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To include biologic factors in parallel-architecture normal-tissue complication probability (NTCP) model for radiation-induced liver disease (RILD) after three-dimensional conformal radiotherapy (3D-CRT) for gastric or hepatic cancer.A total of 151 patients (89 with hepatocellular carcinoma and 62 with gastric cancer) who received 3D-CRT to the liver were included (isocenter dose range 33.0 to 66.0 Gy; mean 48.0 Gy). RILD was defined as grade 3 or higher liver toxicity according to Common Toxicity Criteria Version 2.0 of the National Cancer Institute within 4 months after 3D-CRT. Possible correlations of patient-related or dosimetric factors with RILD were tested. Maximum-likelihood analysis estimated NTCP model parameters for group and subgroups. Goodness-of-fit analysis estimated deviance of NTCP model parameters between subgroups.RILD developed in 25 patients. Hepatitis B virus carrier status (p0.001) was the only significant independent factor. The 4 parallel NTCP model parameters, mean functional reserve (V(50)), width of functional reserve distribution (sigma), dose damage to 50% of liver subunits (D(50)), and slope parameter for subunit dose-response (k), were respectively, 0.54, 0.14, 50 Gy, 0.18 (group); 0.53, 0.07, 50 Gy, 4.6 x 10(-7) (carriers); 0.59, 0.12, 25 Gy, 59.8 (noncarriers). In carrier-state subgroups, goodness-of-fit deviance with 1 subgroup's parameter set would have been worse in the other group. Across subgroups, patients with RILD all had liver fraction damage (f) greater than 0.4 compared with wider distribution for the whole group.RILD is described with a parallel-architecture NTCP model for HBV carriers and noncarriers with a threshold effect greater than 0.4. The main difference is in slope parameter for subunit dose-response.

This paper proposes a mobile patient monitoring system, which integrates current personal digital assistant (PDA) technology and wireless local area network (WLAN) technology. At the patient's location, a wireless PDA-based monitor is used to acquire continuously the patient's vital signs, including heart rate, three-lead electrocardiography, and SpO/sub 2/. Through the WLAN, the patient's biosignals can be transmitted in real-time to a remote central management unit, and authorized medical staffs can access the data and the case history of the patient, either by the central management unit or the wireless devices. A prototype of this system has been developed and implemented. The system has been evaluated by technical verification, clinical test, and user survey. The evaluation of performance yields a high degree of satisfaction (mean=4.64, standard deviation-SD=0.53 in a five-point Likert scale) of users who used the PDA-based system for intrahospital transport. The results also show that the wireless PDA model is superior to the currently used monitors both in mobility and in usability, and is, therefore, better suited to patient transport.

The photoluminescence (PL) spectrum of the ZnTe/ZnSe quantum dot (QD) structure which has a type II band alignment was investigated. A broader structure peaking at 2.180 eV together with the features of the ZnSe buffer layer located at 2.820 eV in the PL spectrum at 10 K were observed. The broadness of the PL attributes to the spatial inhomogeneity of the QD sizes. The PL spectrum was a normal distribution with a variance of 0.002 eV 2 . However, the dot size distribution was a deformed Gaussian. Using only one set of data of dot size distribution measured by the Atomic Force Microscopy (AFM), the statistical estimates with standard errors were evaluated using the bootstrap methodology. The probability distribution was inferred by calculating the means, percentiles and correlation coefficients of the base diameter and the height of the QDs. We concluded that the dot distributions were indeed a deformed Gaussian and the correlation coefficient of the diameter and the height of the QDs was 0.49 ± 0.01. The uniformity of the dot size distribution was poor. To infer the dot size distribution from the PL spectrum, we numerically solved the Schrodinger equation by elaborating on the orthogonal periodic functions (OPF) approximation for the type II lens shaped QDs. The convergence of the probability density was discussed in a great detail. We found that the band edge discontinuities inside the dot acts as a barrier with ΔE c = 315 meV for the conduction band and as a well with ΔE v = 735 meV for the valence band. In the AFM measurement, the offset in dot height is 14 A and the aspect ratio is 0.04. We employed the Schrodinger equation to correlated the PL spectrum (intensity versus optical energy) to the AFM data (number of QDs versus dot size) and the agreement was excellent.

