Iridium-192 is one radioisotope used in brachytherapy, in which a radioactive source is placed inside a patient's body to treat cancer. Brachytherapy allows the use of a higher than normal dose to be placed near the tumor while lowering the risk of damage to healthy tissue. Iridium-192 is often used in the head or breast. Use the radioactive decay curve of iridium-192 to answer the three questions. 100 90 - 80 70 - 60 - 50 - 40 - 30 - 20 - 10- 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 Time (days) If the initial sample is 4.50 g, what mass of the original iridium-192 remains after 35 days? Sample remaining (%)

A medical technician is working with the four samples of radionuclides listed in the table below. Initially, each sample contains 22.00 µmol of the radionuclide. First, order the samples by decreasing initial radioactivity. Then calculate how long it will take for the amount of radionuclide in each sample to decrease to 1/8 of the initial amount. sample A B C D symbol 75 34 133 54 95 41 227 radionuclide 89 Se Xe Nb Ac half-life 120. days 5.0 days 35.0 days 22. years initial radioactivity (choose one) î (choose one) ↑ (choose one) ŵ (choose one) ↑ time for amount of radionuclide to decrease to 1/8 of initial amount X days days days years Ś

Ruthenium-106 (106Ru) is used to treat melanoma in the eye. This isotope decays by β– emission with a half-life of 373.59 days. One source of the isotope is reprocessed nuclear reactor fuel. How many protons and neutrons does the 106Ru nucleus contain? Identify the missing daughter nucleus in the β– emission decay of 106Ru below. How many years after 106Ru is implanted in the eye does it take for its decay rate (or activity) to be reduced to 27.5% of the initial decay rate? Use 1 year = 365 days.

Some Radioactive Isotopes Useful in Medical Imaging Mode of Isotope Decay Half-life Use in Medical Imaging B*, y B+, y 20.3 m Brain scan to trace glucose metabolism Brain scan to trace glucose metabolism Detect eye tumors Diagnose albinism, image the spleen and gastrointestinal tract Bone marrow function, diagnose anemias Whole-body scan for tumors Pancreas scan Lung ventilation scan Scan for bone diseases, including cancer Brain, liver, kidney, bone scans; diagnosis of damaged heart muscle Diagnosis of thyroid malfunction Kidney scan Heart scan and exercise stress test Carbon-11 Fluorine-18 F P Cr Fe Ga 109 m 14.3 d Phosphorus-32 Chromium-51 Iron-59 Gallium-67 Selenium-75 Krypton-81m Strontium-81 Technetium-99m E.C., Y В, у E.C., y E.C., y 27.7 d 44.5 d 78.3 h 118 d BlKr Sr vTe 13.3 s 22.2 m 6.01 h Iodine-131 Mercury-197 Thallium-201 В, у E.C., Y E.C., y 8.04 d 64.1 h 20!TI 3.05 d (1) The radioactive isotope phosphorus-32 is used in medical imaging as indicated on the table above. How…