Passage
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.
-A patient is injected with 20 ng of ⁹⁰Y. Assuming yttrium is not excreted, how long will it take for the initial amount of ⁹⁰Y to be reduced to 2.5 ng?

Question

Passage
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. -A patient is injected with 20 ng of <sup>90</sup>Y. Assuming yttrium is not excreted, how long will it take for the initial amount of <sup>90</sup>Y to be reduced to 2.5 ng? A) 64 hours B) 128 hours C) 192 hours D) 256 hours

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.
-A patient is injected with 20 ng of ⁹⁰Y. Assuming yttrium is not excreted, how long will it take for the initial amount of ⁹⁰Y to be reduced to 2.5 ng?

Quizplus · Accepted Answer

The Answer is C

Passage Nuclear Medicine Uses Radiopharmaceuticals for Disease Treatment and as Tracers