Purpose: To identify the factors associated with radiation-induced liver disease (RILD) and to describe the difference in normal tissue complication probability (NTCP) between subgroups of hepatocellular carcinoma patients undergoing three-dimensional conformal radiotherapy (3D-CRT). Methods and Materials: A total of 89 hepatocellular carcinoma patients who completed 3D-CRT for local hepatic tumors were included. The average isocenter dose was 49.9 ± 6.2 Gy. Logistic regression analysis was used for the association between statistically significant factors and RILD (defined as Grade 3 or 4 hepatic toxicity of elevated transaminases or alkaline phosphatase within 4 months of completing 3D-CRT) in multivariate analysis. Maximal likelihood analysis was conducted to obtain the best estimates of the NTCP model parameters. Results: Of the 89 patients, 17 developed RILD. In univariate analysis, hepatitis B virus (HBV)-positive status and the mean radiation dose to the liver were the two factors significantly associated with the development of RILD. Of the 65 patients who were HBV carriers, 16 had RILD compared with 1 of 24 non–carrier patients ( p = 0.03). The mean radiation dose to liver was significantly greater in patients with RILD (22.9 vs. 19.0 Gy, p = 0.05). On multivariate analysis, HBV carrier status (odds ratio, 9.26; p = 0.04) and Child-Pugh B cirrhosis of the liver (odds ratio, 3.65; p = 0.04) remained statistically significant. The best estimates of the NTCP parameters were n=0.35, m=0.39, and TD 50 (1) = 49.4 Gy. The n, m, TD 50 (1) specifically estimated from the HBV carriers was 0.26, 0.40, and 50.0 Gy, respectively, compared with 0.86, 0.31, and 46.1 Gy, respectively, for non–carrier patients. Conclusion: Hepatocellular carcinoma patients who were HBV carriers or had Child-Pugh B cirrhosis presented with a statistically significantly greater susceptibility to RILD after 3D-CRT.

Multiphoton generated autofluorescence and second harmonic signals are useful luminescent signatures for probing the structural and spectral properties of collagen fibers. However, optimization of image formation deep within a three-dimensional collagen sample may be hindered by index-mismatch induced spherical aberration. In this work, we examined this issue by comparing the axial multiphoton luminescence profiles of bovine tendon under water, glycerin, and oil immersion conditions. Our results show that, although in general, oil immersion imaging resulted in the slowest decay of measured axial luminescence profile, other immersion conditions can perform better at specific locations within the tendon, indicating the existence of local variations of refractive indices within the collagen-filled tendon. Our results suggest that optimizing multiphoton imaging of collagen requires acquiring and comparing imaging results using different immersion fluids and that the results may be used to infer the spatial distribution of refractive indices in biological specimens.

The photoreflectance spectra of an undoped InGaP film grown on a GaAs (001) substrate by gas-source molecular beam epitaxy have been measured at the temperature of 70 K. The band-gap optical transitions attributed to the InGaP epilayer and GaAs substrate have been characterized. Two broad features, which originate from the interface of the InGaP and GaAs layer, also appeared with the transition energies of 1.523 eV and 1.877 eV in the photoreflectance spectra. In addition, the amplitudes of these two optical features show different trends with increasing power of an extra DC pumping laser. The results suggest that the two unusual optical features are attributed to the spatial indirect transitions at the interface.

In this experiment, the centrifugal Taita No.1 left ventricular-assist device was implanted in a calf. The blood pump was driven by constant voltage with the open-loop control method. The pump inflow flow and pump outflow pressure were recorded and analyzed synchronously. According to the status of aortic valve and mitral valve, the cardiac cycle was divided into four stages. The flow in each stage was calculated and an optimal pump control index was obtained. The index suggests an optimal applied voltage of the pump for reducing suction and backflow effects.

