Phantom count

A count is a constructive claim used during the interference to define the contested subject matter between the two parties. A phantom count refers to a constructive claim that does not necessarily correspond to a single claim from either subject application but is assembled to capture the subject matter from two substantially similar claims from the two applications. For purposes of the present discussion, we can think of the count as an ordinary patent claim. 

Double and triple bonds are counted as if they were split into two or three single bonds, respectively, as in the examples in Table 4.1 (note the treatment of the phenyl group). Note that in a C=C double bond, the two carbon atoms are each regarded as being connected to two carbon atoms and that one of the latter is counted as having three phantom substituents. 

Note that in a C=C double bond, the two carbon atoms are each regarded as being connected to two carbon atoms and that one of the latter is counted as having three phantom substituents. 

In vivo counting systems are calibrated using tissue-equivalent phantoms. These phantoms have shapes similar to the human torso and are made of polystyrene or other tissue equivalent material. Standard uranium sources of known activity are inserted into the phantom at locations where uranium would be expected to accumulate in a human body (DOE 1988). Relationships are determined between the uranium activity measured by the detection system and the known activity in the phantom (DOE 1988 HPS 1996). 

An extension of the dual energy method is the use of triple windows in which three windows are chosen with two overlapping windows of different width having the same upper energy level located below the lower level of the photopeak, which is centered on 511 keV. Data are obtained for the object and a calibration phantom. A calibration factor is calculated from the ratio of counts in the two lower scatter windows for both the calibration phantom and the object. The scatter contribution to the photopeak is then estimated from the calibration factor and the narrower energy window data. This method works well for a wide range of activity distribution and object sizes. 

Figure 6.3. NEMA phantoms for PET performance tests, (a) This NEMA body phantom is used for evaluation of the quality of reconstructed images and simulation of whole body imaging using camera-based coincidence imaging technique, (b) This phantom is used for measuring scatter fraction, dead time, and random counts in PET studies using the NEMA NU 2-2007 standard, (c) Close up end of the sensitivity phantom, (d) Set of six concentric aluminum tubes used in phantom (c) to measure the sensitivity of PET scanners. (Courtesy of Data Spectrum Corporation, Hillborough, NC)...

Figure 36. Lead levels in bone can be measured in vivo using XRF spectroscopy, (a) y-rays or X-rays are used (source) to eject either L-shell electrons (L-XRF) or K-shell electrons (K-XRF) from lead in bone when outer-shell electrons fill this vacancy, photons are released (fluorescence) and are monitored by the detector (10, 523). A typical X-ray fluorescence spectrum [(b), e.g., of a 112 pg Pbg phantom ) provides the number of counts observed as a function of photon energy. Emissions characteristic of lead occur at 72.8 keV (PbKa2), 75.0 keV (PbKoti), and 84.9 keV (Pb Kpi) (436, 523). Measurements on actual samples are correlated with those obtained from standard phantoms made of plaster-of-paris and doped with a known amount of lead to obtain bone lead concentrations in micrograms of Pb per gram (pg Pbg bone). The bone lead levels obtained by this method correlate extremely well with independent measurements of BLL (c). [Parts (a) and (c) adapted from (524). Part ( ) adapted from (436).]...

One very important property to remember about collimators is that the spatial resolution gets worse as the source-to-collimator distance increases. This is illustrated in the set of phantom images that were acquired from 5 to 30 cm from the collimator surface. To obtain the best-quality images, spatial resolution comes at the price of count sensitivity therefore it is crucial to keep the collimator as close to the patient as possible. 

To find the free energy of the phantom network, we count the total number of possible conformations of the subchains by integrating over all possible displacements of the T-junctions. However, because there is no definite criterion to distinguish the surface from the inside of the sample from the microscopic viewpoint, it is difficult to identify the a- and T-junctions uniquely. We therefore start here from a microscopic network for which one can find the exact free energy, and grow the junctions step by step to reach the macroscopic one. 

Where the Dhot region is the count density in the hot region and D29.9mm is the count density in the hot region image of 29.9mm diameter located near the edges of the phantom. It is assumed that this region does not experience less attenuation and therefore can be used as a reference hot region for RCR measurements. 

Count profiles were drawn through the centre of hot region images for RCR calculation and the maximum pixel counts were recorded. Then, the deeper hot region image maximum pixel counts were compared to those located nearer to the boundary of the phantom. 

One lobe of the thyroid phantom was filled with a standard potassium iodide solution. The opposite lobe was initially kept empty. The count rate in the iodine K peak obtained by irradiating the filled-in lobe was recorded for varying standard potassium iodide concentrations ranging from O.Ol to 10 mg/ml. Fig. 7 shows the dose-response curve with the thyroid phantom in air and then in the neck phantom. A linear relationship was maintained but as expected the count rate is reduced with the thyroid in the neck phantom due to absorption of the incident and emitted photons by the overlying thickness of wax. Addition of potassium iodide solution in the opposite lobe made no significant difference to the dose response curve for the left lobe. 

FIGURE 2. Theoretical (upper curve) and experimental (lower curve) variation of the net counting rate with mean depth of the thyroid. An Am-241 source with a wide angle collimator and a cylindrical lobe phantom (8 mm inner diameter) embebbed in a scatter medium were used in the experimental arrangement. 

Table 1). It is worthwhile pointing out that the standard deviation of the calculated iodine content was much lower than that of the maximum counting rate (13% vs 26%), thus suggesting that with the proposed method a marked improvement in accuracy could be obtained with respect to methods based on calibration with phantoms of a "normal thyroid" in a fixed geometrical arrangement. 

The results are illustrated in Figure 11. Thickness of the skin is plotted against counts in milligrams of iodine in the tissue-equivalent phantom containing 5, 10, and 20 mg of iodine. From a regression analysis y = and r =... 

With both source and detector collimation, the sensitive volume could be reduced to be close to a point. With this design, a tomographic effect could be achieved. However, such a theoretic design has not found practical application. When the volume was constant, such as in the gelatin phantom, the count response to iodine concentration was linear over a wide range (Fig. 15). The lowest detectable iodine concentration in water-filled phantoms was 0.1 mg/ml. 

FIGURE 15. Iodine weight plotted against total count obtained by fluorescence scanning. Iodine as potassium iodide in solution was added to tissue-equivalent phantoms, and these were scanned by means of standard patient procedures. Measurements were performed in air. Distance from phantom to probe surface was 2.5 cm. 

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