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Nuclear medicine uses radiopharmaceuticals for disease treatment and as tracers in medical imaging studies. Yttrium-90 (⁹⁰Y) is a radiopharmaceutical agent used to treat overgrown joint lining known as pigmented villonodular synovitis, as well as some forms of liver cancer. It has a half-life of about 64 hours.Although the relatively short half-life of ⁹⁰Y is optimal for use in medical applications, transportation and storage of the radiopharmaceutical are not feasible. As a result, strontium-90 (⁹⁰Sr) , with a half-life of 28.8 years, is the most common source of ⁹⁰Y. ⁹⁰Sr is created by a nuclear fission process that begins with uranium-235 (²³⁵U) in a nuclear reactor as shown in Reaction 1.²³⁵U → ⁹⁰Sr + ZReaction 1Fission of ²³⁵U produces ⁹⁰Sr as well as additional fission products (Z) including, but not limited to, technetium-99 (⁹⁹Tc) , iodine-129 (¹²⁹I) , and zirconium-93 (⁹³Zr) . Figure 1 shows the distribution of fission products.
Figure 1 Distribution of ²³⁵U fission products by atomic weightTo create the final ⁹⁰Y required for nuclear medicine studies, ⁹⁰Sr decay is carried out in a controlled ⁹⁰Y generator. ⁹⁰Y is then separated from residual ⁹⁰Sr for use in clinical applications.
Adapted from Wheeler CE. Comments on vaccines, August 1987. J Am Acad Dermatol. 1988;18(1 Pt 2) :232-4.
-Fission of ²³⁵U produces multiple elements. Based on Figure 1, which of the following is the atomic number of the most common fission product?

Question

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Nuclear medicine uses radiopharmaceuticals for disease treatment and as tracers in medical imaging studies. Yttrium-90 (⁹⁰Y) is a radiopharmaceutical agent used to treat overgrown joint lining known as pigmented villonodular synovitis, as well as some forms of liver cancer. It has a half-life of about 64 hours.Although the relatively short half-life of ⁹⁰Y is optimal for use in medical applications, transportation and storage of the radiopharmaceutical are not feasible. As a result, strontium-90 (⁹⁰Sr) , with a half-life of 28.8 years, is the most common source of ⁹⁰Y. ⁹⁰Sr is created by a nuclear fission process that begins with uranium-235 (²³⁵U) in a nuclear reactor as shown in Reaction 1.²³⁵U → ⁹⁰Sr + ZReaction 1Fission of ²³⁵U produces ⁹⁰Sr as well as additional fission products (Z) including, but not limited to, technetium-99 (⁹⁹Tc) , iodine-129 (¹²⁹I) , and zirconium-93 (⁹³Zr) . Figure 1 shows the distribution of fission products.

Passage Nuclear medicine uses radiopharmaceuticals for disease treatment and as tracers in medical imaging studies. Yttrium-90 (<sup>90</sup>Y) is a radiopharmaceutical agent used to treat overgrown joint lining known as pigmented villonodular synovitis, as well as some forms of liver cancer. It has a half-life of about 64 hours.Although the relatively short half-life of <sup>90</sup>Y is optimal for use in medical applications, transportation and storage of the radiopharmaceutical are not feasible. As a result, strontium-90 (<sup>90</sup>Sr) , with a half-life of 28.8 years, is the most common source of <sup>90</sup>Y. <sup>90</sup>Sr is created by a nuclear fission process that begins with uranium-235 (<sup>235</sup>U) in a nuclear reactor as shown in Reaction 1.<sup>235</sup>U → <sup>90</sup>Sr + Z<strong>Reaction 1</strong>Fission of <sup>235</sup>U produces <sup>90</sup>Sr as well as additional fission products (Z) including, but not limited to, technetium-99 (<sup>99</sup>Tc) , iodine-129 (<sup>129</sup>I) , and zirconium-93 (<sup>93</sup>Zr) . Figure 1 shows the distribution of fission products. <strong>Figure 1</strong> Distribution of <sup>235</sup>U fission products by atomic weightTo create the final <sup>90</sup>Y required for nuclear medicine studies, <sup>90</sup>Sr decay is carried out in a controlled <sup>90</sup>Y generator. <sup>90</sup>Y is then separated from residual <sup>90</sup>Sr for use in clinical applications. Adapted from Wheeler CE. Comments on vaccines, August 1987. J Am Acad Dermatol. 1988;18(1 Pt 2) :232-4. -Fission of <sup>235</sup>U produces multiple elements. Based on Figure 1, which of the following is the atomic number of the most common fission product? A) 38 B) 55 C) 92 D) 133

Figure 1 Distribution of ²³⁵U fission products by atomic weightTo create the final ⁹⁰Y required for nuclear medicine studies, ⁹⁰Sr decay is carried out in a controlled ⁹⁰Y generator. ⁹⁰Y is then separated from residual ⁹⁰Sr for use in clinical applications.
Adapted from Wheeler CE. Comments on vaccines, August 1987. J Am Acad Dermatol. 1988;18(1 Pt 2) :232-4.
-Fission of ²³⁵U produces multiple elements. Based on Figure 1, which of the following is the atomic number of the most common fission product?

Quizplus · Accepted Answer

11ecba2d_1189_c9d7_a3bf_490f330bdab9_MD0008_00 Nuclear fission is the splitting of a large atomic nucleus into multiple smaller nuclei. Figure 1 displays the atomic weights of the various nuclear fission products for ²³⁵U. The figure shows atomic weight on the x-axis and the percentage of nuclei with each atomic weight on the y-axis. The tallest peak indicates the greatest fission yield (ie, the isotope released in the greatest quantity). On this graph, the greatest fission yield is located at an atomic weight of approximately 133. The periodic table displays the average atomic weight of each element under the element's symbol, calculated from the natural abundance of each possible isotope for that element. It shows that the elements iodine (I) through barium (Ba) have average atomic weights near 133. Of the answer choices given, only an atomic number of 55 (cesium) falls within this range. (Choice A) Strontium has an atomic number of 38 and an average atomic weight of about 88, likely representing one of the lower peaks of the graph. (Choice C) The element with an atomic number of 92 is uranium. Because the question is about the fission (splitting) of uranium, all fission products must have an atomic number below 92. (Choice D) The atomic weight, not the atomic number, of the most abundant fission product is 133. The atomic weight represents the total number of neutrons and protons; the atomic number is the number of protons only. Educational objective: Nuclear fission is the splitting of a large atomic nucleus into multiple smaller nuclei. The atomic weights (protons and neutrons) of resulting nuclei can be measured and correlated with their most likely atomic numbers (number of protons).

Passage Nuclear Medicine Uses Radiopharmaceuticals for Disease Treatment and as Tracers