PURPOSE: Preamplifier and amplifier are very important parts for developing a portable counting or imaging gamma probe. They can be used for analyzing pulses containing energy and position information for the emitted radiations. The commercial Nuclear Instrument Modules (NIMs) can be used for processing these pulses. However, it may be improper to use NIMs in developing a portable gamma probe, because of its size and high price. The purpose of this study was to develop both preamplifier and amplifier and measure their performance characteristics. MATERIALS and Methodes: The preamplifier and amplifier were designed as a charge sensitive device and a capacitor resistor-rsistor capacitor (CR-RC) electronic circuit, respectively, and they were mounted on a print circuit board (PCB). We acquired and analyzed energy spectra for Tc-99m and Cs-137 using both PCB and NIMs. Multichannel analyzer (Accuspec/A, Caberra Industries Inc., Meriden Connecticut, U.S.A) and scintillation detectors (EP-047 (Bicron Saint-Gobain/Norton Industrial EP-047 (Ceramics Co., Ohio, U.S.A) with 2"x2" NaI (T1) crystal and R1535 (Hamamatsu Photonics K.K., Electron Tube Center, Shizuoka-ken, Japan) with 1"x1"NaI (T1) crystal) were used for acquiring the energy spectra. RESULTS: Using PCB, energy resolutions or EP-047 detectors for Tc-99m and Cs-137 were 12.92% and 5.01%, respectively, whereas R1535 showed 13.75% and 5.19% of energy resolution. Using the NIM devices, energy resolutions of EP-047 detector for Tc-99m and Cs-137 were measured as 14.6% and 7.58%, respectively. However, reliable energy spectrum of R1535 detector could not be acquired, since its photomultiplier tube (PMT) requires a specific type of preamplifier. CONCLUSION: We developed a special preamplifier and amplifier suitable for a small sized gamma probe that showed good energy resolutions independent of PMT types. The RESULTS indicate that the PCB can be used in developing both counting and imaging gamma probe.
Connecticut ; Ohio ; Optics and Photonics

BACKGROUND: Parallel-polarized light (PPL) photography evaluates skin characteristics by analyzing light reflections from the skin surface. OBJECTIVE: The aim of this study was to determine the significance of quantitative analysis of PPL images in rosacea patients, and to provide a new objective evaluation method for use in clinical research and practice. METHODS: A total of 49 rosacea patients were enrolled. PPL images using green and white light emitting diodes (LEDs) were taken of the lesion and an adjacent normal area. The values from the PPL images were converted to CIELAB coordinates: L* corresponding to the brightness, a* to the red and green intensities, and b* to the yellow and blue intensities. RESULTS: A standard grading system showed negative correlations with L* (r=−0.67862, p=0.0108) and b* (r=−0.67862, p=0.0108), and a positive correlation with a* (r=0.64194, p=0.0180) with the green LEDs for papulopustular rosacea (PPR) types. The xerosis severity scale showed a positive correlation with L* (r=0.36709, p=0.0276) and a negative correlation with b* (r=−0.33068, p=0.0489) with the white LEDs for erythematotelangiectatic rosacea (ETR) types. In the ETR types, there was brighter lesional and normal skin with white LEDs and a higher score on the xerosis severity scale than the PPR types. CONCLUSION: This technique using PPL images is applicable to the quantitative and objective assessment of rosacea in clinical settings. In addition, the two main subtypes of ETR and PPR are distinct entities visually and optically.
Humans ; Methods ; Optics and Photonics ; Photography ; Rosacea* ; Skin

The study explored the methods of determining the diameter of clear optic of intraocular lenses by analyzing the design principles and influencing factors of clear optic. Measure and compare the clear optic diameters of intraocular lenses from -10.0 D to 36.0 D respectively. The measurement results of the two methods have good consistency and can be used in the measurement of clear optic. But considering the accuracy and convenience of actual measurement, profile projector measurement principle is more suitable for conventional mass production testing. The Schlieren technique method can provide more useful information in product development and feature description stage, and can be used as an auxiliary verification method for clear optic diameter measurement.
Eye ; Lenses, Intraocular ; Optics and Photonics ; Prosthesis Design

PURPOSE: The goal of this paper is to present the design and performance of a position encoding circuit for 16 x 16 array of position sensitive multi-anode photomultiplier tube for small animal PET scanners. This circuit which reduces the number of readout channels from 256 to 4 channels is based on a charge division method utilizing a resistor array. MATERIALS AND METHODS: The position encoding circuit was simulated with PSpice before fabrication. The position encoding circuit reads out the signals from H9500 flat panel PMTs (Hamamatsu Photonics K.K., Japan) on which 1.5 x 1.5 x 7.0 mm3 L0.9GSO (Lu1.8Gd0.2SiO5:Ce) crystals were mounted. For coincidence detection, two different PET modules were used. One PET module consisted of a 29 x 29 L0.9GSO crystal layer, and the other PET module two 28 x 28 and 29 x 29 L0.9GSO crystal layers which have relative offsets by half a crystal pitch in x- and y-directions. The crystal mapping algorithm was also developed to identify crystals. RESULTS: Each crystal was clearly visible in flood images. The crystal identification capability was enhanced further by changing the values of resistors near the edge of the resistor array. Energy resolutions of individual crystal were about 11.6%(SD 1.6). The flood images were segmented well with the proposed crystal mapping algorithm. CONCLUSION: The position encoding circuit resulted in a clear separation of crystals and sufficient energy resolutions with H9500 flat-panel PMT and L0.9GSO crystals. This circuit is good enough for use in small animal PET scanners.
Animals ; Estrenes ; Fees and Charges ; Optics and Photonics ; Pyridinium Compounds

