Isotope scanning

Isotope scan with 123I or "mTc04 Normal pattern Test not indicated Diffusely enlarged gland... 

Blau, M. and Bender, M.A. 1962. (75Se)selenomethionine for visualization of the pancreas by isotope scanning. Radiology 78, 974-979. 

Heading, R. C.,Tothill, R, McLoughlin, G. P., and Shearman, D. J. C. (1976), Gastric emptying rate measurement in man. A double isotope scanning technique for simultaneous study of liquid and solid components of a meal, Gastroenterology, 71,45-50. 

The question of performance differences among various devices should be addressed on a level much broader than whether a device produces a better size distribution, greater lung penetration, or even better or better particle distribution as measured by isotope scanning. This is not to say that these questions are not important, but, rather, to say that the final answer to drug efficacy does not end with such studies of with short-term efficacy. Long-term outcome is the final determinant of utility of new aerosol modalities, and more such studies are badly needed. 

A 99TC-IDA derivate isotope scan (scintigraphy) can also differentiate between BA and neonatal hepatitis. Phenobarbital must be administered for 3-5 days to jump-start hepatocellular function. If the tracer reaches the duodenum, biliary atresia can be excluded. However, some authors recommend imaging at 24 h to exclude delayed excretion. Scintigraphy has 50%-75% specificity and 90%-100% sensitivity for BA (Petersen and Ure 2003) (Fig. 4.2c,d). 

Radioactivity is often perceived as dangerous however, it is also enormously useful to physicians in the diagnosis and treatment of disease. The use of radioactivity in medicine can be broadly divided into isotope scanning and radiotherapy. 

Which t)qje of radiation is most likely to be used for isotope scanning ... 

Isotope scanning can be used in the medical commimity to detect and identify cancerous tumors. Likewise, isotope scanning can produce necessary images of several different internal organs. 

In a process similar to that described in the previous item, the stored data can be used to identify not just a series of compounds but specific ones. For example, any compound containing a chlorine atom is obvious from its mass spectrum, since natural chlorine occurs as two isotopes, Cl and Cl, in a ratio of. 3 1. Thus its mass spectrum will have two molecular ions separated by two mass units (35 -i- 2 = 37) in an abundance ratio of 3 1. It becomes a trivial exercise for the computer to print out only those scans in which two ions are found separated by two mass units in the abundance ratio of 3 1 (Figure 36.10). This selection of only certain ion masses is called selected ion recording (SIR) or, sometimes, selected ion monitoring (SIM, an unfortunate... 

MS", application of successive mass spectrometric measurements n of them), particularly in linked scanning of m/z, which is the ratio of the mass (m) of an ion and the number of charges (z) on it. Older publications used m/e, but as e is the actual charge on an electron and not the number of charges on the ion, the use of m/e was abandoned, m/z. mass-to-charge ratio, a measure of molecular mass PDB. PeeDee Belemnite (a carbon isotope standard see VPDB)... 

The selective uptake of iodide ion by the thyroid gland is the basis of radioiodine treatment in hyperthyroidism, mainly with although various other radioactive isotopes ate also used (40,41). With a half-life of eight days, the decay of this isotope produces high energy P-particles which cause selective destmction within a 2 mm sphere of their origin. The y-rays also emitted are not absorbed by the thyroid tissue and are employed for external scanning. 

The Mattauch-Herzoggeometry (Fig. 3.20) enables detection of several masses simultaneously and is, therefore, ideal for scanning instruments [3.49]. Up to five detectors are adjusted mechanically to locations in the detection plane, and thus to masses of interest. Because of this it is possible to detect, e. g., all isotopes of one element simultaneously in a certain mass range. Also fast, sensitive, and precise measurements of the distributions of different isotopes are feasible. This enables calculation of isotope ratios of small particles visible in the image. The only commercial instrument of this type (Cameca Nanosims 50) uses an ion gun of coaxial optical design, and secondary ion extraction the lateral resolution is 50 nm. 

Fig. 21. Raman spectra showing improvement of signal-to-noise using multiple scans with computer time averaging over single scan. Lower traces single scan upper traces multiple scans (10 scans) and computer output, (a) i of CCU (b) Hg emission line and n of LiCh (c) n of Na02 with oxygen isotopic counterparts (89).

These four PET scans show how blood flow to different parts of the brain is affected by various activities. In this case, an oxygen isotope that is taken up by the hemoglobin in blood is used as a source of positrons. 

The catalyst for the in situ FTIR-transmission measurements was pressed into a self-supporting wafer (diameter 3 cm, weight 10 mg). The wafer was placed at the center of the quartz-made IR cell which was equipped with two NaCl windows. The NaCI window s were cooled with water flow, thus the catalyst could be heated to 1000 K in the cell. A thermocouple was set close to the sample wafer to detect the temperature of the catalyst. The cell was connected to a closed-gas-circulation system which was linked to a vacuum line. The gases used for adsorption and reaction experiments were O, (99.95%), 0, (isotope purity, 97.5%), H2 (99.999%), CH4 (99.99%) and CD4 (isotope purity, 99.9%). For the reaction, the gases were circulated by a circulation pump and the products w ere removed by using an appropriate cold trap (e.g. dry-ice ethanol trap). The IR measurements were carried out with a JASCO FT/IR-7000 sprectrometer. Most of the spectra were recorded w ith 4 cm resolution and 50 scans. 

In order to identify the new adsorbed species of the band at 895 cm, the effect of the isotope substitution of O, with 0, was examined. The spectra shown in Fig. 4 were recorded for the catalyst in the presence of H, and 0, in the wavenumber region of 700-950 cm with 100 scans. The results show that the absorption band at 849 cm ... 

For the confirmatory procedure, it is recommended that the sponsor develop spectral data based on at least three structurally specific ions that completely define the marker residue molecule. These ions may or may not include the molecular ion. The use of water loss and isotopic ions is usually unacceptable and CVM concurrence should be sought when water loss ions or isotopic ions are selected for the confirmatory analysis. The proposed fragment ion structures should be consistent with the fragmentation pattern, and justification for specificity of selected ions or scan range should be included. All confirmation criteria should be specified in the standard operating procedure. 

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