Scenario While Radioactive Isotopes Are Used in Medicine to Identify Tumors

Multiple Choice

Scenario
While radioactive isotopes are used in medicine to identify tumors and other diseases, they can also be used to treat diseases such as cancer. One method to treat cancerous tumors is to expose them to radiation which can kill the cancerous cells and the tumor. In 2013, the U.S. Food and Drug Administration approved a new cancer treatment based on the radioactive isotope radium-223; this isotope has a half-life of 11.4 days. The radioactive drug, known as Xofigo®, is injected into the patient's bloodstream and travels to certain regions of the body. Because it emits high-energy radiation over short distances, it can kill cancerous cells in the sites where it localizes.
After the drug was injected into a person, the following data were collected regarding the amount of radiation measured in different organs in the person's body.

-A cancer patient receives an injection of the drug on March 1. Suppose that the patient must receive a second injection once the amount of the drug decreases to less than 6% in his or her body. On approximately what day should the cancer patient schedule an appointment to receive another injection?

A) March 13
B) March 23
C) April 3
D) April 25