Radionuclide Imaging

Quantitative in vitro phosphor imaging using [3H] and [18F] radioligands: the effects of chronic desipramine treatment on serotonin 5-HT2 receptors

“…After the optical density readings were taken for each standard spot, background was subtracted by measuring the DLU in an equivalent, but unexposed area near the standards. The standard curves were created using GraphPad Prism v3.00 software and linear regression analysis, because unlike film, phosphor screens have a wide linear dynamic range (Johnston et al, 1990;Upham and Englert, 1998). Because the spots consisted of a known amount of activity, and were measured on a presumably two-dimensional surface (the TLC plate), the standard curves related ROD (in DLU) to activity (in nCi).…”

“…In contrast, phosphor screens of all types have an intrinsic resolution of approximately 50 m, based on the size of the photosensitive phosphor crystals (Yanai et al, 1992). This is fairly high resolution, but is still many times lower than film or emulsions, which can generally resolve on the order of a micron (Upham and Englert, 1998). Finally, the energy of the isotope used to label the ligand contributes substantially to the resolution of the final images.…”

Elimination of background in film-based applications

“…To increase sensitivity and reduce background, several variables, including probe concentration, probe label, buffers, or substrate, can be optimized (1,2,4,5). In addition, data resolution, or the ability to clearly distinguish data, can also be affected by various factors, such as the type and thickness of the film's emulsion, the distance between the sample and emulsion, or the exposure and the development time (3)(68). Along with the required experimental optimization, film quality and handling before and during development of the silver halide emulsion can contribute to background (3,68).…”

“…In addition, data resolution, or the ability to clearly distinguish data, can also be affected by various factors, such as the type and thickness of the film's emulsion, the distance between the sample and emulsion, or the exposure and the development time (3)(68). Along with the required experimental optimization, film quality and handling before and during development of the silver halide emulsion can contribute to background (3,68). Traditionally, many biochemical methods have been based upon detection with radiolabeled probes due to sensitive detection easily visualized by autoradiography (3,7,9).…”

“…Along with the required experimental optimization, film quality and handling before and during development of the silver halide emulsion can contribute to background (3,68). Traditionally, many biochemical methods have been based upon detection with radiolabeled probes due to sensitive detection easily visualized by autoradiography (3,7,9). Since radioactive emission occurs in all directions, overexposure can produce saturation of the film leading to a loss of resolution and difficulties in data interpretation (3,68).…”