Scintillation probes

Thyroid Uptake Systems. Studies involving absolute thyroid uptake can be performed without imaging using small amounts of or and a simple scintillation probe. This is caUbrated using a phantom, ie, a model of a portion of the human body, loaded with the isotope being used. This instmment is also useful for assaying thyroid exposure to radioiodine among personnel. 

As the propint bums, the intensity of the collimated beam increases due to the difference in the density of the solid propint and its combination products. The intensity of the emitted collimated beam of 7-rays that strike the scintillation probe after passing thru the combustion chamber is a function of the density and thickness of the material thru which the 7-rays pass. Since the walls of the combustion chamber remain fixed, their attenuation is constant. The attenuation of the 7-rays by the combustion products of the sample may also be neglected since the attenuation of the 7-rays is chiefly a function of material density. Thus, the emitted beam intensity is a function only of the position of the proplnt sample because the motion of the proplnt provides a variable attenuation of the emitted energy... 

The thrombolytic effect in vivo was studied in rabbits with a radioactive thrombus produced in the inferior vena cava. The radioactivity over the occluded venous segment was measured by a scintillation probe fitted with a collimator adapted to the anatomical conditions. Comparison of equivalent doses of urokinase and benzoyl-urokinase in the model of venous thrombosis showed that the acylated form of the enzyme was more active than the free enzyme [38). 

Nal Scintillation Probe. The Nal Scintillation Probe is part of the PDR-77 extension kit. It uses a 1 inch by 1.5 inch Nal crystal for detection. The probe is very energy dependent. There is no data available concerning the accuracy of this probe. 

The preparation of deoxyfluorohexoses labeled with the positron emitter Fluorine-18, and their use in studies of hexose transport and phosphorylation with isolated perfused working rat hearts is described. Compartmental analysis methods were applied to time courses of F-18, measured with scintillation probes, in hearts given... 

In operatlbh, both instruments need frequent recali-bratlons. Maintenance requirements have also gradually increased. Thus, a commercial scintillation probe and associated rate meter have recently come under evaluation. The new instrument has advantages of smaller size and weight, requires only two D-size batteries for power rather than the assortment needed for the argon and xenon momtors, and is more responsive to uranium accumulations. 

Figure 28. Equipment utilized in a study of the feasibility of using e to mark brook trout (Salvelinus fontinalis). (a) Radioassay of Group I trout, using needle scintillation probe, (b) Constant-geometry tank for radioassay of Group II trout, (c) Relationship between logio (count rate) and time for Group I trout, from radioassay by the needle scintillation probe over the heart-liver region. Values plotted are geometric means for all fish assayed on each day. From Scott (1961).

Figure 65. Detection equipment and accessories for measuring in stems, (a) Lead shield and scintillation probe in position, (b) Portable scaler in position for taking measurements. Courtesy of F. W. Woods.

Woods, F. W., and M. L. McCormack. 1963. Two scintillation probes for radioecological investigations. pp. 205-209. In Advancing Frontiers of Plant Sciences, Vol. 2 (R. Vira, ed.). Institute for Advancement of Science and Culture, New Delhi. 

Liquid scintillation spectrometers. Also known as liquid scintillation counters, these instruments are in widespread use in biomedical laboratories. They possess high efficiencies at detecting low-energy beta emissions, and the electronic spectrometer can be adjusted to identify counts resulting primarily from a selected isotope. Thus these units can also be used to identify unknown contaminants. They operate on the principle similar to the scintillation probe, except a liquid scintillator solution is used in place of a crystal detector. 

Ratemeter with thin sodium iodide-thallium scintillation probe... 

Conduct area surveys and wipe tests after each use and daily if using 5 millicuries or greater per day and weekly if using less. Use a G-M probe or portable sodium iodide crystal scintillation probe for surveys and count wipes in a gamma counter or liquid scintillation counter (see Section 13.10). The contamination limit for iodine is 500 dpm/100 cm. ... 

C.R Harwood, K. Walanski, and R. Semmler. A miniature scintillation probe for use in powder tracer studies. Instrumentation Science Technology, 6 3) 227-237,1975. 

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