Introduction: Hydrogen peroxide is used as a topical antiseptic and hemostatic agent. At higher concentrations, it can induce cell death and has recently been reported to be effective in treating seborrheic keratosis. This study examines the effectiveness of topical hydrogen peroxide to shrink non-melanoma skin cancers of the head and neck prior to excision with the goals of minimizing cost and morbidity. Methods: The protocol involves rubbing a solution of 33% hydrogen peroxide into the lesion and a 1 cm border with a cotton tip applicator until blanching is observed. The process can be repeated after one hour and weekly reapplications to a maximum of three times are included in this study group. At one month from the initial application, the remaining lesion is resected with primary closure. The specimen is sent to pathology for histological analysis and final diagnosis. The study will accrue 50 patients with one or more lesions per patient. Measurements of lesion size are recorded by tracing the border on to clear acetate film at each visit. Results: Initial results from first six patients found a range of responses from no size change to no visible lesion remaining for excision. All excised specimens have had negative margins histologically. Summary: Topical hydrogen peroxide is a simple and effective treatment for reducing the size of non-melanoma skin cancers prior to excision.
Recent advances in the performance of light emitting diodes (LED) that emit near 630 nm has allowed the opportunity to develop efficient red light sources for photodynamic therapy with protoporphyrin IX") (ALA-PDT). LED lamps similar to those described here have been reported along with their clinical effectiveness('`). Light sources for PDT can be characterized by their spectral irradiance, irradiance uniformity, depth of focus, light output stability, electrical to optical conversion efficiency, beam size, cost, simplicity, reliability, maintenance requirements and overall functional lifetime. LED lights, for skin illumination, may be superior to currently available incoherent lights. Several light sources, that have been used for ALA-PDT, were evaluated by Gudgin Dickson et al 3) using a scanning point measurement system.
Most high-resolution optical tomography techniques employ coherence domain or time domain methodologies to
capture non-scattered photons in turbid media. Angular Domain Optical Projection Tomography (ADOPT) uses an
angular filter array (AFA) to observe photons that propagate through a specimen with small angular deviation. We
constructed an ADOPT system consisting of an AFA micro-machined silicon micro-tunnel array with each micro-tunnel
60 μm wide, 60 μm high, 10 mm long, and separated by 5 μm thick walls. The range of acceptance angles was 0° to
0.5°. The system also included an 808 nm CW diode laser, beam shaping optics, a sample cuvette, a Keplerian lens
system, and a CMOS camera. Testing was performed with a target consisting of two graphite rods (0.9 mm diameter)
suspended in the cuvette by a rotation stage. The target was placed in a manner that the line of laser light was
perpendicular to the long axis of the rods. A multitude of projections were collected at increments of 1.8° and compiled
into a sinogram. A transverse image was reconstructed from the sinogram using filtered backprojection. The submillimeter
targets embedded in the 2 cm thick scattering medium (reduced scattering coefficient ≤ 2.4 cm-1) were
discernable in both the sinograms and the reconstructed images. The results suggest that ADOPT may be a useful
technique for tomographic imaging of thick biological specimens (i.e. up to 8 mm across).
The 2E-4A2 electronic transition of ruby at 694 nanometers has a lifetime of approximately 3 milliseconds. The wavelength, decay time and bandwidth of this transition combine to make ruby a nearly ideal fiber optic sensor material for radiation dosimetry of medical linear accelerators. Time-delayed signal detection eliminates, from the ruby signal, extraneous prompt visible light which is generated in the irradiated fiber. The prompt light originating in the fiber is produced by fluorescent and Cerenkov processes during the x-ray pulses. In addition, phosphorescent fiber signals are minimized by isolating the ruby emission with a narrow bandpass interference filter. Data is presented comparing signals from a 1 mm diameter ruby sphere and an ion chamber for a 4 MV photon beam and a 12 MeV electron beam.