Chapter 9, Problem 9.74P

Interpretation Introduction

Interpretation:

Selenium-75 takes 602 days to diminish to only 3% and yet it is used for pancreatic scans without the fear of it causing any harm to the patient. An explanation should be provided for this query as to why Selenium-75 is not considered dangerous despite being radioactive.

Concept Introduction:

Pancreatitis and pancreatic tumor are not easily diagnosed by standard clinical laboratory methods and radiographic techniques. These methods are not able to detect the presence of cancer or tumor in early stages and hence by the time cancer is diagnosed the disease becomes untreatable. Therefore, the interest was shifted towards radioisotope procedures of pancreatic visualization for the clinical diagnosis.

Photo scanningof pancreatic tissue with radioactive selenium was introduced because selenium is similar to sulfur and it can replace sulfur in methionine amino acid as methionine contains sulfur in its molecule. This change does not alter properties of the amino acid. This replacement of selenium for sulfur has made Se-75 the idealelement for pancreatic scanning.