As a major component of the connective tissues, collagen fibers are responsible for various physiological functions inside the body. They provide support for the skin, partial focusing through the cornea, and coordinate movements via tendons, ligaments, and cartilages. In many medical procedures, thermal reorganization of the collagen structure is inevitable or desired. Therefore, the optimization of the therapeutic values of these procedures requires the characterization of thermal changes to collagen fibers. In this presentation, we use multiphoton microscopy to achieve this task. We will show that second harmonic generation (SHG) microscopy can characterize the thermally altered states of collagen and that they have potentials to be used in imaging applications in vivo.

We report a method for extracting the birefringence properties of samples with a novel proposed polarization-sensitive optical coherence tomography (PS-OCT) using linearly polarized incident light.

The thermal disruption of collagen I in rat tail tendon is investigated with second-harmonic generation (SHG) microscopy. We investigate its effects on SHG images and intensity in the temperature range 25 degrees-60 degrees C. We find that the SHG signal decreases rapidly starting at 45 degrees C. However, SHG imaging reveals that breakage of collagen fibers is not evident until 57 degrees C and worsens with increasing temperature. At 57 degrees C, structures of both molten and fibrous collagen exist, and the disruption of collagen appears to be complete at 60 degrees C. Our results suggest that, in addition to intensity measurement, SHG imaging is necessary for monitoring details of thermally induced changes in collagen structures in biomedical applications.

Optical coherence tomography (OCT) is analogous to ultrasound imaging except that it uses infrared light instead of sound. Polarization-sensitive optical coherence tomography (PS-OCT) combines the advantages of OCT and provides additional image contrast of the tested sample. We demonstrate this technique for imaging of back-reflected light, birefringence, and fast-axis orientation simultaneously in different kinds of atherosclerosis plaque. This in vitro study suggests birefringence changes in plaque are due to the prominent deposition of collagen or cholesterol by correlating PS-OCT images with histology. Thus the combination of high resolution structural imaging and birefringence detection make PS-OCT a potentially powerful tool for early assessment of atherosclerosis appearance and prediction of plaque rupture.

The measurement of esophageal pressure (Pes) is a simple technique that can be used to calculate the lung mechanical parameters. In clinical practice the traditional strategy for cardiac beat artifact minimization in Pes measurement is to adjust either the position of esophageal balloon or the posture of the body under test. The authors propose a new scheme combining a modified adaptive noise cancellation (MANC) method and an adaptive FIR (AFIR) filter to eliminate the cardiac beat artifact from Pes measurement. In experiments, the authors also find that the harmonic effect interferes with the measurement of Pes. In using the MANC the authors do not have to carefully adjust the position of the esophageal balloon to avoid the results being affected by body posture, and it is independent of frequency variations of cardiac beat and respiration. In using the AFIR it is found to be suitable for most cases that the frequency of the cardiac beat is different from the respiration frequency but not suitable for the frequencies or harmonics that overlap slightly.

An automatic spike detection algorithm for classification of multi-channel EEG signals based on artificial neural network is presented. Radial basis function (RBF) neural network was chosen for single channel recognition, with model optimization using receiver operating characteristics analysis. Waveform simplification was employed for high noise immunity. Feature extraction with as few as three parameters was used as preparation for the inputs to the neural network. Identification of multi-channel geometric correlation was performed to further lower the false-positive rate by using an incidence matrix. Threshold value for spike classification was chosen for simultaneous maximization of detection sensitivity and selectivity. Evaluation with visual analysis in this preliminary study showed a 83% sensitivity using 16-channel continuous EEG records of four patients, while a high false positive rate was found, which was believed to arise from the extensive and exhaustive visual analysis process. The computation time required for spike detection was significantly less than that needed for online display of the signals on the monitor. We believe that the algorithm proposed in this study is robust and that the simple structure of RBF neural network yields high potential for real-time implementation.