A colloid having a component that consists of radioactive atoms.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



a colloid whose dispersed phase is made up of radioactive substances of low solubility in extremely dilute solutions. As established by the work of I. E. Starik and other investigators, radiocolloids possess a dual nature. One way of regarding radiocolloids is as ordinary colloids with solid particles (dispersed phase) consisting of molecules containing radioactive atoms. Such radiocolloids, known as true radiocolloids, arise only when the content of the radioactive substance in solution exceeds the concentration corresponding to a saturated solution. For poorly soluble substances, the saturation concentration may be very low (1010 mole/liter and lower); thus, the formation of colloid particles is possible in extremely dilute solutions.

A second way of regarding radiocolloids is as a system arising from the sorption of radioactive atoms or the ions and molecules containing these atoms on the solid ultramicroscopic particles that are usually present in water. Radiocolloids of this type, or pseudoradiocolloids, may exist in solutions of radioactive substances having concentrations both above and below the concentration of a saturated solution. The conditions necessary for forming true radiocolloids differ from those for pseudoradiocolloids, and a mixture of both types of radiocolloids is usually present in a solution.

As a result of the formation of radiocolloids, the behavior of radioactive atoms changes markedly. The atoms will no longer enter into chemical reactions or will react at very low rates. The existence of colloid particles in extremely dilute solutions depends mainly on the physicochemical properties of an element and not on the element’s radioactivity. Under analogous conditions, both radioactive and stable atoms of a given element form colloids similar in nature.


The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
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The SLN can be located using intraparenchymal injection of blue dye, radiocolloid alone, or blue dye plus radiocolloid.
(7.) Tang J, Xie XM, Wang X, Xie ZM, He JH, Wu YP, Fan W, Fu JH, Yang MT Radiocolloid in Combination with Methylene Dye Localization, Rather Than Wire Localization, is a Preferred Procedure for Excisional Biopsy of Non palpable Breast Lesions.
Sentinel lymph node biopsy was performed either with blue dye (patent blue) and/or radiocolloid injection by using gamma probe at the discretion of the surgeon.
(1996) to study its effect on clearance of radiocolloid from uterus of mare and was found inferior to both PG[F.sub.2[alpha]] and Cloprostenol.
Akhurst et al., "Intradermal radiocolloid and intraparenchymal blue dye injection optimize sentinel node identification in breast cancer patients," Annals of Surgical Oncology, vol.
In order to facilitate identification of SLN, blue dye was used in conjunction with radiocolloid, using the same method as in the first 30 patients.
A lymph node was recognised as an SLN when it was stained blue, had a blue afferent lymphatic and/or had a radioactive count measured by the gamma probe to be >10% of the highest count at the radiocolloid injection site.
Whereas dual labelling method using both blue dye and radiocolloid ([technetium.sup.99m]) has been shown to provide better results in terms of detection rate in comparison to blue dye alone [53], there is still no consensus about the most accurate method to identify SLN in patients presenting with EC.
(6, 24) Diffuse hepatic disease might be seen as a patch or area of decreased uptake of this radiocolloid; however, this irregularity occasionally results in a false-positive diagnosis.
The "very preliminary" pilot data indicate that the intraoperative combination of isosulfan blue dye and gamma probe detection of radiocolloid may be a diagnostically accurate method of detecting lymph node disease in patients with stage IB1 cervical cancer (less than 4 cm in size).
The combined use of radiocolloid and dye for SLNBX in HNSCC has been described in three reports.
In 1993, Krag and coworkers[9] reported successful localization of sentinel node in breast cancer patients with the use of radiocolloid injection and gamma probe localization; in this study, the status of the sentinel node correctly predicted the status of the rest of the axilla.