Dental impressions are widely used in the field of oral restoration. The materials are used for making impression in oral cavity. In order to measure the thickness of impression for reference in clinic, the real impressions are taken as the object for studying. Through optical method, charge-coupled device (CCD) is used for collecting the grey image of cutting section of the impressions which are located in the same plane with steel dividing ruler. According to convert relationship between dividing ruler and pixels collecting grey image, the thickness of impression specimens can be obtained. The results show that the optical method used for measuring thickness is feasible to the task and the precision can reach micro dimension. The experiment method and technique can also be provided for measuring thickness of similar tissue engineering materials.
Dental Impression Materials ; Dental Models ; Humans ; Materials Testing ; Optics and Photonics

OBJECTIVE: To evaluate the efficacy for spatial resolution and radiation dose of a small-field digital mammographic imaging system using parabolic polycapillary optics. MATERIALS AND METHODS: We developed a small-field digital mammographic imaging system composed of a CCD (charge coupled device) detector and an X-ray source coupled with parabolic polycapillary optics. The spatial resolution and radiation dose according to various filters were evaluated for a small-field digital mammographic imaging system. The images of a test standard phantom and breast cancer tissue sample were obtained. RESULTS: The small-field digital mammographic imaging system had spatial resolutions of 12 lp/mm with molybdenum and rhodium filters with a 25-micrometer thickness. With a thicker molybdenum filter (100 micrometer thick), the system had a higher spatial resolution of 11 lp/mm and contrast of 0.48. The radiation dose for a rhodium filter with a 25-micrometer thickness was 0.13 mGy within a 10-mm-diameter local field. A larger field image greater than 10 mm in diameter could be obtained by scanning an object. On the small-field mammographic imaging system, microcalcifications of breast cancer tissue were clearly observed. CONCLUSION: A small-field digital mammographic imaging system with parabolic polycapillary optics may be a useful diagnostic tool for providing high-resolution imaging with a low radiation dose for examination of local volumes of breast tissue.
Equipment Design ; Humans ; Mammography/*instrumentation ; Molybdenum ; Optics and Photonics/*instrumentation ; Phantoms, Imaging ; Radiographic Image Enhancement/*instrumentation ; Rhodium

Biotic tissues are a kind of highly scattering random media; studies on laser light propagation in biotic tissues play an important role in bio-medical diagnostics and therapeutics. The propagation and distribution of infinitely narrow photon beam in tissues are simulated by Monte Carlo method in this paper. Also presented are the energy distribution with regard to depths, light distribution in tissues, reflection and transmittance on the upper and lower surface. The optical parameters adopted in this study are g, albedo and microa, which have influence on energy distribution. The results show: The energy distribution decreases more quickly with the increase of depths and reveals a peak value close to the surface; g factor plays an important part in the lost energy on the upper surface and lower surface; the decrease of g factor causes weaking of the forward moving ability, so the penetration depth becomes smaller and the energy becomes dispersives variation of albedo has distinct effect on the shallow and deep tissues.
Computer Simulation ; Energy Transfer ; Light ; Models, Biological ; Monte Carlo Method ; Optics and Photonics ; Photochemotherapy ; methods ; Scattering, Radiation

In order to study the light propagation in biological tissue, we analyzed the divergent beam propagation in turbid medium. We set up a Monte Carlo simulation model for simulating the divergent beam propagation in a semi-infinite bio-tissue. Using this model, we studied the absorbed photon density with different tissue parameters in the case of a divergent beam injecting the tissue. The simulation results showed that the rules of optical propagation in the tissue were found and further the results also suggested that the diagnosis and treatment of the light could refer to the rules of optical propagation.
Computer Simulation ; Light ; Models, Biological ; Monte Carlo Method ; Optics and Photonics ; Scattering, Radiation

Selectin/ligand interaction plays an important role in such biological processes as inflammatory reaction, tumor metastasis, etc. External forces affect dissociation of receptor-ligand bonds. A novel approach, upon optical trap technique, was developed in this study to investigate the dissociation of P-selectin/PSGL-1 (P-Selectin Glycoprotein Ligand 1) bindings. Stiffness of optical trap was calibrated with laser power using a viscous drag method. While P-selectin and PSGL-1 molecules were functionally coated on surfaces of glass beads, respectively, the dissociation of interacting molecule bond was studied by measuring the rupture force distribution. It was found that most probable rupture force increased with loading rate at < 25 pN/s. These results complemented and validated the current theory at low loading rates.
Humans ; Membrane Glycoproteins ; chemistry ; Optics and Photonics ; instrumentation ; Protein Binding ; Protein Structure, Tertiary

Optical cochlear implant has been occuring as a new cochlear implant which utilizes laser pulses to stimulate hearing. Compared to electronic cochlear implant, it has demonstrated higher spatial selectivity and less radiation scattering, which could lead to higher fidelity cochlear prostheses. At present, most investigations have focused on experiments in vivo. Although a lot of exciting results have been obtained, the mechanisms of laser stimulation is still open. In this paper, a brief review on the recent new findings of optical cochlear implant is given, and possible mechanisms are discussed. In the end, new experimental proposals are suggested which could help to explore the mechanisms of laser-cochlea stimulation.
Cochlear Implantation ; Cochlear Implants ; Hearing Loss ; rehabilitation ; Humans ; Lasers ; Optics and Photonics