PubMed · 14664129
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2003. Judging dose error reduction systems.. https://pubmed.ncbi.nlm.nih.gov/14664129/
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We present a multicolor multiphoton fluorescence microscope with single-photon counting sensitivity. The system integrates a standard multiphoton fluorescence microscope, an optical grating spectrograph operating in the UV-Vis wavelength region, and a 16-anode photomultiplier tube (PMT). The major technical innovation is in the development of a multichannel photon counting card (mC-PhCC) for direct signal collection from multi-anode PMTs. The electronic design of the mC-PhCC employs a high-throughput, fully-parallel, single-photon counting scheme along with a high-speed electrical or fiber-optical link interface to the data acquisition computer. There is no electronic crosstalk among the detection channels of the mC-PhCC. The collected signal remains linear up to an incident photon rate of 10(8) counts per second. The high-speed data interface offers ample bandwidth for real-time readout: 2 MByte lambda-stacks composed of 16 spectral channels, 256 x 256 pixel image with 12-bit dynamic range can be transferred at 30 frames per second. The modular design of the mC-PhCC can be readily extended to accommodate PMTs of more anodes. Data acquisition from a 64-anode PMT has been verified. As a demonstration of system performance, spectrally resolved images of fluorescent latex spheres and ex-vivo human skin are reported. The multicolor multiphoton microscope is suitable for highly sensitive, real-time, spectrally-resolved three-dimensional imaging in biomedical applications.
This study was undertaken to investigate and compare the accuracy and reliability of dual image and extended field-of-view (EFOV) ultrasound (US) techniques in distance measurements using acoustic phantoms. Ten tissue phantoms were constructed and were scanned twice with an interval of 3 days by two operators. Measurements of various known distance (ranging from 4.6 to 7.2 cm) in the phantoms were made with dual image and EFOV US. Results showed that both dual image and EFOV US have a high accuracy and reliability in distance measurements, with the EFOV US (r = 0.997 to 0.998, reproducibility = 99.8%, repeatability = 98.2 to 99.8%) being slightly more accurate and reliable than dual image US (r = 0.948 to 0.981, reproducibility = 94.6%, repeatability = 89.6 to 97.9%). EFOV US has a higher accuracy and reliability than dual image US in distance measurements. However, the dual image US is a useful alternative with a high accuracy and reliability when EFOV US is not available.
OBJECTIVE: We sought to evaluate whether soft-copy reading of simulated pulmonary chest lesions is influenced by ambient light and automatic optimization of cathode ray tube (CRT) monitor luminance. MATERIALS AND METHODS: Four types of simulated lesions (nodules, lines, micronodules, and patchy opacities) were superimposed over an anthropomorphic chest phantom. Lesion detection with soft-copy reading was assessed using a high-contrast grayscale 2K CRT monitor under the following conditions: (1) subdued lighting (<50 lux); (2) normal lighting conditions (450 lux) without, and (3) with a sensitivity modulation to automatically adjust the CRT luminance to the increased amount of ambient light. Reading data were analyzed according to receiver operating curve. Significance of differences was tested using an analysis of variance for repeated measures. RESULTS: Ambient room light of 450 lux did not significantly influence the detection of nodules and patchy opacities. However, bright ambient light significantly decreased detection of micronodules (0.60 vs. 0.74) and lines (0.52 vs. 0.66) relative to subdued lighting conditions. Automatic luminance adjustment could compensate the effect of ambient light for the micronodules (0.77) but not for the lines (0.53). CONCLUSION: Bright ambient light significantly decreases detection of small low-contrast structures. This may be partially but not completely compensated by an automatic luminance adaptation.