Gamma scintillation probes

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. ... 

Gamma and x back-scattering techniques are based upon the Compton photon back-scatter effect. Collimated low-energy gamma rays or X-rays are emitted and beamed at the inspected material. The rays become scattered back toward the detector in direct proportion to the mass of the material in front of the probe. A. scintillation cry.stal detector is used to convert the back-scattered protons into an electrical signal that can be related to material thickness, provided that the material density is constant. Back-scattered. x-rays can be detected by an ariay of scintillation detectors, and the position of the detector relative to the sample relates to different depths in that sample [84]. 

Human liver tissue analyses to calculate absorbed dose in Gy have been done. Fox [28] patients that received resin microspheres during laparotomy provided an opportunity to measure portions of the liver and tumors directly from small biopsies with a specialized three-channel liquid scintillation P-radiation detection probe, which also detected gamma rays. After infusion of 49-118 million microspheres (diameter 17 or 32 pm) [24-26], Burton estimated that the normal liver received 9.0-75 Gy, and tumor 34-1474 Gy, as calculated by tumor normal ratios of 0.4 1 to 45 1 [26]. Fox et al. [28] studied the left lobe of a patient with metastatic colon cancer which was resected after having previously received resin microspheres. Predicted isodose curves by microspheres which could be seen... 

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