrated a simple method to measure the distance between an intensity modulated
light source and detector in turbid media based on the proportionality of the phase lag to the distance. The
limits of the technique were evident for distances less than 5 mm, particularly when μ1s <0.1mm-1 and distances
greater than 55mm for the phantoms studied. This method may prove useful in industry and medicine as a non
destructive way measure distance through light scattering media.
Phantoms with controlled optical properties are often used for calibration and standardization. The phantoms
are typically prepared by adding absorbers and scatterers to a clear host material. It is usually assumed that the
scatterers and absorbers are uniformly dispersed within the medium. To explore the effects of this assumption, we
prepared paired sets of polyurethane phantoms (both with identical masses of absorber, India ink and scatterer,
titanium dioxide). Polyurethane phantoms were made by mixing two polyurethane parts (a and b) together
and letting them cure in a polypropylene container. The mixture was degassed before curing to ensure a
sample without bubbles. The optical properties were controlled by mixing titanium dioxide or India ink into
polyurethane part (a or b) before blending the parts together. By changing the mixing sequence, we could
change the aggregation of the scattering and absorbing particles. Each set had one sample with homogeneously
dispersed scatterers and absorbers, and a second sample with slightly aggregated scatterers or absorbers. We
found that the measured transmittance could easily vary by a factor of twenty. The estimated optical properties
(using the inverse adding-doubling method) indicate that when aggregation is present, the optical properties are
no longer proportional to the concentrations of absorbers or scatterers.
The propagation of light through complex structures, such as biological tissue, is a poorly understood phenomenon.
Typically the tissue is modeled as an effective medium, and Monte Carlo techniques are used to solve the radiative
transport equation. In such an approach the medium is characterized in terms of a limited number of physical scatter and
absorption parameters, but is otherwise considered homogeneous. For exploration of propagation phenomena such as
spatial coherence, however, a physical model of the tissue medium that allows multiscale structure is required. We
present a particularly simple means of establishing such a multiscale tissue characterization based on measurements
using a differential interference contrast (DIC) microscope. This characterization is in terms of spatially resolved maps
of the (polar and azimuthal) angular ray deviations. With such data, tissues can be characterized in terms of their first
and second order scatter properties. We discuss a simple means of calibrating a DIC microscope, the measurement
procedure and quantitative interpretation of the ensuing data. These characterizations are in terms of the scatter phase
function and the spatial power spectral density
Improving the success of lumpectomies would reduce the number of procedures, cost, and morbidity. A light
source could be placed in a lesion to assist in finding and removing the lesion. A quantitive measurement of the
distance between such a light source and a detector would further aid in the procedure by providing surgeons
with easy to use intra-operative guidance to the lesion.
Two methods, continuous wave and frequency domain, of accomplishing this measurement were compared.
Within one radio frequency experimental system, the amplitude at 15MHz was taken to represent the continuous
wave signal and the phase at 100MHz was taken to represent the frequency domain signal. For the continuous
wave method, data at source-detector separation distances of 20, 30 & 50mm were used to predict other distances
of 10, 20, 30, 40, & 50 mm. Data at source-detector separation distances of 20 & 40mm was used to predict
distances for the frequency domain method.
When the difference between the predicted distance and the actual distance was compared to zero the continuous
wave method was significantly different (student's t-test, p = 0.03) while the frequency domain method was
not statistically different from zero (student'st-test, p > 0.05). The frequency domain method was more accurate
at predicting the source-detector separation distance between 10 & 50 mm. This frequency domain method of
measuring distance may be useful in locating and removing lesions during lumpectomy procedures.
In practice, complete removal of the tumor during a lumpectomy is difficult; the published rates of positive
margins range from 10% to 50%. A spherical lumpectomy specimen with tumor directly in the middle may
improve the success rate. A light source placed within the tumor may accomplish this goal by creating a sphere
surrounding the tumor that can serve as a guide for resection.
In an optical phantom and a prophylactic mastectomy specimen, sinusoidally modulated light within the
medium was collected by optical fiber(s) at fixed distance(s) from the source and used to measure the optical
properties. These optical properties were then used to calculate the distance the light had traveled through the
medium. The fiber was coupled to an 830nm diode laser that was modulated at 100, 200 and 300 MHz. A
handheld optical probe collected the modulated light and a network analyzer measured the phase lag. This data
was used to calculate the distance the light traveled from the emitting fiber tip to the probe.
The optical properties were μa = 0.004mm-1 and μ1s = 0.38mm-1 in the phantom. The optical properties
for the tissue were μa = 0.005mm-1 and μ1s = 0.20mm-1. The prediction of distance from the source was
within 4mm of the actual distance at 30mm in the phantom and within 3mm of the actual distance at 25mm
in the tissue. The feasibility of a frequency domain system that makes measurements of local optical properties
and then extrapolates those optical properties to make measurements of distance with a separate probe was
Calibration standards are needed for measurements of tissues in reflectance mode confocal microscopy. We have
created a three dimensional turbid polyurethane phantom with a grid of inclusions. The grid had a 10 fold
increase in absorption compared to the bulk of the phantom and the same scattering properties. India ink was
used as an absorber for the bulk of the phantom, and Epolin 5532 (absorption peak at 500 nm) was used in the
grid. Titanium dioxide particles were used as scatterers. The optical properties of the constructed phantoms
were characterized with difiuse reflectance and transmission measurements followed by an inverse adding doubling
method. At 488nm the total attenuation coeffcient was 40.6 ± 0.3 cm-1 in the grid and 32.5 ± 0.3 cm-1 in the
bulk of the phantom. The phantom was imaged with reflectance mode confocal microscopy. Image analysis using
the Beer-Lambert-Bouguer Law was performed. In the low absorbing bulk of the phantom the total attenuation
coeffcient was estimated accurately, however in the high absorbing grid, the total attenuation coeffcient was
underestimated by image analysis techniques.