Radioactive microsphere

Vexler ZS, Roberts TP, Bollen AW et al (1997) Transient cerebral ischemia. Association of apoptosis induction with hypoperfusion. J Clin Invest 99 1453-1459 Walsh EG, Minematsu K, Leppo J, Moore SC (1994) Radioactive microsphere validation of a volume localized continu-... 

Farad and Heistad (1992) measured blood flow with radioactive microspheres (15 p. diameter) labeled with 46Sc, 95Nb, 153Gd, 85Sr, and 141Ce in anesthetized rabbits. 

Kowallik et al. (1991) measured regional myocardial blood flow with multiple colored microspheres. The method yielded values very similar to those obtained with radioactive microspheres. 

Lin, P.W., Hemodynamic changes after hepatectomy in rats studied with radioactive microspheres, J. Formos. Med. Assoc., 89, 177, 1990. 

Rakusan, K. and Blahitka, J., Cardiac output distribution in rats measured by injection of radioactive microspheres via cardiac puncture. Can. J. Physiol. Pharmacol, 52, 230, 1974. 

Radiotherapy microspheres, sized 10 to 30 nm, are larger than capillaries and get trapped in first capillary bed when they come across. They are injected to the arteries that lead to tumor of interest. So, in all these conditions, radioactive microspheres deliver high-radiation dose to the targeted areas without damaging the normal surrounding tissues. It differs from drug delivery system, as radioactivity is not released from microspheres but acts within a radioisotope typical distance and the different kinds of radioactive microspheres are a emitters, p emitters, and y emitters. It offers new solutions for patients who need drugs delivered directly to tumors, diabetic ulcers, and other disease sites. 

Blanchard RJ, Grotenhuis I, LaFave JW (1964) Treatment of experimental tumors utilization of radioactive microspheres. Arch Surg 89 406... 

Lodging of the radioactive microspheres in the non-tumoral hepatic tissue would produce not only a decrease in the antitumoral efficacy, but an increase in hepatic toxicity. 

Treatment of liver metastases with radioactive microspheres has shown high response rates (12, 21, 22, 31, 43-46, 54, 57]. SIRT achieves high radiation doses within malignant lesions while reducing radiation exposure to normal liver parenchyma [8,9, 19). This somewhat selective tumor uptake is ob-... 

The early use of radioactive microspheres in the liver is discussed in depth elsewhere in this book but a brief disease-specific discussion is appropriate given the importance it has played in this therapy. Particularly in the USA, mCRC prevalence has provided the most opportunity for applying microspheres although neuroendocrine tumors were also among the first treated worldwide beginning in the early 1960s [1-14]. 

Histopathological basis. Radiation-induced cholecystitis or gall bladder infarction is a rare complication of radioembolization and is due to the radiation effect of the microspheres. Unlike transarterial chemoembolization, Y treatment does not produce a significant embolic effect [25] (Fig. 14.2). Animal studies performed in dogs to examine the tolerance to radioembolization with Y labelled resin microspheres have shown that cholecystitis is encountered to some extent in almost all of the animals who received radioactive microspheres, but was absent in the animals infused with nonradioactive microspheres [26]. Similar studies performed in pigs that received Sirtex particles demonstrated the presence of particles in the gall bladder without inflammatory wall changes [27]. 

Ariel I (1965) Intra-arterial injection of radioactive microspheres of ceramic in the treatment of malignant tumors. Indications and clinical results. Minerva Med 56 2030-2037... 

Theoretically, small microspheres should distribute distally in small arterioles, and one could imagine completely filling a tumoral process with radioactive microspheres or drug-eluting beads. The pathological studies did not confirm this hypothesis tissular distribution of beta-emitting microspheres smaller than 40 pm has been studied experimentally in rabbit liver and clinically [3, 29). Pillai [29] observed an inhomogeneous distribution of microspheres and a formation of clusters, while Campbell [3] found that the median cluster size was ten times the size of the microsphere and the distance between the clusters. 

Kleinstreuer C, Basciano CA, Childress EM, Kennedy AS (2012) A new cathetra- for tumortargeting with radioactive microspheres in representative hepatic artery systems. Part I impact of catheter presence on local blood flow and microsphere delivery. J Biomech Eng Trans ASME 134 051004... 

Like any other experimental method, determination of blood flow by radioactive microspheres is subject to many sources of error, including individual variation among the sample population, the counting accuracy of the total microspheres in the tissue sample by the gamma counter, and the effect of arteriovenous shunting or the migration of the microspheres. Despite all the limitations of this method, the microsphere technique of blood flow determination has become the most powerful method available today and has been used to evaluate the accuracy of other techniques of blood flow measurement. 

FIGURE 14.1.23 In situ cancer treatment using a radioactive microsphere. 

Source Adapted from Archibald LH, Moody FG, Simons M. J Appl Physiol The measurement of gastric blood flow with radioactive microspheres. 38 1051-I056, 1975. 

Ariel IM (1964) Radioactive isotopes for adjuvant cancer therapy. Arch Surg 89 244-249 Ariel IM, Padula G (1982) Treatment of asymptomatic metastatic cancer to the liver from primary colon and rectal cancer by the intraarterial administration of chemotherapy and radioactive isotopes. J Surg Oncol 20 151-156 Blanchard RJ, Grotenhuis 1, LaFave JW (1964) Treatment of experimental tumors utilization of radioactive microspheres. Arch Surg 89 406... 

As in the case for transarterial chemoemboliza-tion (FACE, Chapter 10), radioembolization takes advantage of the preferential hepatic arterial supply of hepatocellular carcinoma (HCC) to deliver targeted therapy to the tumor, relatively sparing the liver parenchyma, which is mostly supported by the portal venous system. Radioembolization is effected via intra-arterial delivery of carrier spheres onto which radioactive particles are attached. There are two types of radioactive microspheres that can be used in the treatment of primary (and metastatic for that matter) liver disease. They both contain Yttrium-90 ( °Y) as the active element but differ in the type of carrier particle. The first is Y glass... 

Blanchard RJ, Grotenhuis I, Lafaye JW et al. (1965) Blood supply to hepatic V2 carcinoma implants as measured by radioactive microspheres. Proc Soc Exp Biol Med 118 465-468... 

Following, we present a comprehensive approach to recent advances on hepatic embolotherapy. Advances on radioactive microspheres embolization are not included, as they are thoroughly discussed in a previous chapter. 

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