PET data

The UNSAT-H model estimates evaporation from the soil in two ways. In the isothermal mode, the user must supply PET data for each day or daily climate data from which the model calculates PET by the Penman method. In the thermal mode, the model estimates evaporation from the difference in vapor density in the atmosphere and in the surface soil layer. 

Figure 14.5 Effect of a commercial solid-stating accelerator (Irgamod 1425) on the rate of intrinsic viscosity enhancement of PET (data obtained from Ciba Specialty Chemicals)...

PET/CT systems are gaining major attention in the last few years. Due to the sequential acquisition of CT and PET data, morphological and functional information can be easily correlated and analysed. The CT data can also be used for attenuation correction of the PET images, thus decreasing the total examination time of the patient. 

Fig. 2. Possibilities for parametric imaging using dynamic PET data obtained from an FDG examination. The cross-section of the liver demonstrates two metastases from a patient with a breast carcinoma. The parametric images demonstrate that in this case the global FDG uptake is mainly related to an enhanced intracellular phosphorylation of the tracer and less dependent on the transport of FDG into the cells upper row SUV image (SUV), fractal dimension (FD) second row SUV image (SUV), k3-weighted image (k3w), and distribution volume (DV), calculated using a non-compartment...

The quantitative assessment of PET data demands the accurate measurement of the injected dose (e.g. considering residual activity in the syringe) and the measurement of the body weight of each patient. Furthermore, for FDG scans the blood glucose level should be checked prior to the FDG application. 

The PMMA and PET data show clearly the limitations of the ISS technique in providing the intrinsic composition of the outermost surface of polymers no static conditions for ISS analysis on polymers has been achieved with acceptable signal/noise ratio. Nevertheless, it has been shown elsewhere (15.16) that ISS, used with other complementary surface techniques, may be helpful for solving practical problems related to the polymers surface. Static SIMS has been shown to be more suitable than ISS for the surface analysis of polymers. ISS and SSIMS... 

Table 25.2 Representative hole mobilities reported for the bulk (TOP) and the surface (PET) of sublimation grown crystals. The PET data were obtained on samples with on-top deposited polymeric gate insulators. Bulk transport refers to the [001] direction and surface transport to the (001) plane. Except for rubrene, all materials offer comparable or lower PET mobilities at the surface.

Figure 3.3. PET data acquisition in the form of a sinogram. Each LOR data (a) is plotted in (r, ) coordinates. Data for all r and values are plotted to yield sinogram indicated by the shaded area (b). (Only a part is shown.) (Reprinted with the permission of The Cleveland Clinic Center for Medical Art Photography 2009. All Rights Reserved)...

PET data are acquired directly into a sinogram in a matrix of appropriate size in the computer memory. The sinogram is basically a two-dimensional (2D) histogram of the LORs in the (distance, angle) coordinates in a given... 

Correction for scattered events is essential, particularly for 3D acquisition of PET data, because of the loss of contrast and resolution in the image. A review by Zaidi and Koral (2004) provides an extensive account of scatter events in patient imaging and methods to correct them. Several methods have been applied for scatter correction, which are briefly described below. 

The 2D PET data acquisition is accomplished in a PET scanner by the use of (a) parallel-hole collimator, (b) lead shield, (c) tungsten septa, or... 

Describe the method of normalization of the acquired PET data to correct for nonuniformity due to variations in the gain of PM tube, location of the detector in the block, and physical variation of the detectors. 

Based on the literature survey of PET data, the FDA concluded that certain PET radiopharmaceuticals, when produced under specific conditions, are safe and effective for certain clinical indications. The three PET radiopharmaceuticals 18F-sodium fluoride for bone imaging, 18F-FDG for use in oncology and for assessment of myocardial viability, and 13N-NH3 for evaluation of myocardial blood flow were approved by the FDA in 2000. 82Rb-rubidium chloride was approved by the FDA for evaluation of myocardial perfusion in 1989. 

After the completion of the PET data acquisition for the last bed position, the patient is released. 

Attenuation correction factors are applied to acquired PET data (Step 15). PET images are then reconstructed from corrected data using either the FBP or the iterative method depending on the vendor s software. 

A graphical method for quantification of P-AR density (B ,ax, pmol/g) from the PET data has been developed (Delforge, 1994 Delforge et al., 1991). This approach requires two injections of ["C](5)-CGP 12177, one at high specific radioactivity followed by a second at low specific... 

Fig. 5. Densities of p-ARs in myocardium measured with ["C](S)-CGP 12177 in a patient with HCM and left ventricular systolic dysfunction. The values are calculated regionally from the acquired PET data according to a graphical method adapted from Delforge (1994) and Delforge et al. (1991).

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